Naturally occurring phenazines have attracted considerable attention because of their interesting biological activities. 1 One of the most promising methods for synthesizing polysubstituted phenazines developed by Holliman and co-workers 2 was the reductive cyclization of o-nitrodiphenylamines (Method C in Scheme 1). However, the yield was poor when competitive cyclization occurred. Recently, N-arylation has become more accessible owing to the advent of a ...
