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The branch-selective C–H alkenylation with alkenes using an iridium catalyst is reported. The Ir(III)-catalyzed reaction of aniline derivatives that contain a pyrimidine-directing group with vinyls...

The cross-electrophile coupling has become a powerful tool for C-C bond formation, but its potential for forging the C-Si bond remains unexplored. Here we report a cross-electrophile Csp2 -Si coupling reaction of vinyl/aryl electrophiles with vinyl chlorosilanes. This new protocol offers an approach for facile and precise synthesis of organosilanes with high molecular diversity and complexity from readily available materials. The reaction proceeds under mild and non-basic conditions, demonstrating a high step economy, broad substrate scope, wide functionality tolerance, and easy scalability. The synthetic utility of the method is shown by its efficient accessing of silicon bioisosteres, the design of new BCB-monomers, and studies on the Hiyama cross-coupling of vinylsilane products.

A set of iridium(I) complexes of formula IrCl(κC,η2-IRCouR′)(cod) or IrCl(κC, η2-BzIRCouR′)(cod) (cod = 1,5-cyclooctadiene; Cou = coumarin; I = imidazolin-2-carbene; BzI = benzimidazolin-2-carbene) have beeen prepared from the corresponding azolium salt and [Ir(μ-OMe)(cod)]2 in THF at room temperature. The crystalline structures of 4b and 5b show a distorted trigonal bipyramidal configuration in the solid state with a coordinated coumarin moiety. In contrast, an equilibrium between this pentacoordinated structure and the related square planar isomer is observed in solution as a consequence of the hemilability of the pyrone ring. Characterization of both species by NMR was achieved at the low and high temperature limits, respectively. In addition, the thermodynamic parameters of the equilibrium, ΔHR and ΔSR, were obtained by VT 1H NMR spectroscopy and fall in the range 22–33 kJ mol−1 and 72–113 J mol−1 K−1, respectively. Carbonylation of IrCl(κC,η2-BzITolCou7,8-Me2)(cod) resulted in the formation of a bis-CO derivative showing no hemilabile behaviour. The newly synthesised complexes efficiently catalyze the hydrosilylation of alkynes at room temperature with a preference for the β-(Z) vinylsilane isomer.

We developed an enantioselective carbonyl-ene-type cyclization using 2-substituted vinylsilane as a nucleophilic ene moiety catalyzed by a chiral copper-BOX complex. This reaction is the first example of enantioselective carbonyl-ene cyclization using a 1,2-disubstituted olefin. This methodology gave chiral indenols with a tetrasubstituted carbon.

In the catalytic cross-coupling reaction of ketimines, derived from 1-acetonaphthone or acetophenone derivatives and benzylamine, with trialkoxyvinylsilanes RuH2(PPh3)4 or RuH2(CO)(PPh3)3 catalyst caused the selective alkenylation and alkylation on each aromatic ring of the ketimines separately (i.e. dual-mode coupling). Alkenylation occurred at the ortho-position(s) of the benzyl unit and alkylation occurred at the ortho-position(s) of 1-arylethylidene moiety of the substrates. By the stoichiometric reaction of N-1-(4-methylphenyl)ethylidene-4-methylbenzylamine with RuH2(CO)(PPh3)3 in the presence of three equivalents of vinylsilane, a novel ruthenium bismetallacylclic complex with two ruthenium-carbon bonds was isolated. This (C,N,C)-bismetallacycle complex was converted to the alkenylated complex by the reaction with two equiv. of vinylsilane. These observations indicate that the dual-mode coupling proceeds in a sequence of alkenylation followed by alkylation via intermediary bismetallacyclic complex formation.

