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In recent years, the applications of low-valent main group compounds have gained momentum in the field of catalysis. Owing to the accessibility of two lone pairs of electrons, NHC-stabilised phosphinidenes have been found to be excellent Lewis bases; however, they cannot yet be used as catalysts. Herein, an NHC-stabilised phosphinidene, 1,3-dimethyl-2-(phenylphosphanylidene)-2,3-dihydro-1H imidazole (1), for the activation of CO2 is reported.A closer inspection of the CO2 activation process by DFT calculations along with intrinsic bond orbital analysis shows that phosphinidene is associated with phenylsilane through a noncovalent π-π interaction between two phenyl rings which activates the Si-H bond facilitating hydride transfer to the CO2 molecule. Detailed DFT studies along with spectroscopic experiments were combined to understand the mechanism of CO2 activation and its catalytic reductive functionalisation leading to the formylation of a range of chemically inert primary amides under mild reaction conditions.

A methodology employing CO2, amines, and phenylsilane was discussed to access aryl- or alkyl-substituted urea derivatives. This procedure was characterized by adopting hydrosilane to promote the formation of ureas directly, without the need to prepare silylamines in advance. Control reactions suggested that FeCl3 was a favorable additive for the generation of ureas, and this 1,5,7-triazabicyclo[4.4.0]dec-5-ene-catalyzed reaction might proceed through nucleophilic addition, silicon migration, and the subsequent formal substitution of silylcarbamate.

The dehydrocoupling of silanes and alcohols mediated by heavier alkaline-earth catalysts, [Ae{N(SiMe 3) 2} 2⋅(THF) 2] (I–III) and [Ae{CH(SiMe 3) 2} 2⋅(THF) 2], (IV–VI) (Ae=Ca, Sr, Ba) is described. Primary, secondary, and tertiary alcohols were coupled to phenylsilane or diphenylsilane, whereas tertiary silanes are less tolerant towards bulky substrates. Some control over reaction selectivity towards mono-, di-, or tri-substituted silylether products was achieved through alteration of reaction stoichiometry, conditions, and catalyst. The ferrocenyl silylether, FeCp(C 5H 4SiPh(OBn) 2) (2), was prepared and fully characterized from the ferrocenylsilane, FeCp(C 5H 4SiPhH 2) (1), and benzyl alcohol using barium catalysis. Stoichiometric experiments suggested a reaction manifold involving the formation of Ae–alkoxide and hydride species, and a series of dimeric Ae–alkoxides [(Ph 3CO)Ae(μ 2-OCPh 3)Ae(THF)] (3 a–c, Ae=Ca, Sr, Ba) were isolated and fully characterized. Mechanistic experiments suggested a complex reaction mechanism involving dimeric or polynuclear active species, whose kinetics are highly dependent on variables such as the identity and concentration of the precatalyst, silane, and alcohol. Turnover frequencies increase on descending Group 2 of the periodic table, with the barium precatalyst III displaying an apparent first-order dependence in both silane and alcohol, and an optimum catalyst loading of 3 mol % Ba, above which activity decreases. With precatalyst III in THF, ferrocene-containing poly- and oligosilylethers with ferrocene pendent to- (P1–P4) or as a constituent (P5, P6) of the main polymer chain were prepared from 1 or Fe(C 5H 4SiPhH 2) 2 (4) with diols 1,4-(HOCH 2) 2-(C 6H 4) and 1,4-(CH(CH 3)OH) 2-(C 6H 4), respectively. The resultant materials were characterized by NMR spectroscopy, gel permeation chromatography (GPC) and DOSY NMR spectroscopy, with estimated molecular weights in excess of 20,000 Da for P1 and P4. The iron centers display reversible redox behavior and thermal analysis showed P1 and P5 to be promising precursors to magnetic ceramic materials.

Reactions of dichlorodimethylsilane with 2,3,4,5-tetrafluorophthalic acid bis(trimethylsilyl) ether (1:1, 20°C, 24 h) without a solvent and dichloro(chloromethyl)methylsilane and dichloro(methyl)phenylsilane with bis(trimethylsilyl) ester of ortho-phthalic acid (1:1, 20°C, 168–264 h) in hexane lead to the formation of previously unknown 14-membered cyclic organosilicon esters of ortho-phthalic acids (silacyclophanones) in 36–85% yields. Molecular structures of 14-membered cyclic ethers 4,10-dimethyl-4,10-diphenyl-3,5,9,11-tetraoxo-4,10-disyla-1,7(1,2)-dibenzacyclododecaphane-2,6,8,12-tetraone, 4,4,10,10-tetramethyl-3,5,9,11-tetraoxo-4,10-disila-1,7(1,2)-di-(tetrafluorobenza)cyclododecaphane-2,6,8,12-tetraone, along with bis(trimethylsilyl) esters of 2,3,4,5-tetrafluorophthalic and orthophthalic acids, were studied by X-ray structural analysis.

