2<i>H</i>-Pyrrole Derivatives from an Aza-Nazarov Reaction Cascade Involving Indole as the Neutral Leaving Group
作者:Nugzar Ghavtadze、Roland Fröhlich、Ernst-Ulrich Würthwein
DOI:10.1002/ejoc.200800384
日期:2008.7
chemical calculations the key step in the reaction cascade is the cleavage of the N–N bond of the hydrazone fragment of a protonated N-(indolin-1-yl)-1-aza-1,4-dien-3-one intermediate such as 10. This intermediate releases 3H-indole as an unusual, but very efficient neutral leaving group. Several 1-aza-1,4-dien-3-ones 4 and some 3-hydroxy-5H-pyrrole derivatives 8 were characterized by X-ray diffraction
三氟甲基取代的 N-indolinyl-1-aza-1,4-dien-3-ones 4 可以从 indolinylimino 酯 6 以良好的产率在两步程序中获得,如果进行处理,会经历一种新型的氮杂-纳扎罗夫环化用强酸得到迄今为止未知的 3-羟基-5H-吡咯衍生物 8a-p。作为酸性反应介质的无溶剂多磷酸/酰基酐体系特别有效并且只需要很短的反应时间。根据量子化学计算,反应级联的关键步骤是质子化 N-(indolin-1-yl)-1-aza-1,4-dien-3- 腙片段的 N-N 键断裂一种中间体,例如 10。该中间体释放 3H-吲哚作为一种不寻常但非常有效的中性离去基团。几个 1-aza-1,