One-Pot Synthesis of Trifluoromethyl-Substituted Imidazobenz[1,2-d]- and -[1,2-c]isoxazoles

Synthesis of regioisomeric 8-trifluoromethyl-4,5-dihydro-3 H -imidazo[4',5':5,6]benz[1,2 -d ]isoxazoles and 8-trifluoromethyl-4,5-dihydro-3 H -imidazo[4',5':3,4]benz[1,2 -c ]isoxazolones was realized by one-pot oxidation of 3-trifluromethyl-6,7-dihydrobenz[ d ]- or [ c ]isoxazoles with selenium dioxide in glacial acetic acid followed by a condensation of formed in situ 3-trifluromethyl-6,7-dihydrobenz[ d ]- or [ c ]isoxazole-4,5-diones with benzaldehydes in the presence of ammonium acetate.