This work focuses on the synthesis of polysiloxane ABx macromonomers with functional groups (A [Si-H] and B [vinyl]) incorporated on to the polymer backbone, and the coupling of these functionalities to form randomly, but highly, branched polymers. The synthesis of the ABx macromonomers was performed by the anionic copolymerization of hexamethylcyclotrisiloxane (D3) and 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane (V3) monomers, followed by an end-capping/termination reaction with chloro(methyl)phenylsilane. The resulting macromonomers were coupled by a Pt(0) catalyzed hydrosilylation reaction, to yield highly branched polysiloxanes. The coupling reaction was investigated at different solution concentrations and using macromonomers with different extents of vinyl content. It was shown that a higher solution concentration resulted in higher degrees of chain coupling and branching, arising from efficient intermolecular coupling in preference to (the competing) intramolecular coupling (cyclization) reaction. Moreover, an increase in the mole fraction of vinyl monomer also resulted in higher levels of branching. With the ability to control the degree of branching, the strategy reported here provides a facile route to synthesize branched polysiloxanes (silicones) with varying flexibility and elasticity.

A quantum-chemical study of the reaction mechanism of 2-mercaptobenzothiazole with (iodomethyl)(dimethyl)phenylsilane in the presence of iodine was performed by the B3LYP/6-311G(d,p) method. Possible routes of formation of annulated heterocyclic systems were proposed. It was found the molecular iodine involved in the reaction has a decisive effect on the thermodynamic and kinetic characteristics of the cyclization process.

Despite being one of the most frequently carried out chemical reactions in industry, there is currently no amidation protocol that is regarded as safe, high yielding, environmentally friendly and inexpensive. The direct amidation of a carboxylic acid with an amine is viewed as an inherently good solution for developing such a protocol. Since the 1960s, there has been a gradual development in the use of silicon reagents for direct amidation. This review covers the methods published to April 2021 for silicon reagent mediated direct amidation of a carboxylic acid with an amine. This review also covers the use of polymeric SiO2 to promote direct amidation.

Hydroperoxides were synthesized in one step from various alkenes using Co(pic)(2) as the catalyst with molecular oxygen and tetramethyldisiloxane (TMDSO). The hydration product could be obtained using a modified catalyst, Co(3-mepic)(2), with molecular oxygen and phenylsilane. Formation of hydroperoxides occurred through a rapid Co─O bond metathesis of a peroxycobalt compound with isopropanol.

Several research studies have been conducted on N-formylation of amines using phenylsilane and CO2. However, most of these studies involved tedious processes of catalyst preparation or complex procedures. In the present study, we describe the use of a simple and commercially available ZnO catalyst for selective N-formylation of amines under mild condition. High-yielding N-formylation products with good recyclability and wide substrate scope were obtained, which can promote fine chemical synthesis and CO2 capture.

The reaction of H3 SiR (R=Ph, nBu) with cationic η5 -C5 Me5 - (Cp*) and benzo[h]quinolinyl-based iridacycle [1 b]+ gives rise to new [(IrH)→SiRH2 ]+ adducts. In the presence of THF these adducts readily undergo elimination of H2 gas at subambient temperature to form THF-stabilized metallacyclic IrIII silylene complexes, which were characterized in situ by NMR spectroscopy, trapped in minute amounts by reactive crystallization, and structurally characterized by XRD. Theoretical investigations (static DFT-D reaction-energy profiling, ETS-NOCV) support the promoting role of THF in the H2 elimination step and the consolidation of the Ir-to-Si interaction in the spontaneous (ΔG

Two novel ferrocene-containing porous organic polymers, FPOP-1 and FPOP-2, have been prepared by Sonogashira-Hagihara coupling reactions of 1,1′-diethynylferrocene with tri(4-bromophenyl)phenylsilane or tetrakis(4-bromophenyl)silane. The resultant polymers show high thermal stability and high porosity with Brunauer-Emmer-Teller (BET) surface area of up to 954 m2 g−1 (FPOP-2) and total pore volume of up to 0.74 cm3 g−1 (FPOP-2). The porosity comparison with other ferrocene-containing porous polymers indicates that the introduction of tetrahedral silicon-centered units is beneficial to enhancing the porosity. The gas sorption investigations reveal that these polymers possess comparable CO2 capacities of 1.44 mmol g−1 (6.3%) at 273 K and 1.0 bar, and 0.91 mmol g−1 (4.0 wt%) at 298 K and 1.0 bar (FPOP-2), and comparable H2 uptakes of 7 mmol g−1 (1.4 wt%) (FPOP-2). The values are higher than other non-ferrocene-containing porous polymers with higher porosity, thereby indicating that the incorporation of ferrocene units can improve the gas sorption property. Furthermore, these results demonstrate that these materials can be promisingly utilized as solid absorbents for storing CO2 and H2.

