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I || xrlil. , I T31» Ir lg. 33.: ‘ MICHI IIIIIIIIIIIIIIIIIIIIIIIII 3 1293 00099 L.2354 LIBRARY Hl Michigan State University This is to certify that the dissertation entitled Plow—Co CL cm: 91in? 0<§~ Bvaw LthVWKL Plum}! KietCMS Cfihtfllhl‘fl. Rimott Double BC Ml} presented by Keep/m9 Natl/w» has been accepted towards fulfillment of the requirements for P‘“ ‘ 0 degree in Ck’I'W‘ISfW’y V r v M?‘ professog Date 00?; Lil/9f? MS U is an Affirmative Action/Equal Opportunity Institution 0-12771 MSU RETURNING MATERIALS: Place in book drop to remove this checkout from LIBRARIES w your record. FINES will be charged if book is returned after the date stamped below. Ex 5005 PHOTOCHEMISTRY OF BIFUNCTIONAL PHENYL KETONES CONTAINING REMOTE DOUBLE BONDS BY KEEPYUNG NAHM A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Chemistry 1987 ABSTRACT PHOTOCHEMISTRY OF BIFUNCTIONAL PHENYL KETONES CONTAINING REMOTE DOUBLE BONDS BY Keepyung Nahm W Intramolecular quenching processes of various alkenoxy- phenyl ketones were studied. The excited triplet benzene rings were quenched internally by the olefins when there were 3 or 4 connecting atoms between them; -O(CH2)2- or -O(CH2)3-. The intramolecular quenching efficiency of the three connecting atoms system was better than those of the others by more than 100 times. With -O(CH2)2-, the para- and ggtng-alkenoxyphenyl ketones yielded photoproducts upon >300-nm irradiation. From the para derivatives, the photoproducts were identified as 5,9 substituted 1-acy1-8-oxatricyclo[7.2.0.0 ]undec-2,10- dienes. From the gztng derivatives, the photoproducts were 3,8] undec-7,10-dienes. The same types of products were isolated identifed as substituted 1-acyl-6-oxa-tricyclo[7.2.0.0 from the -O(CH2)3- system. The whole photoreaction is a two photon process; two intermediates were assigned for these unusual photoproducts. In all cases the double bond undergoes ortho 2 + 2 cyclo- addition to the benzene ring to give a bicyclo[4.2.0] octa- 2,4-diene, which thermally interconverts quickly to a cycloocta-l,3,5-triene. This second intermediate is then converted to a bicyclo[4.2.0]octa-2,7-diene photochemically. This photostable bicyclooctadiene is converted at high temperature to the cyclooctatriene. The solvent effect on product formation showed that the excited states for this cycloaddition are triplet‘n;n* states. From the internal quenching rate constants, the rate constants for inter- Iconversion between the two lowest triplets of the para- 8 10 alkenoxyphenyl ketones were concluded to be >10 and >10 ’ 5.1. W The triplet lifetimes of various YFVinylphenyl ketones were determined. The main product was acetophenone. The intramolecular charge transfer rate constants are > 108 8-1. They increased by 1.5-2.5 times with additional alkyl subs— tituent on the double bonds. 0n the other hand, a 5-viny1- valerophenone did not show efficient internal quenching. From these results, it was concluded that the quenching process requires a kind of 5-membered ring complex between the ketone chromophores and the olefin moieties. TO MY PARENTS ii ACKNOWLEDGMENTS The author wishes to thank Professor Peter J. Wagner for his guidance throughout the course of this reaserch. His insight, humor, and encouragement have been among the most important factors in my graduate career. I would like to thank the Chemistry Department at MSU for financial support and use of its facilities and the National Science Foundation for the research assistantships administrated by Professor Wagner. I will also remember my friends, especially the Wagner group members who introduced to me a lot of "American" knowledge and humor. Most of all, I thank my wife, Jungok, for her love, support, and encouragement. I am also grateful to my parents and parents-in-law, and family for their continuous support. TABLE OF CONTENTS Chapter Page LIST OF TABLES O O O O O O O 0 O O O O O O 0 O O 0 O 0 Vi LIST OF FIGURES O O O O 0 O O O O O O 0 O O O O O O O 0 x1. ii INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 1 RESULTS. . . . . . . . . . . . . . . . . . . . . . . . 25 A. Alkenoxyphenyl Ketones . . . . . . . . . . . . 25 1. Identification of Photoproducts. . . . . . 25 2. Time-based 1H-NMR and UV-Visible spectra . 55 3. Quantum Yields and Kinetic Results . . . . 66 4. Spectroscopy . . . . . . . . . . . . . . . 68' B. 'Y-Vinyl Phenyl Ketones . . . . . . . . . . . . 79 1. Kinetic Results. . . . . . . . . . . . . . 79 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . 85 A. Alkenoxyphenyl Ketones . . . . . . . . . . . . 85 1. Cycloaddition. . . . . . . . . . . . . . . 85 a. Cycloadducts . . . . . . . . . . . . . 85 b. Thermal Rearrangement of Cycloadducts. 91 2. Intramolecular Charge Transfer Quenching . 94 a. Charge Transfer Rate Constants . . . . 94 b. Regioselectivity . . . . . . . . . . . 99 3. Triplets of Phenyl Ketones . . . . . . . . 106 a. fl;n* Phenyl Ketone Triplets. . . . . . 102 . . . * b. Equilibrium Between n;fl and “{fl* triplets. . . . . . . . . . . . . 104 iv Chapter 8. 'Y-Vinyl Phenyl Ketones . . . . . . . . 1. 2. 3. Maximum Quantum Yield for the Type II Reaction . . . . . . . . . . . . . Charge Transfer Quenching. . . . . Products from the Y-vinylbutyrophenones. C. Suggestions of Further Research. . . . EXPERIMENTAL O O I O O O O O O O O O O O O O O A. Preparation and Purification of Chemicals. 1. .2. 3. 4. 5. B. Isolation and Identification of Photoproducts. APPENDIX . REFERENCES Solvents and Additives . . . . . . Internal and External Standards. . Quenchers. . . . . . . . . . . . . Ketones. . . . . . . . . . . . . . Equipment and Procedures . . . . . a. Photochemical Glasswares . . . b. Sample preparations. . . . . . c. Degassing Procedures . . . . . d. Irradiation Procedures . . . . e. Analysis Procedures. . . . . . f. Calculation of Quantum Yields. Page 106 106 107 108 110 112 112 112 113 114 115 130' 130 131 131 131 132 134 134 149 186 Table LIST OF TABLES Rate Constants for Internal Quenching in Triplet PhCO(CH2%§ . . . . . . . Photocycloaddition of Various Substituted Arenes to Olefins . . . . . . . . Intramolecular Cycloaddition of Arenes to Olefins . . . . . . . . . . . . . . Selected Chemical Shift Values and Coupling Constants of the Products of Q-Alkenoxyphenyl Ketones in C606 (250 MHz) . . . . . . . . . . Chemical Shift and Coupling Constants of the Cyclooctatrienes from g-Alkenoxyphenyl in CDC13. . . . . . . . . . . . . . . . . . . Selected Chemical Shift Values and Coupling Constants of the Products of p-Alkenoxyphenyl Ketones in C606 (250 MHz) . . . . . . . . . . Chemical Shift and Coupling Constants of the Cyclooctatrienes from p-Alkenoxyphenyl in CDC13. . . . . . . . . . . . . . . . . . . Results of Stern-Volmer Quenching of Various p-Alkenoxyvalerophenone by 2,5-dimethyl-2,4- hexadiene in Acetonitrile (0.01 M) at 25 oC . I Results of Stern-Volmer Quenching of Various g-Alkenoxyvalerophenone by 2,5-dimethy1-2,4- vi Page 11 14 19 42 43 53 54 71 Table Page hexadiene in Benzene (0.01 M) at 25 oC. . . . . 72 10 Results of Stern-Volmer Quenching of Various m-Alkenoxyvalerophenone by 2,5-dimethyl-2,4- hexadiene in Benzene (0.01 M) at 25 oC. . . . . 73 11 The Plot of 1/¢>vs. the Concentration of the Ketones in Acetonitrile. . . . . . . . . 74 12 Rate Constants for the Quenching of the Triplet p-Methoxyvalerophenone by Various Olefins at 25 oC . . . . . . . . . . 75 13 Quantum Yields of g-(3-methyl-3-buten-1-oxy) valerophenone with 313-nm Irradiation in Various Solvents . . . . . . . . . . . . . . 76 14 UV-Visible Absorption Maxima for a Series of Alkenoxyphenyl Ketones in Heptane. . . . . . 77 15 Results of Stern-Volmer Quenching of PhCO-(CHZ)3-R by 2,5-Dimethyl-2,4- Hexadiene in Benzene at 25 oC . . . . . . . . . 81 16 Results of Stern-Volmer Quenching of PhCO-(CH2)3-R by 2,5-Dimethyl-2,4- Hexadiene in acetonitrile at 25 oC. . . . . . . 81 17 UV-Visible Absorption of a Series of Y-Vinyl Phenyl Ketones in Heptane. . . . . . 82 18 Selected Chemical Shift of the Cyclobutenes from g-(3-Methyl-3-buten-1-oxy)acetophenone and Its Derivatives in C6D6 . . . . . . . . . . 90 19 Photokinetic Data of p-Alkenoxyvalerophenones in Acetonitrile (0.01 M) at 25 oC . . . . . . . 96 vii Table Page 20 Photokinetic Data of g-Alkenoxyvalerophenone in Benzene (0.01 M) at 25 °c. . . . . . . . . . 97 21 Photokinetic Data of m-Alkenoxyvalerophenone in Benzene (0.01 M) at 25 °c. . . . . . . . . . 97 22 Photokinetic Data of PhCO-(CH2)3-R in Benzene at 25 oC . . . . . . . . . . . . . . 109 23 Gas Chromatographic Response Factors for Various Photoproducts . . . . . . . . . . . 135 24 HPLC Response Factors for Various Photoproducts . . . . . . . . . . . . . . . . . 136 25 Quenching of the type II product formation from p-methoxyvalerophenone with 2,5- dimethyl-2,4-hexadiene in acetonitrile at 25 °c. . . . . . . . . . . . . . . . . . . . 150 26 Quenching of the type II product formation from n-methoxyvalerophenone with 2,5- dimethy1-2,4-hexadiene in benzene at 25 °c. . . 153 27 Quenching of the type II product formation from p-allyloxyvalerophenone with 2,5- dimethyl-2,4-hexadiene in acetonitrile at 25 °c. . . . . . . . . . . . . . . . . . . . 154 28 ‘ Quenching of the type II product formation from p-allyloxyvalerophenone with 2,5- dimethyl-2,4-hexadiene in benzene at 25 °c. . . 155 29 Quenching of the type II product formation from p-(2-methyl-2-propen-1-oxy)- valerophenone with 2,5-dimethyl-2,4- viii Table Page hexadiene in acetonitrile at 25 °c. . . . . . . 156 30 Quenching of the type II product formation from p—(2-methyl-2-propen-1-oxy)- valerophenone with 2,5-dimethyl-2,4- hexadiene in benzene at 25 oC . . . . . . . . . 157 31 Quenching of the type II product formation from p-(3-methyl-2-buten-l-oxy)- valerophenone with 2,5-dimethyl-2,4- hexadiene in acetonitrile at 25 °c. . . . . . . 158 32 Quantum yield dependence on the concentration of p-allyloxyvalerophenone in acetonitrile at 25 °c. . . . . . . . . . . . 159 33 Quantum yield dependence on the concentration of p-mathallyloxyvalerophenone in acetonitrile at 25 °c. . . . . . . . . . . . 160 34 Quantum yield dependence on the concentration of p-(3-methy1-2—buten-1-oxy)- valerophenone in acetonitrile at 25 °c. . . . . 161 35 Quenching of product formation from p-(3-buten-1-oxy)valerophenone with 2,5-dimethyl-2,4-hexadiene in acetonitrile at 25 oC . . . . . . . . . . . . . 162 36 Quenching of the cycloaddition product formation from p-(3-buten-1-oxy)valerophenone with 2,5-dimethy1-2,4-hexadiene in acetonitrile at 25 °c. . . . . . . . . . . . 163 ix Table 37 38 39 4O 41 42 43 Page Quenching of the type II product formation from p-(4-penten-1-oxy)valerophenone with 2,5-dimethyl-2,4-hexadiene in acetonitrile at 25 °c. . . . . . . . . . . . 164 Quenching of the type II product formation from p-(5-hexen—1-oxy)valerophenone with 2,5-dimethyl-2,4-hexadiene in acetonitrile at 25 °c. . . . . . . . . . . . 165 Quenching of the type II product formation from p-(9-undecen-1-oxy)valerophenone with 2,5—dimethyl-2,4-hexadiene in acetonitrile at 25 °c. . . . . . . . . . . . 166 Quenching of the type II product formation from p-(3-methyl-3-buten-1-oxy)- valerophenone with 2,5-dimethyl-2,4- hexadiene in acetonitrile at 25 oC. . . . . . . 167 Quenching of the cycloaddition product formation from p-(3-methyl-3-buten-1-oxy)- valerophenone with 2,5-dimethyl—2,4- hexadiene in acetonitrile at 25 oC. . . . . . . 168 Quenching of the type II product formation from p-(3-methyl-3-buten-1-oxy)- valerophenone with 2,5-dimethyl-2,4- hexadiene in benzene at 25 oC . . . . . . . . . 169 Quenching of the type II and the cyclo- addition product formation from p-(3-methyl-3-buten-1-oxy)valerophenone Table Page with 2,5-dimethyl-2,4-hexadiene in benzene at 25 oC . . . . . . . . . . . . . . 170 44 Quenching of the photoisomerization of p-(cis-3-hexen-l-oxy)valerophenone with 2,5-dimethyl-2,4-hexadiene in acetonitrile at 25 °c. . . . . . . . . . . . 171 45 Quenching of the type II product formation from p-(5-methyl-4-hexen-1-oxy)- valerophenone with 2,5-dimethyl-2,4- hexadiene in acetonitrile at 25 °c. . . . . . . 172 46 Quenching of the type II product formation from p-methoxyvalerophenone with Z-methyl- l-pentene in acetonitrile at 25 °c. . . . . . . 173 47 Quenching of the type II product formation from p-methoxyvalerophenone with 2-methyl- 2-pentene in acetonitrile at 25 °c. . . . . . . 174 48 Quenching of the type II product formation from l-phenyl-S-hexen-l-one with 2,5- dimethyl-2,4-diene in benzene at 25 °c. . . . . 175 49 Quenching of the type II product formation from l-phenyl-S-hexen-l-one with 2,5- dimethyl-2,4-diene in acetonitrile at 25 oC . . 176 50 Quenching of the type II product formation from l-phenyl-S-octen-l-one with 2,5- dimethyl-2,4-diene in benzene at 25 °c. . . . . 177 51 Quenching of the type II product formation from 1-phenyl-6-methyl-5-hepten-1-one with xi Table Page 2,5-dimethy1-2,4-diene in benzene at 25 °c. . . 178 52 Quenching of the type II product formation from 1-phenyl-6-methyl-5-hepten-l-one with 2,5-dimethyl-2,4-diene in acetonitrile at 25 °c. . . . . . . . . . . . . . . . . . . . 179 53 Quenching of the type II product formation from 1-phenyl-6-gis-nonen-1-one with 2,5- dimethyl-2,4-diene in benzene at 25 °c. . . . . 180 54 Quenching of the type II product formation from l-phenyl-6-91§-nonen-1-one with 2,5- dimethyl-2,4-diene in acetonitrle at 25 °c. . . 181 55 Effect of pyridine on quantum yield for acetophenone formation from l-phenyl-S- hexen-l-one in benzene at 25 oC . . . . . . . . 182 56 Effect of pyridine on quantum yield for acetophenone formation from 1-phenyl-6- methyl-S-hepten-l-one in benzene at 25 oC . . . 183 57 Quenching of the type II product formation from m-(3-buten-1-oxy)valerophenone with 2,5-dimethyl-2,4-hexadiene in acetonitrile at 25 °c. . . . . . . . .i. . . 184 58 Quenching of the type II product formation from m-(4-methyl-3-penten-1-oxy)valerophenone with 2,5-dimethy1-2,4-hexadiene in acetonitrile at 25 oC. . . . . . . . . . . . 185 xii Figure 10 LIST OF FIGURES A Jablonski Diagram for Phenyl Ketones . . . . 1 Homodecoupling of H-NMR spectra of 1,9 1-acety1-3-methy1-6-oxatricyclo[7.2.0.0 ] undec-7,10-diene (C6D6). . . . . . . . . . . . 13 The C-NMR spectra of 1-acetyl-3-methyl-6- oxatricyc1o[7.2.0.0 ]undec-7,10-diene. . . . 1 Homodecoupling of H-NMR spectra of l-methyl- 3-valeryl-9-oxabicyclo[6.3.0]undec-3,5,7- tiene in CDC13 O O O O O O O O O O O O O O O O 1 The H-NMR spectra of the cyclooctatriene from g-APZZ; before (the top) and after (the bottom) 365-nm irradiation . . . . . . . . . . 1 The H-NMR spectra of Q-AP23 as a function of time of 313 nm irradiation (C6D6) . . . . . 1 The H-NMR spectra of the photoproduct of 2'-(3-methyl-3-buten-1-oxy)-5'-methy1 acetophenone (C6D6, 250 MHz) . . . . . . . . . Homodecoupling of 1H-NMR spectra of the photoproduct from p-Ale in C6D6 . . . . . . . 1 Homodecoupling of H-NMR spectra of the thermally rearranged product from p-AP 1 . . . 2 Coupling constants of vinyl protons of gig- and t;ans—p-(3-hexen-1-oxy)- xiii Page 30 31 32' 33 38 39 46 47 Figure Page valerophenone in C6DG' . . . . . . . . . . . . 49 11 The 1H-NMR spectra of g-AP33 as a function of time of 313 nm irradiation (C6D6) . . . . . 51 12 The 1H-NMR spectrum of the cycloadduct from p-methoxyacetophenone and 1-hexene (CDCl3) . . 52 13 The 1H-NMR spectra of p-Ale as a function of time of 313 nm irradiation (C6D6) . . . . . 58 14 The 1H-NMR spectra of g-AP22 as a function of time of 313 nm irradiation (C6D6) . . . . . 59 15 UV-Visible spectrum of g-AP22 as a function of time of 313 nm irradiation in CH3CN . . . . 60 16 UV-Visible spectrum of g-AP22 as a function of time of 313 nm irradiation in CSH6' . . . . 61' 17 UV-Visible spectrum of g-Achis as a function of time of 313 nm irradiation in CH3CN . . . . 62 18 UV-Visible spectrum of g-AP23 as a function of time of 313 nm irradiation in CHBCN . . . . 63 19 UV-Visible spectrum of the cyclooctatriene from g-APZZ as a function of time of 313 nm irradiation in CH3CN. . . . . . . . . . 64 20 UV-Visible spectrum of p-Ale as a function of time of 313 nm irradiation in CH3CN . . . . 65 21 Stern-Volmer plots for the type II product formation of various p-VPnl in acetonitrile. O O O O O O O O O O O O O O O 69 22 Stern-Volmer plots for the cyclo- adduct formation of various p-VPZn xiv Figure 23 24 25 26 . The 1H-NMR spectrum of g-AP in acetonitrile. . . . . . . . . . . . . The dependence of the type II product formation of p-VPln on the concentration the ketones. . . . . . . . . . . . . . . Stern-Volmer plots for acetophenone formation of various Yevinlybutyrophenone in benzene . . . . . . . . . . . . . . . The effect of the pyridine concentration on the quantum yield . . . . . . . . . . 