Horner-Wadsworth-Emmons reaction for the synthesis of unusual α,β-didehydroamino acids with a chiral axis

Abstract

The Horner–Wadsworth–Emmons reaction of N-benzyloxycarbonyl(dimethoxyphosphinyl) glycine esters with σ-symmetric prochiral 4-substituted-cyclohexanones under basic conditions is described. This reaction gives unusual α,β-didehydroamino acids with a chiral axis in their racemic form. The methodology has been extended to the synthesis of dipeptides containing a phenylalanine residue and these unusual new α,β-didehydroamino acids at the i+2 position.