Enantioselective Hydrosilylation of β,β-Disubstituted Enamides to Construct α-Aminosilanes with Vicinal Stereocenters

Despite the advances in the area of catalytic alkene hydrosilylation, the enantioselective hydrosilylation of alkenes bearing a heteroatom substituent is scarce. Here we report a rhodium-catalyzed hydrosilylation of β,β-disubstituted enamides to directly afford valuable α-aminosilanes in a highly regio-, diastereo-, and enantioselective manner. Stereodivergent synthesis could be achieved by regulating substrate geometry and ligand configuration to generate all the possible stereoisomers in high enantio-purity.     

Synthesis and characterization of α-{ 3-[2-hydroxy-3- （N-methyl-N-hydroxy-ethylamino）propoxy]propyl}-ω- butylpolydimethylsiloxanes

α-{ 3-[2-hydroxy-3-（N-methyl-N-hydroxyethylamino）propoxy]propyl }-α-butylpolydimethylsiloxanes III with various molecu- lar weights were prepared by epoxy addition of α-[3-（2,3-epoxy-propoxy）propyl]-α-butylpolydimethylsiloxanes Ⅱ and N- methylmonoethanolamine. At each step, the outcome compounds were characterized through FT-IR and NMR spectra, the results showed that each step was successfully carried out and objective products were achieved.     

Heterodinuclear M1M2 Complexes (M1=Ni,Pd, Pt; M2=Rh,Ir) Supported by a Tetradentate Phosphine Ligand and Their Application for Hydrosilylation

A new series of cationic heterodinuclear complexes, [M¹M²Cl₂(meso-dpmppp)(RNC)₂]PF₆ (M¹=Ni, M²=Rh, R=^tBu ( 1 a ); M¹=Pd, M²=Rh, R=^tBu ( 2 a ), Xyl ( 2 b ); M¹=Pt, M²=Rh, R=^tBu ( 3 a ), Xyl ( 3 b ); M¹=Pd, M²=Ir, R=^tBu ( 4 a )), supported by a tetradentate phosphine ligand, meso-Ph₂PCH₂P(Ph)(CH₂)₃P(Ph)CH₂PPh₂ (meso-dpmppp), were synthesized by stepwise reactions of meso-dpmppp with NiCl₂ ⋅ 6H₂O or MCl₂(cod) (M=Pd, Pt), forming mononuclear metalloligands of [M¹Cl₂(meso-dpmppp)], and with [M²Cl(cod)]₂ (M²=Rh, Ir) and RNC (R=^tBu, Xyl) in the presence of [NH₄][PF₆]. The related neutral PdRh complex, [PdRhCl₃(meso-dpmppp)(XylNC)] ( 5 ), was also prepared. The structures of 1 – 5 were determined by X-ray analyses to contain two square planar d⁸ metal centers with face-to-face arrangement, where meso-dpmppp supports M¹ and M² metal ions in cis/trans-P,P coordination mode, combining cis-{M¹P₂Cl₂} and trans-{M²P₂(CNR)₂} units. Complexes 1 – 4 showed an intence characteristic absorption around 422–464 nm derived from Rh^I→RNC MLCT transition (HOMO→LUMO+1), which are influenced by changing M¹ (Ni^II, Pd^II, Pt^II) metal ions since HOMO composed of dσ* orbitals appreciably destabilized by changing M¹ from Ni to Pd, and Pt. The electronic structures of 1 a – 4 a were investigated on the basis of DFT calculations and NBO analyses to show weak but noticeable d⁸–d⁸ metallophilic interaction as empirical dispersion energy of 0.9–1.5 kcal/mol without M¹–M² covalent bonding interaction. In addition, 1 – 5 were utilized as catalysts for hydrosilylation of styrene, and the NiRh complex 1 a was found to show higher activity and chemo- and regioselectivity compared with 2 – 5 .     

