Synthesis of the novel 1,7,9-trioxadispiro[4.1.5.2]-tetradecane ring system present in the spirolides
作者:Vittorio Caprio、Margaret A Brimble、Daniel P Furkert
DOI:10.1016/s0040-4020(01)00272-1
日期:2001.4
bis-spiroacetal moiety of the complex marine biotoxins, spirolides 1 and 2 is described. The synthetic strategy adopted is based on assembly of a suitably protected acyclic hydroxyketone precursor. Key intermediate 25 was synthesised as a mixture of diastereomers from 1,3-propanediol using an iterative Grignard addition/hydroboration strategy and converted to cis-enone 28. Attempted acid catalysed cyclisation of
描述了双螺缩醛13的合成,该双螺缩醛13构成复杂的海洋生物毒素螺环化物1和2的双螺缩醛部分。所采用的合成策略基于适当保护的无环羟基酮前体的组装。使用迭代格氏试剂加氢/硼氢化方法,由1,3-丙二醇以非对映异构体混合物的形式合成关键中间体25,并将其转化为顺式-烯酮28。尝试将酸催化的28环化为螺缩醛是不成功的,但是,类似的饱和前体30可以很容易地得到螺缩醛31。然后氧化环化31得到双螺缩醛32。在替代途径中,通过对二酮34进行选择性脱保护来合成双-螺缩醛32。乙炔25的选择性脱保护得到甲氧基缩醛36,其在半氢化时形成不饱和螺缩醛37。最后,双螺缩醛37的氧化环化得到目标双螺缩醛13。