Efficient total synthesis of (-)-cis-clavicipitic acid.

An efficient total synthesis of (-)-cis-clavicipitic acid has been achieved in seven linear steps (42% overall yield) from the known compound 6. The present synthesis features a palladium-catalyzed indole synthesis to provide the optically pure 4-chlorotryptophan derivative and a Heck reaction using aryl chloride as partner. It has also been discovered that the key azepinoindole nucleus could be stereoselectively constructed via a Mg(ClO(4))(2)-mediated intramolecular aminocyclization.