A multi-step, stereospecific total synthesis of steroids utilizing intermediates having a cyanoalkyl A-ring precursor is disclosed. The initial starting materials for this process are the relatively inexpensive and commercially available reagents .gamma.-butyrolactone and sodium cyanide. The process is suitable for the preparation of racemic or optically active, medicinally valuable steroids, particularly 19-norsteroids. It is a feature of this process that conditions employed during the multiple step synthesis are selected so as to retain the normally labile nitrile group even during hydrogenation and hydrolysis steps. In this manner, it is possible to employ the nitrile group as an A-ring precursor without resorting the protective groups as was heretofore found necessary in previous steroid total synthesis processes.
一种利用具有
氰烷基A环前体的中间体进行多步、立体特异性合成类
固醇的总合成方法被揭示。该过程的初始起始物料是相对廉价且商业上可获得的试剂
γ-丁内酯和
氰化钠。该过程适用于制备消旋或光学活性、具有药用价值的类
固醇,特别是19-去甾类
固醇。这个过程的特点是,在多步合成过程中采用的条件被选择为在氢化和
水解步骤中保留通常不稳定的腈基团。通过这种方式,可以在不像以往在先前的类
固醇总合成过程中发现的那样需要使用保护基的情况下,将腈基团作为A环前体。