Nucleophilic additions to fused benzimidazole N-oxides

Abstract

The benzimidazoles 16a-f have been prepared from N-oxides 15a-d. Treatment of N-oxides 15c and 15d with a mixture of acetic anhydride and sodium acetate gave the corresponding acetoxy derivatives 26 and 27 via a regiospecific nucleophilic substitution reaction. N-Oxides 15c and 15d were also deoxygenated by 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ).