A novel transformation of N-alkoxycarbonylprolines 1 to 4-trifluoroacetyl-2,3-dihydropyrroles 2 was efficiently realized by utilizing trifluoroacetic anhydride, in which probable intermediates were mesoionic 1,3-oxazolium-5-olates B.
Heterocyclization of 4-trifluoroacetyl-2,3-dihydropyrroles with hydrazines and amidines: A new access to trifluoromethylated pyrazoles and pyrimidines bearing a β-aminoethyl side chain
Trifluoromethyl-substituted heterocycles have been prepared by condensation of the new 4-trifluoroacetyl-2,3-dihydropyrroles with hydrazines or amidines as a bifunctional N-nucleophile with opening of the dihydropyrrole ring.