Asymmetric synthesis of 3β-acetoxy-17, 17-ethylendioxy-15β, 16β-methylene-5-androsten-7β-ol

Abstract

3β-acetoxy-17, 17-ethylendioxy-15β, 16β-methylene-5-androsten-7β-ol(I) was prepared by 3 steps from 3β-acetoxy-15β, 16β-methylene-5-androsten-17-one (II) with overall yield of 52.7%. Thus, interaction of ethylene glycol and material (II) gave 3β-acetoxy- 17, 17-ethylendioxy-15β, 16β-methylene-5-androsten (III) which was subsequently oxidated and stereoselectively reduced to produce compound(I). The normal influencing factors, such as the types of oxidants and reductives, the mole ratio of reactants, the reaction temperature, and the addition ways of reactants, in oxidation and reduction were discussed. The results show that the oxidation rate order is CrO₃-C₅H₅N (1:1, mole fraction)>CrO₃-C₅H₅N(1:2)>(C₅H₅NH)₂Cr₂O₇ in terms of the oxidant, the yield of the oxidation becomes higher with increasing the oxidant stoichiometry and raising the reaction temperature. And the optimum condition is that the reaction temperature is at 30 °C, and n(III)/n(CrO₃-C₅H₅N(1:2))=1:20. The yield of the −7β alcohol order with Li[Al(OC(CH₃)₃)₃H] (e. g. 78.6%) is more than that with NaBH₄ (e. g. 14.5%) in terms of the reductive agent and the reduction rate decreases in the course of reaction. The compound (I) is characterized by IR and MS.