Organocatalytic Enantioselective Vinylogous Michael Reaction of Vinylketene Silyl-<i>N,O</i>-Acetals

Abstract

The enantioselective vinylogous Michael reaction of vinylketene silyl N,O-acetals derived from α,β-unsaturated N-acyl pyrroles and a broad range of α,β-unsaturated aldehydes proceeds with good regio-, diastereo-, and enantioselectivity when the Hayashi-Jørgensen diphenylprolinolsilylether was employed as a chiral organocatalyst. Products were obtained in generally good yields and as single stereoisomers after chromatographic purification with very high optical purity. They were easily derivatized into a set of useful synthetic building blocks.