An amide-promoted protocol was developed for the reductive functionalization of CO2 with amines/imine and phenylsilane to produce methylamine. Secondary amines and an imine were methylated successfully to methylamines with up to 98% yield under atmospheric pressure of CO2 and 80°C. Furthermore, a tentative mechanism involving amide-promoted CO2 reduction to the silyl acetal species was proposed. Striking features of this metal-free protocol are selective six-electron reduction of CO2 with hydrosilane as a reductant in the presence of amine.

The coordination of tBu PONOP (tBu PONOP=2,6-bis(ditert-butylphosphinito)pyridine) to different ruthenium starting materials, to generate (tBu PONOP)RuCl2 , was investigated. The resultant (tBu PONOP)RuCl2 reactivity with three different silanes was then investigated and contrasted dramatically with the reactivity of (iPr PONOP)RuCl2 (DMSO) (iPr PONOP=2,6-bis(diisopropylphosphinito)pyridine) with the same silanes. The 16-electron species (tBu PONOP)Ru(H)Cl was produced from the reaction of triethylsilane with (tBu PONOP)RuCl2 . Reactions of (tBu PONOP)RuCl2 with both phenylsilane or diphenylsilane afforded the 16-electron hydrido-silyl species (tBu PONOP)Ru(H)(PhSiCl2 ) and (tBu PONOP)Ru(H)(Ph2 SiCl), respectively. Reactions of all three of these complexes with silver triflate afforded the simple salt metathesis products of (tBu PONOP)Ru(H)(OTf), (tBu PONOP)Ru(H)(PhSiCl(OTf)), and (tBu PONOP)Ru(H)(Ph2 Si(OTf)). Formic acid dehydrogenation was performed in the presence of triethylamine (TEA), and each species proved competent for gas-pressure generation of CO2 and H2 . The hydride species (tBu PONOP)Ru(H)Cl, (tBu PONOP)Ru(H)(OTf), and (tBu PONOP)Ru(H)(PhSiCl2 ) exhibited faster catalytic activity than the other compounds tested.

Using microscale high-throughput experimentation, an efficient, earth-abundant iron phenanthroline complex was discovered to catalyze the reductive cyclization of ortho-nitrostyrenes into indoles via nitrosoarene reactive intermediates. This method requires only 1 mol % of Fe(OAc)2 and 1 mol % of 4,7-(MeO)2phen and uses phenylsilane as a convenient terminal reductant. The scope and limitations of the method were illustrated with 21 examples, and an investigation into the kinetics of the reaction revealed first-order behavior in catalyst and silane and zero-order behavior with respect to nitrostyrene.

The alkylation of 4,5-dihydro-1H-imidazole-2-thiol with 1-iodomethyl(dimethyl)phenylsilane, 1-(iodomethyl)-1,1,3,3,3-pentamethyldisiloxane, and 1,3-bis(iodomethyl)-1,1,3,3-tetramethyldisiloxane involved iodine-catalyzed cleavage of the Si–Csp 2 and Si–O bonds with liberated (in situ) hydrogen iodide to afford 2-({[(4,5-dihydro-1H-imidazolium-2-ylsulfanyl)methyl]-1,1,3,3-tetramethyldisiloxanylmethyl}sulfanyl)-4,5-dihydro-1H-imidazolium di- and tetraiodides. Replacement of iodide ion in the products by triiodide gives new organosilicon ionic liquids with several charged fragments.

The adsorption of a number of organic molecules on samples of МCM-41 adsorbent modified with dichloromethylphenylsilane and subsequently treated with sulfuric acid (MDCS) and N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (MNM) is studied. Specific retention volumes equal to the Henry constant are determined by means of inverse gas chromatography at infinite dilution. The thermodynamic characteristics of adsorption, the dispersive and specific components of the Helmholtz energy of adsorption, and the increment of the methyl group to the heat of adsorption are calculated. It is shown that the grafting of aminosilane and phenylsilane groups enhances the forces of dispersion and reduces specific interactions. A greater drop in polarity is observed for MDCS than for MNM, due to the stronger polarity of amoinosilane; the enthalpy factor makes the main contribution to the adsorption of organic compounds on the investigated adsorbents. It is found that the MNM sample is capable of the irreversible adsorption of alcohols.

