Synthesis of both enantiomers of conosilane A

Abstract Conosilane A, an inhibitor of 11β-hydroxysteroid dehydrogenase type 1 isolated from Conocybe siliginea , is a tremulane sesquiterpene with highly oxygenated tetracyclic ring system. In this study, we report the synthesis of both enantiomers of conosilane A. The key steps of this synthesis involve asymmetric aldol reaction, furan-ring oxidation followed by transacetalization and intramolecular reductive Heck-type cyclization.