Synthesis of optically active trifluoromethyl-substituted 2,3-dihydroimidazo[2,1-b]oxazoles

The 2-unsubstituted imidazole N-oxides with a 3,3,3-trifluoro-2-hydroxypropyl group at N(1) in the presence of acetic anhydride undergo cyclization via the intramolecular nucleophilic attack of the hydroxyl group onto C(2) of the imidazole ring to give trifluoromethylated derivatives of 2,3-dihydroimidazo[2,1-b]oxazoles. This method, starting with enantiopure substrates, allows the preparation of enantiopure products in a one-pot procedure.