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).
Donaghy, M. J., & Stanforth, S. P. (1999). Nucleophilic additions to fused benzimidazole N-oxides. Tetrahedron, 55(5), 1441–1448. https://doi.org/10.1016/S0040-4020(98)01116-8