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This is to certify that the
thesis entitled
THE SYNTHESIS OF 5 ,15-BIS(3 , 5-DINITROPHENYL ) -
2,3,7,8,12,13,17,18-OCTAMETHYLPORPHYRIN

presented by

Robert V. Honeychuck

has been accepted towards fulfillment
of the requirements for

M.S. Chemistry
degree in

 

 

at; «cm

Major professor d,

Date (“Vb 14' [387’

 

0-7639

 

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OVERDUE FINES:
25¢ per day per item
RETURNIIKS LIBRARY MATERIALS:

Place in book return to remove
charge from circulation records

 

 

THE SYNTHESIS OF 5, I5-BIS(3,5—DINITROPHENYL)
2,3,7,8,12,13,l7,18—0CTAMETHYLPORPHYRIN

by

Robert V. Honeychuck

A THESIS

Submitted to‘
Michigan State University
in partial fulfillment of the renuinements
for the decree of '

MASTER OF SCIENCE

Department of Chemistrv

I982

ABSTRACT

THE SYNTHESIS OF 5,15-BIS(3,5-DINITROPHENYL)-
2.3.7.8,12,13,17,18-OCTAMETHYLPORPHYRIN

By

Robert V. Honeychuck

The title compound was synthesized from.2-benzyloxycarbonyl-3,“,5-
trimethylpyrrole and 3,5-dinitrobenzoyl chloride. The route involved
condensation of’a.5,5'-free dipyrromethane with 3,5-dinitrobenzaldehyde
in methanol with a catalytic amount of p-toluenesulfonic acid. Conden-

sation in propionic acid produced the corresponding monoaryl compound.

To Nancy, whose infinite patience and understanding

made this work possible.

ii

ACKNOWLEDGEMENTS

I would like to take this opportunity to thank Dr. Chi K. Chang for
his continued interest and guidance in this project. I also thank Dr.
Ching-Bore Wang, Richard Young, Brian Ward, and Dr. Fujio Ebina for many
useful discussions.

Finally, I deeply appreciate the support my parents and parents-

in-law have given me over the years.

111

TABLE OF CONTENTS

LIST OF TABLES .

LIST OF FIGURES

INTRODUCTION . . .

RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . . . . . .
EXPERIMENTAL . . . . . . . . . . . . .

General . . . . . . . . . . . . . . . . . . . . . . . . . .
S-Acetoxymethyl-z-benzyloxycarbony1-3, h-dimethylpyrrole (3)
5 ,5'-Bis(benzyloxycarbonyl)- 3, 3', u ,A'-tetramethy1-2, 2'-

dipyrromethane (fl) . . . . . . . . . . . . . . . .
3, 3' ,u ,u'-Tetramethy1-2, 2'-dipyrromethane-5, 5'-dicarboxylic
acid (5) . . . . . . . . . . . . . . . . . . . .

3,3' ,A,“'-Tetramethy1-2,2'-dipyrromethane (é) . . . .

Preparation of lithium aluminum trifit-butoxy hydride in
ethYI ether 0 O O O O O I O O O O O O I O I O O O O

Attempted preparation of lithium aluminum trifit-butoxy
hydride in diglyme . . . . . . . . . . . . . . . .

3, 5-Dinitrobenzaldehyde (8) .

5,15-Bis(3,S-dinitrophenyl)-2,3,7,8,12,13,17,18-octamethyl-
porphyrinogen (9) . . . . . . . . .

5- (3 5-Dinitropheny1)-2,3,7,8,12,13,17,18-octamethy1-
porphyrin (10) . . . . . . . . . . . . . . .

5, 15-Bis(3, 5-dinitrophenyl)- 2, 3, 7, 8 ,12, 13, 17, 18-octamethy1-
porphyrin (1). . . . . .