The zwitterionic compound [Cp*RhCl{(MeIm)2CHCOO}] is an efficient catalyst for the hydrosilylation of terminal alkynes with excellent regio- and stereoselectivity toward the less thermodynamically stable β-(Z)-vinylsilane isomer under mild reaction conditions. A broad range of linear 1-alkynes, cycloalkyl acetylenes, and aromatic alkynes undergo the hydrosilylation with HSiMe2Ph to afford the corresponding β-(Z)-vinylsilanes in quantitative yields in short reaction times. The reaction of aliphatic alkynes with HSiEt3 is slower, resulting in a slight decrease of selectivity toward the β-(Z)-vinylsilane product, which is still greater than 90%. However, a significant selectivity decrease is observed in the hydrosilylation of aromatic alkynes because of the β-(Z) → β-(E) vinylsilane isomerization. Moreover, the hydrosilylation of bulky alkynes, such as t-Bu–C≡CH or Et3SiC≡CH, is unselective. Experimental evidence suggests that the carboxylate function plays a key role in the reaction mechanism, which has been validated by means of density functional theory calculations, as well as by mass spectrometry and labeling studies. On the basis of previous results, we propose an ionic outer-sphere mechanism pathway in which the carboxylate fragment acts as a silyl carrier. Namely, the hydrosilylation mechanism entails the heterolytic activation of the hydrosilane assisted by the carboxylate function to give the hydrido intermediate [Cp*RhH{(MeIm)2CHCOO–SiR3}]+. The transference of the silylium moiety from the carboxylate to the alkyne results in the formation of a flat β-silyl carbocation intermediate that undergoes a hydride transfer from the Rh(III) center to generate the vinylsilane product. The outstanding β-(Z) selectivity results from the minimization of the steric interaction between the silyl moiety and the ligand system in the hydride transfer transition state., The authors express their appreciation for the financial support from the Spanish Ministry of Economy and Competitiveness MINECO/FEDER under the project CTQ2016-75884-P and the Regional Governments of Aragón/FEDER 2014–2020 “Building Europe from Aragón” (group E42_17R). In addition, the resources from the supercomputer “Memento,” technical expertise, and assistance provided by BIFIZCAM (Universidad de Zaragoza) are acknowledged.

We report here that a cobalt catalyst generated from a cobalt(II) salt and a ligand using magnesium metal is capable of promoting hydroarylation reactions through chelation-assisted C−H activation. With the appropriate choice of the ligand and other reaction conditions, ketimine- or aldimine-directed branched selective hydroarylations of styrenes and ketimine-directed hydroarylations of vinylsilane have been achieved. The reported catalytic systems may serve as more convenient alternatives to previously developed catalytic systems employing Grignard reagents as reducing agents. MOE (Min. of Education, S’pore) Accepted version

Vinylsilanes are versatile and efficient nucleophiles in cross-coupling reactions. Herein is described the use of tetrabutylammonium bifluoride as a mild, cheap and scalable activating agent in several copper-catalyzed vinylsilane cross-couplings.

The functionalization of polysilanes is an important subject in materials science because functionalized polysilanes are expected to exhibit potentially innovative properties. This research aims at the addition of a water-shedding property to polysilanes by introducing perfluoroalkyl groups into their skeleton. The photoinduced iodoperfluoroalkylation of various vinylsilanes takes place successfully upon irradiation with a xenon lamp: vinylmonosilanes undergo iodoperfluoroalkylation with perfluoroalkyl iodides (RfI) regioselectively, and the corresponding perfluoroalkylated silanes are obtained in moderate to high yields. Detailed optimization of the photoinduced iodoperfluoroalkylation has been investigated to apply this method to the functionalization of polysilanes. Polysilanes having vinyl groups can be synthesized by the reductive coupling of dichlorovinylsilanes with samarium diiodide (SmI2) and samarium metal (Sm) upon irradiation with visible light. The synthesized vinylpolysilanes and RfI (about 1.0 mM CHCl3 solution) are coated on a glass plate sequentially, and then the following photoirradiation with light of a wavelength over 300 nm successfully adds an excellent water-shedding property to the glass plate.

Oxide-supported rhodium catalysts with excellent activity in silylative coupling reactions have been developed. Reductive pretreatment of the catalysts in the presence of 0.5 equiv triphenylphosphine under a hydrogen atmosphere enhanced and stabilized the catalytic activity. Of the catalysts examined, ceria-supported rhodium had the highest activity in the homo-coupling of vinylsilanes to bis(silyl)ethenes at 170 °C. A zirconia-supported catalyst selectively gave E-1-aryl-2-silylethenes by cross-coupling of vinylsilanes with styrenes at 130 °C, and a high turnover frequency of >8200 h−1 was achieved at 170 °C. Spectroscopic studies revealed that well-dispersed surface rhodium(I) species predominantly formed on ceria or zirconia were transformed into rhodium hydride species, which are believed to be responsible for the high activity. These catalysts were recyclable without loss of activity, and leaching of rhodium species from the catalysts was not observed.

