Evaluation of C-trialkylsilyl enol and thioenol ethers as intermediates in the synthesis of acylsilanes

C-silyl enol ethers or thioenol ethers have been prepared by a Peterson reaction, as intermediates for acylsilane synthesis. Bis(trialkylsilyl)(methoxy)- or -(methylsulfanyl)methanes bearing identical or different trialkylsilyl groups were used as starting materials in order to assess the selectivity of the Peterson elimination step. A good selectivity was observed only with ethers bearing the TMS and TBDMS groups. However, there is no practical interest to use such reagents owing to the difficulty to obtain them in correct yields. Bis(trimethylsilyl)(methylsulfanyl)methane proved to be a good reagent for the preparation of C-silyl thioenol ethers, which are hydrolyzed under classical acid conditions to give acylsilanes in fair overall yields. This convenient procedure was extended to the synthesis of bis(acylsilanes).     

Synthesis of diarylenenaphthylene- and diaryleneanthrylene-containing organosilicon polymers and their applications to organic EL devices

Stille coupling reactions of bis(stannylphenyl- and stannylthienyl)silane with dibromonaphthalene and bis(bromothienyl)anthracene gave the corresponding polymers containing naphthylene or anthrylene units in the backbone. Applications of the polymers to electroluminescent (EL) devices were examined and it was found that the diphenyleneanthrylene-containing polymer can be used as a good hole-transporting material in a double-layered EL device.     

Synthesis and crystal structures of some cobalt halide derivatives containing alkyl or silanolato groups

The alkylcobalt halide (2) and the lithium silanolatocobaltates Li(THF)₂(μ-Br)₂Co(μ-OSiMe₃)₂Co(μ-Br)₂Li(THF)₂ (4) and [LiBr{Li(THF)}₂{CoBr(OSiMe₃)₃}]₂ (5) form centrosymmetrical halogen-bridged dimers in the crystalline state. Compound 4 shows bromide bridges between lithium and cobalt, and silanolato bridges between the cobalt atoms. Below 200 K there are significant antiferromagnetic interactions between the cobalt centres. Compound 5 crystallises in a novel structure in which two cubane-like fragments containing silanolato bridges are linked together through a Li₂Br₂ ring.     

Orthogonal reactivity of thiols toward chlorovinylsilanes: selective thiol-ene chemistry

A variety of new chlorosilanes were synthesized by the selective thiol-ene reactions of various thiols (ethanethiol, 1,2-ethanedithiol, benzenethiol, and tetrakis(2-sulfanylethyl)silicate) with chlorovinylsilanes (chlorodimethylvinylsilane, dichloromethylvinylsilane, and trichlorovinylsilane). No silylthioester products were observed. All products were obtained in quantitative or near quantitative yields and were characterized using multinuclear NMR (¹H, ¹³C, ²⁹Si) spectroscopy. The products required no further purification. An example is presented which highlights the potential use of these compounds for future applications.     

A highly stereoselective synthesis of new styryl-π-conjugate organosilicon compounds

This work describes very precise and controlled catalytic transformations as useful tools for the synthesis of new trans-π-conjugated molecular and macromolecular organosilicon compounds. Several distyryl-arenes were obtained efficiently via silylative coupling in high yields and with excellent selectivity for new E,E-bis(silyl)arenes.     

Bildung siliciumorganischer Verbindungen. 108. Thermisch induzierte Reaktionen aminosubstituierter Disilane

Formation of Organosilicon Compounds. 108 [1]. Thermally Induced Reactions of Amino-Substituted Disilanes Thermally induced reactions of amino-substituted disilanes yield Si rich silanes. At 300°C, Me₃Si? SiMe₂? NMeH 1 yields Me₃Si? NMeH 2 and Me₃Si? (SiMe₂)₂-NMeH 3 in a ratio 1 : 2 : 3 = 1,6 : 1 : 1, whereas Me₃Si? SiMe₂? N(iPr)H 4 at 350°C yields Me₃Si? N(iPr)H 5 , Me₃Si? (SiMe₂)₂-N(iPr)H 6 and Me₃Si? (SiMe₂)₃? N(iPr)H 7 in a ratio of 4 : 6 : 7 = 0.8 : 1.0 : 0.6. Me₃Si? SiMe₂? NMe₂ 8 at 300°C (72 h) yields Me₃Si? NMe₂ 9 and Me₃Si-(SiMe₂)₂-NMe₂ 10 in a ratio of 9 : 8 : 10 = 1 : 0.22 : 0.44 The thermal stability of these disilanes is determined by the sterical requirements of the amino substituents NMeH < NMe₂ < N(iPr)H. The introduction of a second NMe₂ group decreases the stability and favours the formation of Si rich silanes. Such, Me₂N? (SiMe₂)₂? NMe₂ 11 already at 250°C (2 h) yields Me₂N? SiMe₂? NMe₂ 12 , Me₂N? (SiMe₂)₂? NMe₂ 13 and Me₂N? (SiMe₂)₄? NMe₂ 14 in a ratio of 11 : 13 : 14 = 0.3 : 0.9 : 1.0. The reactions can be understood as insertions of thermally produced dimethylsilylene into the Si? N bond of the disilanes. This process is strongly favoured as compared to the trapping reactions with Ph? C?C? Ph or Et₃SiH. The mentioned reactions correspond closely to those of the methoxy-disilanes[2]. However (MeN? SiMe₂? SiMe₂)₂ 15 , obtained from HMeN? (SiMe₂)₂? NMeH by condensation [3], at 400°C suffers a ring contraction to octymethyl-1,3-diaza-2,4,5-trisilacyclopentane (69 weight %), and yields also some solid residue, the composition of which corresponds to Si₃C₇NH₂₁.     

