A novel insight into the inductive effect in silicon chemistry

A revision of quantitative literature data for the reactivity of organosilicon compounds in light of conceptions stemmed from organic chemistry has been carried out. It has been found that in structure-reactivity analysis for organosilicon compounds, differently of carbon compounds, the inductive effect of substituents, at least in nucleophilic displacement reactions at silicon, must be expressed by two terms involving that for electronegativity. A protocol for the correlation analysis in organosilicon chemistry is now available.     

Pyridylsilanes in the synthesis of heterocycles (review)

The desilylation of pyridylsilanes and pyridylmethylsilanes is one of the most characteristic reactions of organosilicon derivatives of pyridine, and it has been shown to be possible to utilize this reaction in organic synthesis. In many instances, desilylation affords difficultly-accessible pyridine derivatives, which have also been synthesized by insertion of aldehydes into the Si-C bond in pyridylsilanes and reactions of organosilicon pyridinium compounds. 2-Trimethylsilylmethylpyridine has been found to undergo the largest number of reactions leading to the formation of a variety of compounds containing the pyridine ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 5–13, January, 1987.     

杂环型稳定硅烯插入HF、H_2O和NH_3反应

硅烯为卡宾的硅类似物,在有机光和热化学中作为一类重要的反应活性中间体引起了化学界的广泛兴趣.杂环型硅烯是实验合成的稳定硅烯,因其在有机硅化学中的重要作用,十几年来在实验和理论上均有研究报道.本文基于单重态杂环型硅烯的特殊电子性质和丰富的化学反应性,系统探讨了几种杂环型硅烯的插入反应.使用密度泛函理论(DFT),在B3LYP/6-311++G(d,p)水平上研究了三种氮杂环型不饱和硅烯(1,3,4)和两种氮杂环型饱和硅烯(2,5)分别与H—X(X=F,OH,NH2)键的插入反应,阐明了插入反应的机理并对各反应的结果进行了比较.杂环型硅烯与H—X的插入反应机理类似于简单硅烯,体现了硅烯的亲电亲核的双重反应性.由反应势垒和反应热看,五种硅烯与H—X键的插入反应均为HF最容易,H2O次之,NH3最难.饱和硅烯的反应性比不饱和硅烯的反应活性高,这也间接验证了杂环型饱和硅烯在实验中较难合成.     

Cross-coupling reactions of organosilicon compounds: new concepts and recent advances

This review highlights the rapid evolution of the newly-developed class of palladium-catalyzed cross-coupling reactions of organosilicon compounds. A myriad of heteroatom-containing silicon moieties (silyl hydrides, siletanes, silanols, silyl ethers, orthosiliconates, di- and polysiloxanes and pyridylsilanes) undergo mild and stereospecific cross-coupling. The diversity of methods for introduction of silicon groups into organic molecules and the range of organic electrophiles that can be used are emphasized.     

硅杂四元环化合物的合成和反应

硅杂四元环化合物在有机硅化学中是一类非常重要的小分子环系化合物, 广泛应用于有机化学、金属有机化学以及材料化学. 环上只含有一个硅原子的硅杂环丁烷可以通过γ-卤代丙基硅烷的Grignard反应、Si＝C键与烯烃的 [2＋2]环加成反应以及硅杂环丙烷的扩环反应合成, 环上只含有一个硅原子的硅杂环丁烯可以通过格氏试剂或锂试剂参与的Si—C键的关环反应、硅杂环丁烷的转化反应、硅卡宾对C—H键的插入反应、Si＝C键与炔烃的[2＋2]环加成反应以及二炔基硅烷的分子内成环反应等途径合成. 硅杂环丁烷和硅杂环丁烯由于存在环张力和具有一定的Lewis酸性, 能够通过扩环反应生成五元和六元含硅杂环化合物, 也能够通过开环反应生成不同结构的有机硅分子和聚合物, 抑或实现有机反应在温和条件下的转化.     

