The ability to functionalize arenes is one of the quintessential features of modern chemistry. As such, being able to catalytically modify an arene substrate with perfect regioselectivity is a worthwhile goal. To this end, two methods for functionalizing substrates with precise ortho selectivity have been achieved, using the borylating reagent pinacolborane (HBPin), and bis(pinacolato)borane (B2Pin2). The first method involves the ortho borylation of aniline substrates using BPin as an easily removable traceless directing group. By forming an N-BPin bond in situ, the nitrogen's remaining hydrogen is able to act as an outer sphere directing group, coordinating to the oxygen bonds on a BPin group attached to the iridium catalyst. In this way, the ortho borylation of aniline substrates was performed with great success and with even higher yields than were obtained with the similar Boc protected method. The second method involves the use of a new ligand, SiPBz, which enables the ortho borylation of methyl benzoate substrates via a chelate driven mechanism. The full substrate scope of the ligand shows high yields and very good selectivity. Subtle ligand modifications were also tested in order to determine the optimum ligand for different types of substrates.
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