Hydrosilylation Of Alkenes Research Articles

Alkene hydrosilylation with supported and unsupported Ni nanoparticles: strong influence of the Ni environment on activity and selectivity

Isolated nickel nanoparticles in suspension or supported on silica are efficient catalysts for inactivated alkene hydrosilylation.

Anti-Markovnikov terminal and gem-olefin hydrosilylation using a κ4-diimine nickel catalyst: selectivity for alkene hydrosilylation over ether C-O bond cleavage.

The phosphine-substituted α-diimine Ni precursor, (Ph2PPrDI)Ni, has been found to catalyze alkene hydrosilylation in the presence of Ph2SiH2 with turnover frequencies of up to 124 h-1 at 25 °C (990 h-1 at 60 °C). Moreover, the selective hydrosilylation of allylic and vinylic ethers has been demonstrated, even though (Ph2PPrDI)Ni is known to catalyze allyl ester C-O bond hydrosilylation. At 70 °C, this catalyst has been found to mediate the hydrosilylation of ten different gem-olefins, with turnover numbers of up to 740 under neat conditions. Prior and current mechanistic observations suggest that alkene hydrosilylation takes place though a Chalk-Harrod mechanism following phosphine donor dissociation.

Carbonyl and olefin hydrosilylation mediated by an air-stable phosphorus(iii) dication under mild conditions.

The readily-accessible, air-stable Lewis acid [(terpy)PPh][B(C6F5)4]21 is shown to mediate the hydrosilylation of aldehydes, ketones, and olefins. The utility and mechanism of these hydrosilylations are considered.

Waste-free and efficient hydrosilylation of olefins

High purity silicone precursors can now be synthesized by hydrosilylation of solvent-free olefins catalyzed by a highly stable and active glass hybrid catalyst consisting of mesoporous organosilica microspheres doped with Pt nanoparticles.

Regiodivergent hydrosilylation, hydrogenation, [2π + 2π]-cycloaddition and C-H borylation using counterion activated earth-abundant metal catalysis.

The widespread adoption of earth-abundant metal catalysis lags behind that of the second- and third-row transition metals due to the often challenging practical requirements needed to generate the active low oxidation-state catalysts. Here we report the development of a single endogenous activation protocol across five reaction classes using both iron- and cobalt pre-catalysts. This simple catalytic manifold uses commercially available, bench-stable iron- or cobalt tetrafluoroborate salts to perform regiodivergent alkene and alkyne hydrosilylation, 1,3-diene hydrosilylation, hydrogenation, [2π + 2π]-cycloaddition and C-H borylation. The activation protocol proceeds by fluoride dissociation from the counterion, in situ formation of a hydridic activator and generation of a low oxidation-state catalyst.

Alkene hydrosilylation catalyzed by easily assembled Ni(ii)-carboxylate MOFs.

We report the first Ni MOF catalysts for anti-Markovnikov hydrosilylation of alkenes. These catalysts are bench-stable and easily-assembled from simple Ni salts and carboxylic acids. The best catalyst gives turnover numbers up to 9500 and is robust even after 10 recycling runs. The catalyst can be applied for the hydrosilylation of a wide range of alkenes, achieving good synthetic utility and functional group tolerance.

POCN Ni(ii) pincer complexes: synthesis, characterization and evaluation of catalytic hydrosilylation and hydroboration activities.

A series of iminophosphinite POCN pincer Ni(ii) complexes, (POCN)NiMe and (POCN)NiLn(BX4) (L = CH3CN, n = 0, 1; X = F, Ph, C6F5), have been developed and subjected to catalytic hydrosilylation of alkenes, aldehydes and ketones and hydroboration of carbonyl compounds. The stoichiometric reactivity of (POCN)NiMe and (POCN)Ni(BF4) with PhSiH3 and HBPin suggests that catalytic reactions proceed via the hydride intermediate (POCN)NiH. With regard to reactions with HBPin, efficient and mild hydroboration of a variety of carbonyl compounds, including highly chemoselective hydroboration of benzaldehyde in the presence of other common potent reductive functional groups, such as alkenes, alkynes, esters, amides, nitriles, nitro compounds and even ketones, and the first example of base metal catalyzed hydroboration of amides, including mild direct hydroborative reduction of primary and secondary amides to borylated amines were demonstrated for (POCN)NiMe.

Air-stable and reusable cobalt ion-doped titanium oxide catalyst for alkene hydrosilylation

Air-stable and highly reusable cobalt ion-doped titanium oxide catalyst was developed for alkene hydrosilylation.

Platinum on 2-aminoethanethiol functionalized MIL-101 as a catalyst for alkene hydrosilylation.

