Highly Regio- and Enantioselective Synthesis of γ,δ-Unsaturated Amido Esters by Catalytic Hydrogenation of Conjugated Enamides

An efficient and highly regio- and enantioselective catalytic asymmetric hydrogenation of ,-dienamido esters to ,-unsaturated amido esters has been achieved using Rh/TangPhos as the catalyst. A series of ,-unsaturated amido acids were furnished in excellent yields with up to 99% ee. This effective methodology was applied in the asymmetric synthesis of key intermediate of Ramipril, an ACE inhibitor.