Reaction of scandium dimethyl complex LScMe2 (L=[2-{N(DIPP)C(Ph)N}C6 H4 CH=N(DIPP)]- , DIPP=2,6-(iPr)2 C6 H3 ) (2) with bulky phosphine ArPH2 (Ar=2,6-{3,5-(Me)2 C6 H3 }2 C6 H3 ) gives an unprecedented scandium 2,3-azaphosphametallacyclobutane complex L'Sc (L'=[2-{N(DIPP)C(Ph)N}C6 H4 C(H)P(2,6-{3,5-(CH3 )2 C6 H3 }2 C6 H3 )N(DIPP)]3- ) (3) that contains a C-P-N-Sc four-membered ring. Complex 3 was characterized by X-ray crystallography, revealing a short distance between the Sc and P atoms (2.786(1) A), but without a direct Sc-P bonding interaction. The formation of 3 involves a complete cleavage of the imino bond of the tridentate ligand L and C-P and N-P bond coupling. Complex 3 not only activates H2 under mild conditions to give a H-H bond cleavage product, but also reacts with O2 , CO, phenylsilane, and pinacolborane to produce novel products through cleavage and formation of various bonds.

A copper-catalyzed protocol for reductive methylation of amines and imine with formic acid as a C1 source and phenylsilane as a reductant is reported for the first time, affording the corresponding methylamines in good to excellent yields under mild conditions. This protocol offers an alternative method for indirect utilization of CO2, as formic acid can be readily obtained from hydrogenation of CO2.

2-Methyl-1,3-bis[(1-methylsilolan-1-yl)methyl]-1H-imidazolium triiodide, 1,3-bis{[dimethyl-(phenyl)silyl]methyl}-2-methyl-1H-imidazolium iodide and triiodide, and cyclic 3,3,5,5,10-pentamethyl-4-oxa-7-aza-1-azonia-3,5-disilabicyclo[5.2.1]deca-1(10),8-diene iodide were synthesized by solvent-free reactions of 2-methyl-1H-imidazole with 1-(iodomethyl)-1-methylsilolane, (iodomethyl)(dimethyl)phenylsilane, and ethynyl(iodomethyl)(dimethyl)silanes, respectively, in the absence of base catalyst.

The three-component reaction of 1,3-benzothiazole-2-thiol with iodomethyl(dimethyl)phenylsilane and molecular iodine in the absence of a base and phase-transfer catalyst afforded 2-[(dimethyl(phenyl)-silylmethylsulfanyl]-1,3-benzothiazolium triiodide and 2,2-dimethyl-2,3-dihydro[1,4,2]thiazasilolo[5,4-b][1,3]-benzothiazolium triiodide.

The efficient catalytic reduction of imines with phenylsilane is achieved by using the potassium, calcium and strontium based catalysts [(DMAT)K (THF)]∞, (DMAT)2Ca⋅(THF)2 and (DMAT)2Sr⋅(THF)2 (DMAT=2‐dimethylamino‐α‐trimethylsilylbenzyl). Eight different aldimines and the ketimine Ph2C=NPh could be successfully reduced by PhSiH3 at temperatures between 25–60 °C with catalyst loadings down to 2.5 mol %. Also, simple amides like KN(SiMe3)2 or Ae[N(SiMe3)2]2 (Ae=Ca, Sr, Ba) catalyze this reaction. Activities increase with metal size. For most substrates the activity increases along the row K, First s ‐block metal catalysts for imine hydrosilylation are reported. The mechanism is confirmed by stoichiometric reactions, intermediate isolation and DFT calculations.

A catalytic system for the chlorination of alcohols under Appel conditions was developed. Benzotrichloride is used as a cheap and readily available chlorinating agent in combination with trioctylphosphane as the catalyst and phenylsilane as the terminal reductant. The reaction has several advantages over other variants of the Appel reaction, e.g., no additional solvent is required and the phosphane reagent is used only in catalytic amounts. In total, 27 different primary, secondary, and tertiary alkyl chlorides were synthesized in yields up to 95%. Under optimized conditions, it was also possible to convert epoxides and an oxetane to the dichlorinated products.

Organophosphorus-catalyzed Staudinger ligation between carboxylic acids and azides in the presence of phenylsilane reductant produces amides. NMR-based mechanistic investigations revealed that the catalytic Staudinger ligation does not proceed via reduction of phosphine oxide but rather via reduction of iminophosphorane, which can subsequently undergo several transformations to produce the amide product.

A manganese-based catalytic system using the commercially available complex [Mn(CO)5Br] was studied for the selective reduction of levulinic acid (LA) to 2-methyl-tetrahydrofuran (MTHF). We further studied the production of pyrrolidines via its reductive amination using silanes (phenylsilane and tetramethyldisiloxane). The results showed high efficiency and selectivity for this reaction leading to high yields using mild reaction conditions.

International audience; A reduction of various aryl, alkyl, and α,β‐unsaturated amides with phenylsilane, catalysed by a borinic acid, is reported. The unprecedented reaction was carried out under very mild conditions and led to useful amines. Furthermore, the reaction tolerates a variety of functional groups. Initial investigations implicated that an intermediate diarylhydroborane is involved in the reaction mechanism.

