Intramolecular versus intermolecular oxidative couplings of ester tethered di-aryl ethers
作者:Stephen R. Taylor、Alison T. Ung、Stephen G. Pyne、Brian W. Skelton、Allan H. White
DOI:10.1016/j.tet.2007.08.082
日期:2007.11
The oxidative cyclization of 3,4-dimethoxyphenyl 3,4-dimethoxyphenylacetate, through intramolecular biphenyl bond formation, was successful and gave the target seven-membered lactone in good yield (85–86%). All other ester substrates gave biphenyl products or their further oxidized products via intermolecular coupling of their radical cation intermediate with the neutral substrate. It appears that
3,4-二甲氧基苯基乙酸3,4-二甲氧基苯基乙酸的氧化环化通过分子内联苯键的形成是成功的,并以良好的收率(85-86%)得到了目标七元内酯。所有其他酯底物通过其自由基阳离子中间体与中性底物的分子间偶联而得到联苯产物或其进一步的氧化产物。看起来两个苯环的氧化电位和亲核性,环取代基的位置以及酯C-O键的E到Z异构化的容易程度的匹配是促成这些产物结果的重要因素。