Transition metal catalysis has emerged as a powerful strategy to expand synthetic flexibility of protein modification. Herein, we report a cationic Ru(II) system that enables the first example of alkyne hydrosilylation between dimethylarylsilanes and $\textit{O}$-propargyl-functionalized proteins using a substoichiometric amount or low-loading of Ru(II) catalyst to achieve the first C–Si bond formation on full-length substrates. The reaction proceeds under physiological conditions at a rate comparable to other widely used bioorthogonal reactions. Moreover, the resultant $\textit{gem}$-disubstituted vinylsilane linkage can be further elaborated through thiol–ene coupling or fluoride-induced protodesilylation, demonstrating its utility in further rounds of targeted modifications.

The ruthenium hydride complex (PCy3)2(CO)RuHCl was found to be a highly effective catalyst for the regio- and stereoselective hydrosilylation of alkynes to form vinylsilane products. (Z)-Vinylsilane products were selectively formed for sterically nondemanding terminal alkynes, while (E)-vinylsilane products resulted from sterically demanding terminal alkynes. Kinetic data were obtained from the hydrosilylation of phenylacetylene. The phosphine inhibition study showed an uncompetitive Michaelis–Menten type of inhibition kinetics. The empirical rate law rate = kobs[1]1[alkyne]0[silane]0 was established from the reaction rate as a function of both [alkyne] and [silane]. DFT calculations were performed and found that Z/E isomerization is facile via a metallacyclopropene transition state and that the isomerization occurs prior to the silane substrate binding. A detailed mechanistic scheme on the hydrosilylation reaction has been delineated on the basis of both experimental and computational data.

The mechanisms and origins for the Pd- and Ni-catalyzed regioselective hydrosilylation of allene have been investigated by means of density functional theory (DFT) calculations. The free-energy profiles of Pd- and Ni-catalyzed reactions with small and bulky N-heterocyclic carbene (NHC) ligands are calculated to determine the mechanism for regioselectivities. The calculation results show that different metals (Ni vs Pd) lead to regiochemical reversals for the hydrosilylation of allene. The allylsilane is the major product via palladium catalysis with small NHC ligand, while the vinylsilane is the major product via nickel catalysis with bulky NHC ligand. Both electronic and steric factors play a key role in the regioselectivities for the hydrosilylation of allene via Pd and Ni catalysts. The calculation results are in good agreement with observed regioselectivities and could provide insights into the design of new catalysts for the regioselectivity of hydrosilylation reactions.

Soft reaction conditions, particularly important in total synthesis, have dragged many researchers into the field of silylated organic compounds. Hereby, we describe a new copper-catalyzed vinylsilane transformation. Various vinylsilanes were allylated by using a copper(I) salt, and this led to the formation of polysubstituted 1,4-dienes bearing sensitive moieties such as halogens, ketones, and aldehydes. Hereby is described a new copper-catalyzed vinylsilane transformation. Various vinylsilanes were allylated by using copper(I) salts, and this led to the formation of polysubstituted 1,4-dienes bearing sensitive moieties such as halogens, ketones, and aldehydes. TBAT = tetrabutylammonium difluorotriphenylsilicate. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The highly regio- and diastereoselective rhodium-catalyzed [(3+2)+2] carbocyclization reaction of trialkoxysilyl-substituted alkenylidenecyclopropanes (ACPs) with monosubstituted alkynes is reported. This work represents the first example of a metal-catalyzed higher-order carbocyclization with a vinylsilane, which facilitates the regioselective insertion of the alkyne and the selective introduction of a secondary alcohol. For example, stereospecific Tamao oxidation of the allylsilane resulting from the stereoselective cycloaddition provides the corresponding C6 hydroxyl group that is present in an array of related sesquiterpene natural products.

A new ruthenium complex catalyzed procedure for the efficient O -silylation of an SiO–H group on the silica surface of glass beads with controlled pores (CPG) using 1-trimethylsiloxy-3-dimethylvinylsilylpropane leading to Si–O–Si bond formation with the evolution of ethylene is described. The formed linker contains alkyl hydroxyl groups which can be reacted with a nucleoside phosphoramidite unit. The CPG support containing alkyl hydroxyl groups is successfully applied in automatic chemical synthesis of DNA fragments.