BIBLIOGRAPHY .

iv

Page

vi

17

17
17

18

18
19

19

20
20

22

22

23
25

LIST OF TABLES

Table Page

1 Printout of Figure A . . . . . . . . . . . . . . . . . . . 10

2 Printout of Figure 7 . . . . . . . . . . . . . . . . . . . 15,

LIST OF FIGURES
Figure Page
1 Synthesis of 5, 15-bis(3,5-dinitrophenyl)-2,3,7,8, 12,13,
17,18-octamethy1porphyrin (1). . . . . . . . 3
2 250 MHz 1H nmr of porphyrinogen 2_. . . . . . . . . . . . . 6
3 Possible pathway for the production of monoaryl porphyrin 19 8

A 250 MHz 1H nmr of monoaryl porphyrin 10 in 96: 3: 1

CDC13: F3CCO2 H: (CH3 )uS . . . . . . . . . . . . . . . . . 9
5 250 MHz 18 nmr of monoaryl porphyrin 10 in 98: 1: 1

CDC13: FBCCO2 H: (CH3)uSi . . . . . . . . . . . 11
6 250 MHz 1H nmr of monoaryl porphyrin 10 in 99:1

CD013:(CH3)AS . . . . . . . . . . . . . . . . . . . 12
7 250 MHz1H nmr of diaryl porphyrin l. . . . . . . . . . . . . 1”

vi

INTRODUCTION

A considerable amount of work has been done in recent years on
porphyrins coupled to other molecules. These elaborated porphyrins
when mmtalated serve as models of hemoglobin1, myoglobin1’5, enzymes
with two metal ions held in close proximity at the active sitez’n’17,
and cytochromes P-u503. As a precursor to a porphyrin which could be
coupled simultaneously on both sides of the prophyrin plane, the meso-
diaryl compound 5,15-bis(3,5-dinitropheny1)-2,3,7,8,12,13,17,18-octa-

methylporphyrin (1) was synthesized.

 

Several routes to mesa-diaryl porphyrins have already been pub-
lished. Baldwin and coworkers6 attached two benzaldehyde moieties to a

strap and condensed them with benzyl 3,fl-dimethy1pyrrole-2—carboxylate

to give a bis dipyrromethane. After catalytic hydrogenolysis and
cyclization with trimethyl orthoformate a strapped porphyrin, with the
strap stretching from one meso-aryl group to the other, was obtained.
Several diaryloctaethylporphyrins (diaryl OEP'S) have been made by
Ogoshi, et. a1.7 Various benzaldehyde derivatives were combined with
3,3'u,h'~tetraethyl-2,2'-dipyrrylmethane in benzene with trifluoroace-
tic acid yielding 5,15-diaryl-2,3,7,8,12,13,17,18-octaethylporphyrins.
In this study a change in solvent to prOpionic acid gave monoaryl OEP's
in 15-25% yield.

Gunter and Mander8 have reported that the reaction of 3,3',u,uv-
tetramethyl-2,2'-dipyrrylmethane with gynitrobenzaldehyde in methanol
with a catalytic amount of petaluenesulfonic acid gave, after oxida-
tion, 5,15-bis(g¢nitrophenyl)-2,3,7,8,12,13,17,18-octamethylporphyrin.
This approach was used in this work (Figure 1) because the procedure

promised a high yield porphyrin synthesis under mild conditions.

 

 

HOAS

/ <’ Pb(OAc)u,\ ’2?.T§:\ glacial HOAc
PhCHZOZC /\_ 8130131 PhCHZOZC N CHZOSCH3 H20
80 H 0

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TsOH \ 1
HeOI-I 7 -
0 o N
2N L1A1H(o-_t_-Bu) 3 3
CHO ‘ diglyme, _780, 77.6% ' C001
0 o
:9' Q 2N

Figure 1. Synthesis of 5,15-bis(3,S-dinitrophenyl)-2,3,7,8,12,13,17,
18-octamethylporphyrin (ll

RESULTS AND DISCUSSION
The lead tetraacetate method of Siedel and Winkler9 was used to
convert a-methylpyrrole g to a-acetoxymethylpyrrole‘3. This is a clean
reaction which proceeds in high yield in 10 minutes, and is conveniently
monitored by thin layer chromatography (TLC). Solvolysis to the

symetrical dipyrromethane it was accomplished in aqueous acetic acid”.

Bromine vapor is easily used here to develop TLC plates11b. Dipyrro—
methanes oxidize to the red dipyrromethenes immediately; pyrroles turn
yellow temporarily.

