合成路线1

Protection of prasterone (I) with ethylene glycol (II) in the presence of p-TsOH in refluxing benzene gives the corresponding ketal (III), which is further protected as the 3-O-silyl ether (IV) by treatment with TBDMSCl and imidazole in DMF. Allylic oxidation of compound (IV) by means of CrO3 and 3,5-dimethylpyrazole in CH2Cl2 or using RuCl3 and t-BuOOH in cyclohexane/water affords enone (V), which by chemoselective 1,2-reduction with NaBH4 and CeCl3 in THF/MeOH provides (R)-alcohol (VI). Subsequent esterification of alcohol (VI) with Ac2O and DMAP in pyridine produces acetate (VII), which is subjected to double bond hydroboration with BH3·THF in THF and oxidative hydrolysis using H2O2 and NaOH to yield diol (VIII). Protection of diol (VIII) with Ac2O and DMAP in pyridine gives diacetate (IX), which is selectively deprotected at C-3 by treatment with TBAF in THF resulting in the 3-hydroxysteroid (X). Hydrolysis of diacetate (X) using NaOMe in MeOH affords compound (XI), which by deketalization by means of AcOH provides ketone (XII). Protection of the 6,7-diol (XII) with 2,2-dimethoxypropane (XIII) in the presence of CSA then gives acetonide (XIV), which is submitted to a Wittig reaction with CH3PPh3Br in the presence of t-BuOK in refluxing THF to give alkene (XV) .