Hydrosilylation is one of the largest-scale applications for homogeneous catalysis and is widely used to enable the commercial manufacture of silicon products. In this paper, a bifunctional heterogeneous catalyst, Ptδ+/AET-MIL-101 (AET = 2-aminoethanethiol) with a partially positively charged Ptδ+ electronic structure is reported, which was successfully prepared using post-synthesis modification with AET and a platinum precursor. The catalysts were characterized using X-ray diffraction (XRD), nitrogen (N2) adsorption–desorption, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) techniques which showed that the synergy of AET-MIL-101 provides a good dispersion of Ptδ+ in the channels, which can efficiently catalyze the hydrosilylation reaction with almost complete conversion and produce a unique adduct. In addition, the synthetic heterogeneous catalyst Ptδ+/AET-MIL-101 achieves reasonable use of Pt in terms of number cycles and atomic utilization efficiency, indicating the potential to achieve a green hydrosilylation industry.

Titanium-catalyzed hydrosilylation of olefins: A comparison study on Cp2TiCl2/Sm and Cp2TiCl2/LiAlH4 catalyst system

Hydrosilylation of olefins catalyzed by Cp2TiCl2/Sm (Cp = cyclopentadienyl) under solvent free conditions have been investigated. By using Cp2TiCl2/Sm as catalyst system, β-adducts and hydrogenation products were detected. Hydrosilylation of olefins catalyzed by Cp2TiCl2/LiAlH4 under room temperature has also been studied. The influence of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) on Cp2TiCl2/Sm and Cp2TiCl2/LiAlH4, respectively, indicated that hydrosilylation of olefins catalyzed with Cp2TiCl2/Sm went through a free radical reaction pathway while a coordination mechanism was applied for Cp2TiCl2/LiAlH4 catalyst system.

Iridium-Catalyzed Hydrosilylation of Unactivated Alkenes: Scope and Application to Late-Stage Functionalization.

Highly efficient and general Ir-catalyzed hydrosilylation of unactivated alkenes with excellent anti-Markovnikov regioselectivity was described. A broad scope of hydrosilylated products were synthesized economically and conveniently from commercially or naturally available compounds, which provides versatile valuable precursors for organic and medicinal studies.

Cover Feature: Cobalt Catalysts for Alkene Hydrosilylation Under Aerobic Conditions without Dry Solvents or Additives (Eur. J. Inorg. Chem. 45/2018)

Cover Feature: Cobalt Catalysts for Alkene Hydrosilylation Under Aerobic Conditions without Dry Solvents or Additives (Eur. J. Inorg. Chem. 45/2018)

Cobalt Catalysts for Alkene Hydrosilylation under Aerobic Conditions without Dry Solvents or Additives

Alkene hydrosilylation is typically performed with Pt catalysts, but inexpensive base‐metal catalysts would be preferred. Here, we report a simple method for the use of air‐stable cobalt catalysts for anti‐Markovnikov alkene hydrosilylation that can be used under aerobic conditions without dry solvents or additives. These catalysts can be generated from low‐cost commercially available materials. In addition, these catalysts possess good catalytic ability for both hydrosilanes and hydroalkoxysilanes. Finally, a mechanistic study demonstrates that the silane and the catalyst generate a Co–H species in the course of the reaction, which has been observed by in situ Raman spectroscopy.

Hydrosilylation of Olefins with the Cp2TiCl2/Sm Catalytic System

Hydrosilylation of Olefins with the Cp2TiCl2/Sm Catalytic System

Back Cover: Diverse Fates of β‐Silyl Radical under Manganese Catalysis: Hydrosilylation and Dehydrogenative Silylation of Alkenes (Chin. J. Chem. 11/2018)

The back cover picture shows the Janus face of manganese catalysis, namely, hydrogen atom transfer (HAT) and organometallic β‐H elimination pathways can be selectively manipulated by manganese from the common intermediate, β‐silyl radical, thus approaching to the hydrosilylation and dehydrogenative silylation of olefins under the catalysis of Mn(CO)5Br and Mn2(CO)10, respectively. More details on the interplay between radical and organometallic species are discussed in the article by Wang et al. on page 1047–1051. image

One-Pot Pyrolysis to N-Doped Graphene with High-Density Pt Single Atomic Sites as Heterogeneous Catalyst for Alkene Hydrosilylation

Development of noble-metal single atomic site catalysts with high metal loading is highly required for many important chemical reactions but proves to be very challenging. Herein, we report a Na2CO3 salt-assisted one-pot pyrolysis strategy from EDTA–Pt complex to N-doped graphene with isolated Pt single atomic sites (Pt-ISA/NG) with Pt loading up to 5.3 wt %. The X-ray absorption fine structure analysis and spherical aberration-correction electron microscopy demonstrate an atomic dispersion of single Pt species on graphene support and stabilized by nitrogen in Pt–N4 structure. The Pt-ISA/NG catalyst exhibits high catalytic activity and reusability for anti-Markovnikov hydrosilylation of various terminal alkenes with industrially relevant tertiary silanes under mild conditions. In hydrosilylation of 1-octene, the Pt-ISA/NG catalyst delivers an overall turnover frequency of 180 h–1, which is a 4-fold enhancement compared with commercial Pt/C.