2 of 313 nm 2 irradiation (15 mg in 250 ml of benzene) XV Page 70 78 83 84 140 INTRODUCTION In photochemistry, the excited states generated by an electron movement from the ground states to upper energy levels have large energy and they have to return to their ground states chemically or physically. Their lifetimes are short and their reactions are fast and internal energy of some photoproducts is too high to be made via ordinary thermal reactions. The main concern in photochemistry is usually the decay of an excited state to a ground state or a photoproduct. In this part, general photophysics and photochemistry, the properties of excited states of phenyl alkyl ketones, and their related photoreactions will be introduced. Rh2t2nh25129.5nd_2hetgchemistrx - The photophysics of an excited state molecule can be described with a Jablonski dia- gram. Absorption of a photon promotes energetically a molecule from the ground state, So, to an upper excited singlet state which rapidly undergoes internal conversion (kic = 1011 - 10 1 14 8-1) to the lowest excited singlet. The lowest singlet, 81' can decay to the ground state, emitting a photon of light 6 9 -1 (fluorescence) with a rate constant kf of 10 to 10 s or via radiationless decay with a rate constant kd of 105 to 108 s-l.1 Photochemical reactions are possible from the excited singlet. The excited singlet can also undergo intersystem crossing to an excited triplet state (kiSC = 107 - 1010 5.1). "I c ,_-_,.,_ Tn' Tn T2 - 'l by k, kd T1 kequ' k. . kd Q- "U Figure l. A Jablonski diagram for phenyl ketones. This process includes spin inversion of an electron. Usually organic molecules have all paired electrons in the ground states. Therefore, this triplet state has two unpaired electrons. The excited triplet, just like the excited singlet, can undergo internal conversion with nearly the same rate constant as that of the singlet. Also radiative decay (phosphorescence) with a rate constant kp of 10-1 to 104 s—l, radiationless decay to the ground state, or chemical reactions are possible decay pathways form the triplet. Ketong photochemistry - Ketone photochemistry is one of the most intensively studied areas in organic photochemistry and has served as a good model for the understanding of fundamental questions. Even though the excited states of ketones have higher energy than most ground state species, the reactions from the excited states are now more predictable and explainable. However, photochemistry itself is one of the newest fields in organic chemistry and there still remain many questions unanswered. Phenyl ketones have n;n* lowest singlets and their inter- system crossing rates are extremely fast (kisc - 10lo - 1011 8-1) and efficient.2 The quantum yield of the intersystem crossing in phenyl ketones is near unity.2 In other words, every photon promotes a phenyl ketone from the ground state to the excited triplet. Most phenyl ketones have two low lying triplets, an n;n* and a‘n;n*‘trip1et, whose energy levels are affected by the ring substituents.3 In general, electron withdrawing substi— tuents stabilize the n;n* triplets relative to the‘n;n* triplets and conjugating groups lower the‘n;n* triplet energy levels.4 I“-------— EDG H EWG conjugated 4 The n;n* triplet comes from excitation of a nonbonding electron of the carbonyl to a n-antibonding orbital, thus has an electron deficient oxygen. The chemical behavior of the n;n* triplet is similar to that of an alkoxy radical and hydrogen abstraction is the predominant reaction from the 5 triplet. In a n;n* triplet, excitation of a‘n electron to a n-antibonding orbital makes the oxygen atom slightly electron- rich and the hydrogen abstraction reaction slows down.5 Hydrogen abstraction of an n/n* triplet ketone was first reported by Ciamician and Silber. When benzophenone was irradiated in ethanol, benzpinacol was observed as one of the products. It is formed by coupling of diphenylhydroxymethyl radicals, which are created by the hydrogen abstraction of the excited n;n* triplet benzophenone:6 OH HO I I © © __, phAPh + CHBCHOH ___, Ph 2 Ph Intramolecular hydrogen abstraction was observed in 1934 by Norrish and Appleyard.7 When methyl butyl ketone was irra- diated in the gas phase, the ketone photodecomposed to give acetone and propene. Ketones and aldehydes that possess Y'C-H bonds undergo the photoelimination reaction, called the Norrish Type II process. This reaction involves 1,4-biradical via abstraction of a Yehydrogen by the excited carbonyl oxy- 8 gen. The biradical can either cleave into an olefin and the enol of a smaller ketone, or cyclize to a cyclobutanol which provides a direct evidence for 1,4-biradical intermediate.8 This biradical was trapped by alkyl thiols9 and was detected by flash absorption spectroscopy.10 Theoretical calculations11 also show that the 1,4-biradical can be formed as a product during the reaction of an excited ketone: III'//E\¢/r/' 0H Ph © —ri)T*——> ’7', H \ .A’“ =\ Substituted benzophenones (4-methyl or 4-trifluoromethy1) which have n,n* lowest triplets are easily photoreduced by 2- 12 But, 4-phenylbenzophenone, which has a'fl{n* lowest 3 propanol. triplet, shows a 10 -fold decrease in reactivity compared to 13 Similarly, the photoreduction of 4-trif1uoro- benzophenone. methylacetophenone (n;n* lowest triplet) displays a six-fold increase in the rate of hydrogen abstraction, whereas 4- methylacetophenone (n;n* lowest triplet) shows a ten-fold decrease in reactivity, both compared to acetophenone.14 Likewise, the Norrish Type II reaction of substituted butyrophenone and valerophenone follow a similar trend.3a’15 When the nJ1* and‘fl{fl* triplets are close in energy, as in phenyl alkyl ketones, there is an equilibrium between these 16 The following Boltzmann distribution law two triplets. describes the fractions of the upper and lower states with energy difference of AE at temperature T : x —-BP— = exp(-AE/RT) Xlo In case of p-methoxyphenyl ketones, the n;n* triplets are located above the‘fl{n* triplets by about 3 kcal/mol, which means the n,n* triplets have the equilibrium concentration of less than 1 t of the total triplets. These upper triplets still show the hydrogen abstraction, but the observed rate constant is only 1/100 that of the unsubstituted ketones.5'16 In this thesis, some unprecedented photochemical reactions from the'n;n* triplets will be introduced. Although the spectral analyses of benzene and its deriva- tives have received considerable attention, the structure and the properties of these benzenoid systems in their excited states are not fully understood. However, much valuable information about the nature of'1't,‘l'l"l triplets can be obtained from the benzene study. Structural rearrangement on electronic excitation in benzene was first detected by de Groot and van der Waals when they noticed from the magnetic resonance spectrum that the lowest triplet state of benzene (3Blu) is 17 distorted from the regular hexagonal structure, which is benzene (lBlu).18 l9a,20 similar to that of 82 Theoretical19 and EPR results indicates that the lowest triplet of benzonitrile (a model for acylbenzenes) is strongly 1,4-biradical in nature also. Conjugatively electron- withdrawing substituents(e.g., -CN, acyl) stabilize the anti- Scheme I. 1/12 l/4 l/4 ”‘2 U4 1/4 l 11 * TI * A s l l/3 ' 1/12 l/lZ l/4 l/4 1/12 l/lZ 1/4 l/4 1/3 3 11' 11A S Scheme II 113* , ’—""~ .g n‘* 11 * ”” ‘2 CO A ,' . “s . n I \ A i,” \ ‘\\ \\ TICO symmetric (in CZV)‘fl* orbital and destabilize the correspon- ding fl orbital such that S-» La transition is predominantly * . . . . * “A'I‘nA with little contribution from “S‘7'”s . The destabilization of “A in ketones is caused by the mixing of fig 21 The‘fl; orbital is stabilized inductively as well as by strong mixing with the with the lower energy carbonyl TIorbital. carbony fl* orbital (Scheme 1 and 2). Quenching processes - Quenching of a triplet state can be performed by either energy or electron (charge) transfer. One of the requirements for energy transfer quenching is that the triplet energy of a quencher should be equal or less than that 22) Oxygen and conjugated dienes are good triplet quenchers in of a quenchee (for phenyl ketones, about 70 kcal/mol this case: the excitation energy of oxygen is 23 kcal/mol (singlet oxygen) and the triplet energies of the dienes are about 60 kcal/mol.22 In case of electron transfer quenching, the positive hole created on the HOMO of a quenchee by electronic excitation AG LUMO AG HOMO receives an extra electron (or charge) from the HOMO of a quencher, or the electron on the LUMO of a quenchee moves to the empty LUMO of a quencher, then each species returns to its ground state by the back electron transfer:23 For the efficient electron (charge) transfer, either the oxidation potential of a quencher is smaller than that of a quenchee, or the reduction potential of a quencher has to be smaller than that of a quenchee. Weller derived an empirical equation for this process; the rates (kCT) of fluorescence quenching of aromatic hydrocarbons are related to the diffe- rences in free energies QAGCT) which are dependent on the oxidation potential of the donor (E(D/D+)), the reduction potential of the aromatic acceptor (E(A-/A)), the singlet excitation of the acceptor, and a Coulombic term.23a log kCTz ACCT = E(D/D+) - E(A-/A) - E(A0,0) - ez/er In the intramolecular charge transfer interaction, not only the thermodynamic properties of the donors and the acceptors but also the close orbital overlap between the donor orbital and the acceptor orbital (i.e. the accessibility of the donor) and the electronic configuration are important.24 Winnik found intramolecular phosphorescence quenching of benzophenone chromophore in 1 occurs when n > 8 and decreases when n > 13.25 These benzophenones have n{n* triplets whose energies are localized mainly on the carbonyl group. The olefinic moieties can quench the emission intramolecularly only when they can approach the carbonyls to within 17IA. |—‘ Wagner and Siebert26 reported that regioselectivity of internal charge transfer quenching in some amino ketones depends dramatically on the electronic configuration of the lowest triplets: 57 slow quenching 0 >_..— C02(CH2)nNMe2 R >’ fast quenching For R = phenyl, the amino ketones have n,fl* triplets and show long-lived phosphorescence comparable to that of the model methyl ester derivative, k z 105 3'1. However, when R - alkyl, the lowest‘fl{fl* triplets undergo very efficient intramolecular quenching, k > 5 x 108 8-1. This study revealed that there is vast difference between n;n* and‘fl{fl* triplets in the position where the donor can feel sufficient overlap for electron transfer interaction and supports the concept of HOMO and LUMO orbital overlap in electron transfer reactions.24 The study of photochemical intramolecular quenching in Or substituted.urbenzoylalkanes (n,n* triplets) shows another example of significant overlap of the donor HOMO with the ll acceptor LUMO. For the ketones substituted with SBu27 or 28 2 equals (n + 3) and the most rapid quenching appears when n = 2 NMe , the total number of atoms in these cyclic interaction or 3 which represents the formation of five- and six-membered rings. As n becomes larger, the kCT decreses roughly by 10 times with each additional carbon chain, reflecting the expected decreased probability of forming medium-sized rings. When X is vinyl, overlap between two fl orbitals also becomes an important factor in the quenching. p-Vinyl phenyl ketones undergo efficient intramolecular charge transfer quenching 29 upon irradiation, which induced cis-trans isomerization and 30 Intrinsically this quenching is-not also gave photoproducts. rapid as expected from the comparison of the ionization potential of the olefins and the ketone, therfore the szinyl Table 1. Rate constants (1078-1) for internal quenching in triplet PhCO(CH2)nX.29 n/X SBu NMe2 CH=CH2 l 130 <10 2 450 430 so 3 240 740 <10 4 14 50 5 <2 20 intra 30 300 0.8 12 ketone (n = 3) still undergoes the type II reaction in 1 relatively high efficiency.3 The quenching processes of these vinyl ketones were further studied in this thesis. Photocycloadditign - There are many examples of photo- chemical rections of bichromophoric systems. Among them, cycloaddition reactions of arenes to olefins are introduced here. The triplet version of these reactions was studied in this research. The reactions of bichromophoric systems can be divided into two groups; the intermolecular and intramolecular reactions. Intramolecular interaction could be faster than its intermolecular version if two chromophore can reach together. Also the reaction could be more stereospecific because of geometric limitation. Since the discovery of fulvene from the irradiation of 32 benzene, this unexpected lability of the benzene ring induced considerable research intrest, and mechanistic and ”-2 ® * theoretical problems in the area; i.e., photoisomerization of the benzene ring itself and bimolecular reactions. Irradiation of mixtures of benzenoid compounds and olefinic systems gives rise to various products, obtained by adding the olefinic component across the 1,2-, 1,3- or 1,4- positions of the aromatic ring. From an orbital symmetry 33 analysis of the systems, it was deduced that 1,2-addition 13 was allowed from S1 ethene plus So arene, whereas the 1,3- addition required S1 arene and So ethene: in both cases, these dictates could be circumvented by mixing of states, and either could result from charge transfer excitation or if exciplexes 34 Empirically it is known were involved as adduct precusors. that 1,3-addition is preferred35 to 1,2-addition, when the ionization potentials of olefins are similar to those of O+IIL><‘+@+ 1,2 1,3 1,4 arenes, and that olefins with large AIP (> 0.5 eV) undergo - 1,2-addition reactions. The symmetry-allowed 1,3-addition to benzene (81) is apparently the most efficient mode with the following olefins: gig and t;gng-2-butene,36 35 cycloalkene,35 isobutene, 2-methyl- 35 etc. The stereochemistry of the 2-butene, vinyl acetate, ethylene is preserved in the product. However, the relative amounts of the exo and endo isomers depend on the ethylene, although the endo isomer predominates in many cases. 1,3-Addition has been extended to a number of systems involving single alkenes and substituted benzenoid compounds. Their addition patterns and yields are listed in Table 2. The "forbidden" 1,2-cycloaddition of ethylenes to singlet arenes seems to occur readily in those systems having marked 35 donor-acceptor character. Earlier findings that simple ethylenes yield only 1,2-adducts with the strong acceptor 14 Table 2. Photocycloaddition of various substituted arenes to olefins. Substituents position (D olefines ref H meta 0.16 c-CSa e Me 1,3 0.21 c-CS e p-Me,i-Pr 3,5/2,6 (5:1) c-C8b f g-,m-,p-Xylene 1,3 .13/.05/.08 c-C5 e oue 1,3 (2,6) c-C8 (c-cs) f o-,m-,p-Me,0Me 2,6 CS/OEtc/CB g,h,f cu 2,4/1,2 (2:1) Cld i F 2,5 1 p-F,A1kyl 2,6 c-CS k m-OMe,F 2,6 OEt a cyclopentene. b cis-cyclooctene. c vinyl ethyl ether. d cis-l,2-dichloroethene. e J. Cornelisse, et.al. J, Am, Qngm‘_figg‘, 25, 6197 (1973). f A. Gilbert, et. al., Q‘_Qnem‘_ sggL, Perkin I, 1314 (1980). 9 T. R. Hoye, Tetrei_Letti. 22, 2523 (1981). h J. Cornelisse, Tetrai_Letti, 23, 3827 (1982). i A. Gilbert, et. al., 1y_QngmL_§QgLL_QnemL_§gmmy, 750 (1983). j D. Bryce-Smith, et. al., QL_§ngm‘_§QgLL_§nem&_§gmm‘, 112 (1980). k J. Cornlisse, et. al., IgL;1L_L§;L;, 25, 1893 (1985). 15 37 benzonitrile also accord with the donor-acceptor rule. 1,2- Photocycloaddition to benzene is a major process with the 39 donor ethylenes dihydropyran,38 dimethoxyethenes, tetra- 39 and ethyl vinyl ether.39 0 methylethylene, With the acceptor 41 ethylenes (maleic anhydride,4 acrylonitrile, etc.), 1,2- cycloaddition is the only process on irradiation of benzene. endo The 1,2-photoaddition of ethylenes to benzene leads to either exo or endo stereoisomers. The dienophilic ethylenes, maleic anhydride,40 maleimide,42 and acrylonitrile43 gave exo isomers, wherease the endo compound can be obtained from cis- 36 44 2-butene and cis-cyclooctene. But methyl acrylate and methyl methacrylate gave a mixture of exo and endo isomer in 45 the ratio of 2 : 1. In general, exo-1,2-adduct are formed exclusively with the electron-rich alkenes, but electron-poor olefins give a mixture of two isomers.46 Scharf and coworkers have examined the mechanism of the cycloaddition by studying benzene-cyclic vinyl ether system. 1,4-Dioxene gave mainly 1,2-adduct with benzene, but 1,3- dioxoles yielded 1,2- and 1,3-adduct together with 1,4-adducts that are shown to be derived in a secondary photoreaction for 7 the 1,2-adducts.4 Also their exciplex emission was reported for the first time in such benzene-alkene systems.48 16 Photocycloaddition of benzonitrile with alkenes occurs at both nitrile group and the ring. The products are 1,2- adducts at 1 and 2 position of the ring and azetines.37'49 0 R C6H6 + [OX R R = H or CH3 9 h h” / R \1 0‘1“? ' 0 6 + :>290 nm, where only the acetylene absorbs light to 54 Further study55 revealed that irradia- a significant degree. tion of a dilute solution of methyl phenylpropiolate in benzene at wavelengths longer than 290 nm leads to the formation of the tetracyclic compound: f Ph Ph co Me 1 Ph /.§ 2 n9 ——2 Ill ——-> I .__ I 02 3 2 cozne l T / ,Ph c0282 18 With 254 nm, irradiation gave a 13 : 7 ratio of 3 and the cyclooctatetraene, 4, respectively and these two product could be interconverted photochemically or thermally. The authors suggested that the reaction occurs by way of the 1,2-cyclo- adduct (2, not isolated) and the lifetime of this is long enough for it to absorb a second photon in competition with the residual acetylene in the direct irradiation and cyclize to 1. It could not be clearly understood whether the conversion from 2 to A is a photochemical process or thermal isomerization. This reaction was further generalized: methyl t-buthylacethylene carboxylate in benzene gave also S-t- buthyl-4-methoxycarbonyl derivative of 3 with cycloocta- tetraenes (1.5 : 1 ratio).56 The study of the effect of solvent polarity on various photocycloaddition reactions of ethylenes and acetylenes to benzene showed that the 1,3-addition has little sensitivity to solvent polarity change, but the 1,2-addition was dramatically influenced by alteration in thepolarity.57 In some intramolecular systems, where arenes and olefins are connected, the addition pattern and the efficiency of the reaction are dependent on the chain length and the type of chains linking addends. 5-Phenylpent-1-ene gave 2,6- and 1,3- addition products in a quantum yield of 0.11 and 0.045, respectively, and 6-phenylhex-1-ene reacted only at 1,3- 58 position with a quantum yield of <0.005: Both cis- and trag_-6-phenylhex-2-enes gave meta-cycloadducts, the 1,3- product from the former and the 2,6-product from the latter isomer:59 18 With 254 nm, irradiation gave a 13 : 7 ratio of 3 and the cyclooctatetraene, g, respectively and these two product could be interconverted photochemically or thermally. The authors suggested that the reaction occurs by way of the 1,2-cyclo- adduct (3, not isolated) and the lifetime of this is long enough for it to absorb a second photon in competition with the residual acetylene in the direct irradiation and cyclize to 3. It could not be clearly understood whether the conversion from 3 to A is a photochemical process or thermal isomerization. This reaction was further generalized: methyl t-buthylacethylene carboxylate in benzene gave also s-t- buthyl-4-methoxycarbonyl derivative of 3 with cycloocta- tetraenes (1.5 : 1 ratio).56 The study of the effect of solvent polarity on various photocycloaddition reactions of ethylenes and acetylenes to benzene showed that the 1,3-addition has little sensitivity to solvent polarity change, but the 1,2-addition was dramatically influenced by alteration in the‘polarity.57 In some intramolecular systems, where arenes and olefins are connected, the addition pattern and the efficiency of the reaction are dependent on the chain length and the type of chains linking addends. 5-Phenylpent-1-ene gave 2,6- and 1,3- addition products in a quantum yield of 0.11 and 0.045, respectively, and 6-phenylhex-1-ene reacted only at 1,3- 58 position with a quantum yield of <0.005: Both cis- and tzggg-6-phenylhex-2-enes gave meta-cycloadducts, the 1,3- product from the former and the 2,6-product from the latter isomer:59 19 Table 3. Intramolecular cycloaddition of arenes to olefins. compounds orientation (I) ref Ph-(CH2)3-CH=CH2 2,6/1,3 .11/.041 59 Ph-(CH2)3-CMe=CH2 1,3/2,6 .037/.023 60 Ph-(CH2)3-CMe=CMe2 1,3/2,5/2,4 .013/.Oll/.006 60 g-Ph-(CH2)3-CH=CHMe 1,3/isom .26/.011 61 Ph-O-(CH2)2-CH-CH2 2,4 not measurable 58 Ph-CHz-O-CHZ-CH=CH2 1,3/2,6 .052/.017 58 Ph-(CH2)2-O-CH=CH2 2,5/1,3 .23/.006 58 Ph-(CH2)3-O-CH=CH2 2,4/1,3 .05/.01 58 Q-MePh-(CH2)3-CH=CH2 1,3/1,4 .51/.09 60 m-MePh-(CH2)3-CH=CH2 1,3/1,5 .024/.043 60- p-MePh-(CHZ)3-CH=CH2 2,6 .06 60 Q-MeOPh-(CH2)3-CH=CH2 1,3 .50 60 C6F5-OCH2-CH=CH2 1,2 not determined 62 Ph-(CH2)3-CECH 1,2 63 Phenylethyl vinyl ether underwent 2,5-addition, but 3-phenyl- propyl vinyl ether gave 1,3- and 2,4-adducts. More results are summarized in Table 3. In general, meta addition is dominant in the intramolecular photocycloaddition between singlet arenes and olefins. This 1,3-photoaddition was applied in the synthesis of several naturally occurring compounds by Wender and co-workers 20 4 either intramolecularly or intermolecularly.6 For examples, they reported on the synthesis of (t)-crcedrene in three steps 64a from the ethenyl-aryl bichromophoric system, 3 and have shown that the separated product 3 from irradiation of indane and vinyl acetate was converted into (t)-modhephene, 1, in an 4e overall yield of 8.2 % in a total of six further steps.6 03 .11.. +4. —->—+ 10‘ 1N Gilbert et. al. reported that neither Ph-OCHZCHZCH-CH2 nor p-CH3CO-Ph-(CH2)3CH=CH2 gives significant yields of 61 They focused on the singlet cycloadducts upon irradiation. reaction with high energy (254 nm), even though the latter has strong absorption at around 290 nm. In this thesis, intra- molecular quenching efficiencies and photocycloaddition of alkenoxyphenyl alkyl ketones will be studied. It is interesting that a system with a nitrile group on either naphthalene rings or olefins undergoes efficient 1,2- photocycloaddition just like the benzene systems: acrylo- nitrile adds to 1,2-position of naphthalene upon irradia- 65 tion. Naphthalenes substituted by other than nitrile also underwent the photocycloaddion to olefins. Irradiation of 1- 21 or 2-naphthol or their trimethyl Silyl derivatives with achY1°nitrile yielded 1,2-adducts:55 ed \_R——+ so“ Irradiation of 1-cyanonaphthalene with methyl vinyl ether 7 or phenyl vinyl ether gave mainly 1,2-adducts.6 However, 2- cyanonaphthalene with alkyl vinyl ether showed a different type of photoreaction: products were 1,2-adducts, ring- expanded products, and cyclobutene products:68 313 nm . -—*————e> CN <———— IR Upon 313 nm irradiation, only the [2 + 2] cycloadduct was observed. However, irradiation through Pyrex (>290 nm) afforded a cyclobutene as a main product. The 1,2-cycloadduct was assumed to be the precusor for the cyclooctatrienes and the cyclobutene formation. More details are presented in the above figure. 