Catalysis by transition metal complexes of alkene silylation–recent progress and mechanistic implications

Copper-Catalyzed Oxidative ipso-Annulation of Activated Alkynes with Silanes: An Approach to 3-Silyl Azaspiro[4,5]trienones

A novel strategy of silylation and dearomatization of activated alkynes with silanes to synthesize azaspiro[4,5]trienones is developed, which could be facilely achieved through a tandem difunctionalization of alkyne, dearomatization, and oxidation and provided a facile approach to produce useful 3-silyl azaspiro[4,5]trienones in an efficient manner.

An Easily Accessed Nickel Nanoparticle Catalyst for Alkene Hydrosilylation with Tertiary Silanes

The first efficient and non-precious nanoparticle catalyst for alkene hydrosilylation with commercially relevant tertiary silanes has been developed. The nickel nanoparticle catalyst was prepared in situ from a simple nickel alkoxide precatalyst Ni(O(t) Bu)2 ⋅x KCl. The catalyst exhibits high activity for anti-Markovnikov hydrosilylation of unactivated terminal alkenes and isomerizing hydrosilylation of internal alkenes. The catalyst can be applied to synthesize a single terminal alkyl silane from a mixture of internal and terminal alkene isomers, and to remotely functionalize an internal alkene derived from a fatty acid.

Decarbonylative Silylation of Esters by Combined Nickel and Copper Catalysis for the Synthesis of Arylsilanes and Heteroarylsilanes

An efficient nickel/copper-catalyzed decarbonylative silylation reaction of carboxylic acid esters with silylboranes is described. This reaction provides access to structurally diverse silanes with high efficiency and excellent functional-group tolerance starting from readily available esters.

Ionic Liquids as Solvents for Rhodium and Platinum Catalysts Used in Hydrosilylation Reaction

A group of imidazolium and pyridinium based ionic liquids has been synthetized, and their ability to dissolve and activate the catalysts used in hydrosilylation reaction of 1-octane and 1,1,1,3,5,5,5-heptamethyltrisiloxane was investigated. An organometallic catalyst as well as inorganic complexes of platinum and rhodium dissolved in ionic liquids were used, forming liquid solutions not miscible with the substrates or with the products of the reaction. The results show that application of such a simple biphasic catalytic system enables reuse of ionic liquid phase with catalysts in multiple reaction cycles reducing the costs and decreasing the amount of catalyst needed per mole of product.

Moving from Classical Ru-NHC to Neutral or Charged Rh-NHC Based Catalysts in Olefin Metathesis

Considering the versatility of oxidation states of rhodium together with the successful background of ruthenium-N-heterocyclic carbene based catalysts in olefin metathesis, it is envisaged the exchange of the ruthenium of the latter catalysts by rhodium, bearing an open-shell neutral rhodium center, or a +1 charged one. In the framework of in silico experiments, density functional theory (DFT) calculations have been used to plot the first catalytic cycle that as a first step includes the release of the phosphine. DFT is, in this case, the tool that allows the discovery of the less endergonic reaction profile from the precatalytic species for the neutral catalyst with respect to the corresponding ruthenium one; increasing the endergonic character when dealing with the charged system.

Olefin hydrosilylation catalyzed by cationic nickel(ii) allyl complexes: a non-innocent allyl ligand-assisted mechanism

Cationic nickel allyl complexes catalyse selective monohydrosilylation of α-olefins with sec-silanes via a unique mechanism assisted by a non-innocent allyl ligand.

Ruthenium-catalysed hydrosilylation of carbon–carbon multiple bonds

Recent advances in ruthenium-catalysed hydrosilylation of C–C multiple bonds and its application to organic synthesis are highlighted.

Recent developments in free-radical-promoted C–Si formation via selective C–H/Si–H functionalization

As important and valuable alternatives to transition-metal-catalysis, free-radical strategies for C–Si bond construction via selective C–H/Si–H functionalization have been developed recently. These new reactions along with their suggested mechanisms are summarized and discussed here.

Synthesis of novel styryl-N-isopropyl-9H-carbazoles for designing trans-conjugated regular silicon hybrid materials

An efficient and practical method for the synthesis of novel styryl-carbazoles and their catalytic functionalization by vinylsilanes to organic-silicon compounds.

An efficient catalytic synthesis and characterization of new styryl-ferrocenes and their trans-π-conjugated organosilicon materials

A selective and efficient catalytic method for the synthesis of new styryl-π-conjugated silyl-ferrocenes in a stereoselective manner is presented.

E–H (E = B, Si, Ge) bond activation of pinacolborane, silanes, and germanes by nucleophilic palladium carbene complexes

The polarity of the Pd–C bond can be tuned by the phosphine substituents of palladium carbene complexes as shown by the reactions of these compounds with silanes.

Amine synthesis via transition metal homogeneous catalysed hydrosilylation

This review summarizes the preparation of amines involving homogeneous transition metal catalysed hydrosilylation including reductions of imines, amides, nitro and nitriles, reductive aminations and N-methylation of amines with CO₂.

The unusual hydridicity of a cobalt bound Si–H moiety

A paramagnetic cobalt–SiH intermediate possessing the Co–(η¹-H–Si) moiety shows unusual Si–H bond activation studied by ENDOR, XRD and DFT.

Synthesis and characterization of functionalized molecular and macromolecular double-decker silsesquioxane systems

Synthesis and characterization of new, molecular and macromolecular DDSQ-based compounds functionalized by substituted styrenes and distyrylarenes (also with heteroatoms) in a stereoselective manner is presented.

Conversion of alkanes to linear alkylsilanes using an iridium-iron-catalysed tandem dehydrogenation-isomerization-hydrosilylation

The conversion of inexpensive, saturated hydrocarbon feedstocks into value-added speciality chemicals using regiospecific, catalytic functionalization of alkanes is a major goal of organometallic chemistry. Linear alkylsilanes represent one such speciality chemical-they have a wide range of applications, including release coatings, silicone rubbers and moulding products. Direct, selective, functionalization of alkanes at primary C-H bonds is difficult and, to date, methods for catalytically converting alkanes into linear alkylsilanes are unknown. Here, we report a well-defined, dual-catalyst system for one-pot, two-step alkane silylations. The system comprises a pincer-ligated Ir catalyst for alkane dehydrogenation and an Fe catalyst that effects a subsequent tandem olefin isomerization-hydrosilylation. This method exhibits exclusive regioselectivity for the production of terminally functionalized alkylsilanes. This dual-catalyst strategy has also been applied to regioselective alkane borylations to form linear alkylboronate esters.

Rapid, Regioconvergent, Solvent-Free Alkene Hydrosilylation with a Cobalt Catalyst

Alkene hydrosilylation is typically performed with Pt catalysts, but inexpensive base-metal catalysts would be preferred. We report a Co catalyst for anti-Markovnikov alkene hydrosilylation that can be used without added solvent at low temperatures with low loadings, and can be generated in situ from an air-stable precursor that is simple to synthesize from low-cost, commercially available materials. In addition, a mixture of Co catalysts performs a tandem catalytic alkene isomerization/hydrosilylation reaction that converts multiple isomers of hexene to the same terminal product. This regioconvergent reaction uses isomerization as a benefit rather than a hindrance.