Hydrosilylation Products Research Articles

Silylformylation catalyzed by Rh and Rh-Co mixed metal complexes and its application to the synthesis of pyrrolizidine alkaloids

Reactions of hydrosilanes with 1-hexyne catalyzed by Co 2Rh 2(CO) 12, Rh 4(CO) 12, ( tBuNC) 4RhCo(CO) 4, and Rh(acac)(CO) 2 at 25°C and atmospheric pressure to 10 atm of carbon monoxide give (Z)-1-silyl-2-formyl-1-hexenes ( 1), which are the products of “silylformylation”, and/or ( E)-1-silyl-1-hexenes ( 2). The ratio of silylformylation vs. hydrosilylation products depends on the electronic nature of hydrosilane used, e.g., PhMe 2SiH gives 1 almost exclusively whereas (MeO) 3SiH favors the formation of 2. When trialkylsilanes such as Et 3SiH and EtMe 2SiH are used, the reaction catalyzed by Co 2Rh 2(CO) 12 or ( tBuNC) 4RhCo(CO) 4 gives 2,5-bis(n-butyl)-3-silylcyclopent-2-en-1-one ( 3) as a major product, which is a unique silylcarbocyclization product. Mechanism of the formation of 3 is discussed on the basis of deuterium-labeling experiments. Chemoselective silylformylations of alkenynes, a dialkyne, and an alkynyl nitrile proceed in high yields in which alkene and nitrile functionalities are inert for the reaction. Silylformylation is successfully applied to the syntheses of pyrrolizidine alkaloids, (±)-isoretronecanol and (±)-trachelanthamidine, from 5-ethynyl-2-pyrrolidinone ( 6) in combination with amidocarbonylation.

EPR study of spin adducts of silyl and phosphonyl radicals with higher internal perfluoroalkenes

The EPR method was used to study the structure of spin adducts of silyl and phosphonyl radicals with higher internal perfluoroalkenes. The capacity for spin adducts to split off hydrogen atoms is determined by the degree of steric screening of the free radical center. The preparative photochemical reaction of hydrosilanes and dialkyl phosphites with perfluoro-4-methylpent-2-ene leads to regiospecific hydrosilylation and hydrophosphorylation products with yields up to 80%.

ChemInform Abstract: Metallacarboranes in Catalysis. Part 9. Catalytic Hydrosilanolysis of Alkenyl Acetates by Triethylsilane.

AbstractThe title reaction, demonstrated with the closo‐rhodacarborane as catalyst precursor, yields besides (IV) the alkene derived from the alkenyl acetate rather than the hydrosilylation product (over 80 turnovers by 80% conversion of alkenyl acetate to trialkylsilyl acetate).

Metallacarboranes in catalysis. 9. Catalytic hydrosilanolysis of alkenyl acetates by triethylsilane

Reaction of an alkenyl acetate, [CH 3 CO 2 CR=CH 2 ] (R=CH 3 , C 6 H 5 ), with triethylsilane in the presence of either the closo-rhodacarborane [closo-3,3-(PPh 3 ) 2 -3-H-3,1,2-RhC 2 B 9 H 11 ] (I) or the exo-nido-rhodacarborane [exo-nido-(PPh 3 ) 2 Rh-7,8-(μ(CH 2 ) 3 )7,8-C 2 B 9 H 10 ] (II) as catalyst precursors in CH 2 Cl 2 at 40 o C for 42 h yielded triethylsilyl acetate and the alkene derived from the alkenyl acetate rather than the hydrosilylation product. The closo complex I was shown to be a superior catalyst precursor, giving over 80 turnovers, which corresponds to 80% conversion of alkenyl acetate to trialkylsilyl acetate under experimental conditions. Under mild conditions, tris(triphenylphosphine) chlororhodium, [(PPh 3 ) 3 RhCl] (IV), was found to catalyze the hydrosilanolysis as well as the hydrosilylation of isopropenyl acetate. The mechanisms of the hydrosilanolysis and related reactions of alkenyl acetates are discussed

ChemInform Abstract: Unprecedented 1,4‐Methyl Group Migration in a Rhodium‐Catalyzed Hydrosilylation of Ketones by 1,2‐Bis(dimethylsilyl)benzene.

AbstractThe Rh‐catalyzed hydrosilylation of ketones e.g. (I) with the disilylbenzene (II) results in the formation of the expected hydrosilylation products (III) and their rearranged derivatives (IV).

Bis(η5-cyclopentadienyl)diphenyltitanium-catalyzed Hydrosilylation of Ketones

Abstract Bis(η5-cyclopentadienyl)diphenyltitanium activated a Si–H bond of diphenylsilane, methylphenylsilane, and phenylsilane effectively to bring about the reaction with ketones giving hydrosilylation products, alkoxysilanes, in good yields with good selectivity.