The benzyl groups of dipyrromethane 3 were removed by catalytic
hydrogenolysis with 10% palladium on carbon. An acid or base hydrolysis
is not preferred here since under these conditions decarboxylation is
enhanced. The major problem usually encountered in a hydrogenolysis of
a dipyrromethane is precipitation of the product, which is then diffi—
cult to wash away from the catalyst. The best procedure involves use of
a small amount of catalyst. Some extra product may be obtained by
washing the catalyst with methanol or tetrahydrofuran (THF), but this is
not always effective. Hot wash solvents are to be avoided since they
decarboxylate the product.

Dipyrromethane-5,5'-dicarboxylic acid 2 was decarboxylated in
aqueous hydroxide with hydrazine stabilizer under high pressure and

temperature. The recommended8 procedure in a sealed Pyrex tube at 170°C

resulted in an explosion. A steel reaction tube gave satisfactory

5

results. Many problems were encountered in the decarboxylation of this
diacid; Paine12 has presented a discussion of these difficulties.
Decarboxylation in the following solvents failed, due either to acid-
catalyzed rearrangements or lack of decarboxylation:trifluoroacetic
acid, benzene + trifluoroacetic acid, dimethyl fermamide, sodium hy-
droxide + methanol, sodium hydroxide + water, and sodium hydroxide +
diglyme (diethylene glycol dimethyl ether).

13,14,15 from

Lithium aluminum trifitggt-butoxy hydride was prepared
lithium aluminum hydride and 3 equivalents of trbutyl alcohol in ethyl
ether. The dry powdered product was dissolved in diglyme for the
subsequent reduction. Direct preparation of this hydride in diglyme‘u
failed.

The procedure of Siggins, et. al.13, was used in the hindered
hydride reduction of 3,5-dinitrobenzoyl chloride (1) to 3,5-dinitro-
benzaldehyde (§). Over-reduction to the alcohol occurs if too much of
the unhindered species (lithium aluminum hydride, lithium aluminum tr
butoxy hydride, lithium aluminum dietebutoxy hydride) is present. Li-
thium aluminum trifitebutoxy hydride is a white powder when pure, but
gray when contaminated with the other hydrides.

Condensation of 3,5-dinitrobenzaldehyde (8) and 3,3',H,u'-tetra-
methyl-2,2'-dipyrrylmethane (9) took place in methanol with a catalytic
amount of pftoluenesulfonic acid, giving the brown porphyrinogen 2_in
33% yield from Q. The 250 MHz proton nmr ofjg (Figure 2) indicates that
it is present as a mixture of _ci_s and M isomers (phenyls 9E or
t§§g§_to each other). The presence of'u distinct methyl singlets in the
o1.6-2.0 region supports this conclusion. Also, the porphyrinogen

produced is the diaryl species, not monoaryl. Peaks C and D are the cis

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7
or trans benzylic protons. The monoaryl compound can have only a single
peak here for its single benzylic proton. For the area ratios (A and B

are the -CH2- protons):

 

C + D
+ = 0.533

This is close (6.7% error) to the expected value of 0.500 in the diaryl
compound. In any case, the best evidence is that the porphyrin made

from g is clearly diaryl and not monoaryl.

Gunter and Mander have shown8 that no mass spectrum could be

obtained with bis(genitrophenyl)-octamethylporphyrinogen. Consistent
with this, 2 did not give a mass Spectrum.
When dipyrromethane g was condensed with 3,5-dinitrobenzaldehyde

in propionic acid, the monoaryl porphyrin resulted, in agreement with

Ogoshi, et. al.7. This could occur8’16 by acid-catalyzed rearrangement

of the porphyrinogen precursors as shown in Figure 3.
The proton nmr of 19 is presented in Figures A, 5, and 6. These

spectra were taken in the following manner:

Figure A (96:3:1 CDCl CCOZH:(CH Si)

3‘F3 3’11

JLNash with 51 aq NaH003

Figure 5 (98:1:1 CDCl :F CCO H:(CH

3 3 2 3’11“)

\Lwash with 5: aq Ncho3

Figure 6 (No F CCOZH)

3

Figures A and 5 take advantage of the concentration dependent shift
668.6 to 67.“) of trifluoroacetic acid to show no hidden peaks beneath

the large TFA peak. The 19 assignments are made in Figure A. Note that

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the c methyls appear more than 1 ppm upfield of the other methyls due to
shielding by the phenyl ring. The b protons reside on the nitrogens
with lower electron density, presumably those closer to the nitro
groups.

