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Markovnikov Hydrosilylation of Alkynes with Tertiary Silanes Catalyzed by Dinuclear Cobalt Carbonyl Complexes with NHC Ligation
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2021-08-04 , DOI: 10.1021/jacs.1c06583 Dongyang Wang 1, 2 , Yuhang Lai 1, 3 , Peng Wang 1 , Xuebing Leng 1 , Jie Xiao 1 , Liang Deng 1, 2
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2021-08-04 , DOI: 10.1021/jacs.1c06583 Dongyang Wang 1, 2 , Yuhang Lai 1, 3 , Peng Wang 1 , Xuebing Leng 1 , Jie Xiao 1 , Liang Deng 1, 2
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Metal-catalyzed hydrosilylation of alkynes is an ideal atom-economic method to prepare vinylsilanes that are useful reagents in the organic synthesis and silicone industry. Although great success has been made in the preparation of β-vinylsilanes by metal-catalyzed hydrosilylation reactions of alkynes, reported metal-catalyzed reactions for the synthesis of α-vinylsilanes suffer from narrow substrate scope and/or poor selectivity. Herein, we present selective Markovnikov hydrosilylation reactions of terminal alkynes with tertiary silanes using a dicobalt carbonyl N-heterocyclic carbene (NHC) complex [(IPr)2Co2(CO)6] (IPr = 1,3-di(2,6-diisopropylphenyl)imidazol-2-ylidene) as catalyst. This cobalt catalyst effects the hydrosilylation of both alkyl- and aryl-substituted terminal alkynes with a variety of tertiary silanes with good functional group compatibility, furnishing α-vinylsilanes with high yields and high α/β selectivity. Mechanistic study revealed that the stoichiometric reactions of [(IPr)2Co2(CO)6] with PhC≡CH and HSiEt3 can furnish the dinuclear cobalt alkyne and mononuclear cobalt silyl complexes [(IPr)(CO)2Co(μ–η2:η2-HCCPh)Co(CO)3], [(IPr)(CO)2Co(μ-η2:η2-HCCPh)Co(CO)2(IPr)], and [(IPr)Co(CO)3(SiEt3)], respectively. Both dicobalt bridging alkyne complexes can react with HSiEt3 to yield α-triethylsilyl styrene and effect the catalytic Markovnikov hydrosilylation reaction. However, the mono(NHC) dicobalt complex [(IPr)(CO)2Co(μ-η2:η2-HCCPh)Co(CO)3] exhibits higher catalytic activity over the di(NHC)-dicobalt complexes. The cobalt silyl complex [(IPr)Co(CO)3(SiEt3)] is ineffective in catalyzing the hydrosilylation reaction. Deuterium labeling experiments with PhC≡CD and DSiEt3 indicates the syn-addition nature of the hydrosilylation reaction. The absence of deuterium scrambling in the hydrosilylation products formed from the catalytic reaction of PhC≡CH with a mixture of DSiEt3 and HSi(OEt)3 hints that mononuclear cobalt species are less likely the in-cycle species. These observations, in addition to the evident of nonsymmetric Co2C2-butterfly core in the structure of [(IPr)(CO)2Co(μ-η2:η2-HCCPh)Co(CO)3], point out that mono(IPr)-dicobalt species are the genuine catalysts for the cobalt-catalyzed hydrosilylation reaction and that the high α selectivity of the catalytic system originates from the joint play of the dicobalt carbonyl species to coordinate alkynes in the Co(μ-η2:η2-HCCR′)Co mode and the steric demanding nature of IPr ligand.