ChemInform Abstract: Hydrosilylation of α,α,α‐Trichloroalkenes in the Presence of H2PtCl6·6H2O.

AbstractThe trichloropentene (I) reacts with triethylsilane (II) in the presence of hexachloroplatinic(IV) acid to give the hydrosilylation product (III), together with the isomerization product (IV).

Catalysis of hydrosilylation XIII. Gas‐phase hydrosilylation of acetylene by trichlorosilane on functionalised silica supported rhodium and ruthenium phosphine complexes

AbstractGas‐phase hydrosilylation of acetylene by tri‐chlorosilane catalyzed in a continuous flow apparatus by rhodium and ruthenium phosphine complexes immobilized on the silica via mercapto, phosphine, amine and nitrile ligands has been studied. GLC analysis of the reaction products showed vinyltrichlorosilane to be accompanied by products of double hydrosilylation of acetylene and the redistribution of trichlorosilane followed by the hydrosilylation and hydrogenative hydrosilylation of acetylene with dichlorosilane. A scheme for this complex competitive–consecutive reaction was proposed. The yield and selectivity of vinyltrichlorosilane can be much improved under special reaction conditions, e.g. rate flow of the particular substrates, temperature, given catalyst and others. Kinetic measurements carried out in the range of 115–140°C allowed us to evaluate the activation energy, Ea, for the vinyltrichlorosilane synthesis, which varied between 20.5 and 27.6 kJ mol−1 for the selected rhodium and ruthenium supported complexes.

Synthesis of 3-(2,5-dihydrofuryl)-silanes and -germanes and their transformations under catalytic hydrogenation conditions

A number of 3-triorganosilyl- and 3-trimethylgermyl-2,5-dihydrofurans have been prepared by the cyclization of 2-triorganosilyl(germyl)-2-butene-1,4-diols obtained from the hydrosilylation and hydrogermylation products of 1,4-bis(trimethylsiloxy)-2-butyne. It has been found that the liquid-phase heterogeneous hydrogenation of these compounds over palladium catalysts is accompanied by simultaneous isomerization and disproportionation to give the corresponding 3-(4,5-dihydrofuryl)-, 3-tetrahydrofuryl- and 3-furyl- derivatives.

Homogeneous catalysis: VIII. Carbene-transition-metal complexes as hydrosilylation catalysts

Some carbene-transition-metal complexes, particularly those of rhodium(I) but also of ruthenium(II), have proved to be effective catalysts for the hydrosilylation (e.g., using SiHEt 3 or SiH 2Ph 2) of ketones (to afford silyl ethers) or alkynes. The addition of triethylsilane to phenylacetylene or diphenylacetylene, catalysed by cis-[RhCl(COD)L Me] or trans-[RhCl(PPh 3) 2L Me] (COD=cycloocta-1,5-diene, L Me = : CN(Me)(CH 2) 2N Me), proceeds stereoselectively via trans-addition; the stereochemistry of the hydrosilylation products and the catalytic enhancement observed in the presence of air or ultraviolet light suggests that the reaction proceeds via a radical intermediate. Diphenylsilane is catalytically converted into (SiHPh 2) 2, or O(SiHPh 2) 2 in presence of air, when for example cis-[RhCl(COD)L Me] is used.

Rhodium-catalysed hydrosilylation: the direct production of alkenyl(triethyl)silanes from alk-1-enes and triethylsilane

Hex-1-ene undergoes reaction with triethylsilane in 1,2-dichloroethane solution in the presence of [(C 5Me 5Rh) 2Cl 4] catalyst (1) to give the normal hydrosilylation product n-hexyl(triethyl)silane (2), as well as the unexpected E-hex-1-en-1-yl(triethyl)silane (3) and E-hex-2-en-1-yl(triethyl)silane (4). These reactions proceeded smoothly and were not significantly influenced by air, moisture, radical initiators, or radical traps. The relative proportions of (2) and (3) [(4) was a minor product] were determined by the temperature and the ratio of olefin to silane, the vinylsilane (3) being favoured by lower temperatures and a high olefin-to-silane ratio. Under optimum conditions selectivity as high as 69% towards (3) could be achieved. Ethylene, styrene, hept-1-ene, and non-1-ene gave similar results. Other rhodium catalysts were tested; of these, the best was [Rh(PPh 3) 3Cl] which could give results similar to (1). However, the reproducible initiation of these reactions was very difficult, as traces of oxygen were needed and (1) is the catalyst of choice for forming (3). The mechanisms of the reactions leading to (2), (3), and (4) are discussed in the light of kinetic and other data.

