Enantioselective Friedel-Crafts Reaction of Heteroaromatic Compounds with Glyoxals Catalyzed by Chiral Oxazaborolidinium Ion Catalyst.

A catalytic enantioselective Friedel-Crafts reaction of various heteroaromatic compounds with glyoxals has been developed. In the presence of a chiral oxazaborolidinium ion catalyst, the reaction provided chiral α-hydroxyketones in high yield (up to 96%) with excellent enantioselectivity (up to >99% ee ). The synthetic utility of this method was illustrated by conversion of the products to various derivatives such as 1,2-diol and β-amino alcohol.