Catalyzed Diels−Alder Reaction of Alkylidene- or Arylideneacetoacetates and Danishefsky's Dienes with Lanthanide Salts Aimed at Selective Synthesis of <i>cis</i>-4,5-Dimethyl-2-cyclohexenone Derivatives
作者:Tsutomu Inokuchi、Masamitsu Okano、Tomoko Miyamoto
DOI:10.1021/jo010575u
日期:2001.11.1
of 1a. The thermal version of the same cycloaddition results in a decrease in the cis arrangement of the 5-methyl and the 4-alkoxycarbonyl groups on 2-cyclohexenone. The catalyzed reaction of (E)-1a unexpectedly affords the cis-arranged 3a. The reaction path for the catalyzed Diels-Alder reaction is postulated on the basis of these results.
描述了1-甲氧基-3-三甲基甲硅烷氧基-1,3-二烯(Danishefsky's diene,2a)催化的Diels-Alder反应的第一个成功的例子,给出了相应的碳环加合物。(Z)-乙炔基乙酸酯1a与2a的反应在0℃下用镧系元素盐(例如Yb(OTf)(3))催化,以高收率提供相应的2-环己烯酮3a,并且完全具有1a起始几何形状的完整性。相同环加成的热形式导致2-环己烯酮上的5-甲基和4-烷氧基羰基的顺式排列减少。(E)-1a的催化反应出乎意料地提供了顺式排列的3a。基于这些结果推测出催化的Diels-Alder反应的反应路径。