A Ring Contraction Strategy toward a Diastereoselective Total Synthesis of (+)-Bakkenolide A
作者:Vânia M. T. Carneiro、Helena M. C. Ferraz、Tiago O. Vieira、Eloisa E. Ishikawa、Luiz F. Silva
DOI:10.1021/jo100108b
日期:2010.5.7
presented from the readily available optically active Wieland−Miescher ketone. This novel synthesis of this sesquiterpene lactone features the following as key stereoselective transformations: (i) the ring contraction reaction of a octalone mediated by thallium(III) nitrate (TTN); (ii) a hydrogenation to create the cis-fused junction; and (iii) the formation of the C7 quaternary center through an enolate intermediate
从容易获得的旋光的Wieland-Miescher酮中可以发现非对映选择性的途径生成(+)-bakkenolideA。该倍半萜烯内酯的新颖合成具有以下作为关键的立体选择性转化的特征:(i)由硝酸th(III)(TTN)介导的八酮的环收缩反应;(ii)氢化以产生顺式-稠合的连接;(iii)通过烯醇式中间体形成C7四元中心。此外,在这项工作中,分配了从千里光腐殖质分离的三去倍半萜的绝对构型。