聚γ-(β-氰乙硫基)两基硅氧烷铑配合物的合成与催化硅氢化性能

γ-巯丙基三乙氧基硅烷与丙烯腈加成，得到γ－（β-氰乙硫基）丙基三乙氧基硅烷，后者依次与气相法二氧化硅、三氯化铑作用，合成了聚γ-（β-氰乙硫基）丙基硅氧烷铑配合物，研究了其催化烯烃与三乙氧基硅烷硅氢加成反应的特性。     

Synthesis, characterization and study of the chromogenic properties of the hybrid polyoxometalates [PW11O39(SiR)2O] (R = Et, (CH2)nCHCH2 (n = 0, 1, 4), CH2CH2SiEt3, CH2CH2SiMe2Ph)

Reaction of Cl₃SiR or (EtO)₃SiR with [PW₁₁O₃₉]⁷⁻ affords the disubstituted hybrid anions [PW₁₁O₃₉(SiR)₂O]³⁻. These species have been characterized by IR spectroscopy in the solid state and by multinuclear NMR (¹H, ²⁹Si, ³¹P and ¹⁸³W) and cyclic voltammetry in solution. The hydrosilylation of [PW₁₁O₃₉(Si-CHCH₂)₂O]³⁻ has been achieved with Et₃SiH and PhSiMe₂H. These are the first examples of hydrosilylation on a hybrid tungstophosphate core. The chromogenic behaviour of hybrid species has been demonstrated in solution.     

Synthesis and catalytic properties of N -functionalised carbene complexes of rhodium(I)

Reaction of [RhCl(COD)]₂, with 1,3-dialkylimidazolinylidene (1) or 1,3-dialkylbenzimidazolinylidene (2) resulted in the formation of rhodium(I) 1,3-dialkylimidazolin-2-ylidene (3a-c) and 1,3-dialkylbenzimidazolin-2-ylidene (4a,b) complexes. Triethylsilane reacts with acetophenone derivatives in the presence of catalytic amounts of RhCl(COD)(1,3-dialkylimidazolin-2-ylidene) or RhCl(COD)(1,3-dialkylbenzimidazolin-2-ylidene) to give the corresponding silylethers in good yield (57–98%).     

Homogeneous gold-catalyzed hydrosilylation of aldehydes

The catalytic hydrosilylation of aldehydes in the presence of PBu₃ modified Au(I)-complexes was investigated. In situ IR and NMR experiments have revealed that both, the ligand PBu₃ and the substrate aldehyde play an important role in stabilizing the gold catalyst and/or forming the catalytically active species. In their absence the reducing power of silane destabilizes the gold (I) catalyst giving rise to gold clusters or particles. Several side reactions involving water and oxygen were also investigated. A plausible reaction pathway as an alternative to the well-accepted mechanism for the transition-metal homogeneously catalyzed hydrosilylation of aldehydes has been proposed to accommodate the experimental observations.     

Photoswitching of the reactivity involving hydrosilylation of a 1,1,3,3-tetrahydrodisiloxane bearing two azo groups

A pentacoordinate (E,E)-1,1,3,3-tetrahydrodisiloxane bearing two azo groups gave hydrazobenzene in the fluoride ion-induced hydrolysis involving hydrosilylation of the azo groups followed by cleavage of the Si-C bonds, while a tetracoordinate (E,E)-forms formed by its photoirradiation gave an octaarylsilsesquioxane without cleavage of the Si-C bonds.     

Synthesis of a propyldimethylphenylsilane stationary phase using the allyl bonded phase as an intermediate

Summary A propyldimethylphenylsilane stationary phase was prepared by a hydrosilylation reaction on the double bond of an allyl bonded phase intermediate. The carbon load on the silica was between 8.8–9.0%. Evaluation of the material by FTIR indicated high conversion of the double bond by the hydrosilylation reaction. The bonded material displayed reversedphase properties as determined by the retention behavior of alkylarylketones but it was less hydrophobic than either C-8 or C-18. The stability at both low and high pH was excellent. Separations of pharmaceutical compounds, a mixture of anilines, and a mixture of dopamine and epinephrine were satisfactory.     

