Enantioselective Conjugate Addition of Boronic Acids to α,β-Unsaturated 2-Acyl Imidazoles Catalyzed by Chiral Diols.

Abstract

Herein, we report the enantioselective conjugate addition of organic boronic acids to α,β-unsaturated 2-acyl imidazoles using (R)-3,3'-I2-BINOL as the catalyst. The catalytic system shows high efficiency and tolerance to alkenylboronic acids and heteroarylboronic acids. The corresponding Michael addition products were obtained in moderate to excellent yields and with moderate to excellent enantioselectivities (up to 97% ee). A gram-scale reaction was also conducted, and the desired product was obtained in high yield with no erosion in enantioselectivity. Finally, the synthetic utility of the methodology was demonstrated by transforming the 2-acyl imidazole moiety to the corresponding aldehyde, carboxylic acid, ester, and amide derivatives.