1,6-Asymmetric induction during the conjugate addition of arylcopper reagents to a chiral sulfinyl-substituted pyrrolyl α,β-unsaturated amide

Abstract

The asymmetric conjugate addition of arylcopper reagents derived from aryl Grignard reagents and copper(l) iodide to a chiral 1-[2-(p-tolylsulfinyl)]pyrrolyl cinnamide proceeded smoothly to give (3R)-adducts with high diastereoselectivities (≥92% de) in high yields. Conjugate additions either of the cinnamide with the alkyl Grignard reagent-copper(I) iodide combination or of the crotonamide derivative with aryl Grignard reagentcopper(I) iodide gave moderate to good diastereoselectivities. With these sulfinyl pyrrolyl α,β-unsaturated amides, the chiral auxiliary was efficiently recovered without any loss of optical purity after asymmetric conjugate addition.