A Polar Effects Controlled Enantioselective 1,2-Chlorine Atom Migration via a Chlorine-Bridged Radical Intermediate
作者:Eng Wui Tan、Bun Chan、Allan G. Blackman
DOI:10.1021/ja011129r
日期:2002.3.1
An enantioselective 1,2-chlorine atom migration was observed in the tributyltin hydride reduction of various dihalogenated dihydrocinnamic acid derivatives. It is proposed that the reduction involves the formation of a chlorine-bridged radical intermediate, followed by hydrogen atom transfer to either the beta- or the alpha-carbon. The product distribution is affected by electron-withdrawing groups
在各种二卤化二氢肉桂酸衍生物的三丁基氢化锡还原反应中观察到对映选择性的 1,2-氯原子迁移。建议还原涉及形成氯桥基自由基中间体,然后氢原子转移到 β- 或 α-碳。产物分布受吸电子基团的影响,因为有利于氢原子转移到邻近的碳。据推测,这是由于氢传递步骤的过渡态富电子,由于相对带正电的锡自由基。这些结果表明 1,2-氯原子迁移反应受极性效应控制。