Novel steroidal penta- and hexacyclic compounds derived from 12-oxospirostan sapogenins

▶ Polycyclic steroidal skeletons were prepared from 12-oxosteroidal sapogenins. ▶ The route involves regioselective E ring cleavage by BF3·OEt2 and aldol condensation. ▶ The one pot reaction was achieved using low Ac2O concentration in CH2Cl2.