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

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