Mechanism on Remarkably Stereospecific Monochlorination of Adamantylideneadamantane

• 作 者: JiajiaSong;RenFeng;JingKong;Ji-JunZou;XiangwenZhang;LiWang;
• 机 构: Key Laboratory for Green Chemical and Technology,School of Chemical Engineering and Technology,Tianj
• 出 处: 第十二届全国量子化学会议
• 发表日期: 2014年期

　　Herein,we report a comprehensive theoretical investigation on highly stereospecific monochlorination of adamantylideneadamantane(Ad=Ad)with Cl2 and NCS in CCl4.For the reaction without radical initiators,ion-pair mechanism well rationalizes the unique stereospecificity.It involves three consecutive steps: formation of ion-pair species(Ad=Ad-Cl+/Cl-and Ad=Ad-Cl+/NS-),stereospecific proton abstraction from 4-axial(4-a)position and kinetically preferred intramolecular 4-equatorial(4-e)cyclopropylcarbinyl-homoallylic rearrangement.As to the reaction with the presence of radical initiators,the free radical mechanism fails to explain the experimental results,but the radical cation mechanism works well.In this channel,Ad=Ad+· is formed via one-electron oxidization with the assistance of oxidants like Cl·,NS· and Ad=Ad-Cl+.Then the stereospecific 4-e-Ad=Ad+ formed by hydrogen loss from 4-e position of Ad=Ad+· interacts with chloride anion and gives the final product.