The invention relates to a new process for the synthesis of 17β-hydroxy-17α-methyl-2-oxa-5α-androstane-3-one of formula (I). The process according to the invention is as follows: the 17β-hydroxy-17α-methyl-1,3-seco-2-nor-5α-androstane-1,3-diacid of formula (III) is transformed into the ring-closed 17β-hydroxy-17α-methyl-1,3-seco-2-nor-5α-androstane-1,3-diacid anhydride of formula (II) in an inert solvent or without solvent with a C2-C3 alkan acid anhydride or a substituted carbodiimide of formula R1-N=C=N-R2 - wherein R?1 and R2¿ independently are C¿1?-C6 alkyl group, C1-C6 alkyl group substituted by tertiary or quaternary amino group or 1-3 phenyl group, C5-C6 cycloalkyl group, aryl group substituted by 1-3 methoxy, tertiary amino, nitro, C1-C4 alkyl group or 1-3 halogen atom - and the obtained compound of formula (II) is reduced regioselectively by a complex alkali metal hydride in an inert solvent. The new 17β-hydroxy-17α-methyl-1,3-seco-2-nor-5α-androstane-1,3-diacid anhydride of formula (II) is also the subject of the invention.
                            本发明涉及一种合成式(I)的17β-羟基-17α-甲基-2-氧-
5α-雄烷-3-酮的新工艺。根据本发明的工艺如下:用C2-C3烷酸酐或取代的
氨基甲酸酐(式R1-N=C=N-R2,其中R1和R2独立地是C1-C6烷基、由第三或第四胺基取代的C1-C6烷基、1-3苯基、C5-C6环烷基、由1-3甲氧基、第三胺基、硝基、C1-C4烷基或1-3卤原子取代的芳基)在惰性溶剂或无溶剂下,将式(III)的17β-羟基-17α-甲基-1,3-去氧-2-去氢-
5α-雄烷-1,3-二酸转化为环闭合的式(II)的17β-羟基-17α-甲基-1,3-去氧-2-去氢-
5α-雄烷-1,3-二酸酐。然后,用复杂碱
金属
氢化物在惰性溶剂中对所得到的式(II)的化合物进行区域选择性还原。新的式(II)的17β-羟基-17α-甲基-1,3-去氧-2-去氢-
5α-雄烷-1,3-二酸酐也是本发明的对象。