Regio-, diastereo- and enantioselectivity in the photocatalytic generation of carbanions via hydrogen atom transfer and reductive radical-polar crossover

Abstract

A sequence involving photocatalytic hydrogen atom transfer (HAT), reductive radical-polar crossover (RRPCO), and protonation/deuteration for stereochemical editing at benzylic positions is described. A systematic screening of substrates with benzylic C–H bonds provides trends in reactivity for C–H activation by silane thiols. A cis/trans isomerization of dihydrobenzofurans proceeding under kinetic control in the HAT step is presented, and the concept is transferred to a deracemization by chiral silane thiols as HAT reagents in a proof of concept study.