One-Pot Synthesis of Benzo[ c ]phenanthridine Alkaloids from 7-Azabenzonorbornadienes and Aryl Nitrones.

An efficient synthesis of benzo[ c ]phenanthridine alkaloids via a synergistic combination of C-C bond formation and a cycloaromatization reaction is described. Aryl nitrones react with 7-azabenzonorbornadienes in the presence of a Rh(III) catalyst, providing pharmaceutically useful benzo[ c ]phenanthridine derivatives in good to moderate yields. Using this methodology, highly useful alkaloids such as norfagaronine, norchelerythrine, decarine, norsanguinarine, and nornitidine were prepared in a single step.