Synthesis of 2-(Trifluoromethyl)oxazoles from β-Monosubstituted Enamines via PhI(OCOCF₃)₂-Mediated Trifluoroacetoxylation and Cyclization

Abstract

Treatment of β-monosubstituted enamines with phenyliodine bis(trifluoroacetate) (PIFA) was found to give a variety of 4,5-disubstituted 2-(trifluoromethyl)oxazoles. This approach allows the incorporation of the trifluoromethyl moiety in PIFA into the final products, which presumably takes place via the oxidative β-trifluoroacetoxylation of the enamine substrates followed by subsequent intramolecular cyclization.