Biomimetic transamination of α-keto perfluorocarboxylic esters. An efficient preparative synthesis of β,β,β-trifluoroalanine

Article abstract of DOI:10.1016/S0040-4020(97)00517-6

An efficient large-scale preparative synthesis of biologically interesting β,β,β-trifluoroalanine through the biomimetic transamination of the ethyl trifluoropyruvate has been developed. The azomethine-azomethine isomerization of the N-(1-phenyl)ethylimine of ethyl trifluoropyruvate to the N-(l-phenyl)ethylidene alanine ethyl ester, a key stage of the process, was found to occur under the mild reaction conditions, in a triethylamine solution at rt. The proposed working mechanistic rationale accounting for the easiness of the isomerization and its stereochemical outcome, involves unusual non-asymmetric [1,5]-proton shift transfer from the methine carbon to the enolate oxygen.