Studied Directed toward the Synthesis of Phomenoic Acid. Part 2. Stereocontrolled Synthesis of the C(7)-to-C(14) Segment
作者:Hammed H. A. M. Hassan、Christoph Tamm
DOI:10.1002/hlca.19960790219
日期:1996.3.20
corresponding to the C(7)-to-C(14) segment of phomenoic acid (1). Attempts to improve the yields by applying a Julia coupling of (R)-23, which was prepared from (2E,4R)-7, with (R)-24 were unsuccessful. Finally, the coupling of the iodo derivative (2E,4S)-28 with the lithiated derivative of 1,3-dithiane 30 by the Corey-Seebach ‘Umpolung’ led to (3S,4E)-32 which is a derivative of the C(7)-to-C(14) segment
从酯(2 E,4 S)-6和(2 E,4 R)-6开始,溴醛(S)-9和(R)-9以及溴代醇(S)-10和(R)-10,分别准备。溴醇(R)-8被转化为二醇(2 E,4 R)-16。后者的臭氧分解产生醛(R)-17,该醛被(a )转化为Wittig反应至(2 R,4 E,6 R)-18,对应于phomenoic acid(1)的C(7)-C(14)段。通过应用由(2 E,4 R)-7制备的(R)-23与(R)-24的Julia偶联来提高收率的尝试均未成功。最后,将碘代衍生物的偶联(2 ë,4小号) - 28与1,3-二噻烷的锂化衍生物30由科里-Seebach的'极性转换'导致(3小号,4 ë) - 32这是一种衍生物的C(7)的-to-C(14)的段1,适合于进一步转化。