Herein the reductive amination/cyclization of levulinic acid using phenylsilane was presented to selectively produce pyrrolidones versus pyrrolidines under mild conditions by switching the catalyst from AlCl3 to RuCl3. Using AlCl3 as the catalyst, pyrrolidones were solely obtained at room temperature, while RuCl3 as the catalyst selectively afforded pyrrolidines in high yields at 45 °C.

The reaction of carbon dioxide with Et3SiH in the presence of catalytic amounts of [Ru3(CO)12] as a catalytic precursor was achieved to produce silyl formate (Et3SiOCOH) 1s with a TON of 9000. A similar reaction in the presence of KF yielded potassium formate (8s) in a one-pot protocol with high selectivity using water or MeCN as the solvent. In the current report the complete reduction of carbon dioxide to methane was achieved, with the use of a more reactive silane (phenylsilane). A catalytically relevant species was the ruthenium cluster [H4Ru4(CO)12]. This is the second report on the hydrosilylation of carbon dioxide catalyzed by highly active and readily available ruthenium clusters and this is the first report of hydrosilylation of CO2 to methane.

An effective and inexpensive organocatalyst tetrabutylammonium fluoride (TBAF) was developed for the reductive functionalization of CO2 with amines to selectively afford formamides or methylamines by employing hydrosilanes. Hydrosilanes with different substituents show discriminatory reducing activity. Thus, the formation of formamides and further reduction products, that is, methylamines could be controlled by elegantly tuning hydrosilane types. Formamides were obtained exclusively under an atmospheric pressure of CO2 with triethoxysilane. Using phenylsilane as a reductant, methylamines were attained with up to 99 % yield at 50 °C coupled to a complete deoxygenation of CO2. The crucial intermediate silyl formate in the formylation step was identified and thereby a tentative mechanism involving the fluoride-promoted hydride transfer from the hydrosilane to CO2/formamide was proposed. Striking features of this metal-free protocol are formylation and methylation of amines by reductive functionalization of CO2 with hydrosilanes and mild reaction conditions.

The catalytic deoxygenation of fatty acids has recently received significant attention as a low-hydrogen approach to biomass feedstock deoxygenation for production of hydrocarbon fuels with superior properties to biodiesel. Unfortunately, it is a challenging reaction to push to high yields. Of typical catalysts, Pd/C is typically reported to give the best performance, while most oxide supports are inferior, with exceptions for very specific preparation and pre-treatment protocols. Here, we investigate the role of organosilane-modified silicas as supports for the Pd-catalyzed deoxygenation of stearic acid at 300 °C under inert atmosphere. Comparing aminopropylsilane-modified, phenylsilane-modified, and unmodified silica supports with Pd incorporated by several methods, it is first shown that changes in dispersion alone do not account for improvements in deoxygenation yields. Capping silanols with phenylsilane is also ineffective on its own in improving deoxygenation yields. The most effective treatment is shown to be a co-deposition of phenylsilane and aminopropylsilane before Pd incipient wetness impregnation, followed by direct reduction of the catalyst, which gives heptadecane yields >85%, exceeding even the productivity of Pd/C. These results demonstrate that basic, aromatic-rich surfaces are accessible through organosilane grafting and that these surfaces can control Pd particle sizes and the adsorption of stearic acid and products. This work improves our understanding of support effects for biomass feedstock deoxygenation catalysts and could help design new catalysts that take advantage of modified inorganic supports.

Orthogonal protection of amino acid side chains in solid phase peptide synthesis allows for selective deprotection of side chains and the formation of cyclic peptides on resin. Cyclizations are useful as they may improve the activity of the peptide or improve the metabolic stability of peptides in vivo. One cyclization method often used is the formation of a lactam bridge between an amine and a carboxylic acid. It is desirable to perform the cyclization on resin as opposed to in solution to avoid unwanted side reactions; therefore, a common strategy is to use –Alloc and –OAllyl protecting groups as they are compatible with Fmoc solid phase peptide synthesis conditions. Alloc and –OAllyl may be removed using Pd(PPh3)4 and phenylsilane in DMF. This method can be problematic as the reaction is most often performed at room temperature under argon gas. It is not usually done at higher temperatures because of the fear of poisoning the palladium catalyst. As a result, the reaction is long and reagent–intensive. Herein, we report the development of a method in which the –Alloc/–OAllyl groups are removed using a microwave synthesizer under atmospheric conditions. The reaction is much faster, allowing for the removal of the protecting groups before the catalyst is oxidized, as well as being less reagent–intensive. This method of deprotection was tested using a variety of amino acid sequences and side chain protecting groups, and it was found that after two 5-min deprotections at 38°C, all –Alloc and –OAllyl groups were removed with >98% purity. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

This article describes a selective reduction of functionalized amides, including N-acyl amino esters and dipeptides, to the corresponding amines using simple [Rh(acac)(cod)]. The catalyst shows excellent chemoselectivity in the presence of different sensitive functional moieties.

