Asymmetric Synthesis of Chiral γ‐ and δ‐Amino Esters Using Trichlorosilane Activated with a Lewis Base Catalyst

Abstract

AbstractNovel chiral γ‐ and δ‐ amino esters 2 a–k were synthesized by enantioselective reduction of N‐aryl γ‐ and δ‐imino esters with aryl, substituted aryl, and heteroaryl groups 1 a–k using trichlorosilane activated with optically active N‐pivaloyl L‐proline I in high yields (50%–98%) with enantioselectivities (10%–84% enantiomeric excess). The structures of the chiral amino esters 2 a–k were clarified by infrared, nuclear magnetic resonance (1H and 13C) and gas chromatography‐mass spectrometry. The enantiomeric excess of these compounds were identified by chiral high‐performance liquid chromatography using a Chiralpak AD−H column. The highest ee of 84% and highest yield of 98% were found for 2 d.