22 The intramolocular version of the cycloaddition of naphthalenes has been studied by McCullough et.al.69 Later, it was found that neither OCHZCHZCH=CH2 nor CHZCHZOCH=CH2 chain gives 1,2-adducts, only the olefinic chain of CHZOCHZCH=CH 70 2 undergoes the 1,2-addition. The authors claimed that both 71 and intramolecular adduct come from the 2 intermolecular singlet exciplexes. Solvent effects7 and lifetime measure- 73 in this system were studied. ments of the exciplex emission It is interesting to note here that the -CH20CH2- link between the chromophores has also been shown to be a particularly successful intervening unit for dianthryl R==CN(N'H R'= ch‘CN 74 . 75 compounds, but not for phenyl Vinyl systems. Also, _surprisingly, there are just few examples of the triplet 76,77 cycloaddition, even though there are many examples of the photocycloaddition of the singlet or singlet exciplexes. Kinggigg - The triplet lifetime of the ketones in this thesis was measured by the Stern-Volmer quenching technique. 2,5-Dimethyl-2,4-hexadiene was used to quench the triplet ketones by energy transfer. The mathematic expression of this 23 (Do I (Disc kI-ITT "n (b " <15isc: l/tT + kq[Q] (Do/(b: 1 + kq‘tTlQ] ------------ Equation (1) where (bo' - quantum yield in the absence and the presence of a quencher, repectively 1T - l/Eki, triplet lifetime kq ; rate constant for quenching by the diene kH ; rate constant for the product formation [Q] : concentration of a quencher process is given in Equation (1). A plot ofvs. [Q] gives a straight line with an intercept of 1 and a slope of k . The quenching rate of 2,5- qTT dimethyl-2,4-hexadiene is usually close to the rate of diffu- sion in a given solvent. The values for kq are known to be 1 9 -1 '1 equal to 10 x 109 M- s"1 in acetonitrile?8 and 5 x 10 M s in benzene at 25 oC.79 Thus the triplet lifetime can be calculated from the slope of the Stern-Volmer plot. Begggzgh_ggg; - In this thesis, the chain-length effect on intramolecular charge transfer quenching of alkenoxyphenyl ketones (fl;n* lowest triplets) and asbenzoyl-uralkanes (n,fl* triplets) by their olefinic moieties will be explained. For the former, the triplet-cycloaddition will be discussed in quantitative sense (triplet lifetime measurement, intramole- cular quenching efficiencies of the olefinic moieties, the 24 mechanism for the cycloadduct formation). This is the first triplet-state cycloaddition study, as far as we know. LAW The alkenoxyphenyl ketones were made by the 8N2 reaction between the phenolates of the hydroxyphenyl ketones and the corresponding alkenyl halides. For the par; and mat; ketones, anhydrous patassium carbonate in dry acetone was good enough to generate the phenolates from the phenols, but for the ortho ketones more basic condition (sodium metal in ethanol) was' used for the same purpose. 1. '90 0 0:22. '0! :1! 0‘! ' ' - 01 9‘ .10 0- -2_cts a. General - 0.01 to 0.02 M argon-bubbled benzene solution of various alkenoxyphenyl alkyl ketones were irradiated at 313 nm or above 295 nm (Pyrex glass filter). After >90% conversion (from the GC check), the solvent was evaporated below 30 OC, and the products were identified as 1- 3'7]undec-7,10-dienes (from the acy1-6-oxatricyclo[7.2.0.0 ortho ketones) or 1-acyl-8-oxatricyclo[7.2.0.05’71undec-2,10- dienes (from the para ketones). The cycloadducts collected by preparative GC (injection port; 190-200 0C, oven; 160-190(30, detection port; 200-210 0C; helium gas; 65 ml/min) were identified as 7- and/or 8-alkyl-substituted 4-acyl-11- oxabicyclo[6.3.0]undec-1,3,5-trienes (from the para ketones) 25 26 Scheme III 0 / %O(CH2)nR' o-, m-, and p- .B. B_'. APni . CH3 -CH=CH2 n = 1,2,3,4,9. APn2 CH3 - C(CH3)=CH2 n = 1,2. APncis CH3 cis-CH=CHEt n = 2,3. APn3 CH3 -CH=C(CH3)2 n = 1,2,3. VPn1 n-Bu -CH=CH2 n = 1,2,3,4,9. VPnZ n-Bu -C(CH3)=CH2 n = 1,2. VPncis n-Bu cis-CH=CHEt n = 2,3. VPn3 n-Bu -CH=C(CH3)2 n = 1,2,3. 27 or 6-acyl-11-oxabicyclo[6.3.0]undec-1,3,5-trienes (from the 1 . ortho ketones). The homodecoupling technique in H-NMR was mainly used for the identification of products. 0 o, 6 57°“ hv m A I 4 7° )0 2. 0“ 5 hv E3; A ml 04 OR The type II products were synthesized separately in most cases and their retention times were compared on the CC or HPLC. Or they were collected by preparative GC and identified from the 1 H-NMR spectra. The ortho alkenoxyphenyl ketones undergo more efficient photoaddition than the para derivatives and all adducts could be derived from the 1,2-addition between ipsg and ortho (carbons of the phenyl ring and vinyl carbons. b. WZWZZ - Irradiation of 0.5-1.0 gr of Q—(3-methyl-3-buten-1-oxy)valerophenone, g- VP22, or g-(3-methyl-3-buten-1-oxy)acetophenone, g-APZZ, in benzene at either > 295 nm or 313 nm gave the type II product (minor from the Q-VP22) and two other photoproducts. From the 1 intensity of H-NMR signals, the ratio of the two new products 28 was about 7:1. The major photoproduct of g-VP22 was identified 1,9 as 1-valeryl-3-methyl-6-oxatricyclo[7.2.0.0 ]undec-7,10- diene. The minor product was not identified and after 1-2 weeks in a refrigerator it disappeared from the 1H-NMR spectrum. 8 9 The product, 8, which showed the same molecular ion peak as that of the starting ketone in the mass spectrum, has the following spectroscopic data: two peaks at 5 6.04 and 5.81 (H- 11 and H-10) coupled to each other with J = 2.8 Hz. This is a characteristic coupling pattern of the vinyl protons in a 80 At 5 4.98 (H-8) , there is another vinyl proton, cyclobutene. which couples with the proton at 5»3.32 (H-9), J - 6.6 Hz. The proton at 3.32 ppm couples with one of the cyclobutene protons (H-ll at 6.04 ppm) with J = 0.9 szand can be assigned as a bridgehead proton of a bicyclo[4.2.0]octa—2,7-diene. The multiplet at 3.85-3.75 ppm was assigned to two hydrogens at C-5 and indicated a rigid 5-membered ring. All the above coup- lings-were confirmed by the homodecoupling technique (Fig. 2). 13 Also the C-NMR spectrum supports this structure; there are two double bonds. One is a typical enol ether double bond,80 i.e., 163.9 (s, C-8) and 90.8 (d, C-7) ppm. Another double bond (C-10, C-ll) appears at 144.8 (d) and 139.6 (d) ppm (Fig. 3). The carbonyl carbon appears at 207.9 ppm. The nuclear 29 Overhauser effect (NOE) showed about a 5 % increment of the H- 11 peak when the methyl at C-3 was irradiated, but no enhance- ment (< 2%) was observed in the peaks of H-9, H-lo, and acetyl protons; therfore the methyl group at C-3 and the cyclobutene ring should be in the gig-position and the carbonyl group in the trans-position. The UV-Visible spectrum shows no major absorption above 250 nm, except for a weak 295 nm absorption (8 = 200). The IR spectrum confirms that a carbonyl group is present. The major difference between the products from Q-APZZ and Q-VP 2 is in their 1H-NMR spectra. In the 1H-NMR spectrum of 2 the latter, two protons on the ovcarbon next to the carbonyl group show a clear ABX splitting pattern (J = 17.1, 7.1 Hz), which reflects the restriction in bond rotation between the carbonyl carbon and the OL-carbon. The rearranged products, 2, from a preparative 60 or a column chromatograph were acylcyclooctatrienes which were identified mainly by the UV-Visible spectrum and homodecoup- ling of the 1H-NMR spectrum. In the case of 3-acetyl-l-methyl- 9-oxabicyclo[6.3.0]undec-3,5,7-triene, the UV-Visible spectrum shows a Kmax at 374 nm (E - 4400) and 237 nm (Ea 19000) in 1.0 ° ()6) . z’ 0 o 3 9 hexane. ..\\ I 30 on: 08 . coeoc 233i.e-soeaassosad 633133861338-@7902”-fl mo «58% ”—224: .8 unison—025$ .N 953m ELL . e.— m._ a.~ m.~ e6 min a... .n: sh ma em mm jjjjjjjj.f . .. . st..- ijjjjf :22 1 J41: l- #5 . 3.1;}? as 21 1 ”.1 :1 j! 3 Q . j? 30 312 on . soeoc 85-2.5885;5.3.: 53333991508-”H-383..._ «o 880% «27:: mo wandsoooooEo: .N 053m ELL . 9.. m.. e.~ m.~ a6 ma a... .w: sh mm am mm jjjjjjjj: ..-..--JJ{4JJJJJIJJJJ‘JJ]\ £35 . s 5 -113...) j 3;; j 12 31 3 1r 3 31 .516 503651382: _o._o.o.~.n_o_o>ot.axo-o-_>fioe-m-33a-_ Lo «:6on ”—22-02 25. .m 2:me ELL 0 .0 .I— 0.. I”. I8. ’— On. .0. I I .- .~ In .0 In .0 OP 0 P. .0. .fl- .In On” On A!) j-) t) .131111Jfllkl—mfi‘ifl Kr): I11») - ihlyirnt ii» 4&4 I. .1 IL )1 if; 1 - -11 - .43: 4H w i n . acme, Pom 32 .58 s ocosewaéoessaé 26533904523-Tissue-_ we «been; 5147:? Lo wczasooooofio: .v 23E 33 .-m<-d .8 8365293 2: so :2: 3 2:2 2: s 8.58% E0205 2: ”E: mom 8 2m as snow 5 2.2:-fin.méooocaS.032635399188-Wafers-_ Lo guitar: .m 2:3."— 8 . S 8 n 8 W S . U 8 y .s e.~ e. ... a 1. ed a j|ll||l 2 393i)? 34 In the 1 H~NMR spectrum, there are four vinyl protons: two coupled doublets at 7.13 (H-4, J = 5.7 Hz) and 5.17 ppm (H-7, J = 7.7 Hz) and two doublet of doublets at 6.12 (H-6, J = 7.7, 12.5 Hz) and 7.7 ppm (H-5, J a 12.5, 5.7 Hz). Two doublets at 2.91 and 2.45 ppm couple each other (J = 13.2 Hz) and are considered to be the methylene protons (C~2) of the 8-membered ring (Fig. 4). Irradiation of 9 in argon-bubbled benzene-d6 (about 3-4 mg in 0.4 ml) at 313 nm or 365 nm gave the original mixture of two components, 8 and an unknown product, (the same ratio, 1H-NMR spectra (Fig. 5). From 7:1), which was confirmed by the the interconversion, the unknown products is expected to be an isomer of a: possibly a diastereomer or one by different ring closure. .[fj U? i o O 9 c- Ergdusts_fr2m_2:!221_ang_2:A£21 - Irradiation of gr(3-bcten-1-oxy)acetophenone, Q-Ale, or g-(3-buten-1-oxy)- velerophenone, g-VP 1, (0.5-1.0 gr in 250 m1 benzene with 2 argon bubbling) at >295 nm (Pyrex filter) gave 1-acetyl-6— oxatricyclo[7.2.0.03’7Jundec-7,10-diene, 10, (and the type II 1 product, Q-AP 1, from the Q-Vle). Unlike Q-AP 2, the H-NMR 2 2 study showed that the starting ketone could not be completely converted to the cycloadduct; i.e., the starting ketone disappeared continuously, but the product peaks did not grow 35 up after a certain level. From this, it was assumed that the photoproduct is not very stable photochemically. Again from the 1H-NMR spectrum of the product, the cylco- butene ring was identified: two doublets at 5.86 and 5.78 ppm (H-10, H-ll) split each other with J = 2.8 Hz. The doublet at 4.96 ppm (H-8) splits the doublet at 3.26 ppm with J = 6.6 Hz and those came from an enol ether doublet. Two multiplets at 3.78 and 3.50 ppm split each other (J = 8.5 Hz) and also with some other protons, and assigned as two protons next to the oxygen of a rigid 5—membered ring. The product collected from a preparative GC was 3-acetyl- 9-oxabicyclo[6.3.0]undec-3,5,7-triene. This octatriene also was not perfectly pure in the 1H-NMR spectrum and assumed to lH-NMR be not very stable at the oven temperature (170-180°C). spectrum tells that there are four vinyl protons which show two doublets with moderate J coupling constants (H-4, 6'7.13, J - 6.2 Hz: H-7, 5 5.35, J - 8.8 Hz) and two doublet of doublets with another big J coupling constant (H-5, 6 5.75, J = 13.0, 6.2 Hz: H-6, 5 6.06, J = 13.0, 8.8 Hz). Actually H-7 has a doublet of doublet with an additional small coupling (J = 1.9 Hz) to the proton at 3.04 ppm (H-1, d of d, J = 13.4, 0 O ’ 0 ON by ' A . / O . o __l_(_)_ .\\\’s‘ I I I 1.9 Hz). All the above assignments were confirmed also by the homodecoupling of the spectra. _._....~. 36 d- W221: - Irradiation of 94215-3- hexen-l-oxy)acetophenone (0.5-1.0 gr in 250 ml benzene with argon bubbling) at >295 nm (Pyrex filter) yielded two products in a ratio of 4:1 from the 1H-NMR integration. The cyclobutene derivative was a minor product in this case. The major product showed two vinyl protons, one with a J value of 5.1 Hz at 6.32 ppm and another with a small coupling constant (J = 0.9 Hz at 6.00 ppm), but was not identified. After column chromato- graphy, this product turned into a cyclooctatriene, which has four vinyl protons (two doublet of doublets, two doublets). e. Erggugt§_f;gm_g;522; - The initial photoproduct (40-50 % conversion) of g-(4-methyl-3-penten-1-oxy)acetophe- none, g-AP23, (0.5-1.0 gr in 250 ml benzene with argon bubbling at >295 nm of a Pyrex filter) showed four vinyl protons in the 1H-NMR spectrum. A further purified mixture from column chromatography contained less than 20 % of the starting ketone and was a colorless liquid. This product was deduced to be 3-acetyl-2,2-dimethyl-9-oxatricyclo[6.3.0.03'8 ] undec-8,10-diene from the following data (lH-NMR and the decoupling): two vinyl doublets at 5.43 and 5.34 ppm (H-4, H- 7) with J coupling constants of 9.6 and 9.8 Hz, and two doublet of doublets at 5.69 and 5.53 ppm (H-5, H-6) with J = 9.6, 5.6 Hz and J = 9.8, 5.6 Hz, respectively. These are typical values for vinyl coupling constants in a cyclohexene rings.80 The possibility for cyclooctatriene (four vinyl protons) formation was excluded; it has no visible color and its vinyl protons have different 5 values from those of the 37 other cyclooctatrienes. If it was a cyclooctatriene, these doublets should have smaller coupling constants (6-7 Hz), because each doublet proton and their neighboring protons cannot be located on the same double bond or the same plane. Prolonged irradiation of the mixture of the starting ketone and the cyclohexadiene gave 1-acetyl-2,2-dimethyl-6- 3'7]undec-7,10-diene. Two vinyl protons of oxatricyclo[7.2.0.0 the cyclobutene appeared as doublets at 6.00 and 5.76 ppm with J - 2.8 Hz (H-lo, H-ll). Another vinyl proton (H-8, 4.97 ppm, d of d, J - 2.7, 6.4 Hz) split the peak at 3.54 ppm (H-9, d, J 6.4 Hz) and the peak at 2.35 ppm (H-3, d of t, J = 2.7, 10.1 Hz) (see Fig. 6). 3’7]undec- l-Acetyl-Z,2-dimethyl-6-oxatricyclo [7.2.0.0 7,10-diene (direct photoproducts from Q-AP23) was converted to 1—acetyl-2,2-dimethyl-6-oxatricyclo[5.4.0.03'7]undec-8,10- diene on heating at 130 0C for 30-40 min. Also a little of the starting ketone, g-APZB, was detected. ‘0 H 4" hv H O f. s e o- 22 deriygtive - 2'-(3-Methyl-3-buten-1-oxy)-5'-methylacetophenone gave one product upon irradiation (313 nm) in benzene with the same 1 molecular ion peak with the starting ketone. The H-NMR spectrum of the photoproduct showed one peak at 5.49 ppm (J = .eoeo s :23ng E: 2m Lo 08: .8 5:83 a ma m~m<-d Lo «:0on 522+: 25. .o onE M 8‘ fl. A.“ flu in. Mn Gr m? 3% Km 9.? ...J G. u. 3 ll I ‘IJI- l‘|‘|J|J'.‘JIII‘. ‘ — ‘..\l 4: c: 'l‘ln‘ .‘Iv‘t dllq‘l u {1.3—1 ‘n ‘3 a...Q..—'(lc.‘|!‘u“ Q a ‘ c. .~o| I]‘!l‘|!—I..ul 4: “a1 0.—| Y a I o —. c 0 «u . a ul.l| n Id. a . a c —. a a n a -. Jsjfijéfiifii ‘2 {[11:21 2 u a. 1.. s ‘ J}? 11%;] J M1,. .73-. s .1. 1:42:11- . . A _. 1 x 3,111. 1.1 38 I 3 o.» 39 .31: ca .1538 Bogoaaosgssoes A38-~-:os=b-m-;508-mv-.m .8 63838.3 2: Lo 8382: ”—272: 2a. .5 9:.me &.S G.~ &.N Q.fl 8.? E.W &.m E.P is: 1 a - A! 40 1.5 Hz) where two doublets of cyclobutene (J = 2.8 Hz) appear when there is no 5'-methyl group (product from Q-APZZ). Also, as usual, H-8 and H-9 appear at 4.99 and 3.16 ppm with J a 6.7 Hz, respectively. Two protons of C-5 are shown at 3.78 ppm as a multiplet. Three singlet peaks of methyl groups come at 1.88, 1.42, and 1.01 ppm and identified as the methyl of the acetyl group, that on the vinyl carbon (C-10), and that on C- 3, respectively. Unlike g-APZZ, there was no minor product detected (see Fig. 7). 0 0 Me O Irradiation of 2'-(3-methyl-3-buten-1-oxy)-5'-chloro-4'- methylacetophenone (less than 100 mg in argon-bubbled benzene in a test tube) gave one product, whose growth was monitored on a GC. This product showed the same molecular ion peak with the starting ketone (M+ = 254/252 (1/3)). 0n the 1H—NMR spectrum of the photoproduct, two vinyl singlets at 6.71 and 5.15 ppm replaced the two doublets that appeared when there were no 5'-chloro and no 4'-methyl. Another unusual two doublets were shown at 2.98 and 2.25 ppm (J = 13.1 Hz). Also two ABX-type peaks were observed at 1.99 and 1.26 ppm (J a 12.9 Hz). Three methyl group singlets appeared at 1.91, 1.80, and 0.87 ppm. UV-Visible spectrum of the product did not show major absorption at around 350 nm. From these data, this 41 product was assigned again as a cyclobutene, i.e., 1-acety1- 10-chloro-3,9-dimethyl-6-oxatricyclo[7.2.0.03’7]undec-7,10- diene. O 0 O\v/“\r¢' hv jiilllt?\> CI c| ~‘ 0 Me Me Tables 4 and 5 contain some of the chemical shifts and coupling constants of the cyclobutene products and the cyclo- octatrienes of the ortho-alkenoxyphenyl ketones, respectively. 9. o u t -al 0 s - The para-alkenoxyphenyl ketones gave 1-acyl-8-oxatricyclo [7.2.0.0!"9 ]undec-2,10-dienes as products, which thermally rearranged to 4-acy1-11-oxabicyclo[6.3.0]undec-1,3,5-trienes on a preparative GC. Unlike the orthg derivatives, irradiation -— polymer of par; ketones gave colloidal precipitates in the solutions. These were assumed to come from the polymerzation of the tetraenes which could be formed by the ring opening of 1,2- adducts. 42 Table 4. Selected chemical shift values and coupling constants of the products of ortho-alkenoxyphenyl ketones in benzene-d6. (250 MHz) RI R O 2 R}, H ‘ [o ‘1 / O 8 R,=R,=R3;H R3=Me R,=Et R,=R1=Me 5 .J 5 {I 5 .3 6 £3 H-11 5.78 2.8 5.81 . 5.89 2.9 5.74 2.8 H-10 5.86 2.8 6.04 6.04 2.9 5.99 N e 2 8 2 8 8 H-9 3.26 6.6 3.32 6.6 3.52 3.54 6.4 6 6 6 4 H-8 4.96 .6.6 4.98 4.92 4.98 43 TABLE 5. Chemical shift and coupling constants of the cyclootatrienes from g-alkenoxyphenyl ketones in CDC13. from g-butenoxyphenyl ketone g-(3-methyl-3-butenoxy) PPm J. Hz ppm J, Hz H-1 7.13 d 1H J1,2 = 6.2 7.13 d 1H J1,2 = 5.7 H-2 5.75 d,d 1H J1,2 I 6.2 5.84 d,d 1H J1,2 I 5.7 J2,3 I 13.0 J2,3 I 12.8 H-3 6.06 d,d 1H J2’3 I 13.0 6.12 d,d 1H J2,3 I 12.8 J3,4 I 8.8 J7’4 I 7.7 H-4 5.34 d,d 1H J3'4 = 8.8 5.17 d 1H J3,4 = 7.7 J4’5 = 1.9 H-5 3.04 d,d 1H J4’5 = 1.9 2.91 d 1H J5,6 = 13.2 J5,6 I 13.4 H-6 2.23 d,d 1H J5,6 I13.4 2.45 d IH J5,6 I 13.2 J6,11 = 8.3 H-7 1.85 m 1H J7'9‘ 8.1 2.08 t,d 1H J(9,10)=10'4 H-8 1.85 t,d 1H J(9’10)=3.2 H-9 4.13 d,t 1H J = 2.5, 8.1 4.10 d,d 2H J = 3.2 H-10 4.02 d,t 1H J = 5.7, 11.5 H-11 2.73 m 1H J = 8.3 44 h. Products from p-ngl and p-Agzl - Both p-(3—buten- 1-oxy)acetophenone and its valerophenone derivative gave one photoproduct with either 313 nm or > 295 nm (Pyrex) of light in benzene (ca. 0.05 M). The velerophenone derivative gave the type II product additionally. The new product from the aceto- phenone derivative was identified as 1-acetyl-8-oxatricyclo 13c-NMR, GC-MS, IR [7.2.0.05’91undec-2,10-diene by its 1H-NMR, spectra. The molecular ion peak of the product is 190 (m/e) which is the same as that of the starting ketone. Four vinyl protons were observed in the NMR spectra: three of them were doublets and one was a multiplet. Two doublets at 6.06 and 5.85 ppm split each other with J = 2.7 Hz (H-lO, H-1l), which is very similar to that from the grthg derivatives. This strongly suggests the existence of a cyclobutene again. The other doublet at 5.83 ppm (H-2) and the multiplet at 5.59 ppm (H-3) split each other with J I 11.1 Hz. Two protons at 3.64 and 3.51 ppm split each other with J = 8.0 Hz and were identi- fied as methylene protons next to the oxygen of a rigid 0 _ 13C-NMR spectrum showed a carbonyl carbon oxacylcopentane. The at 210.3 ppm and four olefinic carbons (C-2, C-3, C-10, C-11) at 139.0, 138.4, 126.3, and 125.8 ppm. Two thermally rearranged products were collected from a preparative GC. Both showed the same molecular weight as that 45 of the starting ketone. The first product which had nearly the same retention time as that of the starting ketone on SE-30 column shdwed three vinyl protons in the 1 H-NMR spectrum; 7.12 (d, 1H, J - 5.2), 6.07 (d, 1H, J = 12.6), 5.93 (d of d, 1H, J = 5.2, 12.6) ppm. Unfortunately, the amount was too small and variable, and it was not further identified. The second product with a longer retention time was a yellow liquid and identified as 4-acetyl-11-oxabicyclo[6.3.0]undec-1,3,5-triene. 