Synthesis of the omega-brominated alpha-trifluoroacetylcycloalkanones and their isoxazole derivatives

The reactions of a serie of the 2-trifluoroacetyl-1-methoxy-1-cycloalkenes (1a-1e) and 2-trifluoroacetylcycloalkanones (2a-2e) with molecular bromine to obtain omega-bromo-alpha-trifluoroacetylcycloalkanones (3a-3e, 4a) is reported. Was determined that 2-trifluoroacetyl group have established the C-omega as reactive site. The 2-trifluoroacetylcycloalkanones and omega-bromo-alpha-trifluoroacetylcycloalkanones were reacted with hydroxylamine hydrochloride leading to respective 5-trifluoromethyl-5-hydroxy-4,5-dihydro-3,4-polimethyleneisoxazole derivatives (5c-5e and 6c-6e).