A new method for the preparation of α-chlorodifluoromethyl-, α-bromodifluoromethyl-, and α- difluoromethyl-substituted α-hydroxy and α-amino acid esters 11, 19-21 is described. The key step of the synthesis is the regioselective alkylation of ketones 5, 7-9 and imines 16-18 with C-nucleophiles. The ketones 7-9 are readily available from 3, 3, 3-trifluorolactate 1 by a five-step procedure. Subsequent removal of the protecting groups from 19-21 provides the ...
