A total synthesis of (±)-α-cyclopiazonic acid using a cationic cascade

Abstract

The indolic terpene alkaloid alpha-cyclopiazonic acid has been prepared in 11 steps from indole-4-methanol; the key step is a carbocationic cascade, terminated by a 4-nitrosulfonamide group and initiated by benzylic carbocation formation directly from the intermediate , which gives the tetracyclic product in 74% yield.