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21.
A chemoselective method for the hydrosilylation of ketones has been developed, using the combination of triphenylsilane and a catalyst prepared from Ni(COD)2 and the simple N-heterocyclic carbene IMes. The most notable feature of this method is that free hydroxyls are largely unaffected, thus providing a simple one-step procedure for the conversion of hydroxyketones to mono-protected diols, wherein the protecting group is exclusively installed on the ketone-derived hydroxyl. The process is typically high yielding with both simple ketones and more complex hydroxyketone substrates. 相似文献
22.
《Arabian Journal of Chemistry》2020,13(1):799-834
Non-activated olefins represent one of the most explored platform in organic synthesis affording new and useful compounds with several biological applications, among others. The typical reactivity of these compounds is the addition-type reactions. A plethora of transformations and studies were reported in the literature by many research groups. The focus of this review is to organize and describe the most recent synthetic transformations of non-activated alkenes in organic synthesis. Therefore, it is divided into five sections corresponding to each type of the products obtained: synthesis of fluoro-, chloro- and bromo-compounds; synthesis of alkyl/vinyl/aryl/heteroaryl compounds; synthesis of phospho/sulfur/silyl/cyano-compounds; synthesis of amine/amide/oxygenated compounds and synthesis of other functionalized compounds. 相似文献
23.
通过锂化四甲基二乙烯基二硅氮烷分别与甲基氢二氯硅烷和二甲基氢氯硅烷的亲核取代反应合成了AB4和AB2型单体AB4M和AB2M,两种单体通过Karstedt催化剂催化的硅氢加成反应分别生成聚碳硅氮烷PAB4M和PAB2M.单体和聚合物的结构通过FT-IR、1H-NMR、13C-NMR、29Si-NMR和体积排除色谱-多角度激光光散射联用(SEC-MALLS)技术进行了表征,结果表明,单体的结构与设计结构相符合;单体聚合时主要以α-硅氢加成方式为主;聚合物具有超支化结构并由N(Si—C)3链节和大量端基双键组成.PAB4M和PAB2M的重均分子量分别为7800和5860g/mol,分子量分布系数分别为2·54和2·31·对PAB4M稳定性的初步研究表明,该聚合物对氯硅烷和在中性条件下对水稳定,但在HCl水溶液中可以降解,且通过控制HCl浓度可以调节其降解速度,从而实现对其控制降解. 相似文献
24.
Herein we report a Ni-catalyzed formal hydroboration of olefins, which afforded anti-Markovnikov-type alkylboranes with B2pin2 and a stoichiometric amount of water. Formal hydrosilylation using air- and moisture-sensitive silylboranes also proceeded under optimized conditions. The reaction with trans-stilbene and D2O resulted in 1,2-H migration, which suggested that the reaction proceeded via β-hydride elimination and reinsertion mechanisms. 相似文献
25.
Jiayun Li Jiajian Peng Ying Bai Yingqian Hu Huayu Qiu Guoqiao Lai 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):484-490
Ionic liquid–modified silica has been prepared by a “one-pot” reaction of activated silica, 3-chloropropyltriethoxysilane, and alkylimidazole or pyridine. It was found that the catalytic activity and β-adduct selectivity of the supported catalyst Rh(PPh3)3Cl/ionic-liquid–modified-SiO2 for the hydrosilylation reaction of alkenes with triethoxysilane was significantly improved. Furthermore, the catalyst system could be recovered easily. 相似文献
26.
27.
Dorin Dusciac Jean-Noël Chazalviel François Ozanam Philippe Allongue Catherine Henry de Villeneuve 《Surface science》2007,601(18):3961-3964
Direct grafting of organic monolayers on Si is of prime interest in order to give specific properties to a silicon surface. However, for microelectronics applications, this possibility is hampered by the limited stability of the grafted layers. It has been previously established that alkyl layers attached to Si surfaces through Si-C bonds become unstable at 250-300 °C, by desorption of alkenes. Changing the nature of the bonding to the surface might allow one to circumvent this desorption pathway and increase the layer stability. In our work, decanol and decyl aldehyde are reacted with the Si(1 1 1)-H surface at ∼100 °C during 20 h in order to obtain alkoxy monolayers. FTIR measurements performed in ATR geometry show that the grafted molecule surface coverage is on the order of 33% after reaction with decanol and 50% after reaction with decyl aldehyde. Characterization by AFM essentially reveals that the morphology of the grafted surfaces is unaffected as compared to that of Si-H surfaces. However, the edges of the terraces at alcohol-grafted surfaces exhibit some pitting, probably due to the presence of water in the grafting liquid. Thermal stability studies show that alkoxy chains progressively disappear from the Si surface between 200 and 400 °C. From the CH2/CH3 ratio in the CH region (2760-3070 cm−1), it appears that the chains undergo progressive dissociation by C-C bond breaking before their complete disappearance from the surface. Therefore, the thermal behaviour of alkoxy monolayers appears quite distinct from that of alkyl monolayers that tend to leave the surface in a much narrower temperature range (250-350 °C), essentially via breaking of the Si-C bonds. 相似文献
28.
The preparation of various (hex-5-ynyl)silanes was achieved following two different synthetic approaches from readily available materials such as 4-bromobutene, 6-iodohexyne and chlorosilanes. Different reaction conditions for intramolecular hydrosilylation were tested to prepare the corresponding 2-methylidene-1-silacyclohexanes. Notably, the use of Speier’s catalyst allowed the regioselective formation of the desired products in moderate yields. 相似文献
29.
A novel reactive polyorganosiloxane containing nitro groups was first prepared by acid-catalyzed equilibration polymerization. The monomer, 3-(4-nitrophenoxy)propylmethyldichlorosilane (NPPMS), was synthesized by hydrosilylation reaction with dicyclopentadienylplatinum(II) chloride (Cp2PtC12) catalyst in high yield. The synthesized polynitroorganosiloxane, which has potential application as a precursor for synthesizing advanced functional polymers, was characterized by FTIR, 1H-NMR, 13C-NMR, 29Si-NMR, vapor pressure osmometry (VPO) and gel permeation chromatography (GPC). 相似文献
30.
Marcin Jankowiak 《Journal of organometallic chemistry》2005,690(20):4478-4487
Catalytic reactivity of Si-H bond of di-, trisiloxanes with allyl chloride in the presence of platinum catalyst has been examined. Hydrosilylation process competes with hydrogen substitution by chlorine and/or propenyl group. The effect of the reaction conditions as well as structure of siloxane on the yield and selectivity of the number of products has been discussed. Several consecutive-competitive processes have been identified. The results obtained can be helpful in the study of the catalytic hydropolysiloxanes reactions with allyl derivatives-systems of great practical importance, to produce commercial functionalized silicones. 相似文献