Hydrosilylation of 1-hexyne promoted by acetone solvated gold atoms derived catalysts

Supported gold nanoparticles, prepared by deposition of acetone solvated Au atoms on supports as carbon and γ-Al₂O₃, behave as valuable catalysts for the regioselective hydrosilylation of 1-hexyne with different silanes. The catalytic behaviour of gold-based systems is compared with the activity of supported platinum catalysts and a different affinity between the metals and the silanes is observed.     

Copper (I) 1,3-R2-3,4,5,6-tetrahydropyrimidin-2-ylidenes (R=mesityl, 2-propyl): synthesis, X-ray structures, immobilization and catalytic activity

The synthesis of novel copper (I) N-heterocyclic carbene complexes is described. Thus, reaction of CuX with 1,3-di(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene yields CuX(1,3-di(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) (X=Cl, (1a), Br (1b)); however, reaction of CuCl with 1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene yields the bis-N-heterocylcic carbene complex Cu(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)₂⁺CuBr₂⁻ (2). A supported version of 1, i.e. PS-DVB-CH₂-OCO-CF₂-CF₂-CF₂-COOCu(1,3-di(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) (3) was prepared from 1 and PS-DVB-CH₂-OCO-CF₂-CF₂-CF₂-COOAg. A copper loading of 4.15 μmol/g was realized. The new compounds were used as catalysts in carbonyl hydrosilylation and cyanosilylation reactions. Excellent reactivity was observed, giving raise to turn-over numbers (TONs) of up to 100,000. Compounds 1a, 1b, and 2 have also been used as catalysts for the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). A linear conversion of monomer with time was observed, however, no control over molecular weight of PMMA was observed.     

Rhodium Catalysts for Enantioselective Hydrosilylation—A New Concept in the Development of Asymmetric Catalysts

Following a survey of the asymmetric hydrogenation of prochiral olefins with transition metal/phosphane catalysts, the problem of chirality transfer from the optically active ligands of the catalyst to the substrate is discussed. A new concept for this chirality transfer is introduced; the conformational analysis of model compounds as well as the development of catalysts for enantioselective hydrosilylation demonstrate the usefulness of this concept.     

Borane-Catalyzed Tandem Cyclization/Hydrosilylation Towards Enantio- and Diastereoselective Construction of trans-2,3-Disubstituted-1,2,3,4-Tetrahydroquinoxalines

Recent years have witnessed marked progress in the efficient synthesis of various enantioenriched 1,2,3,4-tetrahydroquinoxalines. However, enantio- and diastereoselective access to trans-2,3-disubstituted 1,2,3,4-tetrahydroquinoxalines remains much less explored. Herein we report that a frustrated Lewis pair-based catalyst generated via in situ hydroboration of 2-vinylnaphthalene with HB(C₆F₅)₂ allows for the one-pot tandem cyclization/hydrosilylation of 1,2-diaminobenzenes and 1,2-diketones with commercially available PhSiH₃ to exclusively afford trans-2,3-disubstituted 1,2,3,4-tetrahydroquinoxalines in high yields with excellent diastereoselectivities (>20 : 1 dr). Furthermore, this reaction can be rendered asymmetric by using an enantioenriched borane-based catalyst derived from HB(C₆F₅)₂ and a binaphthyl-based chiral diene to give rise to enantioenriched trans-2,3-disubstituted 1,2,3,4-tetrahydroquinoxalines in high yields with almost complete diastereo- and enantiocontrol (>20 : 1 dr, up to >99 % ee). A wide substrate scope, good tolerance of diverse functionality and up to 20-gram scale production are demonstrated. The enantio- and diastereocontrol are achieved by the judicious choice of borane catalyst and hydrosilane. The catalytic pathway and the origin of the excellent stereoselectivity are elucidated by mechanistic experiments and DFT calculations.