A Practical and Efficient Synthesis of the C-16−C-28 Spiroketal Fragment (CD) of the Spongistatins
作者:Matthew J. Gaunt、David F. Hook、Huw R. Tanner、Steven V. Ley
DOI:10.1021/ol035848h
日期:2003.12.1
A practical and efficient route to the CD spiroketal (C-16-C-28) of the spongistatins is reported. Two stereocenters are introduced from chiral building blocks with the remainder introduced by substrate-controlled transformations. The key beta-keto-1,3-dithiane intermediate is generated by a dithiol conjugate addition to an ynone and the 1,3-dithiane unit in the C-ring plays a key role in the spiroketalization
据报道,一种实用而有效的途径可以使海绵抑素达到CD螺旋体(C-16-C-28)。从手性构件中引入了两个立体中心,其余通过底物控制的转化引入。关键的β-酮-1,3-二硫杂环丁烷中间体是通过将二硫醇共轭物添加到炔酮中而生成的,C环中的1,3-二硫杂环丁烷单元在螺酮化和随后的差向异构化中起关键作用。合成需要24个步骤,最长的线性序列为19个步骤,总产率为14.5%(最长的线性序列)。[反应:看文字]