1112-54-5Relevant articles and documents
Additive-free Semihydrogenation of an Alkynyl Group to an Alkenyl Group over Pd?TiO2 Photocatalyst Utilizing Temporary In-situ Deactivation
Kojima, Yasumi,Fukui, Makoto,Tanaka, Atsuhiro,Hashimoto, Keiji,Kominami, Hiroshi
, p. 3605 - 3611 (2018)
Lindlar's catalyst, i. e., calcium carbonate-supported palladium (Pd) modified with lead, has been used for semihydrogenation of an alkynyl group in the presence of hydrogen gas (H2). We examined hydrogenation of an alkynyl group in organosilane and hydrocarbon in methanolic suspensions of a Pd-loaded titanium(IV) oxide (Pd?TiO2) photocatalyst without the use of additives and H2. In the photocatalytic reaction, Pd particles worked as co-catalysts for hydrogenation and alkyne hydrogenation had priority to alkene hydrogenation. Since the Pd co-catalyst was temporarily deactivated during the reaction owing to accumulation of the oxidized product(s) of methanol, the capacity of hydrogenation of the unsaturated C?C bond was limited. By optimizing the capacity and amount of alkynes, almost complete semihydrogenation of alkynes was achieved under a poison-free condition. Pd?TiO2 can be regenerated by very simple treatments, i. e., washing and drying at room temperature.
THERMAL ISOMERIZATION AND DECOMPOSITION OF 3,3-DIETHYL-2,4-DIMETHYL-3-SILATHIETANE
Gusel'nikov, L. E.,Sokolova, V. M.,Vonina, E. A.,Zalikin, V. G.,Nametkin, N. S.,et al.
, p. 145 - 154 (1981)
Pyrolisis of 3,3-diethyl-2,4-dimethyl-3-silathietane (I) has been studied at temperatures from 300 to 530 deg C using the pulse pyolytic GC-MS method.Decomposition of I proceeds with the elimination of ethane, ethylene, propylene, butadiene, cis- and trans-but-2-ene, and also with the loss of atomic sulphur.Isomerization into sulphur-containing unsaturated compounds is the main transformation process of I.The intermediacy of 1,1-diethyl-2-methyl-1-silaethylene and diethylsilathione is also discussed.
Generation and Trapping of Bis(dialkylamino)silylenes: Experimental Evidence for Bridged Structure of Diaminosilylene Dimers
Sakamoto, Kenkichi,Tsutsui, Shinobu,Sakurai, Hideki,Kira, Mitsuo
, p. 253 - 260 (1997)
Reduction of dichlorobis(diisopropylamino)silane and dichlorobis(cis-2,6-dimethylpiperidino) silane by alkali metals gave the corresponding bis(diisopropylamino)silylene and bis(cis-2,6-dimethylpiperidino)silylene, respectively. These were successfully trapped by toluene and benzene as well as by hydrosilane, olefin, and acetylene. As the first evidence for the existence of the bridged-dimer of the diaminosilylenes, we have found scrambling of the amino-substituents on a silicon atom during the simultaneous generation of two different bis(dialkylamino)silylenes in benzene. Diaminosilyenes generated thermally from the other new precursors designed here gave no evidence for the bridged dimer, due to the high temperature required for the generation.
Ruthenium-Catalyzed Coupling Reactions of CO2 with C2H4 and Hydrosilanes towards Silyl Esters
Kunihiro, Kana,Heyte, Svetlana,Paul, Sébastien,Roisnel, Thierry,Carpentier, Jean-Fran?ois,Kirillov, Evgueni
supporting information, p. 3997 - 4003 (2021/02/01)
A series of in situ-prepared catalytic systems incorporating RuII precursors and bidentate phosphine ligands has been probed in the reductive carboxylation of ethylene in the presence of triethylsilane as reductant. The catalytic production of propionate and acrylate silyl esters was evidenced by high-throughput screening (HTS) and implemented in batch reactor techniques. The most promising catalyst systems identified were made of Ru(H)(Cl)(CO)(PPh3)3 and 1,4-bis(dicyclohexylphosphino)butane (DCPB) or 1,1’-ferrocene-diyl-bis(cyclohexylphosphine) (DCPF). A marked influence of water on the acrylate/propionate selectivity was noted. Turnover numbers [mol mol(Ru)?1] up to 16 for acrylate and up to 68 for propionate were reached under relatively mild conditions (20 bar, 100 °C, 0.5 mol % Ru, 40 mol % H2O vs. HSiEt3). Possible mechanisms are discussed.
