Expedient Synthesis of α-Substituted α, β- Unsaturated γ-Amino Acids (Dipeptide Mimetics); Wittig Reaction of α-Amino Aldehydes with α- Substituted Alkoxycarbonyl Phosphoranes

Abstract

Reacting ethoxycarbonyl triphenyl phosphorane with activated alkylhalides in chloroform gave the ylides 4 -12. They react smoothly and in general without racemisation with oc-amino aldehydes resulting in the dipeptide mimetics 15 - 25. Exceptions are the highly labile aldehydes pyridinoalaninal and serinal. Enantiospecificity is proven via enantioselective chromatography.