Oxidative Carbon−Carbon Bond Cleavage of a [2.2]Paracyclophane Derivative − Efficient Intramolecular Trapping of the Radical Cation
作者:Sethuraman Sankararaman、Henning Hopf、Ina Dix、Peter G. Jones
DOI:10.1002/1099-0690(200008)2000:15<2711::aid-ejoc2711>3.0.co;2-b
日期:2000.8
4-(2,3,4,5-Tetraphenyl)phenyl[2.2]paracyclophane (3) has been prepared by cycloaddition of tetracyclone (2) to 4-ethynyl[2.2]paracyclophane (1). On treatment with FeCl3 or AlCl3 or NOBF4 in nitromethane, 3 undergoes C−C bond cleavage by an electron transfer process to provide the double benzyl radical cation 10. The phenyl groups of the aryl substituent are ideally oriented for intramolecular trapping
4-(2,3,4,5-四苯基)苯基[2.2]对环环糊精(3)是通过将四环酮(2)与4-乙炔基[2.2]对环环糊精(1)环加成而制备的。在FeCl 3或AlCl 3或NOBF 4在硝基甲烷中处理后,3会通过电子转移过程发生C-C键断裂,从而提供双苄基阳离子10。芳基取代基的苯基理想地定向用于分子内捕获,并且在路易斯酸的存在下,以良好的收率(65%)发生与新的phane系统5的闭环。在存在NOBF 4的情况下,半环醛6(66%)产生了。为了进行比较,[2.2]对环芳烷(7)也与后者单电子氧化剂处理,提供联苄-4,4'-二甲醛(8,30%)和它的单肟9(35%)。已经通过X射线结构分析确定了新体模系统3和5的结构,并讨论了导致这些产物的机理。