A Highly Active Manganese Precatalyst for the Hydrosilylation of Ketones and Esters
A Highly Active Manganese Precatalyst for the Hydrosilylation of Ketones and Esters
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DOI：
10.1021/ja4116346
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发表时间：
2014-01-22
影响因子：
15
通讯作者：
Trovitch, Ryan J.
中科院分区：
文献类型：
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作者：
Mukhopadhyay, Tufan K.;Flores, Marco;Trovitch, Ryan J.
（（PDI）-P-Ph 2 PPr）MnCl 2的还原允许形式上零价络合物（（PDI）-P-Ph 2 PPr）Mn的制备，其特征在于五齿双（亚氨基）吡啶螯合物。该配合物是一种用于酮的硅氢加成的高活性预催化剂，在没有溶剂的情况下表现出高达76，800 h（-1）的TOF。采用低至0.01摩尔%的负载量，并且发现（（PDI）-P-Ph 2 PPr）Mn介导Si-H键的原子有效利用以形成季硅烷产物。（（PDI）-P-Ph 2 PPr）Mn还显示出在底物酰基C-O键断裂后催化酯的二氢硅烷化。（（PDI）-P-Ph 2 PPr）Mn的电子结构研究表明，该配合物在金属中心上具有一个未成对电子，因此可能在电子转移到引入的羰基取代基后发生催化作用。
The reduction of ((PDI)-P-Ph2PPr)MnCl2 allowed the preparation of the formally zerovalent complex, ((PDI)-P-Ph2PPr)Mn, which features a pentadentate bis(imino)pyridine chelate. This complex is a highly active precatalyst for the hydrosilylation of ketones, exhibiting TOFs of up to 76,800 h(-1) in the absence of solvent. Loadings as low as 0.01 mol % were employed, and ((PDI)-P-Ph2PPr)Mn was found to mediate the atom-efficient utilization of Si-H bonds to form quaternary silane products. ((PDI)-P-Ph2PPr)Mn was also shown to catalyze the dihydrosilylation of esters following cleavage of the substrate acyl C-O bond. Electronic structure investigation of ((PDI)-P-Ph2PPr)Mn revealed that this complex possesses an unpaired electron on the metal center, rendering it likely that catalysis takes place following electron transfer to the incoming carbonyl substituent.