Ws. Tian et al., AN EFFICIENT SYNTHESIS OF TRIFLUOROMETHYL PYRROLES AND RELATED-COMPOUNDS FROM EASILY PREPARED TRIFLUOROMETHYLOXAZOLONES, Huaxue xuebao, 52(11), 1994, pp. 1126-1132
An efficient way for the synthesis of trifluoromethylpyrroles and rela
ted compounds from easily prepared trifluoromethyloxazolone via 1,3-di
polarcycloaddition and the base promoted cyclocondensation reaction wa
s described. The 1, 3-dipolar-cycloaddition of trifluoromethyloxazolon
e and the activated carbon-carbon multiple bond gave primary cyclo-add
uct 2 or 4, which were transformed into trifluoromethylpyrroles after
decarboxylation. The base promoted cyclocondensation involves the tand
em Michael addition of trifluoromethyloxazolones to electron-deficient
alkenes, intramolecular cyclization and decarboxylation and directly
gave desired trifluoromethylpyrroles in good yield.