Cycloaddition Reaction of Vinylphenylfurans and Dimethyl Acetylenedicarboxylate to [8 + 2] Isomers via Tandem [4 + 2]/Diradical Alkene–Alkene Coupling/[1,3]-H Shift Reactions: Experimental Exploration and DFT Understanding of Reaction Mechanisms
作者:Kai Chen、Feng Wu、Lijuan Ye、Zi-You Tian、Zhi-Xiang Yu、Shifa Zhu
DOI:10.1021/acs.joc.6b00792
日期:2016.9.16
investigate how the reaction between vinylphenylfuran and DMAD took place. Surprisingly, the reaction did not involve the expected [8 + 2] intermediate, o-quinodimethane. Instead, the reaction starts from intermolecular Diels–Alder reactions between DMAD and the furan moiety of vinylphenylfuran, followed by unexpected intramolecular alkene–alkene coupling. This step generates a diradical species, which
进行了设计的[8 + 2]乙烯基苯基呋喃和乙炔二羧酸二甲酯(DMAD)反应的实验测试,结果表明该反应在不同条件下产生了意外的加成产物。当该反应在热条件下在甲苯中进行时,生成了被称为[8 + 2]异构体的环氧苯菲。在本研究中已经研究了该反应的范围。此外,实验和理论计算已进行调查vinylphenylfuran和DMAD之间的反应是如何发生的。令人惊讶地,该反应不涉及预期[8 + 2]中间,ö-喹二甲烷。相反,该反应从DMAD和乙烯基苯基呋喃的呋喃部分之间的分子间Diels-Alder反应开始,然后发生意想不到的分子内烯烃-烯烃偶联。此步骤生成双自由基物质,然后进行[1,3] -H转变,得到实验观察到的环氧苯并菲。DFT计算显示,无法获得[8 + 2]环加合物,因为与[1,3] -H相比,[1,5]-乙烯基转移中间体的[1,5] -H转移过程在动力学上不利。转变为[8 + 2]异构体。