The e usthyls in Figures u and 5 are present as a single sharp
peak. When acid is removed (Figure 6), e splits into two singlets, as
might be predicted for a first order spectrum of 19' Interpretation of
Figures h and 5 as a 1:1 mixture of diarylporphyrin l and octamethyl
porphyrin is thus ruled out. This mixture could not possibly give the
pattern in Figure 6.

These spectra are typical of'many porphyrins in that all impurities
are greatly magnified. Many porphyrins are so insoluble that a reason-
able spectrum can be obtained only on a pulsed Fourier transform
instrument. Figures fl, 5, and 6 are the result of 502, 1021, and 1000
scans, respectively. They all show stopcock grease23 at.60.1, 0.9, and
1.2, methylene chloride at 05.2, and chloroform at 67.2.

Porphyrinogen _9_ was oxidized with 2,3-dichloro-5,6-dicyano-1,1!-
benzoquinone in tetrahydrofuran to give the diaryl octamethyl porphyrin
1. Comparison of the nmr spectra of 10 and 1 (Figures 14-7) shows that in
this case the diaryl compound was obtained. Two methyl singlets are
seen in place of 3 or 14 for monoaryl porphyrin _1_C_) and one meso peak
instead of two. The printout for Figure 7 is given in Table 2.

Several conclusions may be drawn from this work regarding the
synthesis of 5,1S-diary1porphyrins. First, the decarboxylation of
3,3',ll,14'-tetramethyl-2,2'-dipyrrylmethane-5,5'-dicarboxylic acid and
similar dipyrrylmethanes must be done under basic conditions to avoid

acid-catalyzed rearrangements. Second, the porphyrin must be checked

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16

carefully by spectroscopic methods to show that the diaryl (not the
monoaryl) product has indeed been produced. The appearance of the
correct molecular ion in the mass spectrum is helpful in this respect
but cannot be expected in every case since these diaryl porphyrins often
do not melt at the maximum possible temperature of a particular spectro-
meter. Finally, although in one case8 high yield procedures have been
reported, the method may not be generally useful since here a low yield
was obtained in the final oxidation step, and the overall yield (1."01)

is low.

EXPERIMENTAL
General
NMR spectra were obtained on a Varian T-60 or on a Bruker WM-250
instrument with tetramethylsilane as internal standard. Mass spectra
were done on a Finnigan 4021 with INCOS data system. Infrared spectra
were recorded on a Perkin-Elmer 283-8 spectrometer. UV-visible spectra
were taken on a Varian Cary 219 machine with 1 cm quartz cells. Melting

points are uncorrected.

5-Acetoxymethyl-Z-benzyloxycarbonyl-3,u-dimethylpyrrole (3)

To a 3-necked 2 liter round-bottomed flask with a condenser was
added 60.8 g (0.250 mol) of a-methylpyrrole g, 500 ml of glacial acetic
acid, and 133 g (0.300 mol) of lead tetraacetate. The solution was
heated on a steam bath at 800 for 10 min, poured into a beaker, and
diluted with 500 ml of water. The precipitate was filtered and washed
with water and a portion dried on the vacuum pump giving a light yellow
solid: nmr (CDC13) 61.96 (s, 3H), 2.00 (s, 3H), 2.23 (s, 3H), ”.92 (s,
2H), 5.20 (s, 2H), 7.25 (s, 5H); mass spectrum We (rel. inten.) 91
(100), 301 (20, molecular ion); IR (KBr) 1210, 1278, 1500, 1673, 1735,
3310 cm'1; mp 102-105ofl This melting point has been previously reported

018 0‘9
as 118-120 and 169-171

17

18

5,5'-Bis(benzyloxycarbony1)-§,§',9,”'-tetramethyl-2,2'-dipyrromethane
_gg

Pyrrole 3 (75.2 g, 0.250 mol) and glacial acetic acid (2700 ml)
were added to a 3-necked 5 liter round-bottomed flask with a condenser.
The flask was heated with a steam bath and 700 m1 of water was added
after the pyrrole went into solution. If the pyrrole is added to
aqueous acetic acid, it dissolves very sluggishly. The dark solution
was heated for 2 hours and diluted with 1000 ml of water. The product
was filtered and washed with 9 liters of water and 500 ml of 20:80
acetone:water and dried on a vacuum pump giving yellow crystals: yield
h5.6 8 (77.6%); nmr (CDC13) 01.90 (s, 6H), 2.20 (s, 6H), 3.66 (s, 2H),
5.09 (3, RH), 7.10 (s, 10H), 9.” (br s, 2H); mass spectrum m/e (rel.
inten.) 91 (100), #70 (51, molecular ion); IR (KBr) 1270, 1012, 1500,

16u5, 1682, 3352 cm"; mp 17u—17s°; lit. mp2° 179°.

