Synthetic methodology for the preparation of trans- and cis-2,9-disubstituted oxonanes
作者:Robert W. Carling、Neil R. Curtis、Andrew B. Holmes
DOI:10.1016/s0040-4039(01)93860-2
日期:1989.1
Methylenation of the racemic lactone (5), followed by stereoselective hydroboration, gave predominantly the trans-2,9-disubstituted oxonane (7) which was converted into the carbon skeleton (1) of obtusenyne (2). Epimerisation of the trans-aldehyde (18) gave the cis-compound (19). Relative stereochemistry was established by the asymmetric synthesis of trans-(2R),(9R)-dimethyloxonane (13) and meso cis-2,9-dimethyloxonane
外消旋内酯(5)的亚甲基化,然后进行立体选择性氢硼化,主要产生反式-2,9-二取代的氧杂环丁烷(7),该化合物被转化为ob庚烯(2)的碳骨架(1 )。在差向异构的反式构醛(18)给了顺至化合物(19) 。通过不对称合成反式-(2 R),(9 R)-二甲基恶烷(13)和内消旋-2,9-二甲基恶烷(17)建立了相对立体化学。