Diastereoselective copper-catalysed 1,4-addition of Grignard reagents to N-enoyl oxazolidinones

Abstract

Conjugate additions of organometallic reagents to α,β-unsaturated carboxylic acid derivatives give access to numerous β-substituted chiral building blocks. Chiral oxazolidinones serve as useful surrogates of carboxylic function in the asymmetric conjugate addition of Grignard reagents. N-Enoyl oxazolidinones undergo this 1,4-addition with a catalytic amount of copper salt and using either chiral or achiral phosphine ligands. In particular, chiral ferrocenyl phosphane oxazolines proved useful in achieving high diastereoselectivities. The resulting N-acyl oxazolidinones were obtained in good yields and with high diastereoselectivities (up to single diastereomer).