A mechanism for the palladium-catalyzed regioselective silaboration of allene: A theoretical study
A mechanism for the palladium-catalyzed regioselective silaboration of allene: A theoretical study
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DOI：
10.1021/om070110f
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发表时间：
2008-04-28
期刊：
影响因子：
2.8
通讯作者：
Ito, Yoshihiko
中科院分区：
文献类型：
--
作者：
Abe, Yoko;Kuramoto, Kei;Ito, Yoshihiko
从理论上研究了钯催化剂对末端丙二烯的区域选择性硅化反应的机理。特别检查了整个反应方案以确定区域选择性的机制。本催化反应是放热的，决定速率的步骤是将丙二烯插入到Pd络合物的Pd-B键中。 σ-烯丙基和π-烯丙基配合物作为中间体存在，在区域选择性中发挥重要作用。将未取代的 C=C 键选择性插入 Pd-B 键中会产生最稳定的 σ-烯丙基络合物，该络合物会转化为 pi-烯丙基络合物，同时保持 Pd-O 配位。特定σ-烯丙基复合物的选择性形成和两个异构体π-烯丙基复合物之间的大活化势垒主要决定了本反应的区域选择性。主要产物复合物的稳定性低于次要产物复合物，因此动力学控制在本反应中占主导地位。
A mechanism for the regioselective silaboration of terminal allene by a palladium catalyst has been studied theoretically. The overall reaction scheme has been examined in particular to determine the mechanism of the regioselectivity. The present catalytic reaction is exothermic and the rate-determining step is the insertion of allene into the Pd-B bond of the Pd complex. sigma-Allylic and pi-allylic complexes exist as intermediates and play an important role in the regioselectivity. Selective insertion of the unsubstituted C=C bond into the Pd-B bond produces the most stable sigma-allylic complex, which converts to the pi-allylic complex while maintaining the Pd-O coordination. The selective formation of the specific sigma-allylic complex and the large activation barrier between two isomeric pi-allylic complexes dominantly determines the regioselectivity of the present reaction. The major-product complex is less stable than the minor-product complex, and therefore kinetic control is predominant in the present reaction.