Kinetics and mechanism of the pyridinolysis of <i>N</i>
-aryl-<i>P</i>
,<i>P</i>
-diphenyl phosphinic amides in dimethyl sulfoxide
作者:Arun Kanti Guha、Chan Kyung Kim、Hai Whang Lee
DOI:10.1002/poc.1788
日期:2011.6
electron‐withdrawing substituents Z in the leaving group. The negative sign of the cross‐interaction constants (ρXZ) for both electron‐donating (large magnitude of ρXZ = −1.54) and ‐withdrawing (ρXZ = −0.27) substituents Z indicates that the reaction proceeds through a concerted mechanism. These results are indicative of frontside and backside nucleophilic attacks at the P reaction center for electron‐donating
Z- N-芳基-P,P-二苯基次膦酰胺与X-吡啶的反应动力学研究已在85.0°C的二甲基亚砜中进行。X-吡啶中的两个强大的π受体取代基X = 4-Ac和4-CN,与Hammett和Brönsted图都显示出正偏差。哈米特地块为取代基Z的变化是异常与Z = H断点双相凹向上,和的符号ρ Ž从变化负为供电子到阳性吸电子取代基Z中的离去基团英寸 交叉相互作用常数的负号(ρ XZ)两个供电子(大幅度的ρ XZ = -1.54)和吸电子(ρ XZ = -0.27)取代基Z为通过协调一致的机制进行反应。这些结果表明在P反应中心的正面和背面亲核攻击分别是给电子和撤离取代基Z。NHPhZ较差的离去基团迁移率会导致亲核进攻方向发生变化,导致取代基Z变异的双相凹向上Hammett图。版权所有©2010 John Wiley&Sons,Ltd.