Diverse Fates of β‐Silyl Radical under Manganese Catalysis: Hydrosilylation and Dehydrogenative Silylation of Alkenes

AbstractManganese‐catalyzed hydrosilylation of alkenes has been underdeveloped for a long time. Herein, we describe a general, chemo‐ and regio‐ selective hydrosilylation of alkenes by using the Mn(CO)5Br catalyst with ample substrate scopes. Meanwhile, dehydrogenative silylation of aryl olefins can be selectively achieved upon the catalysis of dinuclear Mn2(CO)10. Mechanistic experiments revealed diverse fates of the common intermediate β‐silyl radical, namely, hydrogen atom transfer (HAT) for the hydrosilylation and organometallic β‐H elimination for the dehydrogenative silylation of olefins.

Markovnikov Hydrosilylation of Alkenes: How an Oddity Becomes the Goal

Over the years, hydrosilylation of terminal alkenes has emerged as one of the most prominent applications of homogeneous catalysis. While most of the relevant reports concern β-selective hydrosilylation, yielding linear products which are of industrial importance, the opposite selectivity is also gaining increasing interest and sets the scene for the next challenges. Markovnikov hydrosilylation of alkenes, especially in its asymmetric variant, has become the aim of development of new catalytic systems successfully implementing base-metal complexes—one of the most prominent trends in contemporary catalysis. In this Perspective, we present the current state of this topic and the way it has been achieved, with special emphasis put on the issues still unresolved and prospective directions of development based on the trends present in the literature, but without unnecessary attention to some details of only historical significance.

Hydrosilylation of alkenes and alkynes with silsesquioxane (HSiMe2O)(i-Bu)7Si8O12 catalyzed by Pt supported on a styrene-divinylbenzene copolymer

This paper reports on detailed studies on the hydrosilylation of alkenes and alkynes with silsesquioxane (HSiMe2O)(i-Bu)7Si8O12, catalyzed by Pt, supported on a styrene-divinylbenzene copolymer (Pt/SDB). The obtained results clearly indicate that Pt/SDB was a very efficient catalyst, characterized by high TON in the hydrosilylation of a wide spectrum of reagents. The heterogeneous character of the catalyst permitted reuse up to 20 times. The selectivity of all the hydrosilylation reactions was very high, regardless of the catalyst concentration. Pt/SDB is the first example of a heterogeneous catalyst being used for the functionalization of silsesquioxane (HSiMe2O)(i-Bu)7Si8O12. Under the tested conditions it was found to be more effective than commercially available and industrially applied Pt catalysts supported on activated carbon, making it one of the most versatile and potentially interesting heterogeneous systems in hydrosilylation reactions.

Distinct Catalytic Performance of Cobalt(I)–N-Heterocyclic Carbene Complexes in Promoting the Reaction of Alkene with Diphenylsilane: Selective 2,1-Hydrosilylation, 1,2-Hydrosilylation, and Hydrogenation of Alkene

Selectivity control on the reaction of alkene with hydrosilane is a challenging task in the development of non-precious-metal-based hydrosilylation catalysts. While the traditional way of selectivity control relies on the use of different ligand type and/or different metals, we report herein that cobalt(I) complexes bearing different N-heterocyclic carbene ligands (NHCs) exhibit distinct selectivity in catalyzing the reaction of alkene with Ph2SiH2. [(IAd)(PPh3)CoCl] (IAd = 1,3-diadamantylimidazol-2-ylidene) is an efficient catalyst for anti-Markovnikov hydrosilylation of monosubstituted alkenes. [(IMes)2CoCl] (IMes = 1,3-dimesitylimidazol-2-ylidene) shows Markovnikov-addition selectivity in promoting the hydrosilylation of aryl-substituted alkenes. [(IMe2Me2)4Co][BPh4] (IMe2Me2 = 1,3-dimethyl-4,5-dimethylimidazol-2-ylidene) can catalyze hydrogenation of alkenes with Ph2SiH2 as the terminal hydrogen source. Mechanistic studies in combination with the knowledge on the steric nature of cobalt–NHC species su...