Chiral environments for asymmetric hydrogenation of model didehydro‐amino acid residues

Abstract

Dedicated to Professor John C. Sheehan on the occasion of his sixty‐fifth birthday Nmr and glc analysis of diastereoisomeric mixtures of dipeptides has been used to study the asymmetric hydrogenation of model benzoyldidehydro‐ and trifluoroacetyldidehydro‐dipeptide methyl esters. Chiral enhancement of one isomeric form appears to be independent of the N‐terminal acyl group, but is significantly influenced by the choice of amino‐acid in the C‐terminal position. C‐Terminal aromatic amino‐acids and their derivatives give the best chiral enhancement during hydrogenation of a neighbouring dehydroamino‐acid residue.

A Novel Synthetic Approach to Phosphorylated Peptidomimetics

“…Several methods are available for the double bond reduction in α,β‐dehydroamino acids but none concerning the case when their residues are incorporated into phosphopeptide mimetics. To obtain reduced analogues of compounds 8 , we attempted, unsuccessfully, their direct hydrogenation with zinc in an AcOH:HCl (10:3) mixture.…”