The use of oxygen for catalyst regeneration in photoredox catalysis causes selectivity problems, because the generation of reactive oxygen species initiates overoxidations and side oxidations. Herein, we present a system using the electrochemical regeneration of a flavin catalyst under inert conditions. Our process allows the chemoselective oxidation of primary and secondary benzylic alcohols to carbonyl compounds without unwanted overoxidation to carboxylic acids. The method tolerates other oxidation-sensitive groups such as methyl, methylsulfanyl, or pinacolboryl groups.
Sponar et al. (Tue,) studied this question.