Steric control in the ion radical nitration of 5-triphenylmethylbenzimidazolines using a silver/nitrite system

Nitration of 1,2,2,3-tetrasubstituted 5-triphenylmethylbenzimidazolines using an Ag+/NO2−system shows an unexpected (for benzimidazolines) orientation of the nitro group into position 7, which may be due to the strong steric influence of the rather bulky triphenylmethyl substituent.