The Dakin-West reaction of N-alkoxycarbonyl-N-alkyl-α-amino acids employing trifluoroacetic anhydride

Abstract

The Dakin-West reaction of N-alkoxycarbonyl-N-alkyl-α-amino acids (1a - j) with trifluoroacetic anhydride in the presence of pyridine gave α-amido trifluoromethyl ketones (2a - j), in which probable intermediates were mesoionic 1,3-oxazolium-5-olates (munchnones). The diastereoselective reduction of 2a - f with NaBH4 gave the threo-aminoalcohols (5a - f), which may be explained by the Felkin-Anh model. This was confirmed by converting 5a - f into trans-5-trifluoromethyl-2-oxazolidinones (6a - f) in good yields.