This work demonstrates that the oxidation state and chemistry of uranium hydrides can be tuned with temperature and the stoichiometry of phenylsilane. The trivalent uranium hydride [(C5Me5)2U–H]x (5) was found to be comprised of an equilibrium mixture of U(III) hydrides in solution at ambient temperature. A single U(III) species can be selectively prepared by treating (C5Me5)2UMe2 (4) with 2 equiv of phenylsilane at 50 °C. The U(III) system is a potent reducing agent and displayed chemistry distinct from the U(IV) system [(C5Me5)2U(H)(μ-H)]2 (2), which was harnessed to prepare a variety of organometallic complexes, including (C5Me5)2U(dmpe)(H) (6), and the novel uranium(IV) metallacyclopentadiene complex (C5Me5)2U(C4Me4) (11).

The synthesis of a new bidentate (NN)–Mn(I) complex is reported and its catalytic activity towards the reduction of ketones and nitriles is studied. On comparing the reactivity of various other Mn(I) complexes supported by benzimidazole ligand, it was observed that the Mn(I) complexes bearing 6-methylpyridine and benzimidazole fragments exhibited the highest catalytic activity towards monohydrosilylation of ketones and dihydrosilylation of nitriles. Using this protocol, a wide range of ketones were selectively reduced to the corresponding silyl ethers. In case of unsaturated ketones, the chemoselective reduction of carbonyl group over olefinic bonds was observed. Additionally, selective dihydrosilylation of several nitriles were also achieved using this complex. Mechanistic investigations with radical scavengers suggested the involvement of radical species during the catalytic reaction. Stoichiometric reaction of the Mn(I) complex with phenylsilane revealed the formation of a new Mn(I) complex.

From the viewpoint of green chemistry and sustainable development, it is of great significance to synthesize chemicals from CO2 as C1 source through C-N bond formation. During the past several decade years, many studies on C-N bond formation reaction were involved, and many efforts have been made on the theory. Nevertheless, several great challenges such as thermodynamic limitation, low catalytic efficiency and selectivity, and high pressure etc. are still suffered. Herein, recent advances are highlighted on the development of catalytic methods for chemical fixation of CO2 to various chemicals through C-N bond formation. Meanwhile, the catalytic systems (metal and metal-free catalysis), strategies and catalytic mechanism are summarized and discussed in detail. Besides, this review also covers some novel synthetic strategies to urethanes based on amines and CO2. Finally, the regulatory strategies on functionalization of CO2 for N-methylation/N-formylation of amines with phenylsilane and heterogeneous catalysis N-methylation of amines with CO2 and H2 are emphasized.

A simple and efficient iron-catalyzed protodehalogenation of alkyl and aryl halides using phenylhydrosilane is disclosed. The reaction utilizes FeCl3 without the requirement of ligands. Unactivated alkyl and aryl halides were successfully reduced in good yields; sterically hindered tertiary halides were also reduced including the less reactive chlorides. The scalability of this methodology was demonstrated by a gram-scale synthesis with a catalyst loading as low as 0.5 mol%. Notably, disproportionation of phenylsilane leads to diphenylsilane that further reduces the halides. Preliminary mechanistic studies revealed a non-radical pathway and the source of hydrogen is PhSiH3via deuterium labeling studies. Our methodology represents simplicity and provides a good alternative to typical tin, aluminum and boron hydride reagents.

A series of 1,2-dihydroquinolines were synthesized in good to excellent yields by reacting 2-aminobenzaldehyde derivatives and dialkyl acetylenedicarboxylates with catalytic amounts of phosphine. This reaction was rendered catalytic by the selective in situ phosphine oxide reduction with the use of phenylsilane. Furthermore, with the same starting materials and with an additional role of the reducing agent, a new olefination reaction was discovered. Hydrogen/deuterium (H/D) exchange experiments revealed the possible mechanism of this reaction.

There are a number of π-conjugated organoboron polymers in which π-conjugation is extended via the vacant p-orbital of the boron atom. However, boron incorporation into σ-conjugated systems has not been reported so far. A novel σ-p conjugated copolymer of phenylsilane and mesitylborane was synthesized by dehydrocoupling polymerization using a rhodium catalyst. Change in electronic states due to the incorporation of the boron moiety was determined both by DFT calculations and experiments. The obtained colorless polymers were characterized by 1H-NMR and 11B-NMR spectra. Incorporation of boron was confirmed by 11B-NMR, while the Si/B ratio was calculated by 1H-NMR integration ratios. GPC analysis showed the Mn of the polymer as 1200–2900 g mol−1. The copolymers showed high sensitivity towards fluoride ions both optically and electrochemically exhibiting a “turn on” type of sensing mechanism.

