An Enantioselective Total Synthesis of (-)-Isoschizogamine

Abstract

A concise enantioselective total synthesis of (-)-isoschizogamine, a complex bridged polycyclic monoterpene indole alkaloid, was accomplished. N-Alkylation of an enantio-enriched imine with an alkyl iodide afforded an iminium salt, which, upon heating by microwave irradiation in the presence of pivalic acid, was converted into the hexacyclic structure of natural product by a complex but ordered domino sequence. The one-pot process leading to the formation of one C-C bond and three C-N bonds created three rings and three contiguous stereogenic centers with complete control of both the relative and absolute stereochemistry.

Keywords: alkaloids; cyclizations; heterocycles; natural products; total synthesis.