Unexpected Behavior of the Reaction between 1,2-Diaza-1,3-Butadienes and 3-Dimethylaminopropenoates: A Useful Entry to New Pyrrolines, Pyrroles, and Oxazolines
作者:Orazio A. Attanasi、Gianfranco Favi、Paolino Filippone、Amalija Golobič、Branko Stanovnik、Jurij Svete
DOI:10.1021/jo0480343
日期:2005.5.1
We observed a nucleophilic attack by the ene-amino carbon of 3-dimethylaminopropenoates at the terminal carbon of the azo-ene system of 1,2-diaza-1,3-butadienes. In tetrahydrofuran at 65 °C, this attack produced 1-aminopyrrolines with a high degree of cis-stereoselectivity by means of an unusual zwitterionic adduct intermediate followed by intramolecular ring closure. In toluene under reflux, 1-aminopyrrolines
我们观察到3-二甲基氨基丙酸酯的烯氨基碳在1,2-二氮杂-1,3-丁二烯的偶氮-烯系统的末端碳上发生亲核攻击。在65°C的四氢呋喃中,这种攻击会产生高度顺式的1-氨基吡咯啉-立体选择性是通过不寻常的两性离子加合物中间体,然后进行分子内环封闭。在回流下的甲苯中,1-氨基吡咯啉生成恶唑啉稠合的1-氨基吡咯啉。通过使1,2-二氮杂-1,3-丁二烯与3-二甲基氨基丙酸酯在甲苯中回流反应直接得到恶唑啉稠合的1-氨基吡咯啉。恶唑啉稠合的1-氨基吡咯啉在酸性或碱性介质中的开环提供了高度取代的1-氨基吡咯。在碱性条件下,通过损失二甲基氨基和酯基,从1-氨基吡咯啉获得5-未取代的1-氨基吡咯衍生物。我们讨论了环闭合和打开的合理机制。