135067-90-2Relevant academic research and scientific papers
Catalytic Behavior of Rhodium(I) Complexes in Hydrogermylation and Hydrosilylation of Phenylacetylene
Wada, Fumio,Abe, Seiji,Yonemaru, Norio,Kikukawa, Kiyoshi,Matsuda, Tsutomu
, p. 1701 - 1703 (1991)
Rhodium complexes, Rh(L)(C2H4)2 , catalyze hydrogermylation and hydrosilylation of phenylacetylene with Bu3GeH and R3SiH (R=Bu, Et), respectively, to produce Ph(R3M)C=CH2 (M=Ge, Si) selectively.Other rhodium complexes, that is 2, Rh2Cl2(cod)2, Rh(tmhd)(C2H4)2 , and Rh(dbm)(C2H4)2 , also catalyze these reactions, but with less regioselectivity.
Markovnikov Hydrosilylation of Alkynes with Tertiary Silanes Catalyzed by Dinuclear Cobalt Carbonyl Complexes with NHC Ligation
Deng, Liang,Lai, Yuhang,Leng, Xuebing,Wang, Dongyang,Wang, Peng,Xiao, Jie
supporting information, p. 12847 - 12856 (2021/08/24)
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 PhCCH and HSiEt3 can furnish the dinuclear cobalt alkyne and mononuclear cobalt silyl complexes [(IPr)(CO)2Co(μ-ν2:ν2-HCCPh)Co(CO)3], [(IPr)(CO)2Co(μ- ν2:ν2-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- ν2:ν2-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 PhCCD 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 PhCCH 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- ν2:ν2-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- ν2:ν2-HCCR′)Co mode and the steric demanding nature of IPr ligand.
