The synthesis of α-acylaminoalkyl 1.1-difluoro-3-butenyl ketones is described. Reaction of substituted 5(4H)-oxazolones , obtained from α-amino acids, with 2.2-difluoro-4-pentenoic acid anhydride (for R 2 = C 6 H 5 ) or with 2.2-difluoro-4-pentenoic acid chloride and 4- ...