Chromium Catalyzed Asymmetric Reformatsky Reaction.

This study describes an unprecedented chromium-catalyzed asymmetric Reformatsky reaction, enabling the synthesis of chiral β-hydroxy carbonyl compounds from α-chlorinated or α-brominated esters and amides. By employing a chiral chromium/diarylamine bis(oxazoline) catalyst, we achieved relatively broad functional group tolerance. Distinct from known reports, the protocol operates under both classical and photoredox conditions, facilitated by the in situ formation of a nucleophilic chiral chromium intermediate through a radical-polar crossover mechanism. Preliminary mechanistic insights, supported by DFT calculations, identify the nucleophilic aldehyde addition as the key stereo-determining step. This approach not only overcomes the limitations of existing Reformatsky reactions but also provides a versatile strategy for accessing complex chiral molecules.