New approach to steroidal hemisuccinates and glycosides

New synthesis of hemisuccinate and β-D-glucopyranoside of (20E)-21-ethoxycarbonyl-5,20-pregnadien-3β-ol (XVIII and XXVI) is described, consisting in the preparation of a protected hemisuccinate (XV) or glucoside (XXIII) intermediate, into which the unsaturated ester grouping in the side-chain is incorporated only in the final stage of the synthesis. The primary hydroxyl at C(20) was protected by tert-butyldimethylsilyl, trityl or nitrate groups, the succinate was blocked with 2-(trimethylsilyl)ethyl or 2,2,2-trichloroethyl groups and the glucosides were used in the form of peracetyl derivatives.