International audience; A catalytic intramolecular silapalladation of alkynes affords, in good yields and stereoselectively, syn‐disilylated heterocycles of different chemical structure and size. When applied to silylethers, this reaction leads to vinylic silanols that undergo a rhodium‐catalyzed addition to activated olefins, providing the oxa‐Heck or oxa‐Michael products, depending on the reaction conditions.

A pyridinebis(oxazoline) cobalt complex is a very efficient precatalyst for the hydrosilylation of terminal alkynes with Ph2 SiH2 , providing α-vinylsilanes with high (Markovnikov) regioselectivity and broad functional-group tolerance. The vinylsilane products can be further converted into geminal borosilanes through Markovnikov hydroboration with pinacolborane and a bis(imino)pyridine cobalt catalyst.

We report here that a cobalt catalyst generated from a cobalt(II) salt and a ligand using magnesium metal is capable of promoting hydroarylation reactions through chelation-assisted C−H activation. With the appropriate choice of the ligand and other reaction conditions, ketimine- or aldimine-directed branched selective hydroarylations of styrenes and ketimine-directed hydroarylations of vinylsilane have been achieved. The reported catalytic systems may serve as more convenient alternatives to previously developed catalytic systems employing Grignard reagents as reducing agents.

A pyridinebis(oxazoline) cobalt complex is a very efficient precatalyst for the hydrosilylation of terminal alkynes with Ph2 SiH2 , providing α-vinylsilanes with high (Markovnikov) regioselectivity and broad functional-group tolerance. The vinylsilane products can be further converted into geminal borosilanes through Markovnikov hydroboration with pinacolborane and a bis(imino)pyridine cobalt catalyst.

DFT calculations were performed to investigate the detailed reaction mechanisms in the copper-catalyzed regiodivergent silacarboxylation of allenes. According to our calculations, the catalysis would bifurcate at the allene silylcupration step, followed by CO2 insertion, eventually leading to the carboxylated vinylsilane or allylsilane products. The gaps between the two silylcupration barriers were predicted to be -2.3, -0.4, and 2.2 kcal mol(-1) when using (rac)-Me-DuPhos, dcpe, and PCy3 (+H2 O) as the ligands, which nicely accounted for the experimental vinylsilane/allylsilane ratios of 93:7, 50:50, and 15:85, respectively. By means of transition-state-energy decomposition, we found that the energy penalty of catalyst deformation into its transition-state geometry was the key factor in determining the direction of the reaction. The switchable regioselectivity by using different P ligands could be ascribed to structural changes of the Cu-Si and Cu-P bonds during the silylcupration process.

New impregnated platinum on magnetite catalyst has been prepared, characterized and used for the hydrosilylation of different alkynes. The catalyst showed a wide reaction scope, allowing its use for different functionalized alkynes, localized triple bonds, and silane reagents. The reaction is selective for the case of diynes, obtaining the desired mono- or dihydrosilylation processes. The reaction with disilane reagents lead to the incorporation of two alkyne units to the final product. The catalyst is easily prepared and handled, avoiding the use of expensive and difficult to handle organic ligands, and it could be removed from the reaction medium just by sequestering by a magnet. The catalyst could be reused up to ten times with exactly the same activity.

