合成路线1

Reaction of 3-methoxyandrosta-3,5,9(11)-trien-17-one (XI) with KCN and AcOH in methanol gives a 1:1 mixture of the epimeric cyanohydrins (XVII) and (XVIII) and the desired b-cyano epimer (XVIII) is obtained in a 95% yield by selective crystallization under equilibrating conditions. Protection of the 17-OH group of (XVIII) with TMS-Cl and imidazole yields the silyl ether (XIX), which is reduced with DIBAL and AcOH to afford the carbaldehyde (XX). Reaction of compound (XX) with dibromomethane and LDA provides the dibromo derivative (XXI), which by reaction with more LDA gives the lithium enolate (XXII). Hydrolysis of enolate (XXII) in acid medium yields the a-bromoketone (XXIII), which is acylated with AcOH and TEA in hot acetone to afford the silylated steroid (XXIV). Finally, compound (XXIV) is deprotected by means of HF and TEA in dichloromethane.