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。