Photoredox-Catalyzed Generation of Tertiary Anions from Primary Amines via a Radical Polar Crossover

A method for the generation of tertiary carbanions via a deaminative radical-polar crossover is reported using redox active imines from alpha-tertiary primary amines. A variety of benzylic amines and amino esters can be used in this approach, with the latter engaging in a novel "aza-Reformatsky" reaction. Electronic trends correlate the stability of the resulting carbanion with reaction efficiency. The anions can be trapped with different electrophiles including aldehydes, ketones, imines, Michael acceptors, and H2O/D2O. Selective anion formation can be achieved in the presence of another equivalent or more acidic C-H bond in both an inter- and intramolecular fashion. Mechanistic studies suggest the intermediacy of a discrete carbanion intermediate. A deaminative radical-polar crossover strategy generating carbanions is reported. This so called "aza-Reformatsky" reaction leverages the use of redox-active imines and an iridium photocatalyst to generate a wide array of tertiary benzylic, heteroarylbenzylic and alpha-ester anions, which can be trapped with different electrophiles.image