Hydrosilylation of Terminal Alkynes Catalyzed by a ONO-Pincer Iridium(III) Hydride Compound: Mechanistic Insights into the Hydrosilylation and Dehydrogenative Silylation Catalysis
Pérez-Torrente, Jesús J.,Nguyen, Duc Hanh,Jiménez, M. Victoria,Modrego, F. Javier,Puerta-Oteo, Raquel,Gómez-Bautista, Daniel,Iglesias, Manuel,Oro, Luis A.
, p. 2410 - 2422 (2016/08/02)
The catalytic activity in the hydrosilylation of terminal alkynes by the unsaturated hydrido iridium(III) compound [IrH(κ3-hqca)(coe)] (1), which contains the rigid asymmetrical dianionic ONO pincer ligand 8-oxidoquinoline-2-carboxylate, has been studied. A range of aliphatic and aromatic 1-alkynes has been efficiently reduced using various hydrosilanes. Hydrosilylation of the linear 1-alkynes hex-1-yne and oct-1-yne gives a good selectivity toward the β-(Z)-vinylsilane product, while for the bulkier t-Bu-C≡CH a reverse selectivity toward the β-(E)-vinylsilane and significant amounts of alkene, from a competitive dehydrogenative silylation, has been observed. Compound 1, unreactive toward silanes, reacts with a range of terminal alkynes RC≡CH, affording the unsaturated η1-alkenyl complexes [Ir(κ3-hqca)(E-CH=CHR)(coe)] in good yield. These species are able to coordinate monodentate neutral ligands such as PPh3 and pyridine, or CO in a reversible way, to yield octahedral derivatives. Further mechanistic aspects of the hydrosilylation process have been studied by DFT calculations. The catalytic cycle passes through Ir(III) species with an iridacyclopropene (η2-vinylsilane) complex as the key intermediate. It has been found that this species may lead both to the dehydrogenative silylation products, via a β-elimination process, and to a hydrosilylation cycle. The β-elimination path has a higher activation energy than hydrosilylation. On the other hand, the selectivity to the vinylsilane hydrosilylation products can be accounted for by the different activation energies involved in the attack of a silane molecule at two different faces of the iridacyclopropene ring to give η1-vinylsilane complexes with either an E or Z configuration. Finally, proton transfer from a η2-silane to a η1-vinylsilane ligand results in the formation of the corresponding β-(Z)- and β-(E)-vinylsilane isomers, respectively.
Catalytic study of heterobimetallic rhodium complexes derived from partially alkylated s-indacene in dehydrogenative silylation of olefins
Adams,Riviere,Riviere-Baudet,Morales-Verdejo,Dahrouch,Morales,Castel,Delpech,Manríquez,Chávez
, p. 266 - 274 (2013/11/19)
This work describes the catalytic study of heterobimetallic rhodium compounds derived from partially alkylated s-indacene in dehydrogenative silylation of olefins in order to elucidate as much as possible the effects of: solvent, temperature, chemical substrates, olefin effect, silane effect, and secondary metallic fragment. The rhodium complexes, anti-[Cp*Fe-s- Ic′-Rh(COD)] 1, anti-[Cp*Ru-s-Ic′-Rh(COD)] 2, and syn-[Cp*Ru-s-Ic′-Rh(COD)] 2′ (with s-Ic′: 2,6-diethyl-4,8-dimethyl-s-indaceneiide) were previously synthesized and characterized, and were compared with the catalytic activity of the complexes previously reported; monometallic [(COD)Rh-s-Ic′H] 3, and homobimetallic anti-[{(COD)Rh}2-s-Ic′] 4, and syn-[{(COD)Rh} 2-s-Ic′] 4′. The heterobimetallic complexes show a high activity and selectivity for the dehydrogenative silylation of styrene and these complexes show also the presence of a cooperative effect between both metallic centers, which is evidenced when compared with monometallic complex.
Formation of five- and seven-membered rings enabled by the triisopropylsilyl auxiliary group
Usanov, Dmitry L.,Yamamoto, Hisashi
supporting information; experimental part, p. 414 - 417 (2012/02/15)
A highly convenient synthetic pathway to 2-indanones from aldehydes was established. The introduction of a triisopropylsilyl group greatly facilitated Meinwald rearrangement of the intermediate epoxides and alleviated the necessity of polysubstitution for the clean formation of indenes and cyclopentadienes via cyclodehydration of allylic alcohols; unprecedented freedom with respect to the product structure was thus achieved. The developed methodology could also be applicable to the formation of seven-membered rings leading to dibenzo[7]annulenes and dibenzosuberones.