Synthesis and characterization of new silicon-centred tin-dendrimers Si[CH2CH2SnR3]4. Single-crystal X-ray structure of the tetrahydrofuran adduct of tetrakis[2-(tribromostannyl)ethyl]silane

A series of novel first-generation silicon-centred tin dendrimers Si(CH₂CH₂SnR₃)₄ [R = CH₃ (3), ⁱBu (4), CCCH₃ (5), C₆H₄CH₃-4 (6), C₆H₄OCH₃-4 (7), (CH₂)₄OCH₂CH₂OCH₃ (8), CH₂SiMe₃ (9)] was prepared by the reaction of Si(CH₂CH₂SnBr₃)₄ (2) with the appropriate Grignard reagent or LiCH₂SiMe₃ in tetrahydrofuran. The new compounds were characterized by multinuclear NMR studies (¹H, ¹³C, ¹¹⁹Sn), mass spectrometry (MALDI-TOF, EI) and elemental analyses. The molecular structure of Si[CH₂CH₂SnBr₃(THF)₂]₂[CH₂-CH₂SnBr₃(THF)]₂ (2a) was determined by single-crystal X-ray diffraction.     

Formation,Characterization, and Stability of Novel Aluminocarbosilazane Macromolecules

Abstract

A novel class of polycarbosilazane?AlCl₃ macromolecules (AlCSZ) with a Si/Al molar ratio of 1 : 1, 2 : 1, and 3 : 1 were prepared by a two‐step reaction, formation of H₂NCH₂CH₂NH₂?AlCl₃ adducts followed by condensation of H₂NCH₂CH₂NH₂ with (CH₃)₂SiCl₂ in an aprotic solvent containing triethylamine base. The resulting AlCSZ materials were examined by elemental analysis, infrared spectroscopy (FT‐IR), mass spectrometry (MS), and powder x‐ray diffraction (XRD). The average polycarbosilazane chain–chain distances in the aluminum‐free polycarbosilazane and these AlCSZ macromolecules were estimated from the XRD data and found to be 5.94, 6.75, 6.88, and 7.19 Å, respectively. This demonstrates that AlCl₃ is incorporated between the polycarbosilzane chains and has caused chain–chain expansion. The thermal properties of these AlCSZs were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). They are air stable white solids but decompose in water forming the corresponding dimethylsiloxane, ethylenediamine, and aluminum oxide.     

Synthesis of new imines and amines containing organosilicon groups

The Peterson olefination reaction of terephthalaldehyde with tris(trimethylsilyl)methyl lithium, (Me₃Si)₃CLi, in THF at 0 °C gives 4-[2,2-bis(trimethylsilyl)ethenyl]benzaldehyde (1) and 4,4-bis[2,2-bis(trimethylsilyl)ethenyl]benzene (2). The new aldehyde (1) reacts with variety of amines in ethanol to afford the corresponding imines (3) containing vinylbis(trimethylsilyl) group. The newly synthesized imines (3) can be completely converted into amines containing vinylbis(trimethylsilyl) group with an excess amount of NaBH₄. In the case of N-[4-(2,2-bis(trimethylsilyl)ethenyl)benzyl]-2,6-dimethylaniline LiAlH₄ was used as a reducing agent in THF.     

二氧化硅固载硫、氮杂冠醚铂配合物的合成及其催化烯烃硅氢化性能

二(β-氯乙基)烯丙胺与3,6-二氧杂辛-1,8-二硫醇在乙醇钠存在下关环缩合,得到具有烯基侧链的1,7-二硫杂-10,13-二氧杂-4-氮杂-4-烯丙基环十五烷.后者通过硅氢加成、二氧化硅固载.再与氯亚铂酸钾反应,合成了一种新型有机硅聚合物负载硫、氮杂冠醚及其铂配合物.该配合物对于烯烃硅氢加成反应具有良好的催化性能.