A series of mono- and binuclear rhodium(I) complexes bearing ortho-phosphinoanilido and ortho-phosphinoaniline ligands has been synthesized. Reactions of the protic monophosphinoanilines, Ph(2)PAr or PhPAr(2) (Ar = o-C(6)H(4)NHMe), with 0.5 equiv of [Rh(μ-OMe)(COD)](2) result in the formation of the neutral amido complexes, [Rh(COD)(P,N-Ph(2)PAr(-))] or [Rh(COD)(P,N-PhP(Ar(-))Ar)] (Ar(-) = o-C(6)H(4)NMe(-)), respectively, through stoichiometrically controlled deprotonation of an amine by the internal methoxide ion. Similarly, the binuclear complex, [Rh(2)(COD)(2)(μ-P,N,P',N'-mapm(2-))] (mapm(2-) = Ar(Ar(-))PCH(2)P(Ar(-))Ar), can be prepared by reaction of the protic diphosphinoaniline, mapm (Ar(2)PCH(2)PAr(2)), with 1 equiv of [Rh(μ-OMe)(COD)](2). An analogous series of hemilabile phosphine-amine compounds can be generated by reactions of monophosphinoanilines, Ph(2)PAr' or PhPAr'(2) (Ar' = o-C(6)H(4)NMe(2)), with 1 equiv of [Rh(NBD)(2)][BF(4)] to generate [Rh(NBD)(P,N-Ph(2)PAr')][BF(4)] or [Rh(NBD)(P,N-PhPAr'(2))][BF(4)], respectively, or by reactions of diphosphinoanilines, mapm or dmapm (Ar'(2)PCH(2)PAr'(2)), with 2 equiv of the rhodium precursor to generate [Rh(2)(NBD)(2)(μ-P,N,P',N'-mapm)][BF(4)](2) or [Rh(2)(NBD)(2)(μ-P,N,P',N'-dmapm)][BF(4)](2), respectively. Displacement of the diolefin from [Rh(COD)(P,N-Ph(2)PAr(-))] by 1,2-bis(diphenylphosphino)ethane (dppe) yields [Rh(P,P'-dppe)(P,N-Ph(2)PAr(-))] which, while unreactive to H(2), reacts readily and irreversibly with oxygen to form the peroxo complex, [RhO(2)(P,P'-dppe)(P,N-Ph(2)PAr(-))], and with iodomethane to yield [RhI(CH(3))(P,P'-dppe)(P,N-Ph(2)PAr(-))]. Hemilabile phosphine-amine compounds can also be prepared by reactions of [Rh(P,P'-dppe)(P,N-Ph(2)PAr(-))] with Me(3)OBF(4) or HBF(4)·Et(2)O, resulting in (thermodynamic) additions at nitrogen to form [Rh(P,P'-dppe)(P,N-Ph(2)PAr')][BF(4)] or [Rh(P,P'-dppe)(P,N-Ph(2)PAr)][BF(4)], respectively. The nonlabile phosphine-amido and hemilabile phosphine-amine complexes were tested as catalysts for the silylation of styrene. The amido species do not require the use of solvents in reaction media, can be easily removed from product mixtures by protonation, and appear to be more active than their hemilabile, cationic congeners. Reactions catalyzed by either amido or amine complexes favor dehydrogenative silylation in the presence of excess olefin, showing modest selectivities for a single vinylsilane product. The binuclear complexes, which were prepared in an effort to explore possible catalytic enhancements of reactivity due to metal-metal cooperativity, are in fact somewhat less active than mononuclear species, discounting this possibility.

In order to prevent corrosion of aluminium pigment in water, coated flaky aluminium powder was prepared through the sol–gel process, in which tetraethoxysilane (TEOS) and tris(2-methoxyethoxy)vinylsilane (VTMOEO) were adopted as precursors. The influences of the dosage of precursors, ethylenediamine, water and ethanol, as well as the reaction temperature and reaction time on the corrosion inhibition efficiency were investigated. Under the optimum conditions, the corrosion inhibition efficiency reached 99.2% in alkaline media of pH 11. The analysis with SEM, FTIR, EDS and XPS showed that sol–gel coatings had successfully encapsulated on the surface of clear flaky aluminium powders.

1,3-Diene-2,3-diyl diesters are synthesized by rhodium-catalyzed homocoupling of (1-acyloxyvinyl)silanes. Double transmetalation between vinylsilane and rhodium intermediate in a single catalytic cycle is the key in this reaction. From the homocoupling products, symmetrical α-diketone and its monoacetal are easily synthesized.

We have developed low-valent titanium-mediated 1,3-transpositive cross-coupling reactions of acyclic and cyclic allylic alcohols for the stereoselective introduction of ethyl, 2-silylethyl, 2-phenethyl, and alkenyl groups. Cross-coupling of an allylic alcohol with a vinylsilane or styrene derivative is particularly noteworthy, as an efficient cross-selective coupling of two alkenes has been elusive. The stereochemistry of the cross-coupling alkylation is consistent with syn addition/beta-elimination.

