作者:Ma del Mar Blanco、MiguelA´ngel Alonso、Carmen Avendan˜o、J. Carlos Mene´ndez
DOI:10.1016/0040-4020(96)00224-4
日期:1996.4
normally limits the usefulness of these hetero Diels-Alder reactions. If the C-3 substituent is strongly electron-withdrawing, a multi-step ionic mechanism involving the C5=O carbonyl and leading to the isolation of afuro[2, 3-f]quinolin-7-one derivative competes with the [4 + 2] cycloaddition. This process may be favoured through changes in the polarity of the reaction medium, allowing a selective, one-pot
3-取代的2,5,8-(1H)喹啉三酮相对于其4-取代的类似物对1-二甲氨基-1-氮杂二烯的反应性表现出有趣的差异。因此,它们与甲基丙烯醛二甲基cyclo的[4 + 2]环加成反应得到2,9,10(1H)-1,8-二氮杂蒽环内酯,没有发现因将二甲胺加到起始醌中而产生的副产物的痕迹,该过程通常限制了这些杂Diels-Alder反应。如果C-3取代基具有强吸电子性,则涉及C 5的多步离子机理= O羰基并导致分离出呋喃[2,3-f]喹啉-7-一衍生物与[4 + 2]环加成竞争。通过改变反应介质的极性,可以有利于该过程,从而可以从5、8-二甲氧基羰基苯乙烯基上选择性地一锅合成非呋喃[2,3-f]喹啉-7-酮。