A simple stereoselective steroid synthesis: cyclization of an epoxystannane
Abstract
The highly stereoselective acid-catalysed cyclization of an epoxystannane, together with the stereoselective alkylation by cinnamyl bromide of the enolate derived by conjugate addition of the anion of allyl phenyl sulphide to 2-methylcyclopent-2-enone, are the key steps in a simple synthesis of an aromatic steroid.