The preparation of various (hex-5-ynyl)silanes was achieved following two different synthetic approaches from readily available materials such as 4-bromobutene, 6-iodohexyne and chlorosilanes. Different reaction conditions for intramolecular hydrosilylation were tested to prepare the corresponding 2-methylidene-1-silacyclohexanes. Notably, the use of Speier’s catalyst allowed the regioselective formation of the desired products in moderate yields.

A new ruthenium complex-catalyzed O-silylation of silanols with vinylsilanes leading to siloxane bond formation with the evolution of ethylene is described. A maximum conversion of silanol is reached using an excess of vinylsilane to also yield the product of the homo -coupling of the latter. Under the optimum conditions, when vinylsilane with at least one ethoxy substituent is used, the reaction gives exclusively unsymmetrical siloxanes.

The reaction of α-chlorine-substituted allylsilanes with primary amines was promoted by CuCl to result in the selective formation of secondary amines bearing the vinylsilane functionality by a probable SN2′-allylation keeping the silyl group intact.

Sonogashira coupling of ( E)-α-iodovinylsilanes 1 with (trimethylsilyl)acetylene gave ( Z)-1,3-bis(trimethylsilyl)alk-3-en-1-ynes 2, which underwent a desilylation reaction to afford ( Z)-3-(trimethylsilyl)alk-3-en-1-ynes 3 in high yields. (1 E,3 Z)-1-Halo-3-(trimethylsilyl)-substituted 1,3-dienes 5 could be synthesised stereoselectively via hydrozirconation of ( Z)-3-(trimethylsilyl)alk-3-en-1-ynes 3, followed by trapping with iodine or N-bromosuccinimide.

Pd-catalyzed intra-molecular olefin insertion/carbonylation reaction of optically active α-alkenyl-α-acyloxysilanes is described. The reactions proceeded in a stereoselective manner to give five- and six-membered optically active carbocycles having (E)-vinylsilane in their side chains. Under CO condition, optically active carbocycles containing one-carbon homologated side chain were produced by Pd-catalyzed tandem olefin insertion–carbonylation reaction.

Silyl ethers can be produced from alcohols and vinyl-silanes under a rhodium(I) catalyst. The reaction is believed to proceed through an O-H bond cleavage of alcohol by rhodium(I) complex and a subsequent hydride insertion into vinylsilane followed by β-silyl elimination of the resulting β-silylethyl rhodium(III) complex.

The complex [Cp*Ru(MeCN)3]PF6 is shown to catalyze the hydrosilylation of a wide range of alkynes. Terminal alkynes afford access to alpha-vinylsilane products with good regioselectivity. Deuterium labeling studies indicate a clean trans addition process is at work. The same complex is active in internal alkyne hydrosilylation, where absolute selectivity for the trans addition process is maintained. Several internal alkyne substrate classes, including propargylic alcohols and alpha,beta-alkynyl carbonyl compounds, allow regioselective vinylsilane formation. The tolerance of a wide range of silanes is noteworthy, including alkyl-, aryl-, alkoxy-, and halosilanes. This advantage is demonstrated in the direct synthesis of triene substrates for silicon-tethered intramolecular Diels-Alder cycloadditions.

A series of new vinylsilane complexes of the type [W(CO) 5 (η 2 -H 2 C CHSiR 3 )] ( 1a – e ) and trans -[W(CO) 4 (η 2 -H 2 C CHSiR 3 ) 2 ] ( 2a – e ) (R = Me, OMe, OCH 2 CH 2 OMe, and Cl) have been synthesized photochemically and characterized by IR and 1 H, 13 C and 29 Si NMR spectroscopy. The values of the coordination shifts of the vinylic protons and carbons, Δ δ = δ (free vinylsilane) − δ (coordinated vinylsilane), strongly suggest that trimethylvinylsilane ( a ) is coordinated more loosely to the tungsten atom in compounds of type 1 and 2 than other vinylsilanes ( b – e ). The strongest dπ–π* interaction takes place between the carbonyltungsten moiety and trichlorovinylsilane. Analysis of 13 C NMR data of vinylsilane compounds revealed that the electron-donating methyl substituents and the electron-withdrawing chlorine substituents at the silicon atom cause opposite deviations from the ideal symmetrical η 2 -coordination of vinylsilane to the tungsten atom. The bis(vinylsilane) complexes 2a – e are shown to exist in several isomeric forms, whose solution dynamics were investigated by variable-temperature 1 H NMR studies.

