Study on the reaction of diosgenin acetate with trimethylsilylazide catalyzed by Lewis acids.

The ring opening reaction of diosgenin acetate in presence of Lewis acids and trimethylsilyl azide was explored as a facile approach to the synthesis of an open chain derivative with a nitrogen-containing substituent at C26. The reaction, under optimal conditions (TMSOTf, 1 equiv.; TMSN3, 1.1 equiv.; DCM; 48 h; rt), provided satisfactory yield (40%) of furostane-26-nitrile in a single step.