Regioselective cleavage of 22-oxo-23-spiroketals. Novel cholestanic frameworks with pyranone and cyclopentenone E rings on the side chain

► The regioselective opening of 22-oxo-23-spiroketals using HCl in Ac2O is reported. ► Novel cholestanic frameworks with pyranone or cyclopentenone E rings were obtained. ► The structures of the new derivatives were established using NMR analysis. ► The X-ray analysis for compound 11b confirmed the 23R configuration at C-23. ► A mechanism that accounts for the stereochemistry of the products is proposed.