1 Its H-NMR spectrum showed four vinyl protons: two doublets at 5 7.00 and 5.40 (H-3 and H-2) coupled each other with J = 6.8 Hz, and the doublet (H-S) at 6.27 ppm was coupled with the multiplet (H-6) at 5.92 ppm (J = 12.5 Hz). H-8 appeared at’ 3.06 ppm as a multiplet and the singlet of the acetyl group 1 came at 2.28 ppm. The details of the H-NMR homodecoupling result are shown in Fig 8. The 13 C-NMR showed a carbonyl carbon at 199.3 ppm and six olefinic carbons at 170.5, 144.6, 137.8, 131.6, 125.1, and 96.1 ppm. The upfield peak at 96.1 ppm was assumed to be C-l, which is a usual chemical shift of 77 an enol ether. i. Ezgducts from p-VPzz and p-APZ; - p-(B-Methyl-3- butenoxy)acetophenone and its valerophenone also gave two thermally-rearranged products, one was identified as a .312 cm eosoc 49:3 Eoc 8305823 2: .8 «bosom 5224: Lo wfiazooocoEom .m oSwE a. m. SN m.~ an mm a... Mr am mm 30 mu 8.. We a. 43.21545 13:11.2 is 5.. 1s? 46 :3: :1 55:11 W 1 1 47 .33 own .2083 12888 835a Swag—«2 3.252: 2: so 380% «22+: mo wE—osooocoEom d 0.53..» ELL Gm wa ¢.r . . H n s n m n a y m .. v m e u a n y 4‘, 111111..) 4.11.. .21.ij .lJI)‘ {ljvjl\j'(ljj‘d[f1lll_jjjfi'11r. (jijlll‘l .3 ii _‘é g g 48 cyclooctatriene which has four vinyl protons (three doublets, one multiplet). The other was not identified. But the products from the prep GC contained some other unidentified products, too. j. Erggucts from p-ngcis - Irradiation of p-(gis-3- hexen-l-oxy)valeropenone at 313 or >295 nm in benzene gave its trans derivative efficiently ( co 352280. mazesou .3 oBmE ELL E.m ELL Q.m e.m m..m &.m «a F. m: NA: umlcnmfl u: find 50 k. Ezgducts from p-AEZQ and p-AP3; - p-(4-Methy1-3- penten-l-oxy)phenyl ketones were inert upon irradiation. Seven days of irradiation gave one small new peak, but it was not identified. However, the irradiation of p-(S-methyl-4-hexen-1- oxy)acetophenone gave a product which have two protons (each doublets, J - 3.1 Hz) of a cyclobutene and another pair of vinyl protons (two doublets, J 10.2 Hz). Upon further irradiation, four vinyl protons which are similar to those of cyclooctatrienes, were built up on the 1H-NMR spactra (see Fig. 11). W O h ‘\ >00 /\ ——-” d 1. Bim2lecular_£ngtgsxsloadditign - The product collected by preparative GC after irradiation of p-methoxy- acetophenone in l-hexene with 313 nm light, showed four vinyl protons; two doublets couple each other at 7.08 and 5.19 ppm (J - 5.2 Hz), other doublet at 5.67 ppm (J = 12.3 Hz), and a doublet of doublet at 5.82 ppm (J = 12.3 Hz). These J coupling patterns were similar to those of cyclooctatrienes and this product was considered as a cyclooctatriene derived from the bimolecular addition. Stereochemistry of the product was not determined completely, but from the doublet of doublet at 5.82 ppm, it was assumed that a 1-hexene was added to 3- and 4- positon of the phenyl ring and also the n-butyl group of the saxosaesEEs E: 2m co 2:: mo cones: a we MmmaTd do «been... «22-:— ofi. .3 23¢ 1J4211J: s1. r474 174i4fi1l4 smug 51 j? g) . j .2 owns as: o2 .moooc 220:; 23 osocozdosooazxofioEd Eoc 8.62293 05 co 8.500% «225— 25. .2 Semi 53 Table 6. Selected chemical shift values and coupling constants of the products of para—alkenoxyphenyl ketones in benzene-d6. (250 MHz) .. \\ q ml / RR. 0 RS 1 R1=R1=R3=H R1=Et R,=R1=Me 5 J' 5 .J 5 J’ H-11 5.85 2.7 6.25 6.34 3.1 H-10 6.06 2.7 6.35 6.55 3.5 H-9 5.83 11.1 5.46 10.2 H-8 5.59 11.1 5.39 10.2 54 TABLE 7. Chemical shift and coupling constants of the cyclooctatrienes from p-alkenoxyphenyl ketones -(250 MHz, coc13). From p—butenoxyphenyl ketone p-pentenoxyphenyl ketone ppm coupling ppm coupling H-1 5.40 d 1H J1,2 = 6.8 5.58 d 1H J1,2 = 7.3 H-2 7.00 d 1H J1,2 = 6.8 6.90 d 1H J1,2 = 7.3 H-3 6.27 d IH J3'4 = 12.5 5.35 d 1H J3'4 8 11.3 H-4 5.92 q 1H 33,4 =12.5 6.09 t,d 1H J3’4 = 11.3 J4’5 = 6.8 'J4’5 = 7.6 H-5,6 2.29-2.50 m 2H J4'5 =6.8 J5,6 - 6.3 H-7 1.83 m 1H J7,8 = 6.3 H-8 2.13 m 1H 37,8 - 6.3 H-9 4.16 m 1H J7,8 = 6.8 H-10 4.24 m 1H J7,8 = 6.8 H-11 3.06 m 1H J5,6 J6,7 = 6.3 1';- IN. =- 55 l-hexene was located away from the methoxy group. UV-Visible spectrum showed an absorption maximum at 312 nm (see Fig. 12). O Bu +- 4¢\//\V/ ONh ONE m. roduc f om t e 20 h o e e ’v 'v - Irradiation of p-(3-buten-1-oxy)benzophenone in argon-bubbled benzene-d6 (ca. 0.05 M) at 313 nm for 48 hrs showed small amount of a product (< 2%) from the 1H-NMR spectrum. The product had typical vinyl J-coupling of a cyclobutene in the spectra, but it was not further isolated. O I, 313 nu! :: \‘ I flow \ 0W 0 2. - 1 - - s t To figure out possible intermediates, the time-based NMR and UV-Visible spectra of alkenoxyphenyl ketones were taken with 313 nm irradiation. UV-Visible spectra showed new peak at around 340-370 nm and assumed to come from the acyl-cycloocta- 1 trienes. However, the H—NMR spectra showed growing-up of the cycloutene products from the beginning. . n r ... a-~.._—.-. .4 . < u .- hi '1' f-' I I. (I L1. 56 Chronological UV-Visible spectra were recorded for Q- and p-alkenoxyphenyl ketones in acetonitrile and benzene (10'4- 10'5 M) which were irradiated at 313 nm. Generally, the inten- sity of the new peak at 340-370 nm depends very much on the position and the number of the alkyl substituents on the double bond. For the Q-(3-buten-1-oxy)acetophenone and g-(B- methyl-B-buten-l-oxy)acetophenone, the intensity of new peaks around 370 nm was high and clearly the absorption maximum was observed (Fig. 15, 16). However, for g-(B-hexen-l-oxy)aceto- phenone and Q-(4-methy1-3-penten-1-oxy)acetophenone, the intensity was weak and it was buried under a n;n* peak of the starting ketone (Fig. 17,18). 4 2 (2.5 x 10' M in argon- The UV-Visible spectra of g-AP2 bubbled acetonitrile or benzene in an UV cell) were taken with short time intervals. The spectra showed a quick decrease of n;n* absorption and La band (305 and 245 nm, respectively) and a build-up of two new absorptions with 374 and 237 nm maxima. These two new absorption maxima are identical with those of 6- acetyl-8-methyl-11-oxabicyclo[6.3.0]undec-1,3,5-triene. However, after 1-2 min irradiation, the 374 nm peak decreased slowly and eventually disappeared after ca. 15-20 min irradiation. The final spectrum was very similar to that of 1-acetyl-3-methyl-6-oxatricyc1o[7.2.03'7 .0]undec-7,10- diene. Irradiation (313 nm) of 3-acetyl-1-methy1-9-oxabicyclo [6.3.0]undeca-3,5,7-triene, which was isolated from a prep GC by injecting the tricyclic photoproduct of Q-APZZ, showed a rapid decrease of the 374 nm absorption band in the UV-Visible ._—:ubo—~ —— .. . u. . ,-wa (A.- .0. I U, 5‘” 57 spectrum. The final absorption spectrum was similar to that of 365 nm irradiation of the same cyclooctatriene and also simi- lar to that of the cyclobutene product of g-APZZ (Fig. 19). 1 Time-based H-NMR spactra were also taken for the ketone in argon-bubbled benzene-d6 in a small test tube (every two hours). Irradiation (313 nm) of 0.1-0.05 M solution of g-APZZ 1H-NMR spectra corresponding to 1-acety1-3-methyl-6- 3,7 gave the oxatricylo[7.2.0 .0]undec-7,10-diene from the beginning. UV-Visible absorption spectra of g-(gis-3-hexen-1-oxy) 4 M in argon-bubbled aceto- acetophenone solution (1.4 x 10- nitrile in an UV cell) with 313 nm irradiation also showed a new absorption peak at ca. 350 nm, which disappeared upon prolonged irradiation (15-20 min). Time-based 1H-NMR spectra of the same ketone, gig—Q-APZZ, (0.1-0.05 M in argon-bubbled benzene-d6) showed the growing-up of the major unknown product and the cyclobutene from the beginning. Irradiation of Q-(4-methyl-3-penten—1-oxy)acetophenone (0.1-0.05 M in argon-bubbled benzene-d6) showed the initial formation of the cyclohexadiene at 30-40 % conversion, but the Icyclobutene product was the final photoproduct upon prolonged 1H-NMR spectra. In irradiation (ca. 6 hr) as confirmed by the this case, the UV-Visible spectra also showed two new maxima at 283 and 273 nm which were assumed to come from the cyclo- hexadiene. Then, the intensity at 340-390 nm was increased slowly and it was much weaker than that of g-APZZ. Irradiation of p-(3-buten-1-oxy)acetophenone at higher concentration (0.1-0.05 M) led to the formation of the 6oeo 5 85525 E: 2m co 2:: 5:05: a we _~m<-d so «boom» MEZ+S BE. .9 oSwE u 4.: 6:5 5 8:262: E: 2m co 6E: mo :ouoEc : m: «9:45 Ho 38on ”127:: BE. .3 EsmE 3: m n s n a. m. on nu on an or mi arm .. ma 0. m: an s: or jljjjjjjjj 1i.) 1141;)... jjll|1\u.4v.jf—IJI vl 3; J: 2:: 60 .32 v-9 x med BEEBS: E 55:68.: E: 2m :6 6E: «o 5:83 a m: Nan—<5 «o «58% 033553 .3 oSwE o._ .o.o ole. 61 2.0 .- 0.D. Figure 16. UV-Visible spectra of _g-AP22 as a function of time of 313 nm irradiation in benzene (2.45 x 10'4 M). 62 ?\ (nm) Figure 17. UV-Visible spectra of Q-Achis as a function of time of 313 nm irradiation in acetonitrile (1.4 x 10'4 M). 63 A2 v-9 x 8.5 05::908 E 5:535 E: 9m :0 6E: mo 856:3 : we m~m->D .2 2sz 25 A 2: 8m 65 .32 2: x Q8 BEESan 5 5333.5 E: 3m .«o 2:: Mo .5288 a ma _~m<-d go 380% o_£m_>->D .om 033m 2:: A 08 ’ D ‘ 66 tricyclic product. This ketone also showed new absorption around 320-370 nm upon irradiation, although it was weak (see Fig. 20).- 3. 'e n ' 'c s a. Triplet Lifetime - About 0.01 M solution of a ketone with various amount of a quencher was degassed by the freeze- and-thaw method. The sample solutions were irradiated at 313 nm with the valerolphenone actinometer in a merry-go-round apparatus at room temperature. The triplet lifetimes of the p-alkenoxyphenyl ketones changed dramatically with the chain length between the olefinic moieties and the phenyl groups. Among them, two methylene unit ketones, p-APzn and p-VPzn, showed the shortest triplet lifetimes. Three methylene ketones, p-AP3n and p-VPBn, also presented some changes in the lifetime. The details are summarized in Table 8. Photoisomerization of gig-p-VPZZ to trans-p-VPZZ was monitored by the Stern-Volmer plot within 15 % conversion. The R 12value for this process is 58 M-l. q The values for kg“! of p-VP1 1 0.01 M in acetonitrile) are 3700, 3270, and 1390 M’l, 1, p-VPIZ, and p-VP 3 (all respectively. These changes were assumed to be caused by the bimolecular self-quenching of the olefinic moieties of the ketones. To measure this bimolecular quenching, quantum yields 67 were determined by varying the concentration of a ketone. In other words, the ketone itself was considered as a quencher. P kHT (b: 1 + kbiT [K] 1/o + (km/(P kfln [K] where P = probability to the triplet state kH = rate constant for hydrogen abstraction kbi = rate constant for quenching by a ketone [K] - concentration of a ketone ¢5 ' quantum yield extrapolated to [K] = o Plots of 1/¢>vs. [K] gave straight lines with intercepts of 1/¢b and slopes of kbi/(kH P). As expected, the order for the values of the slopes and intercepts were p-VP13 > p-VPlz > p-VP 1 (Table 11). 1 . For the ortho-alkenoxyphenyl ketones, g-VPzn, two Stern- Volmer plots were made; one from the type II products and another from the cycloadducts. The photoproduct quantum yields and quenching results are given in Table 9. The meta-a1kenoxyvalerophenones were also measured by the Stern-Volmer plot. m-VPZI and m-VPZB have R T values of 320, q 90 M'1 (Table 10). b. Quantgm_xi§1g§ - Qunatum yields for the type II product formation and the cycloadduct formation was measured 5 with the valerophenone actinometer (d>= 0.33).7 The quantum 68 yields were calculated from the following equation and are given in Table 8,9 and 10: ¢>= [photoproduct] x 0.33 [acetophenone] The solvent effect on the quantum yield for the formation of 1-acetyl-3-methyl-6—oxatricyclo[7.2.0]undec-7,10-diene from g-VP 2 was studied. The details are listed in Table 13. 2 4 . SQQQL’IOSCOQ! a- MW : UV-Visible absorption spectra in heptane were recorded for g- and p-alkenoxyphenyl ketones studied in this thesis. Each absorption maxima and molar extinction coefficients were listed on Table 14. Also the absorption spectra of the photoproducts were measured when pure compounds were available. Those were written in the experimantal part. 69 8.0— 1 eIe ‘ O 4.0— . .///'/° M/‘l 0.0 I 1 0.0 5.0 10.0 [QUENCHER], 10 Figure 21. Stern-Volmer plots for the type 11 product formation of various g-VPnl in acetonitrile; VP11 (a), VP21 (G), VP31 (c), VP41 (0). 70 E10— 1L0— 3.0- 2.0-1 1.0 0.0 1 I I l A 1 0.0 1.0 2.0 3.0 4.0 5.0 [QUENCHER] 10 Figure 22. Stern—Volmer plots for the cycloadduct formation of various n-VPzn in acetonitrile; VP21 (D), VP22 ((9); VP2cis (0) from the photoisomerization. 71 Table 8. Results of Stern-Volmer quenching of various p-alkenoxyvalerophenone by 2,5-dimethyl-2,4- 'hexadiene in acetonitrile (0.01 M) at 25130. a b a b R kq‘tII kq‘tc CPU c OCH3 4100 - .17 - OCHZCH=CH2 3700 - .15 - OCI*12C(CI-I3)=CH2 3270 - . 14 - OCH2C3=C(CH3)2 1390 - .045 - 0(CH2)2CH=CH2 109 116 .0032 .028 0(CH2)2C(CH3)-CH2 82 94 .0024 .027 - _ _ c c c1s 0(CH2)2CH—CHC2H5 58 .0016 .27 0(CH2)2CH=-C(CH3)2 - - .00022 - 0(CH2)3CH=CH2 2050 - .062 - 0(CH2)3CH=C(CH3)2 1100 - .040 - 0(CH2)4CH=CH2 4370 - .16 - 0(CH2)9CH=CH2 4400 - .17 - a b for the Type II product formation. c for the cycloadduct formation. for the cis-trans isomerization. 72 Table 9. Results of Stern-Volmer quenching of various g-alkenoxyvalerophenone by 2,5-dimethyl-2,4- “hexadiene in benzene (0.01 M) at 25 0C. R k 1 a k 1 ¢> a ¢>b q II q c II c OCH3 350 - .20 - 0(CH2)ZCH=CH2 123 196 .046 .062 0(CH2)2C(CH3)=CH2 37 31 .014 .20 c 0(CH2)2CH-C(CH3)2 - 30 - .19 a for the Type II product formation. b for the cycloadduct formation. Cfrom the acetophenone derivative. 73 Table 10. Results of Stern-Volmer quenching of various m-alkenoxyvalerophenone by 2,5-dimethyl-2,4- 'hexadiene in benzene (0.01 M) at 25‘3c. a b a b OCH3 350 - .013 - 0(CH2)2CH=CH2 320 - .0073 - 0(CH2)2CH-C(CH3)2 120 60 .0038 .0056c a b for the Type II product formation. for the unknown product, whose molecular weight assumed to be that of the C starting ketone. estimated from the GC peak areas. 74 TABLE 11. The plot of 1/¢>vs. the concentration of the ketones in acetonitrile. a b 7 Ketones Intercept Slope kbi'lo kCT'lo p-VPll 5.3 54 2.2 - p-VP12 9.9 155 6.5 1.7 n-VP13 15 710 29.8 4.0 a b Intercept a 1/¢%. Slope = kbi/(kHP). ._-_-o--—-—_..- 75 Table 12. Rate constants for the quenching of the triplet p—methoxyvalerophenone by various olefins at 25<)C. f Olefins Solvent qua kqb, 106 2-Me-1-pentene CHBCN 2.15 5.4 2-Me-2-pentene CHBCN 5.36 13 PhO-CHZCH=CH2 benzene 1.58 2.0 PhO-CHZC(Me)-CH2 benzene 4.51 5.6 a from the methoxyacetophenone formation (see Table 25), 1/1 - 2.44 x 106 (CH3CN), 1.25 x 106 s'1 (benzene). b in M-ls-l. l—q—vv-a—‘nwo .. ...... .,. 76 Table 13. Quantum yield of orato-(3-methyl-3-buten-1-oxy) valerophenone with 313 nm irradiation in various solvents. Solvent CPI]: (DC benzene 0.022 0.20 acetonitrile 0.012 0.20 methanol <0.001b 0.21 hexane 0.025 0.18 p-dioxane 0.053 0.17 a from the valerophenone actinometer. b estimated from the GC peak. .'_..-v‘-v 77 Table 14. Ultraviolet-Visible absorption maximaa for a series of alkenoxyphenyl ketones in heptane. . Ketone La 11—¥fi* 313-nm Q-VPO 241.4 (7910) 297.0 (3180) 1200 g-Vle 241.8 (7560) 298.0 (3150) 1380 Q-VP22 240.8 (7700) 297.8 (3280) 1570 cis-Q-VP22 241.4 (7540) 298.0 (3070) 1320 g-AP23 241.8 (9320) 299.6 (4120) 2420 S-Me-g-VPZZ, 244.0 (8170) 308.9 (3620) 3380 4-Me-5-Cl-Q-VP22 246.2 (8240) 310.0 (4240) 4110 p-VPO 214.4 (14300) 263.4 (17900) 153 p-VPll 214.4 (13300) 263.8 (18200) 109 p-VP21 214.4 (13600) 264.6 (18700) 94 p-VP31 214.4 (13400) 264.8 (18500) 58 p-VP41 214.4 (13700) 265.0 (19000) 106 a Values in parentheses are molar extinction coefficients. 78 ./ 80-1 1 604 .4. 1 7 A ‘1’ 40-. / 7 1:] A / C] 204$ D O/ / “VD /0 ’0/00 0 1 1 . 1 1 1 0.0 0.1 0.2 0.3 [P’TETONE], M Figure 23. The dependence of the type 11 product formation of p_-VP1n on the concentration of the ketones; VPll (O), VP12 (1:1), V1313 (&). 79 RWW Vinylbutyrophenones were synthesized from benzonitrile and the Grignard reagents of the corresponding vinyl alkyl bromide in THF. Kinetic studies were performed in benzene solutions with 313 nm. The Stern-Volmer plots were obtained from the aceto- 1H-NMR spectra of some of the vinyl- phenone formation. The butyrophenones, which were irradiated in benzene-d6 at 313 nm, showed at least two other products. One of them was assumed to be a cyclized product;78 i.e., a 1-phenyl-3-cyclohexen-1-o1, and no further identification was performed. The followings are the ketones studied in this thesis. R = CH=CH2 BPl 0 cis-CHaCHEt : BP2 R <:> ,\_/ cn=c (CH3) 2 ; BPS cis-CHZCH=CHEt : VP2 ‘0 lomnstiLBeeults The triplet lifetime of a ketone was determined by the Stern-Volmer quenching technique. The quantum yield was measured with the valerophenone actinometer, where the concentration of valerophenone was nearly the same as that of a vinyl ketone. The kinetic data are listed in Table 15 and 16. 80 The maximum quantum yield for acetophenone formation were obtained by adding pyridine in the ketones solution. Usually, 0.4-0.6 M-of pyridine solution provided the maximum yield for actophenone formation. Fig 25 shows the quantum yield depen- dence on the concentration of pyridine. ~——-I_.~ .- .. 33 A... _ 81 TABLE H5. Result of Stern-Volmer quenching of PhC0(CH2)3-R by 2,5-dimethy1-2,4-hexadiene in benzene at 25 oC. R k q 1 q, ¢max CH3 47 .33 1.0 CH=CH2 10.2 .28 .56 CH=CHEt 7.1 .13 .56 cn-CM62 3.2 .13 .47 Z-CHZCH=CHEt 33.5 .23 1.0 TABLE 15: Result of Stern-Volmer quenching of PhCO(CH2)3-R by 2,5-dimethyl-2,4-hexadiene in acetonitrile at 25 °c. R kq‘t CD 1/1, 108 Ctr-CH2 15 0.17 6.67 CH-CHEt 4.7 0.20 21.3 CH=CMe2 5.1 0.26 19.6 Z-CHZCH=CHEt 53 0.45 1.89 82 Table 17. Ultraviolet-Visible absorptiona of a series of Y-vinylbutyrophenones in heptane. Ketone fl-+TI* B-band n.-+fl other VP 238 (12000) 278 (820) 323 (46) 286 (640) -CH=CH2 238 (12400) 278 (940) 323 (47) 286 (740) -CH=CHEt 238 (4900) 279 (330) 322 (36) -CH=C(Me)2 238 (12200) 278 (900) 324 (48) 286 (720) -CH CH-CHEt 238 (12600) 278 (970) 324 (48) 286 (780) 2 Values in parentheses are molar extinction coefficients. A 6.— . D// 4. 9: <9 / 2. O- . 1 ' l ' 1 0.0 0.2 0.4 0.6 [QUENCHERL M Figure 24. Stern-Volmer plots for acetophenone formation of various Y—vinylbutyrophenone in benzene; BPl (I), BP2 (C1), BP3 (A), VP2 (O). 84 0.86 0.6“ /0 fiONQ‘ o o 0 x / (I) o / 0.4“ c: 1/ 15/ 0.24:: 0.0 . I . . , . 