Site selectivity in the reaction of tetracyanoethene with tetracyclo [5.3.2.02,10. 03,6] dodeca-4,8,11-triene
作者:M. Burdisso、A. Gamba、R. Gandolfi、R. Oberti
DOI:10.1016/s0040-4020(01)87499-8
日期:1986.1
homo-Dies-Alder reaction leading to 4 was shown to be reversible. In methanol compound 4 gave rise to a zwitterion which was trapped by solvent. Reaction mechanisms are discussed. A zwitterion is proposed as intermediate on the pathway to 6 whereas experimental findings do not permit a definitive choice between an ionic two step and a concerted cycloaddition in the formation of 4. The neutral and base
根据两种竞争反应模式,四苯并四乙烯[5.3.2.0 2,10 .0 3.6 ] dodeca-4,8,11-三烯(1)与四环[5.3.2.0 2,10 .0 3.6 ] dodeca-4,3-均涉及单一的同噻吩并二烯部分,生成加合物4和6的混合物。通过X射线分析建立结构6。化合物4和6由热允许homocycloaddition结果和禁止[Π 2 5 +σ 2 5 +Π 2小号+Π 2小号]反应,分别。反应速度与6:4从苯到硝基甲烷作为反应介质时,比值增加。导致4的homo-Dies-Alder反应被证明是可逆的。在甲醇化合物4中产生两性离子,其被溶剂捕获。讨论了反应机理。两性离子被提议作为通往6的途径的中间产物,但实验结果不允许在离子两步和形成4的协同环加成反应之间进行明确的选择。中性和碱催化加成甲醇以的四氰基乙烯部分4,6和相关的衍生物也进行了研究。