中文翻译：
带有NHC连接的双核钴羰基配合物催化炔烃与叔硅烷的马尔科夫尼科夫氢化硅烷化
炔烃的金属催化氢化硅烷化是制备乙烯基硅烷的理想原子经济方法，乙烯基硅烷是有机合成和有机硅工业中的有用试剂。尽管通过炔烃的金属催化氢化硅烷化反应制备 β-乙烯基硅烷已取得巨大成功，但报道的用于合成 α-乙烯基硅烷的金属催化反应存在底物范围窄和/或选择性差的问题。在此，我们使用羰基N-杂环卡宾 (NHC) 配合物 [(IPr) 2 Co 2 (CO) 6] (IPr = 1,3-二(2,6-二异丙基苯基)咪唑-2-亚基)作为催化剂。这种钴催化剂影响烷基和芳基取代的末端炔烃与各种具有良好官能团相容性的叔硅烷的氢化硅烷化，从而提供具有高产率和高α / β选择性的α-乙烯基硅烷。机理研究表明[(IPr) 2 Co 2 (CO) 6 ]与PhC≡CH和HSiEt 3的化学计量反应可以提供双核钴炔和单核钴甲硅烷基配合物[(IPr)(CO) 2 Co(μ– η 2 :η 2 -HCCPh)Co(CO) 3 ], [(IPr)(CO) 2 Co(μ-η2 :η 2 -HCCPh)Co(CO) 2 (IPr)]和[(IPr)Co(CO) 3 (SiEt 3 )]。两种二钴桥炔配合物都可以与 HSiEt 3反应生成α-三乙基甲硅烷基苯乙烯并影响催化 Markovnikov 氢化硅烷化反应。然而，单(NHC)二钴络合物[(IPr)(CO) 2 Co(μ-η 2 :η 2 -HCCPh)Co(CO) 3 ]表现出比二(NHC)-二钴络合物更高的催化活性。钴甲硅烷基络合物[(IPr)Co(CO) 3 (SiEt 3 )]在催化氢化硅烷化反应方面无效。使用 PhC≡CD 和 DSiEt 3 进行氘标记实验表明氢化硅烷化反应的顺式加成性质。在由 PhC≡CH 与 DSiEt 3和 HSi(OEt) 3混合物的催化反应形成的氢化硅烷化产物中不存在氘扰乱，这表明单核钴物种不太可能是循环物种。这些观察结果，除了明显不对称的Co 2 c ^ 2 -butterfly芯在[（IPR）（CO）的结构2的Co（μ-η 2：η 2 -HCCPh）的Co（CO）3]，指出单（IPr）-二钴物种是钴催化氢化硅烷化反应的真正催化剂，催化体系的高α选择性源于羰基二钴物种在Co（ μ-η 2 :η 2 -HCCR')Co 模式和 IPr 配体的空间要求性质。
更新日期：2021-08-19
中文翻译：
带有NHC连接的双核钴羰基配合物催化炔烃与叔硅烷的马尔科夫尼科夫氢化硅烷化
炔烃的金属催化氢化硅烷化是制备乙烯基硅烷的理想原子经济方法，乙烯基硅烷是有机合成和有机硅工业中的有用试剂。尽管通过炔烃的金属催化氢化硅烷化反应制备 β-乙烯基硅烷已取得巨大成功，但报道的用于合成 α-乙烯基硅烷的金属催化反应存在底物范围窄和/或选择性差的问题。在此，我们使用羰基N-杂环卡宾 (NHC) 配合物 [(IPr) 2 Co 2 (CO) 6] (IPr = 1,3-二(2,6-二异丙基苯基)咪唑-2-亚基)作为催化剂。这种钴催化剂影响烷基和芳基取代的末端炔烃与各种具有良好官能团相容性的叔硅烷的氢化硅烷化，从而提供具有高产率和高α / β选择性的α-乙烯基硅烷。机理研究表明[(IPr) 2 Co 2 (CO) 6 ]与PhC≡CH和HSiEt 3的化学计量反应可以提供双核钴炔和单核钴甲硅烷基配合物[(IPr)(CO) 2 Co(μ– η 2 :η 2 -HCCPh)Co(CO) 3 ], [(IPr)(CO) 2 Co(μ-η2 :η 2 -HCCPh)Co(CO) 2 (IPr)]和[(IPr)Co(CO) 3 (SiEt 3 )]。两种二钴桥炔配合物都可以与 HSiEt 3反应生成α-三乙基甲硅烷基苯乙烯并影响催化 Markovnikov 氢化硅烷化反应。然而，单(NHC)二钴络合物[(IPr)(CO) 2 Co(μ-η 2 :η 2 -HCCPh)Co(CO) 3 ]表现出比二(NHC)-二钴络合物更高的催化活性。钴甲硅烷基络合物[(IPr)Co(CO) 3 (SiEt 3 )]在催化氢化硅烷化反应方面无效。使用 PhC≡CD 和 DSiEt 3 进行氘标记实验表明氢化硅烷化反应的顺式加成性质。在由 PhC≡CH 与 DSiEt 3和 HSi(OEt) 3混合物的催化反应形成的氢化硅烷化产物中不存在氘扰乱，这表明单核钴物种不太可能是循环物种。这些观察结果，除了明显不对称的Co 2 c ^ 2 -butterfly芯在[（IPR）（CO）的结构2的Co（μ-η 2：η 2 -HCCPh）的Co（CO）3]，指出单（IPr）-二钴物种是钴催化氢化硅烷化反应的真正催化剂，催化体系的高α选择性源于羰基二钴物种在Co（ μ-η 2 :η 2 -HCCR')Co 模式和 IPr 配体的空间要求性质。
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