Novel cycloalkene indole carbazole alkaloids via the ring closing metathesis reaction

Methodology for the synthesis of a series of carbocyclic indole carbazole natural product analogs is presented. The chemistry involves construction of the core indole, followed by attachment of double bond tethered side chains of three and four carbon lengths. The bottom carbocyclic ring system is formed through a ring closing metathesis reaction, and allows the installation of four, five, and six member ring sizes.