Stereoselective Synthesis of Alcohols, L. Stereoselective Synthesis of a C-15/C-27 Segment of the Venturicidines
作者:Reinhard W. Hoffmann、Ulrike Rolle、Richard Göttlich
DOI:10.1002/jlac.199619961104
日期:1996.11
Chain extension of an aldehyde by two “propionate” units has been attained by stereoselective allylboration with the chiral 1-methylbutenyl boronate 3 to give, e.g., the homoallylic alcohol 6, followed by a regioselective hydroboration/carbonylation procedure to give, e.g., the epimeric aldehydes 8. The latter were converted into the lactols 10, which equilibrated to the desired epimer. The lactols
通过与手性的1-甲基丁烯基硼酸酯3进行立体选择性的烯丙基硼化得到例如均丙醇6,然后进行区域选择性的硼氢化/羰基化过程得到例如的差向异构体,可以使醛通过两个“丙酸酯”单元进行链扩展。醛8。后者被转化为内酯10,其平衡为所需的差向异构体。内酯可以再次进行烯丙基硼化反应,引发第二轮扩链方案。该技术已被用于以15个步骤合成文丘二烯C-15 / C-27片段23,该片段包含8个具有适当绝对构型的立体异构中心。