Bismuth(III) triflate catalyzed tandem esterification–Fries–oxa-Michael route to 4-chromanones
作者:Kevin Meraz、Krishna Kumar Gnanasekaran、Rup Thing、Richard A. Bunce
DOI:10.1016/j.tetlet.2016.10.005
日期:2016.11
An efficient tandem reaction approach is described to prepare 4-chromanones from electron-rich phenols and 3,3-dimethylacrylic acid or trans-crotonic acid in boiling toluene using 20 mol % bismuth(III) triflate as the catalyst. The reaction is also successful from the corresponding aryl esters of each of these acids under the same conditions. The procedure is convenient to perform, and 25–90% yields
描述了一种有效的串联反应方法,该方法使用20摩尔%的三氟甲磺酸铋(III)在沸腾的甲苯中,由富含电子的苯酚和3,3-二甲基丙烯酸或反式巴豆酸制备4-苯并二氢呋喃。在相同条件下,由这些酸各自的相应芳基酯也可以成功地进行反应。该程序易于执行,色谱分离后产品的收率可达25-90%。包括多种底物(每种酸14种底物)以帮助定义过程的范围。报告了其他实验,这些实验证实了事件的顺序涉及(1)酯化,(2)薯条重排和(3)oxa-Michael环闭合。