Asymmetric Reduction of (Z)-α,β-Dehydrotryptophanyl-containing Biological Peptides with Sulfur Functionality. Influence of Substrate on Stereoselectivity

Two (Z)-α,β-dehydropentapeptides, Boc-βAla-ΔZ Trp-Met-Asp-Phe-NH2 1 and Boc-βAlaΔZ-Trp-NLeu-Asp-Phe-NH2 2, have been synthesized by enzymatic α,β-dehydrogenation, and then submitted to rhodium-catalysed asymmetric hydrogenation. The influence of the S-atom on the rate and stereoselectivity of the reduction have been investigated.