Synthesis of a chiral steroid ring D precursor starting from carvone

A chiral five-membered, silyl enol ether containing, steroid ring D precursor has been synthesized front carvone. This silyl enol ether has been applied in the synthesis of a chiral C17 functionalized steroid skeleton using the addition of a carbocation, generated with ZnBr2 from a Torgov reagent, followed by cyclization of the adduct by treatment with acid