1 r 0.0 0.4 0.8 1.2 1.6 [PYRIDINE], M Figure 25. The effect of the pyridine concentration on the quantum yield for the acetophenone formation: from BPl (0), from BP3 (C1). AW 1.915219305112106 a. cycloadducts - Photoproducts from ortho and para- alkenoxy phenyl ketones (g- or p-APzn) were identified as cyclobutene compounds. Now, the question is whether these cyclobutene products are 'direct' photoproducts or secondary photoproducts (two or more photons) or thermally driven from 'hot' photoproducts. This question arose just because there are not many examples of such a photoreaction. The first possible mecha- nism for this reaction is that the intramolecular 1,2-addition of the olefinic moieties to the benzene rings photochemically, then the rearrangement to the cyclobutenes either thermally or photochemically. The second mechanism is that the 1,2-addition occurs first, then the adduct undergoes a ring opening to the cyclooctatriene either thermally or photochemically, finally this cyclooctatriene is converted to the tricyclo compound photochemically. If the first mechanism is real, the conversion from the 1,2-adducts to the tricycloproducts will be very fast or the 1 adducts will be very unstable, because time-based H-NMR spectra of most ketones (except g-AP 3) shows no peaks of the 2 85 86 1w_ hvorA 0 0 cyclohexadiene even on short-time irradiation. If this conversion is photochemical process, the cyclohexa- diene will be sensitized to the tricyclo product by the starting ketone, because the extinction coefficient of the cyclohexadiene is not expected to be big enough for the direct irradiation. Experimental data favor the second process. Especially, chronological UV-Visible absorption spectra of the alkenoxy phenyl ketones show a quick build-up of a new broad peaks at 340-390 nm. This would reflect the existence of a cycloocta- triene intermediate, because isolated cyclooctatrienes showed the absorption maxima at 340-370 nm. Thermal interconversion between bicyclo[4.2.0]octa-2,7-diene and cyclooctatriene is 82 well known. Although the transient UV-visible absorption strongly supports the cyclooctatriene, we still do not know how fast the conversion from the cyclohexadiene to the cyclo- octatriene is. But it can be assumed to happen in minutes, 4 because even at lower concentration (ca. 10- M) of g-AP 2 and 2 In. I“! I. 1" *4 I" '0 87 at low conversion, only a cyclooctatriene and a cyclobutene were observed by the 1H-NMR (within 30 min) and UV-Visible spectra (within 5 min). Another experimental data supporting the cyclooctatriene mechanism were obtained from the irradiation of g-AP23. The UV-Visible spectra of the ketone during irradiation showed weak new absorption at ca. 340 nm and another two absorption maxima at 285 and 270 nm. Irradiation of the same ketone (30- 40 % conversion) yielded only one product whose 1H-NMR shows the peaks of a cyclohexadiene. Two terminal methyl groups on the double bond could create steric hindrance in the cyclo- octatriene structure and move the equilibrium toward the azb'c This valence tautomerism will be discu- cyclohexadiene. seed in more details later. Eventually this intermediate was led to the cyclobutene product (Fig. 6). From this, we can get at least two important informations. The first one is that one of the 1,2-adducts (cyclohexadienes) was directly detected. The second one is that the cyclohexadiene is not converted to the cyclobutene via a photochemical way (direct irradiation or sensitization), because this ketone is the only one that _yields the detectable cyclohexadiene even though every cycle- hexadiene from other ortho ketones has the same chromophore (the same potential photoreaction, qualitatively and quantita- tively). 88 However, there is important inconsistancy in experimental 1 data; in most cases, the time-based H-NMR spectra do not show the cyclooctatriene peaks, but from UV-Visible spectra they 1 were detected. For example, the time-based H-NMR spectra of Q-AP 2 do not show any cyclooctariene even at the very initial 2 stage of the irradiation, but only the cyclobutene product appears (Fig 14). On the other hand, as seen in Fig 15 and 16 the absorption spectra of the same ketone show strong evidence for the formation of the cyclooctatriene intermediate. But it has to be mentioned that for the 1H-NMR spectra the concentration of the solution was usuallay 0.1-0.01 M, and -4_10-5 for the UV-Visible spectra it was 10 M. At higher concentration of the starting ketones, it can be assumed that cyclooctatrienes undergo very efficient reaction to the tri- cyclic products, but at lower ketone concentration (100-1000 times lower) some amount of octatrienes were built up before the next transformation and detected on the UV-Visible absorption spectra. Actually, some amount of the octatriene £1 .1 V&# were observed with a tricyclic product on the 1H—NMR spectrum -3 -4 upon the irradiation of a dilute solution (10 -10 M). Irradiation of 3-acethyl-1-methy1-9-oxabicyclo[6.3.0] undeca-3,5,7-triene collected by preparative GC (oven tempe- rature 170 0C) from the cyclobutene product of g-AP22, gave 1?h a.» m: . .Ae. Rb ‘5 4 a... $5 89 the original tricyclo product, which means the cyclooctatriene and the tricyclo product interconvert photochemically from the former and thermally from the latter. Here, the next question is how these cyclohexadienes were formed and converted to the cyclooctatrienes or the mechanism. There can be two answers for the question. The first one is a concerted 1,2-addition, the second one is a stepwise 1,2- addition. However, it is clear that the 1,2-addition is not synchronous process from the result that para-(gig-3-hexen-1- oxy)valerophenone undergoes very efficient isomerization (d>= 0.27). The rapid cyclohexadiene to cyclooctatriene rearrange- ment probably results from the weakened character of the middle C-C bond caused by donor-acceptor conjugation. From the identification of the photoproducts of 2'-(3- methyl-3-buten-1-oxy)-5'-methy-acetophenone and 2'-(3-methyl- 3-buten-1-oxy)-4'-methyl-5'-chloroacetophenone, it is possible to determine the position of the aromatic carbons in the cyclobutene compounds. The former ketone showed two vinyl protons; a singlet at 5.49 ppm and a doublet at 4.99 ppm (J = 6.7 Hz). The singlet was assumed to be a cyclobutene vinyl 90 proton. Therefore, the methyl substituent has to be on the C- 10. The chloro ketone gave one singlet at 6.72 ppm another singlet at 5.14 ppm on the 1 H-NMR spectrum. The chlorine atom is on the C-9. Therefore, the six carbons, C-1 and C-7 to C- 11, come from the aromatic rings, and the sequence seems not to be changed. Table 18 Selected chemical shift of tricycloproducts from g-(3-methy1-3-buten-1—oxy)acetophenone and its derivatives in C D . 6 6 protons 5(Ppm) J(Hz) 5 J 5 J H-11 5.78 2.8 5.49 - 6.72 ‘ - H-10 5.86 2.8 - - - - H-9 3.26 6.6 3.16 6.7 - - H-8 4.96 6.6 4.99 6.7 5.14 - 4° ’0 .w- “a 91 b. e o C oadduc s - In the cyclooctatriene system, there are two thermal rearrangement processes. The first one is the conversion between a bicyclo- [4.2.0]octa-2,4-diene (a cyclohexadiene) and a cycloocta- 1,3,5-triene, and the second is that between a cyclooctatriene and a bicyclo[4.2.0]octa-2,7-diene which has a cis-fused cyclobutene. The second rearrangement is an irreversible one-way process thermally; only from a cyclobutene to a cycloocta- triene. The main products collected by a preparative GC (170- 180 0C) are cyclooctatrienes by injecting the cis-fused cyclobutene products. This thermal rearrangement is symmmet- rically forbidden. But the rearrangement from the strained cyclobutenes to more stable all gig-cyclooctatrienes apparently happened. Again the middle C-C bond seems to be weakened by donor-acceptor conjugation between the carbonyl and the alkoxy group. In the cyclooctatetraene tautomerism (3 fl-bonds), the equilibrium concentration of the cis-fused cyclobutene was estimated to be 0.01 % at 100 oC, and its lifetim was calcu- 92 lated to be 14 min at 0 0C.83 If our cyclobutenes had a trans- fused geometry (twisted 2 fl-bonds), they could undergo . symmetry-allowed rearrangement to the all-cis cyclooctatrienes even at low temperature, just like the allowed rearrangement of the above bicyclo[4.2.0]octatriene to cyclooctatetraene. But, the bicyclo[4.2.0]octa-2,7-dienes were stable in a refrigerator (ca. 000) for weeks. Besides the NOE results, this is another indirect evidence for the cis-fused geometry of the cyclobutene photoproducts. : OE] Valence tautomerism between bicyclo[4.2.0]octa-2,4-dienes and cycloocta-l,3,5-triene is known to be affected by the 83 When R,R' - H, the additional bulky groups on the ring. concentration of the bicyclic compound was 11 %, but when R,R' a methyl (trans), it was 94 %. When R a two methoxys, the bicyclic population was measured to be >95 %. R ’n' R .—O:I,, 1 In our system with an extra 5-membered ring, R is expected to have less steric hindrance because the extra ring twists other be es‘ of 35 nethy which drama 17.2. refle inter till cf: 4.5e Upon .1P 93 twists the R1 group outside of the cyclooctatriene. 0n the 2 other hand, if R is an bulky group, the steric hindrance can be estimated to be more severe than without the S-membered 1,R2,R3 = H, the energy-minimized conforamtion by 84 ring. When R the molecular mechanics calculation has the dihedral angle 1 and R2. This is why irradition of g-(4- of 35° between R methyl-B-penten-l-oxy)aceto-phenone affords a cyclohexadiene which is stable thermally. The methyl group at R2 position dramatically reversed the equilibrium. Fr 8" Rearrangement from l-acetyl-z,2-dimethyl-6-oxabicyclo [7.2.0.03’7Jundec-7,10-diene of g-AP23 to the cyclohexadiene reflects a change in the cyclohexadiene-cyclooctatriene interconversion. It can be concluded that some cyclooctatriene still is formed from 11, but the unfavorable equilibrium is offset by the irreversible photoisomerization of 1; to 1_. Upon being heated, 1; opens to 12, which rearranges 11 12 13 imed.‘ unsta) be hi: react. 11' p0: and 0. tialue 1 CODSist 94 immediately to the thermodynamically preferred 1;, which is unstable and interconverts with the starting ketone thermally. The quantum yields for the cyclobutene formation should be higher than the values in Table 8 and 9, because the whole reaction is an two-photon process. From the equation of<1>l<21>2 = the range of each values will be 1 > ¢reported ' reported and (preported < (1)2 < 1, repectively. 2. ecu a ans e n a. W - It is known that alkenes quench triplet ketones by a charge transfer process.85 Quenching efficiency increases 3-4 times with each additional alkyl substituent on the double bond. To figure out the charge transfer (CT) rate constants (kCT), it is necessary to determine the rate constant for'Y- hydrogen abstration (kn) and the intrinsic decay rate constant (kd). Both kH and kd appear to be characteristics of chromo- phores. The kH can be calculated from the equation RH a ggx/T with the assumption that none of the biradicals reverts to the ground state ketone. The values for kH in Table 19 were calcu- lated from the values for ¢EI and represent the rate constants for the formation of the type II product rather than those for the formation of the biradical. However, the uniformity of the value for kH for all the ketones studied presents the internal consistency of these data and this is not surprising because _fl- 95 all ketones have the same chromophore, an alkoxyphenyl alkyl ketone. The exact process that determines the values of kd for p- alkoxyphenyl ketones is not known. Typical values for kd in 5 6 -1 86 phenyl ketones are on the order of 10 -10 s . Wagner has found that the kd values for p-methoxyphenyl alkyl ketones and the ortho derivatives are on the order of 1.6 x 106 107 s-l, respectively.87 and 1.1 x It is unlikely that kd values are sensitive to the nature of the alkoxy substiuents, therefore, we can use the same values of kd throughout the calculation. The kCT values in Table 19 equal to 1/1 — kH -kd. These k T values include both intramolecular and intermolecular C quenching rate constants for the triplet p-alkenoxyphenyl ketones. In our system, -0(CH2)nCH=CH intramolecular 2. quenching appeares only when n - 2 or 3. For the n - 2 phenyl ketone derivatives, intramolecular quenching rates are at least 100 times faster than the rates for the bimolecular quenching (Table 19). In the n a 2 ketones, the inner vinyl carbon can make a 5-membered ring with the two chain carbOns, the oxygen, and the 19:9 carbon on the phenyl ring. 0 0 ’ O From the comparison of the RCT values with the quantum yields for the photoproduct formation, it is clear that not all CT quenchings lead to the products. The rate constants for 96 TABLE 19. Photokinetic data of p-alkenoxyvalerophenones in acetonitrile (0.01 M) at 25 OC. KETONES 1/1, 106 <1>a H,10 kd,10 kCT,1O p-VPO 2.44 .17 4.2 2.0 p-VPll 2.70 .15 4.1 2.0 0.3 p-VP12 3.06 .14 4.3 2.0 0.7 p-VP13 6.25 .045 2.8 2.0 4.0 p-VP21 90.9 .0032 2.9 2.0 89 p-VP22 122 .0037 4.5 2.0 120 p-Vchis .0016 240b p-VPZB .00022 1800b n-VP31 4.88 .062 3.0 2.0 2.6 p-VP33 9.0 .04 3.6 2.0 6.5 p-VP41 2.3 .16 3.6 2.0 p-VP91 2.27 .17 3.9 2.0 a The Type II product formation. b estimated from the quantum yields. 2131 14': 97 TABLE 20. Photokinetic data of Q-alkenoxyvalerophenones in benzene (0.01 M) at 25 oC. 7 a b 6 7 KETONES 1/1,10 ¢3I 95%) and quantum yield (0.03), but p-(3-buten-1-oxy)benzophenone for 48 hrs yielded an adduct (< 2 %) in very poor quantum yield. The main difference between the alkenoxyphenyl alkyl ketones and the alkenoxybenzophenones is that the former have the‘n;n* lowest triplets and the latter have the n/fl* lowest triplets. The cycloadduct and the type II product of the former ketone are quenched well by 2,5-dimethyl-2,4-haxadiene, a known triplet quencher. Therefore, the efficient cyclo- addition of alkenoxyphenyl alkyl ketones occurs from the lowest n,‘n"‘ triplets . Another experimental evidence which supports this conclu- sion can be found from the dependence of the quantum yield on the solvents. The quantum yield for the type II product formation of Q-(3-methyl-3-buten-1-oxy)valerophenone, g-VPZZ, was changed dramatically from 0.053 in p-dioxane to <0.001 in methanol. But those for the cycloadduct formation were not much affected by the change in solvents; 0.20 in benzene, 0.21 in methanol. In methanol, the type II quantum yield decreased 103 very much, and this is well fit by the fact that n;n* triplet 4 and this reduced the states are stabilized by polar solvents9 equilibrium concentration of the upper n,fl* states. The consistency in the quantum yield for the cycloadduct formation gives another evidence for the cycloaddition from the n;n* triplets. In photochemistry, it is not easy to figure out the elec- tronic configuration of an excited state, simply because its lifetime is too short and its concentration is dilute enough to make difficulties in the analyses. However, if there is any chemical reaction from the excited states, many informations about them could be obtained from the photoproduct. As a matter of fact, this is one of the most general and safe way for that purpose. The n,fl* triplets of phenyl ketones undergo well-known hydrogen abstaction, if the triplets are the lowest states and there are proper hydrogen donors. From the comparision of the properties of these triplets with those of alkoxy radicals, it is known that the n;fl* triplet has a biradical-type carbonyl group, i.e., one radical in the n* orbital of the carbon and another in the half-filled n-orbital of the oxygen, therefore, it is very similar to alkoxy radicals.5 0n the other hand, few photochemical reactions from the n;n* triplets of phenyl ketones are known. The phenyl ketones substituted with electron-donating groups have the'n;n* lowest triplets and show dramatically reduced reactivity in the hydrogen abstraction. The hydrogen abstraction of alkoxyphenyl ketones having the lowest'n;fl*'triplets slows down as much as 104 200 times compared to that of an hydrogen-substituted phenyl ketone and explained to be caused by the equilibration between two different triplets.5'85b In the phenyl alkyl ketones, the carbonyl substituent stabilizes the n; orbital and destabilizes the “a orbital by mixing with the carbonyl Ttorbital, which enchances the contribution of the fla-z‘fl; transition to the S -’Ihhtran- sition. The following valence bond representation describes the‘TI,‘1'I"I triplets of phenyl ketones (3L3).4 : —~ e—<:'—~ Although the 1,2-addition of an alkene to a triplet 34a fast benzene was predicted to be allowed and concerted, isomerization of gis-p-VPZZ to the trans ketone indicates that the cycloaddition of alkenoxyphenyl ketones is stepwise. The quenching efficiencies of the olefinic moieties toward the ‘fl;fl*‘triplets did not increase with additional alkyl substituent as much as expected from that toward the n;n* triplets. The combined results once again suggest that the quinoidal forms of the n;n* triplets are important rosonance structures. b. 111 ' 11* 1111* ' t -It is now well known that there is a equilibrium between n/n* and 19,85b ‘n;n* triplets of p-alkoxyphenyl ketones. However, the . .....-na-.... . . -......— 105 equilibrium constants between two triplets has never been studied. The two independent reactions from two equilibrated states make it possible to measure the equilibrium rate 95 The cyclization reaction clearly occurs from the constants. I nyn triplet states of the ketones and hydrogen abstraction from the n;n* triplet states. From this, it is possible to estimate the equilibrium rate constants: kn \ n,n* As shown on Table 19 and 20, the values for the kH of p— and g-alkenoxyphenyl ketones were not changed significantly, while the kCT values reached up to 108 . The consistency in kH values means that the population of the upper n,n* triplets does not change, i.e. still in an equilibrium state. It can be concluded that the value for k1, the rate constant for the conversion from the lowest fl;n*‘triplet to the upper n;n* triplet, can be estimated to be bigger than kc (>108 371). From the Boltzmann distribution law, the values for k_1, the rate constant from the upper n,1't* triplet to the 11m" triplet, can be also estimated to be >1010 s-l, because the equilibrium concentration of the n;n* triplet is roughly 1/100 of the‘flffl* triplet. 106 3.1-1W5 1.11me To determine the hydrogen abstraction rate, it is essential to measure the maximum quantum yield especially when the reactivity of Y-C-H's are different in a system. Wagner reported that hydrogen bonding by the Norrish Type II biradical to solvent molecules or a Lewis base suppresses reverse hydrogen abstration of the biradical to the starting ketone and increases the yields for the type II product formation:96 For valerophenone, the maximized quantum yield for acetophenone formation is unity with the addition of t-butyl 81 This indicates that the radiationless decay rate of alcohol. the valerophenone triplet is slower than that of the type II cleavage. The 'absolute' hydrogen abstraction rate constant can be calculated from the expression kH = Adduct 2. e 'c icat' o o 0 di Synthetic methods for the 8-membered rings have been 98 always the challenge to organic chemists. Certainly, the high fcrha that pheny olefi bond with fl,fl good info: trip] 111 high quantum and chemical yileds for the cyclooctatriene formation from the alkenoxyphenyl ketones is a good news in that sence. It would be useful to expand this reaction to other phenyl ketone systems. Instead of oxygen between arene and olefins, carbon, sulfur, and nitrogen could be used. The ester bond between them also would be tried. 0 / . -‘——X- CH -v n l \ I ( 2)n I y X = carbon, sulfur, nitrogen, ester, etc. Irradiation of p-methoxyacetophenone yielded 1,2-adduct' with 1-hexene. Bimolecular cycloaddition of other substituted 11,11. triplet acetophenones to various olefins also would be a good trial for the synthetic purpose. This would give useful information of the electronic configuration of the‘fl;fl* triplet phenyl ketones. BS benzene ric aci colorle were se distill sodium ; neutral “939511 flask. 