Synthesis of Optically Pure (+)-Puraquinonic Acid and Assignment of Absolute Configuration to Natural (−)-Puraquinonic Acid. Use of Radical Cyclization for Asymmetric Generation of a Quaternary Center
作者:Derrick L. J. Clive、Maolin Yu、Mousumi Sannigrahi
DOI:10.1021/jo040115b
日期:2004.6.1
key reactions used to make optically pure allylic alcohol 40. Radical cyclization of the derived Stork bromo acetals gives lactol ethers 43, which were degraded to generate a quaternary center carrying a methoxycarboxyl group (44 → 47). Compound 47 was converted into (+)-puraquinonic acid; and comparison with a natural sample established that the configuration of the natural compound is 2R (1).
醛31和酰亚胺32之间的不对称羟醛反应,随后在随后的阶段进行闭环复分解(38 → 40),是用于制备光学纯烯丙基醇40的关键反应。衍生的鹳溴代乙缩醛的自由基环化产生乳醇醚43,其被降解以生成带有甲氧基羧基(44 → 47)的季中心。将化合物47转化为(+)-嘌呤醌酸;并与天然样品进行比较,确定天然化合物的构型为2 R(1)。