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Enantioselective aerobic oxidative cross-dehydrogenative coupling of glycine derivatives with ketones and aldehydes via cooperative photoredox catalysis and organocatalysis.

Xiaorong YangZhi-Xiang XieYing LiYuan Zhang
Published in: Chemical science (2020)
The combination of photoredox catalysis and enamine catalysis has enabled the development of an enantioselective aerobic oxidative cross-dehydrogenative coupling between glycine derivatives and simple ketones or aldehydes, which provides an efficient approach for the rapid synthesis of enantiopure unnatural α-alkyl α-amino acid derivatives in good yield with excellent diastereo- (up to >99 : 1) and enantioselectivities (up to 97% ee). This process includes the direct photoinduced oxidation of glycine derivatives to an imine intermediate, followed by the asymmetric Mannich-type reaction with an enamine intermediate generated in situ from a ketone or aldehyde and a chiral secondary amine organocatalyst. This mild method allows the direct formation of a C-C bond with simultaneous installation of two new stereocenters without wasteful removal of functional groups.
Keyphrases
  • visible light
  • electron transfer
  • structure activity relationship
  • amino acid
  • ionic liquid
  • room temperature
  • high intensity