1| Solutiol thr011cm ”era m iith hen 1 L or a refluxed mfiat the“ dis1 Benzene : One gallon of thiophene free reagent grade benzene was repeatedly stirred with 150 ml portions of sulfu- ric acid for 20-24 hr periods until the sulfuric acid remained colorless (about 5-6 times). The benzene and sulfuric acid were separated and the benzene washed with 500 ml portions distilled water twice, then with 200 m1 of a saturated aqueous sodium bicarbonate solution until the aqueous phase remained neutral or basic. Then benzene was separated, dried over magnesium sulfate, and filtered into a 5 liter round bottem flask. To the flask phosphorus pentoxide was added and the solution was refluxed overnight. The benzene was distilled through a one meter column packed with stainless steel helices .at a rate of 100 ml/hr. The first and last 10% were discarded. Aggtgnitrilg : Practical actonitrile was first treated with benzoyl chloride according to the following procedure:99 4 L of acetonitrile and 50 ml of benzoyl chloride were refluxed for 1 hr. Distill into a receiver containing 50 ml of water at 5-10 ml/min. Add 100 gr of NaZCO3, reflux for 2 hr, then distilled into a receiver fitted with a drying tube. Add 112 113 50 gr of anhydrous NeZCO3 and 75 gr of KMnO4 and distill at 5 to 10 ml/min with protection from atmospheric moisture. The distillate is made slightly acidic with concentrated sulfuric (acid. Decent from precipitated ammonium sulfate and distill through 92 inch column packed with glass helices and repeat it again. The first and last 10% were discarded each times. Meehenel : Absolute methanol (1 L) was refluxed for 2 hr with magnesium turning (1 gr) and distilled. The first and last 10 % were discarded. zyzigine : pyridine was refluxed over barium oxide over- night and distilled through a one meter column packed with glass helices. The first and last 10% were discarded. 2. Internel_Standards Eengefieeene : Pentadecene (Columbia Organics) was washed with sulfuric acid and distilled (b.p. 131 0C at 10 Torr.) by Dr. Peter J. Wagner. flexegeeene : Hexadecane (Aldrich) was purified by washing with sulfuric acid, followed by distillation, b.p. 105 °c (10 Torr) by Dr. Peter J. Wagner. 114 Hengegeeene : Heptadecane (Chemical Samples Company) was purified by washing with sulfuric acid, then distilled by Dr. Peter J. Wagner. b.p. = 158 °c (8 Torr) Megnyl_penzeeee : Methyl benzoate (reagent grade) in ether was washed with aqueous sodium bicarbonate solution, with water, then dried over anhydrous sodium sulfate, finally distilled under reduced pressre. n:Qg;xl_henzee;e : This was prepared by the reaction of benzoyl chloride with n-octyl alcohol. n-Octyl alcohol (40 gr) was added to benzoyl chloride (40 gr) in 200 m1 ether. The solution was refluxed overnight with stirring. Then it was cooled, washed with water, extracted with ether, dried over 3 anhydrous sodium sulfate, finally concentrated in yeeng. 1 Distillation gave a clear liquid. H-NMR spectrum confirmed the expected structure: b.p. 197-198 °C (0.5 torr): m/e 234 04“) . 3- Quenchers — - — ’ : 2,5-Dimethy1-2,4-hexadiene (Chemical Samples Company) was allowed to sublime in the refrigerator. E§h¥l_§QIh§L§ : It was used as received (Aldrich). 115 4. 8529055 Azfixdroxxxelsroehsngne and z:hxdrexxyelsr92hsnenelo° : Phenyl valerate was converted to the ketone by the Fries 101 Aluminum chloride (270 gr, 2 moles) was rearrangement. placed in a three-necked flask equipped with a mechanical stirrer and heated to 70 0C on an oil bath. Phenyl valerate (80 gr, 0.5 mole, from phenol and valeryl chloride) preheated to 40 °C was added as quickly as possible. The reaction mixture was brought rapidly to 140 oC and stirred for 1 hour. Then the mixture was cooled to room temperature and hydrolyzed by adding 500 ml ice-cold 6 N hydrochloric acid. The solution was heated on a steam bath for half an hour and a viscous oil was separated. The aqueous layer was washed with 50 ml ether‘ twice. The ether layer was combined with the oil and dried over magnesium sulfate. After evaporating ether under vacuo, the oil was vacuum-distilled to remove unreacted reactants and 2-hydroxyvalerophenone. The residual 4-hydroxyvalerophenone was recrystallized (pet ether-benzene): %Yie1d = 40 %: m.p. = 61-63 °c (Lit.1°2, 60-62 °0): lu-NMR (FT-80, c0013) 5 0.93 (t, 3H), 1.15-1.85 (m, 4H), 2,92 (t, 2H), 6.80 (d, 2H), 7.75 (d, 28). 2-Hydroxyvalerophenone was redistilled: %Yield - 35%: b.p. = 83-85 °c (0.1 torr): 1H-NMR (60 MHz, coc13) 5 12.2 (s, 1H, 03), 7.9-6.5 (m, 4H, Ar-H's), 2.9 (t, 2H, c32c0), 2.0-0.9 (m, 7H, cnzcnzcn3); MS (m/e), 178 (M+), 149, 136, 121 (Base), 93, 65. nJIUHLl-n-Iudimdfli_ J ‘ 1") r ll ’f‘l '. l‘,‘ 12 116 '- - - - v : 4-hydroxyvalerophe- none (3.5 gr, 0.04 mole), allyl bromide (6 ml, 0.08 mole) and anhydrous potasium carbonate (5.6 gm, 0.04 mole) in 50 ml of dry acetone were refluxed for 40 hours under nitrogen atmos- phere. After cooling down the solution, potasium bromide was filtered off. Acetone and the remained allyl bromide were evaporated under vacuo. The reaction mixture was disolved in ether and washed with 20 ml of 2 N NaOH solution twice to remove unreacted 4-hydroxyvalerophenone, then washed with water and dried over magnesium sulfate. After the evaporation of ether the product was purified by the low temperature. recrystallization in hexane to give colorless liquid: 1H-NMR (FT-80, CDC13) 0 0.90 (t, 3H), 1.15-1.85 (m, 4H), 3.86 (t, 23), 4.52 (d, 2H), 5.20-5.50 (m, 2H), 5.70-6.40 (m,lH), 6.89 (d, 28), 7.87 (d, 28); Ms (m/e) 218 (M+), 176, 161 (base), 121, 105, 92, 77: IR (CC14) 2950, 2875, 1675 (C80), 1600, 1225, 980 cm’l; UV (heptane), 214.4 (13300), 263.8 nm (18200). '- - - - - - : This compound was synthesized from 4-hydroxyvalerophenone and 3-chloro-2- methylpropene (Aldrich) by the same method as that of p-(z- propenoxy) valerophenone. The product was recrystallized twice from hexane: m.p. = 29—30 0C; 1 H-NMR (FT-80, coc13) 5 0.92 (t, 3H), 1.2-1.9 (m, 48), 1.80 (s, 3H), 2.86 (t, 2H), 4.9 (d, 2H), 6.87 (d, 2H), 7.87 (d, 28); Ms (m/e), 232 (M+), 190, 175 (base), 161, 147, 121, 55; IR (cc14), 2940, 2875, 1675 (c=0), 1230, 1000 cm'l. 117 - - - - - 103 : It was used just after being made. In a 100 ml round-bottomed flask were placed 17 ml (30 gr, 0.11 mole) of hexachloroacetone and 4.5 ml (3.7 gr, 0.05 mole) of 3-methy1-2-buten-1-ol (Aldrich). The solution was cooled to 0 oC and 13.5 gr (0.05 mole) of triphenylphos- phine was added in small portions with stirring. After tri- phenylphosphine was disolved completely (20 min), the brown solution was warmed up to room temperature. After 30 min the brown thick slurry was flash-distilled into a receiver in dry ice-acetone bath: 18-NMR (T-60, c0c13) a 1.7 (d, 68), 4.1 (d, 28), 5.2-5.6 (m, 18). '- - - - - - : This ketone was made from 4-hydroxyvalerophenone and 1—chloro-3-methyl-2- butene by the same method as that of the propenoxy derivatives 1H-NMR and recrystallized twice (hexane): m.p. - 41.5-42.5 °C: (250 82, c0c13), 60.93 (t, 38), 1.38 (h, 28), 1.67 (h, 28), 1.74 (s, 38), 1.78 (s, 38), 2.89 (t, 28), 4.55 (d, 28), 5.47 (t, 18), 6.91 (d, 28), 7.91 (d, 28): Ms (m/e), 246 (M+), 232, 217, 204, 178, 136, 121 (base), 93, 69; IR (cc14), 2940, 1680 ,(c-0), 1600, 1225, 980 cm'l. '- - - - : This compound was synthesized from 1-bromo-3-butene (Aldrich) and 4-hydroxy- valerophenone: b.p. - 110-112 0C (0.1 Torr), 1H-NMR (T-60, CDC13) 6 0.97 (t, 3H), 1.27-1.93 (m, 4H), 2.57 (m, 2H), 2.92 (t, 2H), 4.08 (t, 2H), 5.05-5.30 (m, 2H), 5.63-6.25 (m, 1H), 6.93 (d, 28), 7.95 (d, 28): 13c-NMR (c0c13) (5198.9, 162.5, 118 133.8, 130.1, 130.0, 117.1, 114.0, 67.2, 37.6, 33.3, 26.5, 22.3, 13.8; MS (m/e), 232 (M+), 190, 175, 121 (base), 55; IR (cc14), 2960, 2940, 2870, 1680 (eao), 1600, 1245, 1170 om'l: UV (heptane), 214.4 (13600), 264.6 (18700) nm. '- - - - : This was made from 1- bromo-4-pentene (Aldrich) and p-hydroxyvalerophenone. b.p. = 119-121 °c (0.1 Torr). 1 H-NMR (FT-80, c0c13) a 0.90 (t, 3H), 1.20—2.00 (m, 68), 2.20 (m 28), 2.88 (t, 28), 4.00 (t, 2H), 4.90-5.20 (m, 28), 5.80-6.10 (m, 18), 6.90 (d, 28), 7.90 (d, 28): 13 c-NMR (00013) a 199.1, 162.8, 137.5, 130.2, 130.0, 115.3, 114.1, 67.3, 37.9, 29.9, 28.2, 26.7, 22.5, 13.9: 85 (m/e), 246 (M+), 217, 204, 189, 136, 121 (base), 104, 93; IR (cc14), 2925, 1675 (c=0), 1600, 1575, 1225 cm'lr UV (heptane), 214.4 (13400), 264.8 nm (18500). '- - - - v : 5-Hexen-1-ol (Aldrich) was converted to the tosylate, which was then reacted with 4- hydroxyvalerophenone. S-hexen-l-ol (5 gr, 0.05 mole) was dissolved in 25 ml pyridine. The solution was cooled in ice- water bath. p-Toluenesulfonyl chloride (11 gr, 0.057 mole) was added by portions. After 3 hr stirring at 0 0C, 10 ml of conc sulfuric acid with 50 gr of ice was added, then the solution was extracted with ether. The organic layer was washed with 2 N NaOH solution once, with water twice, then dried over sodium sulfate. After the evaporation of ether, a slightly yellowish oil was obtained, which was used in next step without further purification: 121 1250 (1901 1110 with chro 23, 1.SC 2925 330 €ch to 1 solL Satr the 119 1H-NMR (FT-80, CDCl3) for the tosylate: 5 1.25-1.75 (m, 4H), 2.00 (m, 2H), 2.45 (s, 3H), 4.00 (t, 28), 4.80-5.00 (m, 28), 5.50-6.00 (m, 1H), 7.30 (d, 2H) 7.75 (d, 2H). 1H-NMR (FT-80, For the ketone: b.p. = 132-133 0C (0.1 Torr), c0013), 6 0.90 (t, 38), l.15-1.90 (m, 68), 2.10 (m, 28), 2.88 (t, 28), 4.00 (t, 28), 4.90-5.10 (m, 28), 5.55-6.05 (m, 18), 6.90 (d, 2H), 7.90 (d, 28): Ms (m/e), 260 (M+), 218, 203, 136, 121 (base), 104, 93, 55; IR (0014), 2925, 1675 (c=0), 1600, 1250, 1170 cm-1: UV (heptane), 214.4 (13700), 265.0 nm (19000). '- - en- - v e : 9-Undecen-1-ol (Aldrich) was converted to the tosylate by the same method with 1-hexen-1-ol. The ketone was purified on column chromatography (silica gel, hexane): 1 H-NMR (coc13), 5 7.85 (d, 28), 6.84 (d, 28), 5.82-5.65 (m, 1H, -CH-C), 4.98-4.82 (m, 28, c-cnz), 3.92 (t, 28, -OCH2-), 2.83 (t, 28, 0820-0), 1.80- 1.50 (m, 48), 1.45-1.10 (m, 168), 0.90 (t, 3H): IR (cc14), 2925, 2850, 1675 (c=0), 1600, 1360, 1250, 1175 cm'l; Ms (m/e), + 330 (M ), 288, 275, 136, 121 (base), 91, 55. .1zBreme:1:methxlnsnt:3:sns1O4 : 0.5 mole (42 or) of cyclopropyl methyl ketone in 50 ml of ether was added slowly to the Grignard solution of methyl iodide (0.55 mole). The solution was heated up for 30 min, then hydrolized with saturated NH4C1 solution. The ether layer was separated and the aqueous layer was extracted with ether. The combined ether solution was washed with water twice, dried (MgSO4), then 120 ether was evaporated to give 2-cyclopropylpropen—2-ol, which was used in the next step without futher purification. 40 gr of the alcohol in 250 ml flask was cooled in ice-water bath. 47% HBr solution (160 ml) was added slowly over 10 min with stirring. The mixture was warmed to 40 oC and kept another 10 min, then extracted with ether. The ether layer was washed several time with water, once with saturated NeHCO3 solution, again with water. The ether solution was dried (MgSO4), O evaporated. The halide (38 gr) was collected between 60-63 C at 25 Torr. The overall yield was 50%. 18-NMR-(F'r-80, coc13) : a 1.65 (s, 38), 1.72 (s, 38), 2.55 (m, 2H), 3.40 (t, 2H), 5.10 (m, 1H). t. - - - - - : This ketone' was made from p-hydroxyvalerophenone and 1-bromo-4-methyl-3- pentene: m.p. - 36.5-37.5 °c, 1 8-NMR (FT-80, c0c13) 5 0.90 (t, 38), 1.50 (m, 48), 1.62 (s, 38), 1.72 (s, 38), 2.45 (m, 28), 2.85 (t, 28), 3.95 (t, 28), 5.20 (m, 18), 6.88 (d, 28), 7.88 (d. 28): 13 C-NMR (coc13) 5 199.1, 162.8, 134.7, 130.2, 130.0, 119.2, 114.1, 67.8, 37.9, 28.0, 26.7, 25.7, 22.5, 17.8, 13.9; 85 (m/e) 260 (M+), 218, 136, 121, 83, 55 (base); IR (cc14), 2970, 2945, 2885 (aliphatic C-H's), 1680 (c=0), 1600 (C=C), 1250, 1170 cm'l. '- - - - - - o : This ketone was made from p-hydroxyvelerophenone and the corresponding tosylate which was prepared by the usual way from 3-methyl-3- o 1 buten-l-ol: b.p. = 110-112 C, H-NMR (FT-80, CDC13) 5 0.95 s1 11' 31% 13 12 29. The 3:0 121 (t, 38), 1.50 (m, 48), 1.80 (s, 38), 2.50 (t, 28), 2.85 (t, 13c- ZH), 4.15 (t, 2H), 4.80 (s, 2H), 6.90 (d, 2H), 7.90 ,2H): NHR (CDC13) 6 199.1, 162.2, 141.7, 130.2, 130.1, 114.1, 112.2, 66.6, 37.9, 37.0, 26.7, 22.7, 22.5, 13.9: MS (m/e), 246 (M+), 204, 189, 136, 121 (base), 41: IR (CC14), 2970, 2940, 2880, 1680 (C30), 1600, 1245, 1170 cm-1. |- - - - - o : The ketone was synthesized from hydroxyvalerophenone and the bromide of (Z)- 3-hexen-1-ol (Alfa). The alcohol was converted to the tosylate, which was reacted with potasium bromide to make (Z)- 1-bromo-3-hexene as described before. The ketone was recrystallized (hexane) at low temperature and is a colorless liquid at room temperature: 1 H-NMR (250 MHz, coc13) a 0.95 (t, 38), 1.00 (t, 38), 1.50 (m, 48), 2.11 (m, 28), 2.56 (m, 28), 2.85 (t, 28), 4.00 (t, 28), 5.45 (m, 28, CH=CH, J = 10.7 Hz), 6.90 (d, 28), 7.90 (d, 28); 13 C-NMR (00013) 6 199.1, 162.7, 134.6, 130.2, 130.1, 123.6, 114.1, 67.7, 37.9, 27.1, 26.7, 22.5, 20.6, 14.2, 13.9; 88 (m/e), 260 (M+), 218, 203, 136, 121, 83, 55 (base): I.R. (CCl4), 3030 (aromatic C-H), 2970, 2950, 2885 (aliphatic C-H's), 1685 (c=0), 1600 (c=C), 1250, 1160 cm'l. l:flromozizmsthxlzizhexsns and Illzlzbremozszhsetsns : These bromides were made from the one carbon-shorter 105 bromides. In a 500 ml round bottomed flask, were placed 25 gr of magnesium (0.19 mole) and 25 ml of THF. Magnesium was 122 activated with 0.5 ml of 1,2-dibromoethane and 0.5 ml of 1- bromo-4-methyl-3-pentene. Then 30 gr of the bromide (0.19 mole) in 100 ml THF was added slowly to keep gentle reflux over 30 min. After another 15 min on a steam bath, 6 gr of paraformaldehyde (0.2 mole, dried in vacuum overnight with phosphorous pentoxide) was added, then the solution was stirred overnight at room temperature. 100 ml of saturated ammonium chloride solution was added and the aqueous layer was extracted with ether. The ether solution was washed with saturated sodium chloride solution and dried over sodium sulfate, then ether was evaporated. Finally 5-methyl-4-hexen- l-ol (15.5 gr, 71 %) was fractionated at 92-95 0C (30 Torr): 1H-NMR (FT-80, c0013) 6 1.61 and 1.69 (2s, 2CH3's), 3.36 (t, 2H), 5.13 (m, 1H). The alcohol was converted to the tosylate and finally to 1- bromo-S-methyl-4-hexene: bp7o =92-95 °C: 1H-NMR (FT-80, CDCl3) 61.64, 1.70 (28, 2CH3's), 3.40 (t, 28), 5.08 (m, 18): I.R. (CC14), 3025 (aromatic C-H), 2975, 2895 (aliphatic C-H's), 1680 (c-0), 1600 (080), 1250, 1170 cm’l. '- - - - - o : This was made from (Z)-1-bromo-4-heptene and p-hydroxyvalerophenone: b.p. = 156- 158 °c (0.1 Torr). 18-NMR (00013), 5 7.93 (d, 2H), 6.92 (d, 23), 5.50-5.30 (m, 28, CH=CH, J = 10.9 Hz), 4.03 (t, 2H), 2.89 (t, 2H), 2.22 (m, 2H), 2.03 (m, 2H), 1.85 (m, 2H), 1.70 (m, 28), 1.40 (m, 28), 0.95 (t, 38), 0.93 (t, 3H): 13 C-NMR (CDC13) 5119.1, 162.9, 132.9, 130.2, 130.0, 127.5, 114.1, 67.3, 37.9, 28.9, 26.7, 23.3, 22.5, 20.4, 14.2, 13.9; MS (m/e), 274, 232, 21 rat add sol aqu la: 123 217, 136, 121 (base), 55: I.R. (0014), 3025, 2975 2895, 1680 (c=0), 1600 (C=C), 1250, 1170 cm-1. ; '- - - - : This ketone was obtained from 4-hydroxybenzophenone (Aldrich) and 1-bromo-3-butene (Aldrich) by the same method as that for the acetophenone derivatives; 1H-NMR (00013) 57.80 (m, 4H), 7.50 (m, 3H), 6.97 (d, 23), 5.85-6.00 (m, 1H), 5.25-5.15 (m, 2H), 4.12 (t, 23), 2.58 (m, 2H); MS (m/e), 252 (M+), 198, 121 (base), 105, 77, 55; IR (0014), 3050, 2925, 2875, 1665 (0:0), 1600, 1250 cm‘l. Qrth9:313snorxnbenxl.kstons§ : The following method was used for all ketones. 0.7 gr of metal sodium was added to ethyl alcohol flushed by nitrogen bubbling. After sodium was dissolved, equimolar amount of g-hydroxyphenyl ketone was added to the solution. After 30 min stirring at room tempe- rature, slight excess of a corresponding alkenyl bromide was added, then refluxed overnight under nitrogen atmosphere. The solvent was changed to ether, and the solution was washed with aqueous KOH solution three times, then ether was evaporated. The product ketones were usually purified by vacuum distil- lation.‘ '- - - - : This is a liquid and was recrystallized at low temperature in haxane: 1 H-NMR (250 MHz, 0606) 6 8.02 (d, 1H), 7.07 (m, 1H), 6.75 (m, 1H), 6.40 (d, 1H), 5.67-5.50 (m, 1H), 4.88-5.00 (m, 2H), 3.42 (t, 2H), 2.52 124 (s, 33), 2.09 (m, 23): MS (70 eV, m/e), 190 (3*), 1175, 162, 149, 136, 121, 91, 77, 55 (base); IR (0014), 3075, 2930, 1675 (c-0), 1600, 1450, 1290, 1240, 1050 cm'l. I- - - - : This was recrystallized in haxane: m.p. 25-28 °C, 1 H-NMR (250 332, c0c13), 5 7.64 (d, IH), 7.40 (m, 1H), 6.97 (m, 1H), 6.85 (m, 1H), 6.00-5.80 (m, 13), 5.20-5.10 (m, 23), 4.10 (t, 23), 2.93 (t, 23), 2.55 (m, 23), 1.70-1.55 (m, 23), 1.45-1.30 (m, 23), 0.95 (t, 33); us (70 eV, m/e), 232 (3+), 203, 190, 175, 162, 147, 133, 121 (base), 105, 93, 77, 65, 55; IR (0014), 2960, 1675 (c-0), 1600, 1450, 1250, 1050 cm-1; UV (heptane), 209.6 (24200), 241.8 (7560), 298.0 nm (3150). '- - - - - - : This was vacuum-distilled: b.p. 98-100 °C (0.1 Torr): 1 H-NMR (250 332, 0606) 5 8.02 (d, 13), 7.06 (m, 13), 6.74 (m, 13), 6.42 (d, 13), 4.73 (br.s, 13), 4.65 (br.s, 13), 3.57 (t, 23), 2.53 (s, 33), 2.10 (t, 23), 1.51 (s, 33); MS (70 eV, m/e), 204 (3+), 189, 159, 149, 136, 121 (base), 91, 69; IR (0014), 2925, 1680 (0:0), 1600, 1450, 1290, 1230, 890 cm‘l. '- - - - - -o v on : This was vacuum-distilled: b.p. 129-130 °c (0.1 Torr); 13-NMR (250 332, c0013) 5 7.62 (d, 13), 7.49 (m, 13), 6.95 (m, 13), 6.91 (d, 13), 4.84 (br.s, 13), 4.80 (br.s, 13), 4.15 (t, 23), 2.97 (t, 23), 2.54 (t, 23), 1.78 (s, 33), 1.62 (qn, 23), 143 (h, 23), 0.90 (t, 33): MS (70 eV, m/e), 246 (3+), 231, 217, 204, 189, III I] 125 147, 136, 121 (base), 69; IR (0014), 2960, 1675 (c=0), 1600, 1450, 1290 cm-1; UV (heptane), 209.6 (24700), 240.8 (7700), 297.8 nm (3080). v- - - - - : This was distilled: b.p. 114-115 °c (0.1 Torr): 1 3-NMR (250 32, 00013) 5 7.74 (d, 13), 7.43 (m, 13), 6.97 (m, 13), 6.93 (d, 13), 5.40-5.63 (m, 13), 4.08 (t, 23), 2.62 (s, 33), 2.59 (m, 23), 2.10 (m, 23), 0.98 (t, 33); MS (70 eV, m/e), 218 (3+), 149, 136, 121, 882, 67, 55 (base); IR (0014), 2960, 1650 (c-o), 1600, 1450, 1025 cm 0 v- - - - - : This was distilled: b.p. 142-144 °c (Torr): 1 H-NMR (250 332, 0606) 5 7.92 (d, 13), 7.07 (m, 13), 6.77 (m, 13), 6.46 (d, 13), 5.50-5.25 (m, 13), 3.51 (t, 23), 3.01 (t, 23), 2.24 (m, 23), 1.91 (m, 23), 1.82 (m, 23), 1.35 (m, 23), 0.89 (t, 33), 0.87 (t, 33): MS (70 ev, m/e), 260 (3+), 178, 149, 136, 121, 105, 82, 67, 55 (base);IR (0014), 2960, 2930, 1645 (0:0), 1600, 1450, 1230, 1025 cm'l: UV (heptane), 209.6 (25400), 241.4 (7540), 298.0 run (3070). a- _ - - - - o : This was distilled at 111-113 °c (0.1 Torr): 1 H-NMR (250 MHz, 0606) 5 8.03 (d, 13), 7.06 (m, 13), 6.75 (m, 13), 6.45 (d, 13), 5.06 (m, 13), 3.48 (t, 23), 2.54 (s, 33), 2.18 (m, 23), 1.59 (s, 33), 1.43 (s, 33); MS (70 eV, m/e), 218 (3+), 149, 136, 121, 82, 67, 55 (base); IR (0014), 2975, 2930, 1675 (c=0), 1600, 124 (s, 33), 2.09 (m, 23); MS (70 eV, m/e), 190 (3*), 1175, 162, 149, 136, 121, 91, 77, 55 (base); IR (cc14), 3075, 2930, 1675 (c-0), 1600, 1450, 1290, 1240, 1050 cm’l. '- - - - : This was recrystallized in haxane: m.p. 25-28 °c, 13-NMR (250 MHz, c0013), 5 7.64 (d, 13), 7.40 (m, 13), 6.97 (m, 13), 6.85 (m, 13), 6.00-5.80 (m, 13), 5.20-5.10 (m, 23), 4.10 (t, 23), 2.93 (t, 23), 2.55 (m, 23), 1.70-1.55 (m, 23), 1.45-1.30 (m, 23), 0.95 (t, 33); 3s (70 eV, m/e), 232 (3+), 203, 190, 175, 162, 147, 133, 121 (base), 105, 93, 77, 65, 55; IR (0014), 2960, 1675 (c-0), 1600, 1450, 1250, 1050 cm'l; UV (heptane), 209.6 (24200), 241.8 (7560), 298.0 nm (3150). '- - - - - - : This was vacuum-distilled: b.p. 98-100 °C (0.1 Torr); 1H-NMR (250 MHz, c606) 5 8.02 (d, 13), 7.06 (m, 13), 6.74 (m, 13), 6.42 (d, 13), 4.73 (br.s, 13), 4.65 (br.s, 13), 3.57 (t, 23), 2.53 (s, 33), 2.10 (t, 23), 1.51 (s, 33); MS (70 eV, m/e), 204 (3+), 189, 159, 149, 136, 121 (base), 91, 69; IR (cc14), 2925, 1680 (c=0), 1600, 1450, 1290, 1230, 890 cm'l. '- - - - e - -o v : This was