Enantioselective Organo-SOMO Catalysis:  The α-Vinylation of Aldehydes

The first enantioselective organocatalytic α-vinylation of aldehydes has been accomplished. Selective oxidation of chiral enamines, derived from the condensation of aldehydes and a chiral secondary amine catalyst, leads to the production of highly reactive radical cations that exist in an asymmetric environment. These SOMO-activated species undergo direct coupling with readily available potassium organotrifluoroborate salts to yield enantioenriched α-vinyl aldehydes. The described reaction procedure achieves carbon−carbon bond formation in an efficient manner with consistently high levels of enantioinduction and geometrical control for the trans-olefin product. A wide range of both aldehydes and potassium organotrifluoroborate salts, including those typically susceptible to oxidative conditions, are accommodated under the reaction conditions. Results herein further demonstrate the capacity of the SOMO catalysis platform to achieve asymmetric carbon−carbon bond formations that are difficult to access via traditional methods.