Synthesis of betamethasone from waste of Thai A. sisalana is described. ... Synthesis of betamethasone from waste of Thai A. sisalana is described. ... 3β??Acetoxy??5α??pregn??9(11),16??diene??20??one (6) was prepared from hecogenin (2) (Scheme 1), the latter being obtained from fermentation of the waste of A. sisalana. For example the black precipitate from the fermentation was hydrolyzed using 1 M hydrochloric acid in ethanol to give hecogenin and tigogenin. Acetylation of ...