Efficient conversion of carbon dioxide (CO2) into valuable chemicals is a very attractive topic. Herein, we conducted the first work on the utilization of biomass-derived γ-valerolactone (GVL) as the solvent and catalyst for transformation of CO2 with various primary and secondary amines in the presence of phenylsilane (PhSiH3), and the corresponding desired formamides were produced with high yields without any additional catalyst. Systematic studies indicated that the lactone structure of GVL played a key role in the formation of the active silyl formates and the activation of N–H bonds in amines, thus leading to the excellent performance of GVL for the catalytic reactions.

We presented the immobilization of ionic liquids on the channel walls of COFs using a post-synthetic strategy. The ionic [Et4NBr]50%-Py-COF afforded a high CO2 adsorption capacity of 164.6 mg g(-1) (1 bar, 273 K) and was developed as an effective heterogeneous catalyst for the transformation of CO2 into value-added formamides under ambient conditions.

Alkane elimination reaction of phosphinimino-amine ligand HL (L = (2,6-iPr2-C6H3)NC(Me)CHP(Cy2)N(2,6-Me2-C6H3)) with MgnBu2 and Sc(CH2SiMe3)3(THF)2, respectively, can afford the corresponding phosphinimino-amine supported magnesium monoalkyl complex LMgnBu(THF) (1) and scandium dialkyl complex LSc(CH2SiMe3)2 (2). 2 can initiate the polymerization of ethylene efficiently under the activation of [Ph3C][B(C6F5)4]. Magnesium hydride complex [LMgH]2 (3) can be easily obtained by the reaction of 1 and phenylsilane. The hydride species in 3 can conduct the dearomatisation of pyridine to give dearomatisation product 1,2-dihydropyridide (4).

The Mitsunobu reaction is renowned for its mild reaction conditions and broad substrate tolerance, but has limited utility in process chemistry and industrial applications due to poor atom economy and the generation of stoichiometric phosphine oxide and hydrazine by-products that complicate purification. A catalytic Mitsunobu reaction using innocuous reagents to recycle these by-products would overcome both of these shortcomings. Herein we report a protocol that is catalytic in phosphine (1-phenylphospholane) employing phenylsilane to recycle the catalyst. Integration of this phosphine catalytic cycle with Taniguchi’s azocarboxylate catalytic system provided the first fully catalytic Mitsunobu reaction.

Treatment of heteroscorpionate zinc benzyloxy complex LZnOBn (1, L = (MePz)2CP(Ph)2NPh, MePz = 3,5-dimethylpyrazolyl) with phenylsilane (PhSiH3) gave a zinc hydride complex LZnH (2) containing a rare terminal hydride fragment. X-ray diffraction analysis and the DFT calculation confirm the zwitterionic structure of complex 2. The stoichiometric reaction of 2 with CS2 readily afforded a dithioformate complex LZnSCH(S) (3) of the C═S insertion into the Zn–H product. Moreover, complex 2 was an efficient catalyst for the hydrosilylation reaction of a series of silanes and aldehydes under mild conditions, featuring excellent functional group tolerance. The preliminary mechanistic study revealed that both zinc benzyloxy complex 1 and zinc hydride complex 2 were involved in the hydrosilylation process as the reaction intermediates.

The CO2-involved synthesis of chemicals is of significance. In this work, we found that 1-alkyl-3-methylimidazolium ionic liquids (ILs) had high efficiency for catalyzing the formylation of amines using CO2 and phenylsilane at room temperature, producing the corresponding formylated products in excellent yields under the metal-free condition. The ILs acted as bifunctional catalysts, which activated the Si-H bond of phenylsilane to react with CO2 to form the formoxysilane intermediate and simultaneously activated the amine substrate through the hydrogen bond. Moreover, the imidazolium cation and the anions of the ILs showed an excellent synergistic effect on catalyzing the formylation of amines.

Monocationic bis(hydrocarbyl)yttrium complexes [YR2(THF)2][A] (R = CH2SiMe3, CH2C6H4-o-NMe2; A = weakly coordinating anion) underwent hydrogenolysis using dihydrogen or phenylsilane to give a mixture of polynuclear solvent-stabilized dihydride cations [YH2(THF)2]n[A]n. The mixture composition as well as the nuclearity n depended on the starting material, solvent, and reaction conditions. NMR spectroscopic data in solution and X-ray diffraction data suggested that the main product was tetranuclear, although conclusive structural data were not obtained. DFT calculations supported a closo-type tetrahedral [YH2(THF)2]44+ core. The hydridic character of these cations was revealed by their reaction with benzophenone to give the bis(diphenylmethoxy) cation [Y(OCHPh2)2(THF)4][AlR4]. The reaction of this cluster with the (NNNN)-type macrocycle Me4TACD under dihydrogen gave the dinuclear tetrahydride dication with quadruply bridging hydride ligands, [Y2(μ-H)4(Me4TACD)2][A]2, analogous to the previously characterized lutetium derivative. NH-acidic (Me3TACD)H gave the dinuclear dihydride dication [Y2(μ-H)2(Me3TACD)2(THF)2][A]2.

