The Cu-catalyzed asymmetric conjugate addition with chiral diphosphite ligands derived from D-(-)-tartaric acid

Abstract

ABSTRACTA series of diphosphite ligands, which were derived from D-(-)-tartaric acid, have been synthesized and successfully applied in the Cu-catalyzed asymmetric conjugate addition of organozincs to enones. There was a synergic effect between the stereogenic centers of the D-(-)-tartaric acid skeleton and the axially H8-binaphthyl moieties of ligand 2c. And ligand 2c shows a comparative catalytic performance to ligand 1-N-benzylpyrrolidine-3,4-bis[(S)-1,1′-H8-binaphthyl-2,2′-diyl]phosphite-L-tartaric acid1d derived from L-(+)-tartaric acid. Therefore, for cyclic enones, both enantiomers of the addition products can be obtained in high enantioselectivity (ees up to 96%) by simply selecting ligands 1d or 2c derived from D-(-)-tartaric acid or L-(+)-tartaric acid. Moreover, the sense of enantiodiscrimination of the products was mainly determined by the configuration of the binaphthyl phosphite moieties.