[CNC]-Pincer Cobalt Hydride Catalyzed Distinct Selective Hydrosilylation of Aryl Alkene and Alkyl Alkene,Organometallics

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[CNC]-Pincer Cobalt Hydride Catalyzed Distinct Selective Hydrosilylation of Aryl Alkene and Alkyl Alkene
Organometallics ( IF 2.5 ) Pub Date : 2020-06-19 , DOI: 10.1021/acs.organomet.0c00251
Shangqing Xie ₁ , Xiaoyan Li ₁ , Hongjian Sun ₁ , Olaf Fuhr ₂ , Dieter Fenske ₂

Affiliation

The reactions of unsymmetrical N-heterocyclic carbene (NHC) [CNC]-pincer preligands with CoMe(PMe₃)₄ gave rise to NHC [CNC]-pincer cobalt(III) hydrides, [(C_carbeneN_aminoC_naphthyl)Co(H)(PMe₃)₂] (3a) and (3b), via C_sp2–H activation and the unexpected trans-bischelate [C_carbene, N_amino] cobalt(II) complexes 4a and 4b via a disproportionation reaction, respectively. It was found that both 3a and 3b are efficient catalysts for hydrosilylation of alkenes. With aryl alkenes as substrates, 3a has high Markovnikov selectivity in excellent yields, while 3a is an efficient anti-Markovnikov catalyst in good yields with alkyl alkenes as substrates. The catalytic process could be promoted with pyridine N-oxide as an initiator. The catalytic mechanisms for the two different selectivities were proposed. Complexes 3a, 3b, 4a, and 4b were characterized by spectroscopic methods, and the molecular structures of 3b, 4a, and 4b were determined by single crystal X-ray diffraction.

中文翻译：

[CNC]-氢化钴钴催化芳烃和烷基烯烃的独特选择性氢化硅烷化

不对称的N-杂环卡宾（NHC）[CNC]-钳子预配体与CoMe（PMe ₃）_{4的反应生成}了NHC [CNC]-钳式钴（III）氢化物，[（C_卡宾N_氨基C_萘基）Co（ H）（PMe ₃）₂ ]（3a）和（3b），分别通过C _sp2- H活化和意外的反式双螯合物[C_卡宾，N_氨基]钴（II）络合物4a和4b通过歧化反应进行活化。发现3a和3b都是烯烃氢化硅烷化的有效催化剂。以芳基烯烃为底物，3a以优异的收率具有高的马尔可夫尼可夫选择性，而3a是以烷基烯烃为底物且具有高收率的有效的抗马尔科夫尼科夫催化剂。以吡啶N-氧化物为引发剂可以促进催化过程。提出了两种不同选择性的催化机理。通过光谱法表征复合物3a，3b，4a和4b，并通过单晶X射线衍射确定3b，4a和4b的分子结构。

更新日期：2020-07-13

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