Improvements in or relating to the reduction of 9(11)-dehydro-12-keto spirostanes

The invention comprises a process for the reduction of a 9(11) dehydro-12-keto-spirostane to the corresponding 12-desoxyspirostane by formation of the 12-dithioketal followed by reduction by means of an alkali metal or alkaline earth metal in liquid ammonia, a primary amine containing 1 to 5 carbon atoms or a polymethylene diamine. The conversion of 9(11) dehydrohecogenin acetate to 9(11) dehydrotigogenin acetate is exemplified; the acetate group is removed during reduction and subsequent reacetylation is necessary. The Provisional Specification discloses the application of the process of the invention to 9(11) dehydro-12-keto-steroids in general. Specification 956,272 is referred to.