Roush W R, Pfeifer L A
Department of Chemistry, University of Michigan, Ann Arbor 48109, USA.
Org Lett. 2000 Mar 23;2(6):859-62. doi: 10.1021/ol005629l.
[formula: see text] The final stages of a total synthesis of mycalamide A are described. A key step is the aldol reaction (mismatched) of imide 4 and aldehyde 5 which provided a ca. 5:4 mixture of aldols 10a and 10b, with incorrect C(7) stereochemistry. Elaboration of the 10a-10b mixture to mycalamide A required epimerization of C(7) at the stage of beta-keto imide 11. Alternatively, Swern oxidation of the 10a-10b mixture under conditions that minimize C(7) epimerization led to 7-epi-mycalamide A selectively.
[化学式：见正文] 描述了麦卡酰胺A全合成的最后阶段。关键步骤是酰亚胺4与醛5的羟醛反应（不匹配），该反应生成了约5:4的羟醛10a和10b混合物，其C(7)立体化学不正确。将10a - 10b混合物转化为麦卡酰胺A需要在β-酮酰亚胺11阶段对C(7)进行差向异构化。或者，在使C(7)差向异构化最小化的条件下对10a - 10b混合物进行斯文氧化，可选择性地生成7-表麦卡酰胺A。
