Lewis Base Catalysis: I. Catalytic Enantioselective Aldol Additions of Methyl Trichlorosilyl Ketene Acetal to Ketones. II. Catalytic Enantioselective Alpha-Additions of Isocyanides to Aldehydes

Abstract

The first catalytic, enantioselective alpha-addition reaction of isocyanides has been demonstrated with a SiCl4·bisbinaphthyldiamine phosphoramide catalyst. Good yields have been obtained with aromatic, heteroaromatic, conjugated non-aromatic and non-branched aliphatic aldehydes. Aromatic, aliphatic and functionalized isocyanides provided high yields of alpha-addition products. Enantiomeric ratios ranging from 92/2 to 99/1 have been achieved in the addition of tert-butyl isocyanide to aromatic aldehydes. The imidoyl chloride intermediates has been directly converted into chiral alpha-hydroxy amides and carboxylic esters without loss in enantiomeric purity.