Total synthesis of (+)-13-ethyl-3-methoxygona-1,3,5,9(11)-tetraen-17-one via the tandem Claisen-ene strategy
作者:E. M. Groen-Piotrowska、M. B. Groen
DOI:10.1002/recl.19931121204
日期:——
5(10)-triene-9,17-dione (21), which reacted with triphenylphosphine under high pressure conditions (12 kbar, 55°C) to give the corresponding phosphonium salt 22. The intramolecular Wittig reaction of 22 proceeded with epimerization at C-8 to give exclusively (8α)-13-ethyl-3-methoxygona-1,3,5,9(11)-tetraen-17-one (23) which, upon treatment with acid, isomerized to the title compound 2.
描述了标题化合物2的全合成,标题化合物2是孕酮去氧孕烯和3-酮去氧孕烯的潜在前体。类固醇的骨架是通过1,2-二氢-4,7-二甲氧基萘(12)和[ S-(Z)]-8,9-二羟基-7-乙基-6-壬烯-2-炔基的缩合而组装的。由[ R -(+)]-甘油醛丙酮化物(4)制备的丙烯酸甲酯9-(叔丁基二甲基)甲硅烷基醚(11),然后进行克莱森重排。将所得的二类甾类固醇(14)在170°C加热,得到9,11-类固醇类固醇15和16的1:1混合物分别具有8α,13β,14α-和8α,13α,14α构型。将13β-受体15转化为与三苯膦反应的11-溴-13-乙基-3-甲氧基-9,11-焦酮-1,3,5(10)-三烯-9,17-二酮(21)。在高压条件下(12 kbar,55°C)得到相应的phospho盐22。22的分子内Wittig反应在C-8处进行差向异构化,仅得到(8α)-13-乙基-3-甲氧基gona-1