Catalytic asymmetric synthesis of enantioenriched β-nitronitrile bearing a C-CF3 stereogenic center

CF3 substituted beta-nitronitriles with an all-carbon quaternary stereogenic center have been synthesized via asymmetric cyanation reaction. In situ generated chiral Ti-IV salen complexes were used as catalysts for asymmetric addition of TMSCN to nitroolefins containing a trifluoromethylated prochiral center in the beta-position, to afford the corresponding beta-nitronitriles in excellent yield (up to 93%) with good enantioselectivity (up to 99%). This newly developed catalytic protocol led to the efficient synthesis of useful but challenging chiral alpha,alpha'-disubstituted beta-amino acids.