Zeise-type complexes with vinylsilanes as π-ligands [K(18C6)][PtCl3(η2-CH2=CHX)] (X = SiMe3, 4; SiPh3, 5; Si(OMe)3, 6; 18C6 = 18-crown-6) and [K(18C6)]2[(PtCl3)2{η2,η2-(CH2=CHSiMe2)2O}] (7) have been prepared by the reaction of [K(18C6)]2[Pt2Cl6] (3) with the appropriate vinylsilanes. The identities of the complexes have been confirmed by NMR spectroscopy as well as for 4, 5 and (PPh4)[PtCl3{η2-CH2=CHSi(OMe)3}] (6′) also by single-crystal X-ray diffraction measurements. DFT calculations exhibited, that the coordination induced C=C bond lengthenings and the pyramidalization angles of the olefins in the vinylsilane complexes [PtCl3(η2-CH2=CHX)]− (X = SiMe3, 4c; SiPh3, 5c; Si(OMe)3, 6c) are the same as in Zeise's anion [PtCl3(η2-CH2=CH2)]− (8c) while the amount of the π back-donation in the vinylsilane complexes 4c–6c is higher than that in the ethylene complex 8c.

A catalytic acylation of vinylsilane with acid anhydride is accomplished by the use of [RhCl(CO)2]2, in which the transmetalation between vinylsilane and rhodium(I) carbonyl complex plays a key rol...

Two novel silicon-containing acetylenic synthons, 1-[dimethyl(ethynyl)silyl]-2-[ethynyl(methyl)-(vinyl)silyl]ethyne and bis[(ethynyldimethylsilyl)ethynyl](methyl)vinylsilane, were obtained by the reaction of diethynyl(methyl)vinylsilane with ethylmagnesium bromide and ethynylfluorodimethylsilane. The reaction of magnesium derivatives of the products and diethynyl(methyl)vinylsilane with organylhalosilanes gave macrocyclic polyunsaturated silahydrocarbons containing numerous endo- and exocyclic miltiple bonds.

Bismetallative cyclization of enynes with Bu3SnSiMe3 catalyzed by Pd(0) complex was realized for the first time, which gives cyclized products containing a vinylsilane moiety and a homoallyltin moiety in good yield. In this cyclization, Pd2(dba)3·CHCl3 or Pd(OH)2 on charcoal is effective as a Pd(0) catalyst and the addition of a phosphine ligand increased the formation of alkyne bismetallation by-product. On the other hand, it was found that a nucleophilic N-heterocyclic carbene could be utilized as a ligand for this cyclization. The utility of the cyclized products obtained from this cyclization in synthetic organic chemistry have been proven by transformation into cyclopropanol derivatives.

Reaction of the Cramer's complex [{Rh(C 2 H 4 ) 2 (μ-Cl)} 2 ] with the appropriate vinylsilane molecules yields, by displacement of the ethylene ligands, the complexes [{Rh(η 2 -CH 2 CHSiR 3 ) 2 (μ-Cl)} 2 ] (where R 3 =Me 3 ( 1 ), Me 2 Ph ( 2 ), MePh 2 ( 3 ), Ph 3 ( 4 ), Me 2 (OSiMe 3 ) ( 5 )). The structures of 1 , 2 and 3 complexes have been determined crystalographically. There are the first crystal structures of dinuclear rhodium(I) complexes with monovinylsilanes. All complexes have been characterised by multinuclear NMR spectroscopy.

The substitution of a carbon atom by silicon provides an attractive, novel approach to modification of the thermal stability and volatility of metal-organic chemical vapor deposition precursors supported by β-diketonate ancillary ligands. The low temperature reaction of the lithium enolates of acetyltrialkylsilanes with acyl chlorides affords the sila-β-diketones, R′C(O)CH2C(O)SiR3 (R′=Me, Et, n-Pr, i-Pr, n-Bu, i-Bu, s-Bu, t-Bu; SiR3=SiMe3, SiEt3, SiMe2(t-Bu), SiMe2(t-hexyl), Si(i-Pr)3), in good yields. Multinuclear NMR studies suggest that the sila-β-diketones exist as the enolic tautomer with a vinylsilane isomeric structure. Homoleptic Cu(II) sila-β-diketonate complexes were prepared in a first pass study to evaluate how precursor performance is affected by modulation of the peripheral substituents in the ligands. Thermal analyses, (TGA, DSC) show that the silylated Cu(II) precursors (SiR3=SiMe3; R′=t-Bu or i-Bu) have greater volatility than the corresponding carbon analogues. Some of the new Cu(II) complexes exist as liquids or low melting solids, which are preferred states for industrial deposition processes. X-ray diffraction studies of selected copper complexes showed them to have typical, square planar geometry; calculations of molecular volumes suggest that packing in the solid-state is less efficient for the silicon-containing complexes than for the non-silylated analogues.