Probing the catalytic potential of chloro nitrosyl rhenium(i) complexes
Jiang, Yanfeng,Blacque, Olivier,Berke, Heinz
experimental part, p. 2578 - 2587 (2011/05/03)
The reduction of the mononitrosyl Re(ii) salt [NMe4] 2[ReCl5(NO)] (1) with zinc in acetonitrile afforded the Re(i) dichloride complex [ReCl2(NO)(CH3CN)3] (2). Subsequent ligand substitution reactions with PCy3, PiPr 3 and P(p-tolyl)3 afforded the bisphosphine Re(i) complexes [ReCl2(NO)(PR3)2(CH3CN)] (3, R = Cy a, iPr b, p-tolyl c) in good yields. The acetonitrile ligand in 3 is labile, permitting its replacement with H2 (1 bar) to afford the dihydrogen Re(i) complexes [ReCl2(NO)(PR3) 2(η2-H2)] (4, R = Cy a, iPr b). The catalytic activity of 2, 3 and 4 in hydrogen-related catalyses including dehydrocoupling of Me2NH·BH3, dehydrogenative silylation of styrenes, and hydrosilylation of ketones and aryl aldehydes were investigated, with the main focus on phosphine and halide effects. In the dehydrocoupling of Me2NH·BH3, the phosphine-free complex 2 exhibits the same activity as the bisphosphine-substituted systems. In the dehydrogenative silylation of styrenes, 3a and 4a bearing PCy3 ligands exhibit high catalytic activities. Monochloro Re(i) hydrides [Re(Cl)(H)(NO)(PR3)2(CH3CN)] (5, R = Cy a, iPr b) were proven to be formed in the initiation pathway. The phosphine-free complex 2 showed in dehydrogenative silylations even higher activity than the bisphosphine derivatives, which further emphasizes the importance of a facile phosphine dissociation in the catalytic process. In the hydrosilylation of ketones and aryl aldehydes, at least one rhenium-bound phosphine is required to ensure high catalytic activity.
Facile synthetic access to rhenium(II) complexes: Activation of carbonbromine bonds by single-electron transfer
Jiang, Yanfeng,Blacque, Olivier,Fox, Thomas,Freeh, Christian M.,Berke, Heinz
scheme or table, p. 2240 - 2249 (2010/07/05)
The five-coordinated Re1 hydride complexes [Re(Br)(H)(NO) (PR3)2] (R = Cy la, iPr lb) were reacted with benzylbromide, thereby affording the 17-electron mononuclear ReII hydride complexes [Re(Br)2(H)(NO)(PR3)2] (R = Cy 3a, iPr 3b), which were characterized by EPR, cyclic voltammetry, and magnetic susceptibility measurements. In the case of dibromomethane or bromoform, the reaction of 1 afforded ReII hydrides 3 in addition to Re1 carbene hydrides [Re(= CHR1)(Br)(H)(NO)(PR3)2,] (R 1 = H 4, Br 5; R = Cy a, iPr b) in which the hydride ligand is positioned cis to the carbene ligand. For comparison, the dihydrogen Re 1 dibromide complexes [Re(Br)2(NO)(PR3MIf- H2)] (R = Cy 2 a, iPr 2 b) were reacted with allyl- or benzylbromide, thereby affording the monophosphine ReII complex salts [R 3PCH2R'][Re(Br)4(NO)(PR3)] (R' = -CH=CH2 6, Ph 7). The reduction of ReII complexes has also been examined. Complex 3 a or 3 b can be reduced by zinc to afford la or lb in high yield. Under catalytic conditions, this reaction enables homocoupling of benzylbromide (turnover frequency (TOF): 3a 150, 3b 134 h-1) or allylbromide (TOF: 3a 150, 3b 562 h-1). The reaction of 6 a and 6 b with zinc in acetonitrile affords in good yields the monophosphine Re 1 complexes [Re(Br)2(NO)(MeCN)2(PR 3)] (R = Cy 8a, iPr 8b), which showed high catalytic activity toward highly selective dehydrogenative silylation of styrenes (maximum TOF of 61 h-1). Single-electron transfer (SET) mechanisms were proposed for all these transformations. The molecular structures of 3 a, 6 a, 6 b, 7 a, 7 b, and 8 a were established by single-crystal X-ray diffraction studies.
Highly selective dehydrogenative silylation of alkenes catalyzed by rhenium complexes
Jiang, Yanfeng,Blacque, Olivier,Fox, Thomas,Freeh, Christian M.,Berke, Heinz
experimental part, p. 2121 - 2128 (2009/09/30)
Rhenium(I) complexes of type [ReBr2(L)(NO)(PR3) 2] (L = H2 (1), CH3CN (2), and ethylene (3); R = iPr (a) and cyclohexyl (Cy; b)) catalyze dehydrogenative silylation of alkenes in a highly selective ma
