Unexpected epimerization and stereochemistry revision of IMDA adducts from sorbate-related 1,3,8-nonatrienes |
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| Authors: | Jinlong Wu Yan Wang Wei-Min Dai |
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| Institution: | a Laboratory of Asymmetric Catalysis and Synthesis, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
b Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China |
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| Abstract: | Intramolecular Diels-Alder (IMDA) reaction of two sorbate-related 1,3,8-nonatrienes has been investigated in MeCN at 180 °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. |
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| Keywords: | Intramolecular Diels-Alder reaction Isomerization Lactone Microwave Sorbate Stereochemistry |
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