Synthesis of the tricyclic BCD-ring segment with high stereoselectivity has been achieved starting from a sugar derivative directed toward the synthesis of the left part of ciguatoxin 1B. The central reactions in the synthesis are (i) ether ring formation mediated by an acetylene cobalt complex, (ii) decomplexation of the endo-acetylene cobalt complex to the vinylsilane, and (iii) ring-opening reaction of the epoxysilane into the allylic alcohol.

The ruthenium hydride complex-catalyzed N-silylation of primary and secondary amines with substituted vinylsilanes, with the general formula R(1)CH=CHSiR (where R(1) = H, Ph, n-Bu, Si(OEt)3), leading to the formation of a Si-N bond with the evolution of olefin is described. Vinylsilane acts as a silylative reagent and hydrogen acceptor. Under optimum conditions, the reaction offers an attractive route for the synthesis of silylamines. The preliminary mechanistic view of this novel general silylation reaction based on catalytic and deuterium labeling experiments, using NMR and GC-MS methods, confirm the synthetic observations.

Soft reaction conditions, particularly important in total synthesis, have dragged many researchers into the field of silylated organic compounds. Hereby, we describe a new copper-catalyzed vinylsilane transformation. Various vinylsilanes were allylated by using a copper(I) salt, and this led to the formation of polysubstituted 1,4-dienes bearing sensitive moieties such as halogens, ketones, and aldehydes. Hereby is described a new copper-catalyzed vinylsilane transformation. Various vinylsilanes were allylated by using copper(I) salts, and this led to the formation of polysubstituted 1,4-dienes bearing sensitive moieties such as halogens, ketones, and aldehydes. TBAT = tetrabutylammonium difluorotriphenylsilicate. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

During the course of our study on the formation of a complex having a zirconium-silicon bond, we found that zirconium-silene complex 7 was formed from Cp2ZrCl2 and Me2PhSiLi. In the presence of alkyne, diarylalkyne reacted with silene coordinated with zirconium to give silazirconacyclopentene 8. On the other hand, dialkylalkyne inserted into a zirconium-silene complex gave silazirconacyclopentene 9. Hydrolysis of 8 or 9 afforded vinylsilane 13 or allylsilane 16. Transmetalation of zirconacycle 8 into copper in the presence of allyl halide gave a bis-allylated compound in high yield, indicating that alkylation occurred on the alkyne carbon and the methyl group of silicon. From bis-allylated compounds, eight-membered ring compounds having silicon were obtained in high yield using olefin metathesis.

A synthetic route to the BCDE rings of ciguatoxin 1B has been explored through acetylene biscobalthexacarbonyl complex and vinylsilane strategy. The key issues in the current synthesis are (i) ether ring cyclization by means of the acetylene cobalt complex and (ii) reductive decomplexation of the product endo -complexes into the corresponding vinylsilanes. A sequential cyclization route is also described along this line.

The intramolecular carbomagnesiation of a vinylsilane at 25 °C in THF has been found to proceed in a stereospecific (>95%) syn-addition of carbon and magnesium to the double bond. The resulting α-silylalkylmagnesium compounds are not configurationally stable under the reaction conditions. They epimerize with a half-life of 2.7 d at room temperature.

A synthetic route to the (D)EF analog of ciguatoxin has been explored through acetylene cobalt complex and vinylsilane strategy. The central reactions in the synthesis are: (i) ether ring formation mediated by acetylene cobalt complex and (ii) decomplexation of the endo -acetylene cobalt complexes to vinylsilanes or olefins. Unusual rearrangement of epoxy-silane to allylic alcohol is also described.