Four-membered N-heterocyclic compounds exhibit a broad range of pharmacological activities. Herein, we report a useful rhodium-catalyzed protocol for the activation of phenylsilane to reduce tertiary β-lactams. Reaction with the tertiary amides was selective over secondary amides, esters, olefins and nitriles, with no erosion of stereochemistry. A one-pot protocol from commercially available starting materials and a selective reduction of a complex penicillin derivative demonstrate the synthetic utility of this facile procedure.

International audience; The direct synthesis of organocalcium compounds (heavy Grignard reagents) by the reduction of organyl halides with activated calcium powder succeeded in a straightforward manner for organic bromides and iodides that are bound at sp2-hybridized carbon atoms. Extension of this strategy to alkyl halides was very limited, and only the reduction of trialkylsilylmethyl bromides and iodides with activated calcium allowed the isolation of the corresponding heavy Grignard reagents. Substitution of only one hydrogen atom of the methylene moiety by a phenyl or methyl group directed this reduction toward the Wurtz-type coupling and the formation of calcium halide and the corresponding C−C coupling product. The stability of the methylcalcium and benzylcalcium derivatives in ethereal solvents suggests an unexpected reaction behavior of the intermediate organyl halide radical anions. Quantum chemical calculations verify a dependency between the ease of preparative access to organocalcium complexes and the C−I bond lengths of the organyl iodides. The bulkiness of the trialkylsilyl group is of minor importance. Chloromethyltrimethylsilane did not react with activated calcium; however, halogen-exchange reactions allowed the isolation of [Ca(CH2SiMe3)(thf)3(μ-Cl)]2. Furthermore, the metathetical approach of reacting [Ca(CH2SiMe3)I(thf)4] with KN(SiMe3)2 and the addition of N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (pmdeta) allowed the isolation of heteroleptic [CaCH2SiMe3N(SiMe3)2(pmdeta)]. In the reaction of this derivative with phenylsilane, the trimethylsilylmethyl group proved to be more reactive than the bis(trimethylsilyl)amido substituent.

Using bis(amide) Zn(HMDS)2 (HMDS = 1,1,1,3,3,3-hexamethyldisilazide) as a precursor, this study explores the synthesis of N-heterocyclic carbene stabilized mixed amido-hydride zinc complexes using two alternative hydride sources, namely dimethylamine borane (DMAB) and phenylsilane PhSiH3. Hydride-rich zinc cluster Zn4(HMDS)2H6·2IPr (1) (IPr = 1,3-bis(2,6-di-isopropylphenyl)imidazol-2-ylidene), which can be envisaged as a co-complex of IPr·ZnH2 and (HMDS)ZnH, is obtained when DMAB is employed, with the concomitant formation of heteroleptic bis(amido)borane [HB(NMe2)(HMDS)] and H2 evolution. NMR studies in d8-THF show that although the bulky carbene IPr does not bind to the zinc bis(amide), its presence in the reaction media is required in order to stabilise 1. Reactions using the slightly less sterically demanding NHC IXy (IXy = 1,3-bis-(2,6-dimethylphenyl)imidazol-2-ylidene) led to the isolation and structural elucidation of the carbene adduct Zn(HMDS)2·IXy (2). Contrastingly, mixtures of equimolar amounts of PhSiH3 and the zinc bis(amide) (60 °C, 3 h, hexane) afforded monomeric heteroleptic hydride (HMDS)ZnH·IPr (3). NMR studies, including DOSY experiments, revealed that while the integrity of 3 is retained in polar d8-THF solutions, in lower polarity C6D6 it displays a much more complex solution behaviour, being in equilibrium with the homoleptic species ZnH2·IPr, Zn(HMDS)2 and IPr.

This work describes the catalytic activity of several oxo-rhenium complexes containing the heterocyclic ligands 2-(2-hydroxy-5-methylphenyl)benzotriazole (Hhmpbta), 2-(2-hydroxyphenyl)benzothiazole (Hhpbt), 2-(2-hydroxyphenyl)benzoxazole (Hhpbo), 2-(2-hydroxyphenyl)-1 H -benzimidazole (Hhpbi), isoquinoline-1-carboxylic acid (iqcH), and 4-methoxy-2-quinolinecarboxylic acid (mqcH) in the reduction of 4-nitrobenzaldehyde using phenylsilane as reducing agent. In general, all of the catalysts tested gave good to excellent yields of the 4-nitrobenzyl alcohol. Although, the best result was obtained with the catalytic system PhSiH 3 /[ReOBr 2 (hmpbta)(PPh 3 )] (5 mol %). This system was also applied to the reduction of a large variety of aldehydes, producing the corresponding primary alcohols in good to excellent yields and good chemoselectivity.