Rearrangements of N-Heterocyclic Carbenes of Pyrazole to 4-Aminoquinolines and Benzoquinolines
作者:Andrij Dreger、Rafael Cisneros Camuña、Niels Münster、Tibor András Rokob、Imre Pápai、Andreas Schmidt
DOI:10.1002/ejoc.201000507
日期:2010.8
pyrazolium salts, formed by quaternization of pyrazoles with benzyl halides or long-chain alkyl halides, deprotonate to pyrazol-3-ylidenes that undergo a sequence of ring-opening, ring-closure, and tautomerization to new substituted 4-aminoquinolines. Similarly, 1-naphthyl-substituted pyrazolium-3-carboxylates decarboxylate on heating in toluene to give benzoquinolines in excellent yields by an analogous reaction
1-苯基取代的吡唑鎓盐,由吡唑与苄基卤化物或长链烷基卤化物的季铵化形成,去质子化为吡唑-3-亚基,经过一系列开环、闭环和互变异构化为新的取代的4-氨基喹啉。类似地,1-萘基取代的吡唑鎓-3-羧酸盐在甲苯中加热时脱羧,通过类似的反应途径以优异的产率得到苯并喹啉。DFT 计算表明,环转化通过一系列分子内消除、亚胺反转和 6π-电环化步骤进行。