Probing for a Leaving Group Effect on the Generation and Reactivity of Phenyl Cations
作者:Erika Abitelli、Stefano Protti、Maurizio Fagnoni、Angelo Albini
DOI:10.1021/jo300290v
日期:2012.4.6
by the photoheterolytic cleavage of an Ar–LG bond (LG = leaving group). With the aim of evaluating the scope of the method, a series of 4-methoxy-2-(trimethylsilyl)phenyl derivatives (sulfonic, LG = MeSO3 and CF3SO3, phosphate, LG = (EtO)2(O)PO esters and the corresponding chloride) have been compared as probes for evaluating the leaving group ability. The photocleavage was a general reaction, with
苯阳离子是通过Ar-LG键(LG =离开基团)的光解裂解而平稳生成的。为了评估该方法的范围,提出了一系列4-甲氧基-2-(三甲基甲硅烷基)苯基衍生物(磺酸,LG = MeSO 3和CF 3 SO 3,磷酸盐,LG =(EtO)2(O)PO酯和相应的氯化物)已作为比较探针,用于评估离去基团的能力。光裂解是一个普遍的反应,(EtO)2(O)PO〜Cl > CF 3 SO 3 > MeSO 3(CF 3 CH 2 OH中的Φ= 0.50至0.16,而MeCN–H中的值较低)2 O)。随之而来的反应并不取决于LG,而仅取决于苯基阳离子的结构(甲硅烷基将三重态调节为单重态系统间穿越和亲电性)和介质(与水形成络合物会减慢亲电反应)。