摘要:
4-Trifluoroacetyl-2-phenyloxazol-5-one (1) is a versatile template for the synthesis of various trifluoromethyl-substituted heterocycles. Cyclocondesation of 1 with hydroxylamine and hydrazine afforded isoxazole and pyrazole, respectively. Another key protocol involves nucleophilic ring opening of 1 with H2O or MeOH to give alpha-amido trifluoromethyl ketones which are transformed into trifluoromethyl-substituted thiazoles, oxazoles, imidazoles, pyrazoles, and pyrimidines.