Cleavage of ?,?- and ?,?-mono- and diunsaturated organyl alkenyl sulfides by trialkyl- and trialkoxysilanes

Organyl alkenyl sulfides of general formula RS(CH2)nCH=CH2 react with triethyl- and triethoxysilane in the presence of PdCl2(C6H5CN)2 and P(C6H5)3, with cleavage of the S-C bond and the formation of the corresponding Si-substituted organylthiosilanes RSSiR3' and disilthianes R3'SiSSiR3'. The reaction is accompanied by the disproportionation of the starting silanes R3'SiH with the formation of R4'Si. Hydrosilylation products were not detected.

Photoinduzierte addition von R 3SiH an (η 4-butadien)tricarbonyleisen

Irradiation of a mixture of 1,3-dienes, silanes, and pentacarbonyliron leads to mixtures of isomeric hydrosilylation products. The reaction is shown to proceed via the intermediate formation of (η 3- anti-butenyl)tricarbonyliron-trialkylsilicon complexes which are accessible by photoinduced addition of R 3SiH to (η 4-butadiene)tricarbonyliron and, upon thermal decomposition, yield similar mixtures of isomeric butenyltrialkyisilicon derivatives.

Organofluorosilicates in organic synthesis. 1. A novel general and practical method for anti-Markownikoff hydrohalogenation of olefins via organopentafluorosilicates derived from hydrosilylation products

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrganofluorosilicates in organic synthesis. 1. A novel general and practical method for anti-Markownikoff hydrohalogenation of olefins via organopentafluorosilicates derived from hydrosilylation productsKohei Tamao, Junichi Yoshida, Masatada Takahashi, Hiraku Yamamoto, Toshio Kakui, Hiroshi Matsumoto, Atsushi Kurita, and Makoto KumadaCite this: J. Am. Chem. Soc. 1978, 100, 1, 290–292Publication Date (Print):January 1, 1978Publication History Published online1 May 2002Published inissue 1 January 1978https://doi.org/10.1021/ja00469a054RIGHTS & PERMISSIONSArticle Views348Altmetric-Citations44LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (417 KB) Get e-Alerts Get e-Alerts

ChemInform Abstract: REACTION OF DIETHYLSILANE WITH 2‐ETHOXYACROLEIN

AbstractDiäthylsilan (II) reagiert in Gegenwart von Hydrochinon und Platinchlorwasserstoffsäure in Isopropanol mit 2‐Äthoxy‐acrolein (I) zu einem Gemisch aus (I), (II) und 1‐Diäthylsiloxy‐2‐äthoxy‐ 2‐propen (III), das nach 3 Monaten zu 95% (III) bildet.

Reaction of diethylsilane with 2-ethoxyacrolein

1. Depending on the nature of the catalyst and the temperature, the hydrosilylation of 2-ethoxyacrolein with diethylsilane in the presence of H2PtCl6 or colloidal nickel leads to the formation of the 1,2- and 1,4-addition products, and specifically 1-(diethylsiloxy)-2-ethoxy-2-propene and 1-(diethylsiloxy)-2-ethoxy-1-propene, respectively, and also 2-ethoxy-3-diethylsiloxypropyl-(2-ethoxy-1-propenoxy)diethylsilane. Depending on the nature of the catalyst, isomerization of the 1,2-adduct to the 1,4-addition product, and the reverse, occurs. 2. The intramolecular hydrosilylation product of 1-(diethylsiloxy)-2-ethoxy-2-propene in the presence of H2PtCl6 is 2,2-diethyl-4-ethoxyoxasilolane; the latter is also formed by the direct hydrosilylation of 2-ethoxyacrolein with diethylsilane under certain conditions.

Hydrosilylation of 3-substituted 1-propyne derivatives

1. The reaction of triethylsilane with 3-substituted 1-propyne derivatives (HC≡CCH2X) leads to the formation of the addition products both by the Farmer rule (trans-isomer) and contrary to it (gem-isomer). Electronegative substituents cause the predominant formation of the gem-isomer. 2. The isomers of the hydrosilylation products can be identified on the basis of the IR spectral data from the bands of the stretching vibrations of the C=C bond for the trans-isomer, and from the frequencies of the stretching and deformation vibrations of the C-H bond of the =CH2 group for the gem-adduct.

Hydrosilylation of carbonyl compounds catalysed by ruthenium complexes

Summary The ruthenium complex [RuCl2(PPh3)3] catalyses the reaction of triethylsilane with ketones, RR′CO, and aldehydes, RCHO, to give the hydrosilylation products RR′CHOSiEt3 and RCH2OSiEt3, respectively, but it is not as effective a catalyst as [RhCI(PPh3)3]. The complex [RuCIH(PPh3)3] was obtained by treatment of [RuCl2(PPh3)3] with triethylsilane, and [RhCl(PPh3)2(CO)] was isolated from reaction between p-methoxybenzaldehyde and triethylsilane catalysed by [RhCl(PPh3)3].