[2+3]-Cycloadditions of diazoalkanes with imines of hexafluoroacetone and chloral

The reactions of N-arylimines 1 and 2 of hexafluoroacetone and chloral, respectively, with diazoalkanes at –60°C to room temperature led to the corresponding 4,5-dihydro-1H-[1,2,3]triazoles 4 and 5, respectively, in a regioselective [2+3]-cycloaddition. The structure of one example in each case has been established by X-ray crystallography. The thermal decomposition of these adducts yielded the corresponding aziridines, bearing two trifluoromethyl and one trichloromethyl group, respectively, at C(2).