Highly Regio- and Enantioselective Catalytic Hydrogenation of Enamides in Conjugated Diene Systems: Synthesis and Application of γ,δ-Unsaturated Amino Acids

Abstract

An extremely efficient method has been found for the catalytic asymmetric hydrogenation of conjugated α,γ-dienamide esters using the Et-DuPHOS-Rh catalyst system. α,γ-Dienamide ester substrates were prepared via the Suzuki cross-coupling reaction and the Horner−Emmons olefination. Full conversion to the corresponding γ,δ-unsaturated amino acids with very high regio- and enantioselectivity was achieved after short reaction times. This new methodology was applied to the synthesis of the natural product bulgecinine from a prochiral dienamide ester.