Concise Syntheses of the Oxo Derivatives of Benzo(c)phenanthridine Bases by N‐Deformylated Cyclization Based on Vilsmeier‐Haack Reaction.

Chelerythrine-type oxobenzo[c]phenanthridine bases were effectively synthesized by the action of 1, 3-dimethoxy-benzene on 2-(2-methoxycarbonylphenyl)-1-(N-methylformamido)naphthalenes in the presence of phosphorus oxychloride. The N-deformylation based on the Vilsmeier-Haack reaction is also discussed.