Selective Hydrosilation of CO<sub>2</sub>to a Bis(silylacetal) Using an Anilido Bipyridyl-Ligated Organoscandium Catalyst
作者:Francis A. LeBlanc、Warren E. Piers、Masood Parvez
DOI:10.1002/anie.201309094
日期:2014.1.13
A rigid anilido bipyridyl ligand has been designed for use in an organoscandium‐based carbon dioxide hydrosilation catalyst. Ligand attachment by alkane elimination results in metalation of an aryl CH bond in a 3,5‐di‐tert‐butylphenyl group installed on the pyridyl unit, thus rendering the ligand tetradentate. Insertion of CO2 into the newly formed ScC bond leads to a κ1 carboxylate which, when treated
刚性苯胺基联吡啶配体已设计用于有机scan基二氧化碳氢硅化催化剂。通过烷烃消除的配体连接导致在吡啶基单元上安装的3,5-二叔丁基苯基中的芳基CH键金属化,从而使配体变为四齿。CO的插入2到新形成的钪 C键通向κ 1个羧酸酯,其在与所述硼烷B(C处理过的6 ˚F 5)3,变得hemilabile。除活化催化剂外,k 1羧酸盐还有效隔离了游离的B(C 6 F 5)如图3所示,在过量的Et 3 SiH存在下,该组合物能够有效地硅氢化CO 2,几乎仅对R 3 SiOCH 2 OSiR 3而言。观察到最大周转数约为3400(硅烷转化)。机理实验表明,半不稳定的羧酸盐螯合游离的B(C 6 F 5)3有助于观察到的选择性并防止甲烷过度还原。