Total synthesis of pyrrolo[2,3-]quinoline alkaloid: trigonoine B.

The first total synthesis of the pyrrolo[2,3-]quinoline alkaloid trigonoine B () was accomplished via a six-step sequence involving the construction of an -substituted 4-aminopyrrolo[2,3-]quinoline framework via electrocyclization of 2-(pyrrol-3-yl)benzene containing a carbodiimide moiety as a 2-azahexatriene system. The employed six-step sequence afforded trigonoine B () in 9.2% overall yield. The described route could be employed for the preparation of various -substituted 4-aminopyrroloquinolines with various biological activities.