vacuum-distilled: b.p. 129-130 0C (0.1 Torr); 1H-NMR (250 332, 00013) 5 7.62 (d, 13), 7.49 (m, 13), 6.95 (m, 13), 6.91 (d, 13), 4.84 (br.s, 13), 4.80 (br.s, 13), 4.15 (t, 23), 2.97 (t, 23), 2.54 (t, 23), 1.78 (s, 33), 1.62 (qn, 23), 143 (h, 23), 0.90 (t, 33); MS (70 eV, m/e), 246 (3+), 231, 217, 204, 189, 125 147, 136, 121 (base), 69; IR (cc14), 2960, 1675 (c=0), 1600, 1450, 1290 cm'l; UV (heptane), 209.6 (24700), 240.8 (7700), , 297.8 run (3080) . '- - - - - : This was distilled: b.p. 114-115 °c (0.1 Torr): 13-33R (250 32, 00013) 5 7.74 (d, 13), 7.43 (m, 13), 6.97 (m, 13), 6.93 (d, 13), 5.40-5.63 (m, 13), 4.08 (t, 23), 2.62 (s, 33), 2.59 (m, 23), 2.10 (m, 23), 0.98 (t, 33); 35 (70 eV, m/e), 218 (3+), 149, 136, 121, 882, 67, 55 (base); IR (c014), 2960, 1650 (c-0), 1600, 1450, 1025 L_ cm-1. ‘ ‘ v- - - - - : This was distilled: b.p. 142-144 °c (Torr): 1 3-33R (250 332, 0606) 5 7.92 (d, 13), 7.07 (m, 13), 6.77 (m, 13), 6.46 (d, 13), 5.50-5.25 (m, 13), 3.51 (t, 23), 3.01 (t, 23), 2.24 (m, 23), 1.91 (m, 23), 1.82 (m, 23), 1.35 (m, 23), 0.89 (t, 33), 0.87 (t, 33); 35 (70 eV, m/e), 260 (3+), 178, 149, 136, 121, 105, 82, 67, 55 (base);IR (cc14), 2960, 2930, 1645 (c=0), 1600, 1450, 1230, 1025 cm'l; UV (heptane), 209.6 (25400), 241.4 (7540), 298.0 nm (3070). '- - - - - - o h o : This was distilled at 111-113 °c (0.1 Torr): 13-33R (250 332, 0606) 5 8.03 (d, 13), 7.06 (m, 13), 6.75 (m, 13), 6.45 (d, 13), 5.06 (m, 13), 3.48 (t, 23), 2.54 (s, 33), 2.18 (m, 23), 1.59 (s, 33), 1.43 (s, 33); MS (70 eV, m/e), 218 (3+), 149, 136, 121, 82, 67, 55 (base); IR (c014), 2975, 2930, 1675 (c=0), 1600, 126 1 1450, 1190, 1230 cm'l; UV (heptane), 209.6 (31400), 241.8 (9320), 299.6 nm (4120). " ‘ ' ' ' ' ‘ " : This ketone was prepared from 1-bromo-3-methy1-3-butene and 2- acetyl-4-methylphenol which was made from 4-methylphenyl acetate by the Fries rearrangement: 1 H-NMR (00013), 5 7.50 (d, 13, J - 2.8 32), 7.24 (d of d, 13, J = 2.8, 8.5 32), 6.83 (d, 13, J - 8.5 32), 4.82 (br. s, 23), 4.10 (t, 23), 2.65 (s, 33), 2.60 (m, 23), 2.28 (s, 33), 1.80 (s, 33); 3s (70 eV), m/e 218 (3+), 203, 173, 163, 150, 135 (base), 121, 69; IR (cc14), 2925, 1675 (oao), 1240, 900 cm'l; UV (heptane), 213.2 (27500), 244.0 (8170), 308.8 nm (3620). This ketone was prepared from 1-bromo-3-methyl-3-butene and 2- acetyl-4-ch1oro-5-methylphenol which was made from 3-methyl-4- 13-33R chlorophenyl acetate by the Fries rearrangement: (coc13), 5‘7.69 (s, 13), 6.76 (s, 13), 4.82 (br. s, 23), 4.15 (t, 28), 2.56 (s, 3H), 2.54 (m, 2H), 2.37 (8, 3H), 1.80 (s, 38): MS (70 eV), m/e 254:252 (1:3, M+), 186:184 (1:3), 171:169 (1:3), 77, 69 (base): IR (CC14), 2930, 1680 (c-0), 1600, 1375, 1255, 1225 cm'l; UV (heptane), 217.8 (32500), 246.2 (8240), 310.0 nm (4240). mznxdroxxxsleropnsnone : l-Bromobutane (41 9r. 0-3 mole) was turned to the Grignard solution with magnesium turning (7.5 gr, 0.32 mole) in THF. m-Methoxybenzonitrile (32 gr, 0.24 4" o 127 mole) was added to the Grignard solution, then the solution was refluxed overnight. Acid hydrolysis gave 37.5 gr of m- methoxyvalerophenone (81% yield): 1 H-NMR (CDC13) 6 7.50-7.00 (m, 4H, Ar-H's), 3.85 (s, 3H), 2.90 (t, 2H), 2.00-1.20 (m, 4H), 0.98 (t, 33). m-Methoxyvalerophenone (32.5 gr) and 50 gr of AlCl3 in 160 ml benzene were heated on a steam bath for 3 hr.106 After cooling down, the dark brown solution was hydro- lyzed with cold HCl-water. The benzene layer was extracted with NaOH solution. The aqueous layer was acidified with conc. HCl. The resulting oil was extracted with ether. The ether solution was washed twice with saturated NaCl solution, dried over 39504, then ether was evaporated. The final slightly yellow solid was identified as m-hydroxyvalerophenone and used without further purification: m.p. = 65-67 °C: 1 3-33R (FT-80, 00013) 6 7.61-7.05 (m, 43), 2.98 (t, 23), 1.84-1.29 (m, 43), 0.97 (t, 33); 35 (m/e), 178 (3+), 136, 121 (base), 108, 93, 77, 65: IR spectrum‘(CCl4), 3450 (br, OH), 2975, 1675 (c-0), 1600, 1450, 1275 cm’l. uefazalksnoxxxsleronhenonss : The corre8pondin9 bromides, .m-hydroxyvalerophenone, and patassium carbonate in dry acetone were refluxed overnight. The products were purified by vacuum distillation. .- - - - : b.p. - 114.5-116 °c (0.1 Torr): 1 H-NMR (00013), 6 7.52-7.45 (m, 23), 7.32 (m, 13), 7.07 (m, 13), 5.87 (m, 13, -CH=C), 5.19-5.07 (m, 23, c=032), 4.04 (t, 23, -CH20-), 2.92 (t, 23, -0320=0), 2.53 (m, 23), 1_.__.—_....._ 128 1 1.69 (m, 2H), 1.35 (m, 23), 0.96 (t, 3H); MS (m/e), 232 (M+), 190, 175 (base), 162, 146, 136, 121, 108, 55; IR (0014), 2960, 1675 (c=0), 1590, 1250 cm’l. .- - - - ; b.p. = 124-126 °c (0.1 1 Torr): H-NMR (CDC13), 6 7.51-7.44 (m, 23), 7.32 (m, 13), 7.06 (m, 10, 5.95-5.75 (m, 1H, -CH-C), 5.08-5.00 (m, 2H, C=CH2), 4.00 (t, 2H, C320), 2.92 (t, 23, CH C‘O), 2.21 (m, 2H), 1.88 2 (m, 2H), 1.69 (m, 2H), 1.38 (m, 2H), 0.93 (t, 3H); MS (m/e), 246 (3+), 204, 189, 147, 136, 121 (base), 93, 55; IR (cc14), 2950, 1675 (c=0), 1580, 1430, 1250 cm'l. .- - - - - - ; b.p. - 135- 1 135.6 0C (0.1 Torr): H-NMR (CDC13), 6 7.52-7.45 (m, 2H), 7.32 (m, 13), 7.06 (m, 13), 5.25-5.15 (m, 13, -03-C), 3.96 (t, 23, -0c32), 2.96 (t, 23, 0320-0), 2.47 (m, 23), 1.75-1.65 (m, 23), 1.71 (s, 33), 1.65 (s, 33), 1.38 (m, 23), 0.93 (t, 33); 35 (m/e), 260, 203, 178, 121 83 (base), 55; IR (cc14), 2960, 2925, 2875, 1685 (0:0), 1580, 1430, 1250 cm-1. '- - e -4-he en- -ox val o e one : b.p. = 143-145 1 °c (0.1 Torr): H-NMR (c0013), 5 7.52-7.44 (m, 23), 7.32 (m, 13), 7.06 (m, 13), 5.17-5.08 (m, 13, -CH=C), 3.97 (t, 23, c320), 2.92 (t, 23, CH 020), 2.15 (m, 23), 1.88-1.75 (m, 23), 2 1.75-1.65 (m, 2H), 1.68 (s, 3H), 1.58 (5, 3H), 1.38 (m, 2H), 0.93 (t, 33); 35 (m/e), 274 (3+), 217, 179, 161, 136, 121, 96 (base), 81, 69, 55; IR (cc14), 2910, 2880, 1680 (c=0), 1575, 1430, 1250 cm‘l. D‘- K) 129 X;2in2lbutxr9nhsn9nss_and_§:yinxlxalsronhenones : The following general method was used. To the Grignard solution of 1 a alkenyl bromide in THF, were added equimalar amount of benzonitrile, then the solution was refluxed overnight. After acid hydrolysis, acidic aqueous solution was heated on a steam bath for 2 hr, cooled, then extracted with ether. The ether solution was combined with that collected during acid hydrolysis. After the evaporation of ether, the ketone was purified by vacuum distillation. - - - - - : b.p. 80-80.5 °c (0.1 Torr); 13- NMR (250 332, 00013) 6 7.92 (d, 23), 7.53-7.40 (m, 33), 5.90- 5.70 (m, 1H), 5.06-4.95 (m, 2H), 2.96 (t, ZH), 2.14 (m, 2H), 1.83 (m, 23); 35 (70 ev, m/e), 174 (3+), 120, 105 (base), 77, 51; IR (c014), 3065, 2940, 1675 (c-0) cm'l; UV (heptane), 238.2 (12400), 278.2 (940), 286.2 (740), 323.2 nm (47). - - - - - - ; b.p. 103-105 °c (0.5 Torr): 13-33R (250 332, 00013) 5‘7.93 (d, 23), 7.54-7.40 (m, 33), 5.36 (m, 23), 2.95 (t, 23), 2.11 (m, 23), 2.05 (m, 23), 1.78 (m, 23), 0.92 (t, 3H): I.R. (C014), 3075 (aromatic C-H), 3010, 2975, 2940 (aliphatic C-H's), 1685 (c=0), 1450, 1225, 680 cm’l; 35 (70 eV, m/e), 202 (3+), 120, 105 (base), 77, 51, 44; UV (heptane), 237.8 (4900), 278.6 (330), 321.6 nm (36). - -6-meth - - e - - : b.p. 83-85 °c (0.1 1 Torr): H-NMR (FT-80, CDC13) 6 7.82 (m, 23), 7.45 (m, 3H), 5.10 (m, 13), 2.87 (t, 33), 1.98 (m, 43), 1.70 (s, 33), 1.52 130 (s, 33); 3s (70 eV, m/e), 202 (3+), 120, 105, 82 (base), 77, 67, 51; IR (0014), 2970, 2930, 1665 (c-0) cm’l; UV (heptane), 238.0 (12200), 277.6 (900), 285.8 (720), 324.0 nm (48). - - - - - - : b.p. 113-115 °c (0.= Torr): 1H-NMR (FT-80, c0013) 5 7.85 (m, 23), 7.45 (m, 23), 5.32 (m, 220, 2.85 (t, 33), 2.05 (m, 43), 1.75 (m, 43), 0.97 (t, 33); 35 (70 eV, m/e), 216 (3+), 133, 120, 1055 (base), 94, 77, 67, 51; IR (cc14), 2925, 1685 (c-o) cm'l: UV (heptane), 238.0 (12600), 278.0 (970), 286.0 (780), 324.2 nm (48). 5- Equipmenf_snfi_£rosednre§ a. Rhetosnemissl_§lsasusre§ - All pipettes end volu- metric flasks were Class A type. This glassware was rinsed with acetone three times, then with water, and boiled in a solution of Alconox laboratory detergent in distilled water for 12 hr. The glassware was rinsed with distilled water, and soaked in boiling distilled water for 12-24 hr. This process was repeated at least three times. This method was also used for syringes and the Pyrex test tubes used for irradiations. After the final distilled water rinse, the glassware was dried in an oven reserved specially for photochemical glassware at 150 °c. Ampoules used for irradiation were made by heating the previously cleaned Pyrex tubes (13 x 100 mm) approximately 2.5 131 cm from the top with an oxygen-natural gas torch and drawing them out to a uniform 15 cm length. b. figmplg_£;gpa;a§ign§ - All solution were prepared by either direct measurement into volumetric flasks or diluting a stock solution. A constant volumn (2.8 ml) of the final solution were transfered via syringe into each ampoule. Usually standards used for analyses were weighed directly into the ketone stock solution flasks (internal standards). Or a constant volume of external standard solutions were added to each solutions after irradiation. c. Degassing_£;ggggurg§ - Sample tubes were attached to 4 torr) equipped with a diffusion pump. When a vacuum line (10' the excited triplets have longer lightimes (us scale), a diffusion pump was used. These tubes were connected on a circular manifold equipped with twelve vacuum stopcocks each fitted with one hole rubber (size 00). The sample tubes were slowly frozen in liquid nitrogen bath from the bottom to the top and evacuated for 5-10 min. The vacuum was disconnected and the tubes allowed to thaw at room temperature. This freeze-pump-thaw cycle was repeated three times. After the final cycle, the tubes were frozen, evacuated for 5 min, and sealed with an oxygen-natural gas torch while still under vacuum . 'd. Irradiation Procedures - All samples for lifetime measurement or quantum yield measurement were irradiated in 132 parallel with actinometer solutions in a Merry-Go-Round . apparatus immersed in a water bath at approximately 25 0C. A water cooled Hanovia medium pressure mercury lamp was used as the irradiation source. An alkaline potassium chromate solution (0.002 M K Cro in 1% aqueous potassium carbonate) 2 4 was used to isolate the 313 nm emission band. A Corning 7-83 filter was used to isolate the 365 nm emission band. Preparative scale photolyses were performed using a Hanovia medium pressure mercury lamp filtered through Pyrex. Samples (200 mg) dissolved in 250 m1 spectral grade benzene were irradiated at tap water temperature under a steady stream of argon. Photolyses for direct 1 H-NMR measurement were performed in a water bath with 313 nm. Samples (15 mg) were dissolved in 2 ml benzene-d6, bubbled with argon before irradiation. e. Ana1y§1§_£rgggdurg§ - All GLC analyses were performed on either a Varian Model 1200 or 1400 Gas Chromatogram with a flame ionization detector. Gas chromatograms were connected to either Infotronics CRS 309 Digital Integrator or Hewlett- .Packard Model 3393 A Integrator. Analyses by HPLC were performed on a Beckman Model 332 Gradient Liquid Chromatograph System equipped with a Perkin- Elmer LC-75 Ultraviolet-Visible Detector and DuPont 860 Column Compartment. An Altex Ultrasphere Si Absorption Phase column were used for separations. Solvents used were either HPLC Grade or Spectral Grade and were filtered through a 0.45 pm 133 Nylon 66 membrane prior to use. The UV detecting system was connected to a Hewlett-Packard Model 3380 Integrator. For gas chromatography, all samples were introdued by on- column injection with a carrier gas (nitrogen) flow rate of 40 ml/min. The following 1/8" o.d. aluminum columns were used - - Column #1 - 6' 3% QF-l on Chromsorb G 6' 3% QF-l with 2% ROM on Chromsorb G Column #2 5' 5% SE-30 on Chromsorb G - Column #3 - Column #4 - 25' Fused Silica Megabore Column The concentration of the photoproducts was calculated from the following equation. A [photo] = (R.F.) x [std] x -§h9§9 std Response factors for each of the photoproducts and their respective internal standard were obtained by gas chromatography and calculated from the following equation: - 3.51:5. mo1"“‘mhoxzc2 ReFe "" X Aphoto m‘Dlesstd When a photoproduct isolated was not enough to measure the response factor, the following calculation was applied: (# of C's + 1/2(# of C-0 bonds))§td (# of C's + l/2(# of C-0 bonds)) photo 134 For all HPLC analyses, the first equation was used. The response factors are summarized in Table 23 and 24. L W - The amount of photons absorbed by samples was determined by valerophenone actino- metry. A degassed 0.10 M valerophenone in benzene was irradiated in parallel with the samples to be analyzed. After completion of the irradiation, valerophenone solution was analyzed for acetophenone, using the same equation as that for ketones. The quantum yield for the photoproduct formation was calculated from the acetophenone concentration knowing that the quantum yield for valerophenone is 0.33. <1>= 4.3%.), 0.33 B-MWMLWH In general, photoproducts were obtained by a large scale photolysis of 0.01 to 0.1 M solutioins of a ketone in spectral grade benzene or acetonitrile under argon atomosphere. The conversion was monitored by an analytical GC. A medium pres- sure Hanovia mercury vapor lamp was used as a light source. A pyrex filter was used to filter out the light below 295 nm. Identification of the primary photoproduct from ortho-(3- 1 methyl-3-buten-1-oxy)acetophenone was based on H-NMR, homo- 135 Table 2 3 . photoproducts. Gas chromatographic response factors for various conditionsa Standard/Photoproduct R.F Clé/Acetophenone #1, 140°C 1.92 CBBz/4-valeryl-cyclooctatrieneb #2, 190°C 0.938 C7Bz/3-valeryl-cyclooctatrienec #2, 190°C 1.077 0732/3-valeryl-1-Me-cyclooctatriened #2, 192°C 0.966 C7Bz/1-actyl-hexadienee #4, 160°C 0.933 CSBz/m-(3-butenoxy)acetophenone #4, 160°C 1.200 CloBz/m—(4-Me-3-pentenoxy)acetophenone #4, 180Gb 1.289 acolumns and temperatures b c d 4-valry1-11-oxabicyclo[6.3.0]undec-1,3,5-triene. 3-valery1-9-oxabicyclo[6.3.0]undec-3,5,7-triene. 3-va1eryl-1-methyl-9-oxabicyclo[6.3.0]undec-3,5,7-triene. e1-acetyl-2,2-dimethyl-6-oxatricyclo[5.4.0.03'7Jundec-8,10- diene. 136 Talbe 24. HPLC response factors for various photoproducts. Standard/Photoproducts R.F. C1Bz/p-methoxyacetophenone (p-APO) 0.04868 Cle/p-APll 0.04485 Cle/p-APlz 0.04352 Cle/p-AP13 0.03804 Cle/p-APZI 0.0412 CIBz/p-APZZ 0.0403 Cle/p-AP31, p—AP41, p—APgl, p—AP33, p—AP32 0.0412 aUltrasphere Si column, hexane/ethyl acetate (97/3), 9 270 nm. 137 13 decoupling, NOE technique, C-NMR, partially decoupled 13C- NMR, IR, GC-MS, and UV-Visible spetra. Direct products from other ketones were identified basically from 1 H-NMR spectra and all spectral data of the primary photoproduct from EILEE- (3-methyl-3-buten-1-oxy)acetophenone were used as references. The attempt for purifing photoproduct resulted in the thermal rearrangement and a preparative TLC gave the same rearranged products as those from a preparative GC. Usually the major rearranged products were cyclooctatrienes. The preparative GC (Varian Model 920) was set as injecting port temperature of 180 to 200 °c. the detector temperature of 200 to 210 °c, and the oven temperature of 160 to 180 °c. To see the direct photoproducts, about 0.05-0.1 M of alkenoxyphenyl ketones in benzene-d6 were bubbled in small test tubes with argon for 5-10 min, then irradiated outside the 313-nm filter solution. The 1 H-NMR were taken repeatedly after a certain time interval irradiation (2-12 hours). The spectra showed one major photoproduct in most cases. The sample solutions for the time-based UV-Visible spectra were prepared by adding a certain volume of stock .solution into an UV cell and diluting with 3 ml of solvent. Then the septum-capped cell was bubbled with dried argon at least 10 min. Usually, the changes in the spectra were detectable within 30 sec. 1 13 Structural assignments were based on H-NMR and C-NMR, Infrared spectroscopy, and mass spectroscopy. 1H-NMR spectra were recorded on either a Varian T-60 NMR Spectrometer, a Varian CFT-20 NMR Spectrometer (80 MHz), or a Bruker WM-250 138 13C-NMR spectra were Fourier Transform NMR Spectrometer. recorded on the Bruker WM-250 instrument (62.9 MHz). All spactra werer calibrated using either tetramethylsilane (5a- 0.0 ppm) or solvents (chlorofrom, 6 7.24 ppm: benzene, 6 7.15 ppm) as an internal standard. Infrared spectra were recorded on a Perkin-Elmer Model 237 B Grating Infrared Spectrophoto- meter. Mass spectra were recorded on a Finnigan 4000 GC/MS using the direct inlet mode. This instrument was operated by Mr. Ernest A. Oliver or Dr. Rick Olson. Ultraviolet-Visible absorption were recorded on a Varian Carey 219 Spectrophoto- meter or a Shimazu UV-160 Spectrophotometer. Melting points were recorded on a Thomas Hoover Capillary Melting Point Apparatus and are not corrected. 21:i3:Methxl:1:buten:1:oxxlsostonhsnone.(o-APZZ) = 5-10 m9 of the ketone in 2 ml of benzene-d6 was irradiated and its 13- NMR spectra were taken every two hours. Two photoproducts were 1 observed and the ratio was 7:1 from the integration of H-NMR spectrum. The major product was characterized as 1-acetyl-3- methyl-6-oxatricyclo[7.2.0.03'71undec-7,10-diene: 1 H-NMR (250 332, 0606) 6 6.04 (dd, 13, J - 0.9, 2.8), 5.81 (d, 13, J = 2.8), 4.98 (d, 13, J = 6.6), 3.77 (m, 23), 3.32 (dd, 13, J = 0.9, 6.6), 1.90 (d, 23), 1.85 (s, 33), 1.38 (dt, 13, J - 11, 9.5), 1.25 (dd, 13, J = 11, 4.1), 1.02 (s, 33); 13 C-NMR (62.9 332, c606) «5207.9 (s), 163.9 (s), 144.8 (d, J = 130.7 32), 139.6 (d, 128.1), 90.8 (d, J = 111.8), 67.3 (t, J = 92.0), 63.2 (s), 46.3 (d, J = 83.8), 41.7 (t, J = 55.5), 40.0 (t, J = 60.1), 39.5 (s), 25.3 (q, J = 61.0), 24.0 (q, J = 50.0); 35, 139 m/e 204 (3+), 189, 161, 136, 121, 105, 91, 43 (base); FT-IR (CHCla) 2995, 2961, 2930, 2899 (m, aliphatic C-H stretching), 1688.5 (5, carbonyl), 1665 (w, c=C), 1160 (s) cm'l; UV-Visible (c33c3) 295 nm (200) Thermal rearrangement of the tricyclic product in a preparative GC gave 6-acetyl—8-methyl-11-oxabicyclo[6.3.0] undec-1,3,5-triene: 13-33R (250 332, c0013) 6 7.13 (d, 13, J = 5.7), 6.12 (dd, 1H, J - 12.5, 7.7), 5.84 (dd, 1H, J - 12.8, 5.7), 5.17 (d, 1H, J = 7.7), 4.10 (dd, 2H, J = 3.2), 2.91 (d, 13, J - 13.2), 2.45 (d, 13, J = 13.2), 2.08 (td, 13, J - 10.4), 1.87 (8, 3H), 1.85 (td, 13, J 8 3.2), 1.02 (s, 33): MS, m/e 204 (3+), 189, 136, 121, 105, 43 (base); UV-Visible (hexane) 237 nm (19,000), 374 nm (4,400). Irradiation (313 or 365 nm) of the above cyclooctatriene (ca. 0.01 M) in benzene-d6 gave the identical tricyclic product on 1H-NMR spectra. Also the unknown minor product was observed: 13-33R (0606), 66.31 (d of d, 13, J - 4.8, 2.9 32), 6.07 (d of d, 13, J - 2.9, 1.5 32), 5.75 (d, 13, J - 2.9 32), 3.35 (d, 13, J - 5.5 Hz), 1.91 (s, 3H), 0.74 (s, 33), others not determined. Irradiation of 15 mg of g-AP 2 in 250 ml benzene at >295 nm 2 for 30 min gave both the cyclooctatriene and the cyclobutene product. (see Fig. 26) 140 65588205 05 :3 65:52vo 0.: Adv ”Accesses Co 1: SN 5 we no 8:585 e: 2m 16 N925 ca 5859: 222+: 9:. .3 26mm 141 '- - - - , (g-Ale) : 10-20 mg of the ketone in argon-bubbled benzene-d6 was irradiated at 313 nm. A single product was detected on the 1H-NMR spectrum after 3-4 hrs. Continuous irradiation (overnight) could not give 100% conversion but ca. 70-80% conversion. The direct photoproduct was 1--acetyl-6-oxa-tricyclo[7.2.0.0:""7 1 ]undec-7,10-diene: H- NMR (250 332, c606) 65.86 (d, 13, J - 2.8 32), 5.78 (d, 13, J = 2.8), 4.96 (d, 1H, J = 6.6), 3.78 (t, 1H, J = 8.5), 3.50 (dq, 13, J - 8.5, 5.7), 3.26 (d, 13, J - 6.6), 2.09 (m, 13), 1.84 (s, 33), 1.78 ( , 13, J = 5.1), 1.48 (t, 13, J = 13), 1.46 (t, 1H, J = 12.5), 1.21 (m, 1H, J I 8.5, 11.5). After through a preparative GC column (SE-30) at 170-180 0C, the tricyclo product underwent thermal rearrangement to give lH_. yellow 6-acethyl-11-oxabicyclo[6.3.0]undec-1,3.5-triene: NMR (250 MHz, C0013) 6‘7.13 (d, 1H, J I 6.2), 6.06 (dd, 1H, J - 13, 8.8), 5.75 (dd, 13, J - 13, 6.2), 5.34 (dd, 13, J - 8.8, 1.9), 4.13 (dt, 1H, J I 2.5, 8.1), 4.02 (dt, IH, J I 5.7, 11.5), 3.04 (dd, 13, J - 1.9, 13.4), 2.73 (m, 13, J - 8.3), 2.23 (dd, 1H, J I 13.4, 8.3), 1.85 (m, 1H, J I 8.1). 