Synthesis of a fumed silica-supported poly-3-(2-aminoethylamino)propylsiloxane platinum complex and its catalytic behavior in the hydrosilylation of olefins with triethoxysilane

A novel fumed silica-supported bidentate nitrogen platinum complex was conveniently prepared from N-(2-aminoethyl)-3-aminopropyltriethoxysilane via immobilization on fumed silica followed by a reaction with hexachloroplatinic acid. The title complex was systematically characterized and analyzed by Fourier Transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and specific surface area analysis (BET). The resulting title complex was found to be efficient and stable in catalyzing the hydrosilylation reaction of olefins with triethoxysilane. Furthermore, the polymeric platinum complex could be separated by simple filtration and reused four times without any appreciable loss of catalytic activity.     

二茂铁取代的笼型八聚(二甲基硅氧基)倍半硅氧烷的合成与表征

在Karstedt催化剂的催化作用下,通过把合成的笼型八聚(二甲基硅氧基)倍半硅氧烷与乙烯基二茂铁进行氧化硅烷化反应,合成了二茂铁取代的笼型八聚(二甲基硅氧基)倍半硅氧烷,产物经红外光谱、核磁共振氢谱与硅谱等进行了表征.     

Synthesis and characterization of a-{3-[(2,3-dihydroxy) propoxy]propyl}-v-butyl-polydimethylsiloxanes

Hydrosilylation has been carried out between Si-H terminated polydimethylsiloxanes with narrow molecular weight distribution and protected 3-allyloxy-1,2-propanediol, and after subsequently alcoholyzed, α-{3-[(2,3-dihydroxy)propoxy]propyl}-ω-butyl-polydimethylsiloxanes with varying number of ((Si(CH₃)₂-O) unit were obtained. At each step, the produced compounds were carefully characterized. The results showed that each step was successfully carried out and target products were achieved.     

SILICON-CONTAINING POLY(p-ARYLENE VINYLENE)S:SYNTHESIS AND PHOTOPHYSICS

A series of new silicon-containing poly(p-arylene vinylene)s(PAVs)with anthracene units in the main chain were synthesized by hydrosilylation reaction.The introduction of organosilicon units improved the solubility of the polymers,and theπ-πconjugation of polymeric chains was interrupted.These polymers behaved as blue-green light emitters with their fluorescence maximum at 447—499 nm and quantum yields in the range of 0.28-0.30 in solution.     

SYNTHESIS AND CHARACTERIZATION OF POLYSILOXANE CONTAINING OLIGO(OXYETHYLENE)SULFATE SALT

Solvent-free polymeric alkali-metal ion conductors, consisting of a comb-like polysiloxane with oligo(oxy-ethylene) side chains and pendant sulfate groups were synthesized by the hydrosilylation of allyl oligo(oxyethylene) sulfatesalt and allyl methoxy oligo(oxyethylene) with poly(methylhydrosiloxane). The factors influncing the ionic conductivity ofthe resulting polymer such as the electrolyte content and the nature of the alkali-metal were investigated. The temperaturedependence of conductivity was determined, and the ionic conductivity of the polymer follows the Vogel-Tammann-Fulcher(VTF) equation.     

聚γ-[N,N-双(β-乙硫乙基)胺基]丙基硅氧烷铑配合物的合成及其催化硅氢化性能

从二(β-氟乙基)烯丙胺出发,通过乙硫醚化、硅氢加成、气相法二氧化硅固载,再与三氯化铑作用,合成了标题配合物,它们是烯烃与三乙氧基硅烷的硅氢加成反应的有效催化剂,对其催化特性进行了研究。     

有机锡二聚体对醛的选择性催化

以Bu2SnO与CF3SO3H(TfOH)直接反应合成了有机锡二聚体[Bu2Sn(OH)(OTf)(H2O)]2, 以[Bu2Sn(OH)(OTf)(H2O)]2为催化剂考察了醛的硅氢化反应. 与传统的路易斯酸催化剂相比, 有机锡二聚体催化剂不仅具有合成简单、贮存容易、使用方便、易于分离、用量少和催化效率高等优点, 而且对醛基的还原催化具有很高的选择性, 且不受分子内和反应体系中其它羰基化合物或可还原基团的影响.