Research on heterocyclic compounds. XX. Synthesis of trifluoromethyl derivatives of fused imidazole systems

A series of heterocyclic compounds having an imidazole ring fused with another ring with a bridgehead nitrogen atom and bearing a trifluoromethyl moiety was synthesized by reaction of 3‐bromo‐1,1,1‐trifluoroacetone with various heteroarylamines. In some cases, an intermediate compound obtained together with the required product was isolated and its structure was elucidated: e.g. , starting from 2‐aminopyridine we have obtained 2‐trifluoromethylimidazo[1,2‐a]pyridine and 2‐hydroxy‐2‐trifluoromethyl‐2,3‐dihydro‐1 H ‐imidazo [1,2‐ a ]pyridinium bromide. Such results confirmed the mechanism previously proposed for this reaction.