0 --.’o H H I .. A 9’ 5 ° 0 I- - _ -bute - - - 'I 3 The fi‘s I starting ketone in the argon-bubbled benzene-d6 in a test tube was irradiated at 313 nm and yielded a photoproduct. After >95 % conversion checked by 1H-NMR spectra, the solvent was 142 evaporated. The photoproduct was 1-acety1-3,10-dimethyl-6- 3'7]undec-7,10-diene: 1H-NMR (250 MHZ; oxatricyclo[7.2. 0.0 0606) 65.49 (d, 13, J - 1.5), 4.99 (d, 13, J - 6.7), 3.78 (m, 2H), 3.16 (d, IH, J = 6.7), 1.93 (d, 1H, J = 14.9), 1.88 (s, 33), 1.84 (d, 13, J = 14.9), 1.42 (s, 33), 1.34 (m, 23), 1.01 (s, 33): MS (70 eV), m/e 218 (M+), 203, 175, 163, 150, 135, 119, 108, 91, 77, 69, 55, 43 (base). Irradiation (313 nm) of the ketone in benzene-d6 gave one product which was monitored by NMR. The product was identified as 1-acety1-10-chloro-3,9-dimethyl-6-oxatricyclo[7.2.0 .0] undec-7,10-diene: 1H-NMR (250 MHZ, C «56.71 (s, IH), 5.15 606) (8, 1H), 3.64 (t, 1H, J I 8.7), 3.52 (m, 1H, J I 5.5, 8.7), 2.98 (d, 18, J I 13.1), 2.25 (d, 18, J I 13.1), 1.99 (ABX, 1H, J - 12.9, 3.0), 1.91 (s, 33), 1.80 (s, 33), 1.26 (ABX, 13, J = ‘ 12.9, 5.5), 0.87 (s, 33); MS (70 eV), m/e 254:252 (1:3 ratio, M+), 237, 217, 209, 184, 169, 153, 100, 91, 77, 69, 55, 43 (base): UV (CH3CN), no major absorption above 300 nm. IQ“, Cl 55.-.4." 3131-31 143 21:i9ia:3:stsnzlzoxxlacetonhenone (o-Aonis) = Irradiation (313 or >295 nm) of the ketone in benzene gave two photo- products. One of these was idendified as a tricyclo- 3'7.0]undec-7,10-diene. Major product was not identified [7.2.0 yet. But after column chromatography, the major product converted to a cycloocta- triene. 1-Acetyl-2-ethyl-6-oxatricyclo[7.2.0.03'7]undec-7,10-diene: 13-33R (C6D 5 6.04 (d, 13, J = 2.9 32), 5.89 (d, 13, J = 6)! 2.9 Hz), 4.92 (d of d, 1H), 3.07 (d, 1H) ppm, others not mm‘. (5' a determined. 2 l The major product: H-NMR (C6D 6 6.32 (d, 13, J - 5.1 Hz), 5). 6.00 (s, 13), 3.55-4.98 (m, 23), 3.37 (d, 13, J - 5.1 32), 3.18 (m, 13), 1.94 (s, 33), 1.85-1.95 (m, 23), 1.60-1.70 (m, 23), 1.35-1.50 (m, 23), 1.00 (t, 33); 35, m/e 218 (3+), 203,~ 189, 175, 147, 133, 120, 105, 91, 77, 65, 55. 13-33R The rearranged product from the major photoproduct: (0606), 6 6.62 (d, 13, J - 5.3 32), 5.98 (d of d, 13, J - 5.7, 11.1 Hz), 5.60 (d Of d, 1H, J I 5.3, 11.1 Hz), 5.48 (d, 1H, J I 5.7 Hz), 3.85-3.55 (m, 23), 1.92 (s, 3H), others not determined: MS, m/e 218 (M+), 203, 189, 175, 147, 133, 120, 105, 91, 77: UV-Visible (heptane), kmax 335, 237 nm. .- - - - - - , (Q-APZB) : This ketone gave initially a cyclohexadiene derivative (30-40 %) on 144 313 or >295-nm irradiation, which converted to a cyclobutene derivative on prolonged irradiation. The cyclohexadiene (up to 80 % purity) was isolated by column chromatography (silica gel, hexane/ether (99/1)). 3; 1-Acety1-2,2-dimethy1-6-oxa-tricyclo[5.4.0.0 7]undec-8,10- diene: 1 3-33R (250 332, 0606) 6 5.69 (dd, 13, J - 9.6, 5.6), 5.53 (dd, 13, J - 9.8, 5.6), 5.43 (d, 13, J a 9.6), 5.34 (d, 13, J - 9.8), 3.68 (m 23), 2.47 (dd, 13, J = 8.5, 1.8), 2.31 (s, 33), 1.52-1.60 (m, 13, J = 1.8), 1.34-1.45 (m, 13, J = 8.5), 1.25 (s, 33), 1.19 (s, 33). 1-Acety1-2,2-dimethyl-6-oxatricyclo[7.2.0.03'71undec-7,10- diene: 1 3-33R (250 332, 0606) 5 6.00 (d, 13, J - 2.8 32), 5.76 (d, 13, J I 2.8), 4.97 (dd, 1H, J I 2.7, 6.4), 3.79 (dt, 1H, J - 2.4, 8.5), 3.57 (m, 13, J - 8.5), 3.54 (d, 13, J - 6.4), 2.35 (dt, 13, J - 2.7, 10.1), 1.88 (s, 33), 1.37 (m, 23), 0.91 (s, 3H), 0.70 (s, 3H). Also two small singlets appeared at 0.84 and 0.76 ppm and were considered to come from a isomer: 35 (70 eV, m/e), 218 (3+), 203, 185, 175, 161, 147, 133, 120, 105, 91, 83, 55, 43 (base). After the cyclobutene was heated at 130 °C on an oil-bath under argon gas for 45 min, it was dissolved in benzene-d6. 1 The H-NMR spectrum was the same as that of the cyclohexa- diene. 145 u- - - - , (p-Ale) : 1H-NMR spectrum was taken from the direct photoproduct, which was derived from the 313-nm irradiation in benzene-d6. Some precipitate were formed and filtered off with haxane-ether solvent through a glass filter filled with silica gel in a short time period. 1- 5'9] undec-2,10-diene: 13-33R (250 Acetyl-B-oxatricyclo[7.2.0.0 332, c606) 6 6.06 (d, 13, J - 2.7), 5.85 (d, 13, J - 2.7), 5.83 (d, 1H, J I 11.1), 5.59 (m, 1H, J I 11.1), 3.64 (dt, 1H, J - 2.7, 8.0), 3.51 (m, 13, J - 8.0), 2.09 (s, 33), 1.86 (m, 33), 1.78 (m, 13), 1.34 (m, 13); 13 C-NMR (62.9 332, 00013) 6 '210.3, 139.0, 138.4, 126.3, 125.8, 68.9, 68.6, 66.7, 39.5, 28.7, 28.0, 24.5; 35 (70 eV) m/e 190 (3+), 175, 162, 147, 129, 121, 105, 91, 77, 55, 43 (base). The procuct collected by prep GC was identified as 4-acetyl- 11-oxa- bicyclo[6.3.0]undeca-1,3,5-triene: 1 H-NMR (250 332, 00013) 6 7.00 (d, 13, J - 6.8), 6.27 (d, 13, J - 12.5), 5.92 (q, 13, J - 12.5, 6.8), 5.40 (d, 13, J - 6.8), 4.24 ( m, 13, J - 6.8), 4.16 (m, 13, J - 6.8), 3.06 (m, 13, J - 6.3), 2.38 (s, 33), 2.29-2.50 (m, 23, J - 6.8, 6.3), 2.13 (m, 13, J-- 6.3), 1.83 (m, 13, J - 6.3); 13 C-NMR (62.9 332, 00013) 5 199.3, 170.5, 144.6, 137.8, 131.6, 125.1, 96.1, 69.3, 40.1, 31.3, 30.9, 26.4. From the valerophenone derivative, another product was collected by preparative GC. This product has three vinyl protons: 1 H-NMR (250 332, coc13) 67312 (d, 13, J - 5.2), 6.07 (d, 13, J - 12.6), 5.93 (dd, 13, J - 5.2, 12.6), 4.23 (t, 23),others not determined. 146 E\ A 05» o O '- ' - : p-Methoxyacetophenone (0.1 gr) in 1-hexene (10 ml) was irradiated with 313 nm light after bubbling with argon for 10 min. The conversion was monitered on GC. After about 10 % conversion, a product was collected from a preparative GC. The product was not 100 % 1 pure, but clearly four vinyl protons were observed on H-NMR spectrum: 1 3-33R (250 332, 00013) 5 7.08 (d, 13, J = 5.2 32), 5.82 (dd, 13, J = 12.3, 4.6), 5.67 (d, 13, J = 12.3), 5.19 (d, 13, J - 5.2), 3.72 (s, 33), 2.38 (s, 33); 35 (70 eV), m/e 234 (31), 219, 203, 191, 177, 161, 135 (base), 121, 91, 77, 58; - A - UV Visible (heptane), max 312 nm. 0 O ONh '- - - - -o , (p-Vchis) : The efficient photoisomerization of the gig ketone gave the trans— derivative. After 7-8 hr irradiation, HPLC analyses showed that the solution reached an equilibrium state which has about 85 % of the tggng and 15 % of the gig ketone. The trans ketone has the following spectroscopic data: 1 H-NMR (250 332, coc13) Q7.92 (d, 23), 6.91 (d, 23), 5.56 (m, 23, J = 15.7 32), 4.02 (t, 23), 2.86 (t, 23), 2.48 (m, 0-c-c32), 2.04 (m, c=c-c32), 5:71.11 arm-126T- . 2.:- 147 1.68 (m, 23), 1.39 (m, 2H), 0.99 and 0.95 (2 t, each 33): I.R. (cc14), 2970, 2940, 2890 (aliphatic C-H's), 1675 (c=0), 1600 (c=C), 1245, 1160 cm'l. The gig acetophenone derivative in benzene was irradiated with argon bubbling at >295 nm overnight and a product was observed on GC. It showed the vinyl proton peaks of a cyclobutene in 1H-NMR spectrum: two doublets at 6.25 and 6.35 ppm with J = 3 Hz. 0 [I6 Et 0 '- - - - - - , (p-AP33) : The initial product (<20 % conversion) was identified as 1-acety1- 4.4-dimethy1-9-oxatricyclo[8,2, 0,05'10 1 ]dodec-2,11-diene: H- NMR (250 M2, c606) 5 6.55 (d, 1H, J I 3.1 Hz), 6.34 (d, 1H, J I 3.1), 5.46 (d, 1H, J I 10.2), 5.40 (d, 1H, J I 10.2), 3.45 .(m, 1H), 3.23 (m, 1H), 2.33 (s, 3H), 0.85 (s, 3H), 0.74 (s, 3H), others not determined. I Further irradiation gave a cyclooctatriene-like product which has four vinyl protons: 1 H-NMR 6(c606), 6.22 (d, 13, J = 7.7 32), 6.01 (d of d, 13, J - 7.7, 6.0 32), 5.77 (d, 13, J - 6.0 32), 5.57 (d of d, 13, J - 6.0, 2.4 32), 3.24 (d of t, 13, J = 2.4, 10.6 Hz), 2.53 (s, 3H) ppm, others not determined. A i 148 J \ i l I 1 O '- - - - : The benzophenone in benzene- d6 in a small test tube was bubbled with dried argon and irradiated at 313 nm for 24 hr. The 1H-NMR spectrum showed new peaks which correspond to a cyclobutene, but the conversion to F'- ‘7'”?73171'7‘13—3‘ the product was estimated to be less than 1 %. The new peaks: 1H-NMR (250 MHz, C606), (56.14 (d, J I 3 Hz), 5.98 (d, J I 3 Hz), 5.85 (d, J = 10.5 Hz), others were not determined. APPENDIX The tables in this Appendix show the raw data from quantum yield measurements and Stern-Volmer quenching studies. Analysis conditions, concentrations of the materials used (ketones, internal & external standards, products, and actinometry), as well as other pertinent experimental conditions are also provided. In all cases, g.c. or HPLC peak area ratios are the average of at least two injections. The following abbreviations are used for the actinometer and the standards; ACP - acetophenone, VP = valerophenone, MeBz = methyl benzoate, C4Bz = n-butyl benzoate, C882 8 n-octyl benzoate, CnBz = n-alkyl benzoate, etc. 149 12",qu 31.- . ' I" 150 TABLE 25. Quenching of the type II product formation from p- methoxyvalerophenone with 2,5-dimethyl-2,4-hexadiene in acetonitrile at 25°C. Run 1.a k ‘t= 3900, CD = 0.16 q II HPLC analysis: Ultrasphere Si Hexane : EtOAc (98.5 : 1.5) 1.2 ml/min, 270 nm [diene] , 10'43 (Pr/St) area [p-MeO-ACP] , 10'43 (pa/(p 0.0 .658 2.67 1.00 0.52 .592 2.40 1.14 1.3 .441 1.79 1.53 2.6 .356 1.45 1.89 5.2 .264 1.07 2.55 10.4 .131 0.53 5.15 [KETONE] = 0.24 M, [MeBz] = 0.00833 M, 313 nm, 15 min. b VP actinometer: [VP] = 0.11 M, [C16] = 0.0124 M, [ACP] = 0.000618 M. Run 2.a 151' _ b kq‘tI 4400, II — 0.12 -4 -4 [diene] , 10 3 (Pr/St) area [p-MeO-ACP] , 10 3 (pa/q; 0.0 3.083 8.30 1.00 0.67 2.823 7.60 1.09 1.69 1.449 3.90 2.13 3.37 1.114 3.00 2.77 6.74 0.721 1.94 4.28 10.11 0.590 1.59 5.21 13.49. 0.427 1.15 7.21 a [KETONE] - 0.028 3, [MeBz] - 0.00553 3, 313 nm, 40 min. b VP actinometer; [ACP] - 0.00226 3 ETTTTSTI‘TFKQ’ "fl 1 I 152 Run 3.a _ b kq‘tI 4100, <1>II -— 0.19 [diene],10'43 (Pr/5t)area [p-3e0-Acp],10'53 (po/¢; 0.0 .807 25.56 1.00 1.93 .500 15.83 1.61 3.86 .357 11.31 2.26 7.71 .210 6.66 3.84 11.57 .142 4.50 5.68 15.43 .112 3.55 7.20 a [KETONE] = 0.024 3, b [MeBz] I 0.00651 M, VP actinometer: [ACP] - 0.000451 M 313 nm, 15 min. 153 TABLE 26. Quenching of the type II product formation from p- methoxyvalerophenone with 2,5-dimethy1-2,4-hexadiene in benzene at 25°C.a b k ‘t- 4000, (bII = 0.18 HPLC analysis: Ultrasphere Si q Hexane : EtOAc (98.5 : 1.5) 1.2 ml/min, 270 nm [diene] , 10'43 (Pr/St) area [p-MeO-ACP] , 10'43 olo/

]"’,10'3 0.0 2.291 28.6 1.00 1.66 1.450 18.1 1.58 4.16 0.841 10.5 2.72 8.31 0.497 6.21 4.61 16.6 0.280 3.50 8.17 24.9 0.182 2.27 12.6 3 [331033] - 0.013 3, [MeBz] - 0.00303 3, 313 nm, 30 min. b VP actinometer; [ACP] - 0.00578 3. . ii" .4 Id.l-)£4§91fil_ 1 1’ l n 166 TABLE 39. Quenching of the type II product formation from p- (9-undecen-1-oxy)valerophenone with 2,5-dimethyl- 2,4-hexadiene in acetonitrile at 25°C.a quII 4400 HPLC analysis: Ultrasphere Si Hexane : EtOAc (98.5 : 1.5) 1.2 ml/min, 270 nm -4 -4 [diene],10 M (Pr/St)area [type II],10 M <1>olo/ ; 0.0 0.214 3.93 1.00 0.43 0.164 3.00 1.31 0.85 0.110 2.01 1.96 1.71 0.095 1.74 2.26 2.56 0.0676 1.24 3.17 3.41 0.0556 1.02 3.85 1 [331033] - 0.014 3, [MeBz] - 0.00455 3, 313 nm, 2 hr. b VP actinometer; [ACP] I 0.00350 M. 168 TABLE 41. Quenching of the cycloaddition product formation from p-(3-methyl-3-buten-1-oxy)valerophenone with 2,5-dimethyl-2,4-hexadiene in acetonitrile at 25°C.a kq‘t I 94, CPI]: = 0.0271) GC analysis: 7' QF-l column 193°C -2 -4 [diene],10 3 (Pr/5t)area [type 111,10 3 o/ 0.0 0.745 9.00 1.00 0.53 0.577 6.97 1.29 1.05 0.434 5.24 1.72 1.58 0.336 4.06 2.22 2.11 0.253 3.06 2.94 3.16 0.194 2.34 3.85 3 [331033] - 0.021 3, [C882] - 0.00137 3, 313 nm. b VP actinometer: [ACP]total = 0.0112 3. f ‘I' 73137.3 , 3.; 17.171. 1. 169 TABLE 42. Quenching of the type II product formation from p- (3-methyl-3-buten-1-oxy)valerophenone with 2,5- dimethyl-2,4-hexadiene in benzene at 25°C.a b k 1- 74, <1> = 0.0045 q II HPLC analysis: Ultrasphere Si Hexane : EtOAc (98.5 : 1.5) 1.2 ml/min, 270 nm 2 [diene],10- 3 AII/Ast <1>ol<1> 1) _ "“3 0.0 .291 1.00 0.34 .254 1.24 0.68 .201 1.56 1.37 .146 2.16 2.05 .121 2.60 2.74 .105 2.99 b. VP actinometer; [KETONE] I 0.012 M, [ACP] I 0.00413 M. [MeBz] I 0.00477 M. 170 TABLE 43. Quenching of the type II and the cycloaddition product formation from p-(3-methyl-3-buten-1-oxy) valerophenone with 2,5-dimethyl-2,4-hexadiene in benzene at 25°C.a [diene] , 10'23 [addn] b (DA/4’3 AII/Agt <1; O/cp 0.0 8.85 1.00 3.63 1.00 0.52 6.60 1.34 2.73 1.33 1.03 4.57 1.94 2.01 1.80 1.55 3.63 2.44 1.78 2.04 2.07 3.76 2.35 1.57 2.31 3.10 2.28 3.88 1.28 2.84 a [KETONE] - 0.011 3, [C882] - 0.00114 3, VP actinometer: b 4 [ACP]total - 0.0131 M. Addition product, 10' M: GC analysis (7' QF-l column, 193°C), kq‘t - 95, (DH - 0.022. c Type II product: HPLC analysis (Hexane : EtOAc (98.5 : 1.5), 1.2 d ml/min, 270 nm), k ‘tI 60,¢II I 0.0039. excluded from the q calculation. 171 TABLE 44. Quenching of the photoisomerization of p-(gig-3- hexen-l-oxy)valerophenone with 2,5-dimethyl-2,4- hexadiene in acetonitrile at 25°C.a b k.‘t= 58, (bisom = 0.27 HPLC analysis: Ultrasphere Si q Hexane (100) 1.2 ml/min, 270 nm [diene] , 10'23 Atrans/Atotalc <1>°/<1> 0.0 14.7 1.00 0.60 11.0 1.34 1.19 9.1 1.61 2.38 6.4 2.31 3.57 4.5 3.28 4.76 4.1 3.63 a [KETONE] - 0.011 3, [MeBz] - 0.00464 3, 313 nm, 25 min. b c VP actinometer: [ACP] I 0.00200 M. area ratio of the trans to the total ketone. 172 TABLE 45. Quenching of the type II product formation from p- (5-methyl-4-hexen-1-oxy)valerophenone with 2,5- dimethyl-2,4-hexadiene in acetonitrile at 25°C.a kq‘ts 1100, (bII = 0.040b HPLC analysis: Ultrasphere Si Hexane : EtOAc (98.5 : 1.5) 1.2 ml/min, 270 nm [diene] , 10'33 (Pr/5t) area [type II], 10'53 <1>°/ 0.0 0.780 14.63 1.00 0.34 , 0.570 10.68 1.37 0.85 0.436 8.17 1.79 1.71 0.258 4.84 3.02 3.41 0.166 3.11 4.70 5.12 - 0.127 2.39 6.12 a [KETONE] - 0.014 3, [MeBz] - 0.00455 3, 313 nm, 30 min. b VP actinometer: [ACP] = 0.00350 M. 173 TABLE 46. Quenching of the type II product formation from p- methoxyvalerophenone with 2-methy1-l-pentene in acetonitrile at 25°C.a k ‘II 2.15 HPLC analysis: Ultrasphere Si Hexane : EtOAc (98.5 : 1.5) 1.2 ml/min, 270 nm [quencher], M (Pr/St) area (Do/(b 0.0 1.61 1.00 0.098 1.57 1.03 0.246 1.26 1.28 0.492 0.90 1.80 0.983 0.552 2.92 1.475 0.395 4.08 a. [KETONE] I 0.055 M, [C4Bz] - 0.00342 3. 174 TABLE 47. Quenching of the type II product formation from p- methoxyvalerophenone with 2-methyl-2-pentene in acetonitrile at 25°C.a .r~- - nun-aw kq‘t = 5.36 HPLC analysis: Ultrasphere Si Hexane : EtOAc (98.5 : 1.5) 1.2 ml/min, 270 nm [quencher] , M (Pr/St) area (Do/(D 0.0 3.57 1.00 0.035 2.82 1.27 0.088 2.24 1.59 0.177 2.00 1.79 0.354 1.23 2.90 0.530 0.91 3.91 [KETONE] - 0.044 3, [C832] I 0.00187 M. 175 TABLE 48. Quenching of the type II product formation from Y- vinylvalerophenone with 2,5-dimethyl-2,4-hexadiene in benzene at 25°C.a <0 - 0.28b k 12- 10.2, GC analysis: 7' QF-1 column I Lu‘lj In!” _ ‘ q II 160 °C -3 [diene] , 3 (Pr/St) area [ACP] , 10 3 o/ .000 0.660 2.18 1.00 .046 0.460 1.52 1.43 .092 0.336 1.11 1.96 .138 0.257 0.85 2.56 .184 0.236 0.78 2.79 .276 0.173 0.57 3.82 a [KETONE] - 0.030 3, [017] - 0.00111 3, 313 nm, 1hr. b VP actinometer: [ACP] I 0.00257 M. 176 TABLE 49. Quenching of the type II product formation from Y- vinylvalerophenone with 2,5-dimethyl-2,4-hexadiene in acetonitrile at 25°C.a kq‘t .. 14.9, ¢II = 0.1713 HPLC analysis: Ultrasphere Si Hexane : EtOAc (99.2 : 0.8) 1.2 ml/min, 270 nm [diene], 3 (Pr/5mm.“l [ACP],10'43 CDC/0 .000 0.565 17.8 1.00 .017 0.464 14.6 1.22 .043 0.365 11.5 1.55 .086 0.263 8.28 2.15 .172 0.162 5.10 3.49 .259 0.117 3.68 4.84 a [KETONE] - 0.023 3, [C882] - 0.00164 3, 313 nm, 1hr. b VP actinometer: [ACP] I 0.00342 M. 177 TABLE 50. Quenching of the type II product formation from 1- phenyl-S-octen-l-one with 2,5-dimethyl-2,4-hexadiene in benzene at 25°C.a kq12= 7.1, (bII = 0.16b GC analysis: 7' QF-l column 160 °C . -4 [diene] , 3 (Pr/St) area [ACP] , 10 3 <1>o/ .000 0.281 14.00 1.00 .091 0.164 8.17 1.71 .182 0.133 6.60 2.12 .273 0.105 5.24 2.67 .364 0.0689 3.82 3.66 .546 0.0575 2.86 4.90 ‘ [KETONE] - 0.030 3, [016] - 0.00262 3, 313 nm, 3 hr. b VP actinometer: [ACP] - 0.00257 3. 178 TABLE 51. Quenching of the type II product formation from 1- phenyl-6-methyl-5-hepten-1-one with 2,5-dimethyl- 2,4-hexadiene in benzene at 25°C.a kqft= 3.2, (DII = 0.13b HPLC analysis: Ultrasphere Si Hexane : EtOAc (99.2 : 0.8) 1.2 ml/min, 270 nm ’3 i-v [diene] , 3 (Pr/5t)areal [ACP] , 10‘43 cpo/cb .000 0.1621 8.07 1.00 .077 0.1587 7.90 1.36 .154 0.1193 5.94 1.52 .231 0.0902 4.49 1.80 .307 0.0808 4.02 2.01 .461 0.0571 2.84 2.84 [KETONE] = 0.026 3, [C882] = 0.00262 3, 313 nm, 3hr. b VP actinometer: [ACP] = 0.00209 M. 179 TABLE 52. Quenching of the type II product formation from 1- phenyl-6-methyl-5-hepten-1-one with 2,5-dimethyl- 2,4-hexadiene in acetonitrile at 25°C.a kq‘t- 5.1, ¢II = 0.26b HPLC analysis: Ultrasphere Si Hexane : EtOAc (99.2 : 0.8) 1.2 ml/min, 270 nm [diene] , 3 (Pr/St) area [ACP] , 10‘43 <1>°/<1> .000 0.560 17.3 1.00 .076 0.395 12.2 1.42 .189 0.276 8.52 2.03 .378 0.185 5.73 3.02 .756 0.115 3.57 4.85 1.134 0.067 2.07 8.36 [KETONE] I 0.0195 M, [C882] I 0.00161 M, 313 nm, 3hr. b VP actinometer: [ACP] = 0.00112 M. 180 TABLE 53. Quenching of the type II product formation from 1- phenyl-6-g1g-nonen-1-one with 2,5-dimethyl-2,4- hexadiene in benzene at 25°C.a _ b kq‘t- 33.5, (DH — 0.23 HPLC analysis: Ultrasphere Si Hexane : EtOAc (99.2 : 0.8) 1.2 ml/min, 270 nm [diene] , 10'23 (Pr/St) area [ACP] , 10'43 ol<1> 0.00 0.884 14.20 1.00 1.04 0.666 10.70 1.33 2.08 0.532 8.54 1.66 3.11 0.443 7.12 1.99 4.15 0.367 5.89 2.41 b VP actinometer: [ACP] I 0.00229 M. ‘ [KETONE] - 0.022 3, [C8Bz] - 0.00135 3, 313 nm, 45 min. TABLE 54. Quenching of the type II product formation from 1- 181 phenyl-6-gig-nonen-1-one with 2,5-dimethyl-2,4- hexadiene in acetonitrile at 25°C.a kq‘tI 53 (DII = 0.46b HPLC analysis: Ultrasphere Si Hexane : EtOAc (99.2 : 0.8) 1.2 ml/min, 270 nm [diene] (Pr/St) area [ACP] , 10 3 (Do/<9 0.000 0.366 1.84 1.00 0.068 0.086 0.431 4.27 0.137 0.044 0.222 8.29 0.205 0.031 0.156 11.80 ‘ [KETONE] - 0.019 3, [C882] - 0.00262 3, 313 nm, 45 min. b VP actinometer: [ACP] - 0.00135 3. 182 TABLE 55. Effects of pyridine on quantum yield for acetophenone formation from 1-phenyl-5-hexen-1-one in benzene at 25°C.a GC analysis: 7' QF-l column 160 °C [pyridine] 3 (Pr/5t) [ACP] 10’33 <9 ° 1 I area ’ II 0.000 0.126 0.82 .28 r 0.258 0.239 1.55 A .54 0.515 0.270 1.75 .61 0.773 0.241 1.56 .54 1.03 0.256 1.66 .58 1.55 0.264 1.71 .59 a b C [KETONE] - 0.027 3, [017] - 0.00218 3, 313 nm, 25 min. VP actinometer: [ACP] I 0.00095 M. corrected from the absorption ratio (k313= 40). 183 TABLE 56. Effects of pyridine on quantum yield for acetophenone formation from l-phenyl-6-methy1-5- hepten-l-one in benzene at 25°C.a GC analysis: 7' QF-l column 0 160 c [ ridine] 3 (Pr/St) [ACP] 10'33 <9 ° py ' area ' II .000 0.168 1.09 .200 .203 0.331 2.15 .394 .406 0.373 2.42 .447 .610 0.413 2.68 .495 a [KETONE] = 0.026 3, [C17] - 0.00218 3. b VP actinometer: [ACP] - 0.00193 3. c corrected from the absorption ratio (A313- 40). 184 TABLE 57. Quenching of the type II product formation from m- (3-buten-1-oxy)valerophenone with 2,5-dimethyl-2,4- hexadiene in benzene at 25°C.a kq‘ta 320, (bII = 0.0073b GC analysis: 25' Megabore 160 ° C e -3 -5 [d1ene], 10 3 (Pr/St)area [type II] ,10 3 ¢ol<1> 0.0 0.104 15.6 1.00 0.51 0.0305 4.57 3.41 1.01 0.0210 3.15 4.95 1.52 0.0177 2.65 5.89 a [KETONE] - 0.010 3, [0582] - 0.00125 3, 313 nm, 2.5 hr. b VP actinometer: [ACP] - 0.00709 3. 185 TABLE 58. 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