Abstract 2-Phenyl-5 (4H)-oxazolones, obtained from α-amino acids, are reacted with di-and trifluoro acetic anhydride by a modified Dakin-West procedure to yield in a one-pot reaction α-benzamidoalkyl-di-and trifluoromethyl ketones in good yields. The monofluoromethyl analogues were also prepared from α-amino acids, however the use of the highly toxic fluoroacetic anhydride was avoided. The key step is the halogen exchange reaction on ...