Nitrene Cyclization of 2-(Trichloromethyl)-5-phenylpyrimidines: Application to the Synthesis of 2-(Trichloromethyl)pyrimido[4,5- b ]indoles and Related Heterocycles

An aromatic C–H nitrene insertion of 2-trichloromethylpyrimidines bearing a phenyl substituent in C-5 position is described. Treatment of 2-trichloromethyl-4-chloro-5-phenylpyrimidines with sodium azide in DMF or the reflux of 2-trichloromethyl-4-azido-5-phenylpyrimidines in toluene provided 2-trichloromethylpyrimido[4,5-b]indole derivatives in moderate yields. Excellent yields of this heterocyclic systems were obtained through of the aromatic C–H insertion with Du Bois catalyst. This is an attractive approach for synthesizing pyrimido[4,5-b]indoles with a trichloromethyl substituent in the pyrimidine moiety.