3,3',M,”'-Tetramethyl-2,2'-dipyrromethane-5,5'-dicarboxylic acid (5)
To a 100 ml 1-necked round-bottomed flask with a magnetic stirring
bar on a one atmosphere hydrogenation apparatus were added 2.110 g
(0.00510 mol) of dipyrromethane dibenzyl ester 3 and 50 m1 of tetrahy-
drofuran. After the starting material dissolved, 0.203 g of 10%
palladium on carbon was added and the flask was evacuated and filled
with hydrogen three times. The hydrogenolysis was complete in 8 hrs,
using 260 ml (0.0106 mol) of hydrogen. The catalyst was filtered on a
Biichner funnel, washed with 500 m1 of THF, dried, and weighed to
determine whether any product remained on it. (A visual inspection will
suffice at this point since palladium on carbon is gray when contami-

nated with 5 and black when uncontaminated.) The filtrate was filtered

19

5 more times to remove residual catalyst and evaporated on the rotary
evaporator. The white solid was dried on the vacuum pump: yield 1.fl8 g
(100%); nmr (DMSO-d6) 01.86 (s, 6H), 2.07 (s, 6H), 3.63 (s, 2H), 10.7

(br 3, NH); lit.21

nmr (DMSO-d6) 61.89 (s, 6H), 2.11 (s, 6H), 3.72 (s,
2H), 10.96 (8, NH); mass Spectrum m/e (rel. inten.) an (5”), 152 (18),
290 (13, molecular ion); IR (KBr) 86a, 1035, 3000-3u00 cm-1; mp 16h°

dec.

3,3',fl,u'-Tetramethy1-2,2'-dipyrromethane (6)22

In a 75 m1 steel reaction tube were placed 1.00 8 (3.“5 x 10.3 mol)
of dipyrromethane dicarboxylic acid 5, 6.9 ml of 10% w/w aqueous sodium
hydroxide solution, and 0.10 ml of hydrazine hydrate (containing 2.1 x
10'3 mol of hydrazine). Nitrogen was bubbled through the solution for
10 minutes and the tube was sealed and heated at 170°C in an oil bath for
4 hrs. The vessel was chilled to 00 and opened and the tan product
removed with water. The base was neutralized with sulfur dioxide and
the product filtered, washed with cold water, dried, and weighed: yield
0.519 g (71.51). The product was used immediately in the condensation

with 3,5-dinitrobenzaldehyde.

Preparation of lithium aluminum tri-t-butoxyhydride in ethyl etherw’15

All of the glassware in this reaction was oven dried and kept under
dry nitrogen. .A 3-necked 2 liter round-bottomed flask was equipped with
an overhead stirrer, condenser, and 250 ml addition funnel. Ethyl ether
(“80 ml) and lithium aluminum hydride (7.28 g, 0.192 mol) were placed in
the flask; A solution of'uu.6 g (0.60M mol) of t—butyl alcohol in 150 m1

of ethyl ether was added through the addition funnel over 2 hrs. The

20

suspension was stirred another 30 minutes, at which time slow evolution
of hydrogen still occurred. The solvent was decanted, leaving a gray
solid. The solid was dried on the vacuum pump with a heat gun. The
dried solid was light gray, but weighed only 37.5 3, not the desired
48.8 g. Accordingly, H80 ml of ethyl ether was added along with 22.3 g
(0.302 mol) of t—butyl alcohol in 100 m1 of ethyl ether» The suspension
was stirred under nitrogen for 19 hrs. At the end of 19 hrs, the
suspension still evolved hydrogen very slowly. Decantation and drying
gave a light gray solid which when dissolved in diethylene glycol
dimethyl ether (diglyme) satisfactorily reduced 3,5-dinitrobenzoyl

chloride to the corresponding aldehyde.

