Internal Nucleophilic Termination in Acid-Mediated Polyene Cyclizations. Part 5
作者:Roger L. Snowden、Simon Linder
DOI:10.1002/hlca.200690276
日期:2006.12
proceed via non-concerted pathways (see Schemes 5 and 7), fully consistent with our earlier work. In contrast, another set of reaction conditions (CF3CO2H, CH2Cl2, − 15° to − 10°) was used for the cyclization of the monocyclic dienols (E)-3 and (Z)-3, which resulted in the non-stereoselective formation of the major products 1c,d and 1a,b, respectively, in 35–37% yield. Representing novel didehydro analogues
外消旋的三环醚1c的非对映异构体混合物,用过量的ClSO 3 H在2-硝基丙烷中的-80°立体选择性处理无环四烯醇(E)-和(Z)-2 ,d和1a,b以及20(表)。在相同条件下,但以无环戊烯醇10(1:1非对映异构体混合物)为底物,分离出三环醚22a / 22b(10:1),收率为27%。这些动力学控制的立体定向转化被认为是通过非协商途径(请参阅方案5和7),与我们之前的工作完全一致。与此相反,另一组反应条件(CF 3 CO 2 H,CH 2氯2, - 10° - 15°)被用于该单环dienols的环化(ë) - 3及(Ž) - 3,其分别导致主要产物1c,d和1a,b的非立体选择性形成,产率为35-37%。代表已知的龙涎香气味物质(±)的新颖二脱氢类似物-艾姆罗克斯®简要描述了新型四氢类似物22a / 22b的1a - d和10:1非对映异构体混合物的定性感官特性。