Total synthesis of (±)-5β,8α- androst-9(11)-ene-3,17-dione

Abstract

A total synthesis of (±)-5β,8α- androst-9(11)-ene-3,17-dione is described. The key step is a ring C forming SnCl4-catalyzed Diels–Alder reaction in which the geometry of the diene controls syn–anti stereochemistry while the catalyst guides the addition to the desired endo orientation. A preparation of ethyl E-2-methyl-4-oxo-2-butenoate and the dehydration of a tertiary allylic alcohol by the pyrolysis of the corresponding tosyl carbamate are also described.