Switchable highly regioselective synthesis of 3,4-dihydroquinoxalin-2(1<i>H</i>)ones from <i>o</i>-phenylenediamines and aroylpyruvates
作者:Juraj Dobiaš、Marek Ondruš、Gabriela Addová、Andrej Boháč
DOI:10.3762/bjoc.13.132
日期:——
4-dihydroquinoxalin-2(1H)-one regioselectivity in a predictable manner. For comparison, all regioselective cyclocondensations were performed with the same standardized conditions (DMF, rt, 3 days), differing only by the additives p-TsOH or HOBt/DIC (hydroxybenzotriazole/N,N'-diisopropylcarbodiimide). Both selected methods are simple, general and highly regioselective (72-97%). A mechanism for the regioselectivity was
3-酰基亚甲基-3,4-二氢喹喔啉-2(1H)-1是具有广泛的物理和药物应用的化合物。这些化合物可以通过邻苯二胺和芳酰基丙酮酸酯的环缩反应容易地制备。不对称取代的邻苯二胺可以从3,4-二氢喹喔啉-2(1H)-一的区域异构体混合物中获得。在不控制反应选择性和利用复杂的NMR技术(HSQC,NOESY,HMBC)的情况下,获得纯的区域异构体并确定其结构通常非常困难。本文研究了我们研究的六个单取代的邻苯二胺(-OMe,-F,-Cl,-COOH,-CN,-NO2)与对氯苯甲酰基丙酮酸(酯或酸)衍生物之间的环缩反应的区域选择性。六个区域异构体3 选择性地制备并表征了4-二氢喹喔啉-2(1H)-对。根据我们的经验,提出了一种用于确定区域异构体结构的简化方法。我们从相同的邻苯二胺和活化的4-氯苯甲酰基丙酮酸酯(酯或酸)开发了两种通用且高度选择性的方法,从而能够以可预测的方式切换3,4-二氢喹喔啉-2(1