Cobalt‐Catalysed, Ligand‐Controlled Regiodivergent Alkene Hydrosilylation

Abstract

Alkene hydrosilylation is amongst the largest industrial homogenous catalysis processes. Cobalt catalysis offers a sustainable alternative to commonly used platinum catalysts to achieve this transformation. Using two bisiminopyridine cobalt(II) catalysts the regiodivergent hydrosilylation of alkenes has been developed. Variation of pre‐catalyst activator and ligand substituents were investigated to enable the controlled, regiodivergent hydrosilylation of both aryl‐ and alkyl‐substituted alkenes with phenylsilane. In contrast to other regiodivergence strategies, excellent regioselectivity for either isomer was achieved using the same ligand class but differing by a single methyl group (ethyl vs isopropyl).

The synthesis of heterogenous Co‐MOFs and application in the catalytic hydrosilylation of alkenes

“…Based on the experiments and literatures, [33,34] a proposed mechanism was showed in Scheme 2. First, the cobalt catalyst precursor reacts with silane and NaBEt 3 H to provide low-valent [Co] + silyl species I; second, the species I then inserted into alkenes to generate cobalt alkyl intermediate II and forms to intermediates III; in the third step, the species III react with the silane to form the hydrosilylation adduct and the cobalt catalyst enter into the next catalytic cycle.…”

Synthesis of aryl cobalt and iron complexes and their catalytic activity on hydrosilylation of alkenes

“…In relevant reports, cobalt(II) chlorides have good catalytic activity for hydrosilylation of alkenes. 4,[23][24][25][26][27] In 2016, Huang's group realized the hydrosilylation of aliphatic alkenes using cobalt(II) chlorides supported by phosphine-iminopyridine ligands, and obtained the Markovnikov addition product. 4 In 2017, Lu's group used cobalt(II) chlorides supported by chiral [NNN] pincer ligands to realize the highly enantioselective Markovnikov addition reaction of alkenes and silanes.…”

“…[28][29][30] In the study of the mechanism of alkene hydrosilylation, it is found that metal hydride really plays a catalytic role in the catalytic cycle although the pre-catalyst is a metal halide or a metal nitrogen-complex. 22,25,26 In an early study of C-F bond activation, our research group used Co(PMe 3 ) 4 as a catalyst and sodium formate as a reducing agent to realize the selective hydrodefluorination of arylfluoride. 31 In a mechanism study, although the cobalt(II) hydride intermediate could not be isolated, the formation of the cobalt(II) hydride intermediate was confirmed by IR and 1 H NMR spectroscopy.…”

Synthesis of silyl cobalt hydrides and their catalytic activity on hydrosilylation of alkenes

“…[1] It has been found that cobalt(II) chlorides have good catalytic activity for hydrosilylation of olefins. [2][3][4][5][6] In the study of the mechanism of olefin hydrosilylation, it is found that metal hydrides do play a catalytic role in the catalytic process although the pre-catalyst is metal halides or metal nitrogen complex. [4,5,7] However, due to the difficult synthesis and instability of metal hydrides, there are relatively few reports on the direct use of cobalt hydrides as catalysts for olefin hydrosilylation.…”

“…[2][3][4][5][6] In the study of the mechanism of olefin hydrosilylation, it is found that metal hydrides do play a catalytic role in the catalytic process although the pre-catalyst is metal halides or metal nitrogen complex. [4,5,7] However, due to the difficult synthesis and instability of metal hydrides, there are relatively few reports on the direct use of cobalt hydrides as catalysts for olefin hydrosilylation. [8] In this paper, two silyl [P, Si]-chelate cobalt hydrides, respectively.…”