Solvent-Free Thermal and Microwave-Assisted [3 + 2] Cycloadditions between Stabilized Azomethine Ylides and Nitrostyrenes. An Experimental and Theoretical Study
作者:Ana Arrieta、Dorleta Otaegui、Aizpea Zubia、Fernando P. Cossío、Angel Díaz-Ortiz、Antonio de la Hoz、M. Antonia Herrero、Pilar Prieto、Concepción Foces-Foces、José L. Pizarro、María I. Arriortua
DOI:10.1021/jo062672z
日期:2007.6.1
[3 + 2] cycloaddition between stabilized azomethine ylides and nitrostyrenes have been analyzed using experimental and computational approaches. It has been observed that, in the absence of solvent, three stereoisomers are formed, both under classical heating conditions and under microwave irradiation. This result contrasts with that observed in solution under classical thermal conditions. The 4-nitropyrrolidines
在热和微波辅助的[3 + 2]环加成反应中,使用实验和计算方法分析了稳定的偶氮甲碱和硝基苯乙烯之间的立体化学结果。已经观察到,在不存在溶剂的情况下,在经典加热条件下和在微波辐射下均形成三种立体异构体。该结果与在经典热条件下在溶液中观察到的结果形成对比。可以将这样获得的4-硝基吡咯烷在进一步的微波辐射下芳构化,得到吡咯和4-硝基吡咯的混合物。发现亚胺和硝基苯乙烯之间的基态环加成反应是通过三步机理进行的。第一步涉及起始亚胺的烯醇化,然后是伪周环的10电子[1。4]-氢转移。最后,通过相对异步的芳族六电子发生环加成反应上文-上文热机制。