Attempted preparation of lithium aluminum tri-t-butoxyhydride in

diglmem

To a dry 3-necked 200 ml round-bottomed flask under dry nitrogen
with a magnetic stirring bar and addition funnel were added 1.82 g
(0.0u80 mol) of lithium aluminum hydride and no ml of dried diglyme.
EggE-butyl alcohol (13.1 ml, 0.143 mol) was added over 1 hr through the
addition funnel. The flask was stirred for 2 more hours. The resulting
gray suspension was filtered through a fritted glass funnel under
nitrogen. Much gray material was filtered out, and the filtrate did not

reduce 3,5-dinitrobenzoyl chloride to the aldehyde.

3,5-Dinitrobenzaldehyde (8)13

A diglyme solution of lithium aluminum trietebutoxy hydride was
prepared in the following way. To an Erlenmeyer flask was added 11.6 g
(0.0“56 mol) of the hydride and #0 m1 of dry diglyme. The flask was

stoppered and stirred overnight. The gray suspension was filtered the

21

next day through a fritted glass funnel, pushed by dry nitrogen, through
Celite 5H5, directly into the addition funnel used in the reduction
step. The resulting solution was nearly clear and light gray.

The reduction took place as follows. To a 3-necked 250 ml round-
bottomed flask with an overhead stirrer, the above addition funnel, and
the exit bubbler, was added 9.59 g (0.0u1u mol) of 3,5-dinitrobenzoyl
chloride and 40 ml of dry diglyme. The entire reaction was done under
nitrogen. After the acid chloride went into solution, the flask was
placed in a dry ice-isopropyl alcohol bath and cooled for several
minutes. The reducing agent was added through the addition funnel over
70 min. The reaction mixture turned red on addition of the hydride.
Stirring continued for 30 more minutes.

The cold reaction mixture was poured with stirring into a #00 ml
beaker containing 13 ml of concentrated hydrochloric acid, 26 ml of
saturated aqueous sodium chloride, and 13 g of crushed ice. An
additional 13 ml of saturated aqueous sodium chloride was added and a
brown upper layer formed. The contents were transferred to a separatory
funnel and the upper layer was reserved while the bottom was extracted
with three 100 ml portions of benzene. The upper layer and the benzene
extracts were combined and washed with seven 300 ml portions of 0.12 M
aqueous hydrochloric acid. Two 125 ml portions of aqueous 21 sodium
bicarbonate neutralized remaining acid in the benzene layer; the pH of
the second washing was 8. The organic layer was dried overnight over
anhydrous sodium sulfate, filtered, and reduced on the rotary evapora-
tor to dryness. The product was dried on the vacuum pump to give 3,5-

dinitrobenzaldehyde as a tan solid yield 6.30 g (77.61); nmr (CD013)

22

68.88 (d, 2H), 9.11 (t, 1H), 10.01 (s, 1H); mass spectrum m/e (rel.
inten.) 195 (100), 196 (79, molecular ion); IR (CHC13) 13u8, 1555, 1721

1

cm- ; mp 71-78°. A portion recrystallized from toluene/hexanes gave a

melting point of 76-780.

5,15-Bis(3,5-dinitrophenyl)-2,3,7,8,12,13,17,18-octamethylporphyringggn
(2)

In a 1-necked 100 ml round-bottomed flask were placed 0.611 g (3.02
x 10.3 mol) of 5,5'-free dipyrromethane 6, 0.592 g (3.02 x 10'3 mol) of
3,5-dinitrobenzaldehyde, 0.1”3 8 (7.55 x 10'“ mol) offlpgtoluenesulfonic
acid unnohydrate, and 35 ml of methanol. The flask was stoppered and
left for 12 hrs. Filtration of the reaction mixture on a fine fritted
glass funnel gave brown crystals which were washed with ice cold
methanol, pumped dry, and stored in the dark under nitrogen at 0°. The
product was obtained as a mixture of gig and 25223 isomers: yield 0.37?
8 (32.9%); nmr (00013) 61.68 (s, 12H, CH3), 1.71 (s, 12H, CH3), 1.92 (s,
12H, CH

), 1.96 (s, 12H, CH ), 3.3a (3, un, 032), 3.7 (m, an, CH2), 5.50

3 3
(s, 2H, CH), 5.60 (s, 23, CH), 7.5 (br 8, NH), 8.32 (d, an, Aer), 8.30

(d, NH, ArHZ), 8.8 (m, HH, 0 N—C-CH-C-NOZ). This material does not melt

2
but turns black gradually from 150-3000C; thus, no mass spectrum could

be obtained.

