Paquette Leo A, Parker Gregory D, Tei Takahiro, Dong Shuzhi
Evans Chemical Laboratories, The Ohio State University, Columbus, OH 43210, USA.
J Org Chem. 2007 Sep 14;72(19):7125-34. doi: 10.1021/jo070861r. Epub 2007 Aug 15.
D-Glyceraldehyde acetonide has been used as the starting point for accessing the enantiomeric cyclobutanols 11 in optically pure condition. The dextrorotatory enantiomer has been transformed in five steps into the [3.2.0] bicyclic lactone 22. While the deoxygenation of 22 proved to be problematical, the uncyclized variant 25 underwent the Barton process smoothly. These findings guided the related conversion of (-)-11 into 34. Use was also made of ring-closing metathesis to bring about the conversion of (+)-11 into [4.2.0] bicyclic lactone building blocks. In general, all three pathways are efficient and offer the prospect of practical side-chain appendage for the purpose of installing the nine-membered ring of pestalotiopsin A (1).
D-甘油醛丙酮化物已被用作在光学纯条件下制备对映体环丁醇11的起始原料。右旋对映体已通过五步反应转化为[3.2.0]双环内酯22。虽然22的脱氧反应存在问题，但未环化的变体25顺利进行了巴顿反应。这些发现指导了(-)-11向34的相关转化。还利用闭环复分解反应将(+)-11转化为[4.2.0]双环内酯结构单元。总体而言，所有这三条途径都是有效的，并为安装 Pestalotiopsin A（1）的九元环而进行实际侧链连接提供了前景。
