Unexpected epimerization and stereochemistry revision of IMDA adducts from sorbate-related 1,3,8-nonatrienes
Unexpected epimerization and stereochemistry revision of IMDA adducts from sorbate-related 1,3,8-nonatrienes
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山梨酸相关 1,3,8-九三烯 IMDA 加合物的意外差向异构化和立体化学修正
DOI：
10.1016/j.tetlet.2007.07.046
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发表时间：
2007-09-10
影响因子：
1.8
通讯作者：
Dai, Wei-Min
中科院分区：
文献类型：
--
作者：
Wu, Jinlong;Yu, Haihua;Dai, Wei-Min
研究了两种山梨酸酯相关的1，3，8-壬三烯的分子内Diels-Alder（IMDA）反应。在纯化前检查粗产物混合物时，在反应期间发现主要加合物的部分差向异构化。经硅胶柱层析纯化后，仅得到两个顺式加合物，其结构已通过X-射线晶体学分析完全确定。它的结论是假定的主要反式加成物预测的IMDA反应机理进行了容易的差向异构化在高温下或在硅胶的存在下。对加合物进行了结构修正。(C)2007爱思唯尔有限公司保留所有权利。
Intramolecular Diels-Alder (IMDA) reaction of two sorbate-related 1,3,8-nonatrienes has been investigated in MeCN at 180 degrees C for 1.5 h under controlled microwave heating. On checking the crude product mixture before purification, partial epimerization of the major adduct was found during the reaction. After column chromatographic purification over silica gel, only two cis adducts were obtained and their structures have been thoroughly established by X-ray crystallographic analysis. It is concluded that the putative major trans adduct predicted by the IMDA reaction mechanism undergoes facile epimerization at high temperature or in the presence of silica gel. Structural revision on the adducts has been made. (C) 2007 Elsevier Ltd. All rights reserved.