5-(3,5-Dinitrophenyl)-2,3,7,8,12,13,17,18-octamethylporphyrin (10)

In a 500 ml 1-necked round-bottomed flask was placed 6.56 3 (0.0226
mol) of dipyrromethane dicarboxylic acid 5. The flask was fitted with a
septum and filled with nitrogen and 10 ml of trifluoroacetic acid was

added via syringe. After 3 min the trifluoroacetic acid was collected

23
in a vacuum pump trap, leaving behind a red oil. The oil was
transferred to a 1000 ml 1-necked round-bottomed flask and a. solution

of 3.63 g (1.85 x 10'2

mol) of 3,5-dinitrobenzaldehyde in 500 ml of
propionic acid was added. The magnetically stirred flask was heated
under reflux open to the air for 20 hrs. Solvent was evaporated with
heat and an air line, giving a black tar. A portion of the tar was
chromatographed on a silica gel preparative TLC plate with toluene. The
first band near the solvent front was collected giving 19 as a brown
solid: yield 0.0030 3 (0.0557); nmr (96:3:1 CD013:F3 3)“
3.00 (s, 2H), -2.10 (s, 2H), 2.25 (s, 6H), 3.33 (s, 6H), 3.58 (s, 12H),

CCOZH:(CH 31) o
9.59 (s, 2H), 9.61 (s, 1H), 10.37 (s, 1H), 10.09 (s, 2H); nmr (99:1

CD013:(CH 81) 02.91 (s, 6H), 3.59 (s, 6H), 3.60 (s, 6H), 3.62 (8, 6H),

3’0
9.30 (s, 2H), 9.53 (s, 1H), 10.01 (8, 1H), 10.18 (s, 28); “max (CH2C12)
nm 396 (Soret), 506, 591, 573, 626. This compound does not melt at less

than “00°C and therefore gave no mass spectrum.

5,15-Bis(3,5-dinitrqphenyl)-2,3,7,8,12,13,17,18-octamethylporphyrin (1)
Porphyrinogen 9 (0.377 g, 11.96 x 10."l mol), 2,3-dichloro-5,6-
dicyano-1,0-benzoquinone (000, 0.009 g, 1.98 x 10'3 mol), and tetrahy-
drofuran (00 ml) were placed in a 100 ml 1-necked round-bottomed flask.
The flask was stoppered, left at room temperature for 3 hrs, and put in
the freezer for 30 min. Filtration on a fine fritted glass funnel
(funnel A) gave a black solid containing some product. The solid was
dissolved in methylene chloride and passed through a silica gel pad on
another funnel (funnel B) giving a red filtrate. The filtrate from
funnel A was reduced to dryness on the rotary evaporator and the solid

transferred to a funnel (funnel C), where it was rinsed with 2 liters of

24
10% aqueous sodium hydroxide, removing the hydroquinone of DDQ. The
aqueous filtrate at the end of the 2 liters was faint yellow. The
material on funnel C was then rinsed with distilled water, dissolved in
methylene chloride, and passed through another silica gel pad (funnel
D). The filtrates from funnels B and D were reduced to dryness on the
rotary evaporator. The solids were combined and dried on the vacuum
pump giving 1 as a purple solid: yield 0.0310 g (8.291); Amax(CH2012) nm
(e) 395 (9.07 x 10”), 512 (1.00 x 10"), 506 (5.53 x 103), 578 (5.32 x
103), 630 (2.26 x 103); IR (KBr) 1300, 1505 cm“. A portion of the solid
was further purified on a silica gel preparative TLC plate with
CH2C12/CH30H and gave the following nmr (95:9:1 CD013:F30002H:(CH3)H-
Si): o-1.60 (s, 4H), 2.23 (s, 12H), 3.26 (s, 12H), 9.59 (s, 9H), 9.61
(s, 2H), 10.33 (s, 2H). The product does not melt below 000°C and gave

no mass spectrum.

BIBLIOGRAPHY

10.

11.

12.

13.

14.

15.
16.

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