Funes-Ardoiz Ignacio, Sameera W M C, Romero R Martín, Martínez Claudio, Souto José A, Sampedro Diego, Muñiz Kilian, Maseras Feliu
Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain.
Fukui Institute for Fundamental Chemistry, Kyoto University, 606-8103, Kyoto, Japan.
Chemistry. 2016 May 23;22(22):7545-53. doi: 10.1002/chem.201600415. Epub 2016 Apr 23.
A computational study of the mechanism for the iodine(III)-mediated oxidative amination of alkenes explains the experimentally observed substrate dependence on product distribution. Calculations with the M06 functional have been carried out on the reaction between PhI(N(SO2 Me)2 )2 and three different representative substrates: styrene, α-methylstyrene, and (E)-methylstilbene. All reactions start with electrophilic attack by a cationic PhI(N(SO2 Me)2 )(+) unit on the double bond, and formation of an intermediate with a single C-I bond and a planar sp(2) carbocationic center. The major path, leading to 1,2-diamination, proceeds through a mechanism in which the bissulfonimide initially adds to the alkene through an oxygen atom of one sulfonyl group. This behavior is now corroborated by experimental evidence. An alternative path, leading to an allylic amination product, takes place through deprotonation at an allylic C-H position in the common intermediate. The regioselectivity of this amination depends on the availability of the resonant structures of an alternate carbocationic intermediate. Only in cases where a high electronic delocalization is possible, as in (E)-methylstilbene, does the allylic amination occur without migration of the double bond.
一项关于碘（III）介导的烯烃氧化胺化反应机理的计算研究解释了实验观察到的底物对产物分布的依赖性。使用M06泛函对PhI(N(SO2Me)2)2与三种不同代表性底物：苯乙烯、α-甲基苯乙烯和（E）-甲基茋之间的反应进行了计算。所有反应均始于阳离子PhI(N(SO2Me)2)(+)单元对双键的亲电进攻，并形成具有单个C-I键和平面sp(2)碳正离子中心的中间体。导致1,2-二胺化的主要途径是通过一种机理进行的，其中双磺酰亚胺最初通过一个磺酰基的氧原子加成到烯烃上。现在实验证据证实了这种行为。导致烯丙基胺化产物的另一条途径是通过在共同中间体的烯丙基C-H位置去质子化发生的。这种胺化反应的区域选择性取决于另一种碳正离子中间体共振结构的可用性。只有在像（E）-甲基茋这样能够实现高度电子离域的情况下，烯丙基胺化反应才会在不发生双键迁移的情况下发生。