生物有机硅化合物研究新进展

本文概述了近十几年生物有机硅化学的新进展。全文分三部分:1)利用有机硅基取代有机药物中的活性官能团的硅基化反应;2)有机药物中的某一碳原子被硅原子取代的硅药(sila-drugs)研究;3)在有机药物中没有类似结构的具有生物活性的新型有机硅化合物研究。     

A Route to Organyl(trialkoxysilyl)chalcogenides and Dichalcogenides, Bis(trialkoxysilylmethyl)chalcogenides and Dichalcogenides

Reactions of organylchalcogenomagnesium halides RYMgX (in situ) (R = Me, Et, Ph; Y = S, Se, Te; X = Br, I) with (halomethyl)trialkoxysilanes X'CH₂Si(OR')3 (X' = Cl, I; R' = Me, Et) at reflux in tetrahydrofuran and the systems of tetrahydrofuran-acetonitrile 1:2, and ether-acetonitrile 1:2 are studied. These reactions are shown to lead to formation of mixtures of corresponding organyl(trialkoxysilylmethyl)chalcogenide and -dichalcogenide, bis(trialkoxysilyl methyl)chalcogenide and -dichalcogenide, as well as the contaminants 2,2,6,6-tetraalkoxy-2,6-disila-4-chalcogen-1-oxane, diorganylchalcogenide and -dichalcogenide, and other organic and organosilicon compounds. Composition of the formed mixtures debends considerably on the structure of R, nature of the chalcogen Y (S, Se, Te), and halides X and X' in the initial reagents, and reaction conditions. The most of synthesized and isolated organosilicon chalcogenides are newly obtained compounds.     

Heterophase polymerization of styrene in the presence of organosilicon compounds of various natures

The heterophase polymerization of styrene has been carried out in the presence of surfactants—organosilicon compounds with different solubilities in aqueous and styrene phases and surface activities at the interface. It has been demonstrated that the stability of polymer suspensions prepared with water-insoluble organosilicon compounds is much higher than that in the presence of organosilicon surfactants soluble in organic and aqueous phases. In the former case, suspensions with narrower particle-size distributions are produced. The stability of polymer microspheres prepared at various monomer-to-water volume ratios has been tested. An increase in the monomer concentration above 25 vol % leads to the loss of system stability.     

A New Protocol to Generate Catalytically Active Species of Group 4–6 Metals by Organosilicon-Based Salt-Free Reductants

Herein, we provide a new protocol to reduce various transition-metal complexes by using organosilicon compounds in a salt-free fashion with the great advantage of generating pure low-valent metal species and metallic(0) nanoparticles, in sharp contrast to reductant-derived salt contaminants obtained by reduction with metal reductants. The organosilicon derivatives 1,4-bis(trimethylsilyl)-2,5-cyclohexadiene ( 1 a ), 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene ( 1 b ), 1,4-bis(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene ( 2 a ), 2,5-dimethyl-1,4-bis(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene ( 2 b ), 2,3,5,6-tetramethyl-1,4-bis(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene ( 2 c ), and 1,1′-bis(trimethylsilyl)-1H,1′H-4,4′-bipyridinylidene ( 3 ) all served as versatile reductants for early transition-metal complexes and produced only easy-to-remove organic compounds, such as trimethylsilylated compounds and the corresponding aromatics, for example, benzene, toluene, pyrazine, and 4,4′-bipyridyl, as the byproducts. The high solubility of the reductants in organic solvents enabled us to monitor the catalytic reactions directly and to detect any catalytically active species so that we could elucidate the reaction mechanism.     

Palladium-catalyzed hydrosilylation of ynones to access silicon-stereogenic silylenones by stereospecific aromatic interaction-assisted Si–H activation

Hydrosilylation is one of the most important reactions in synthetic chemistry and ranks as a fundamental method to access organosilicon compounds in industrial and academic processes. However, the enantioselective construction of chiral-at-silicon compounds via catalytic asymmetric hydrosilylation remained limited and difficult. Here we report a highly enantioselective hydrosilylation of ynones, a type of carbonyl-activated alkynes, using a palladium catalyst with a chiral binaphthyl phosphoramidite ligand. The stereospecific hydrosilylation of ynones affords a series of silicon-stereogenic silylenones with up to 94% yield, 20:1 regioselectivity and 98:2 enantioselectivity. The density functional theory(DFT) calculations were conducted to elucidate the reaction mechanism and origin of high degree of stereoselectivity, in which the powerful potential of aromatic interaction in this reaction is highlighted by the multiple C–H-π interaction and aromatic cavity-oriented enantioselectivitydetermining step during desymmetric functionalization of Si–H bond.     

过渡金属膦配合物在硅氢化反应中的应用研究

过渡金属膦配合物在有机合成和催化反应中的应用非常广泛, 大量含膦杂原子配体被设计合成, 利用其特定的配位能力, 和过渡金属配位成过渡金属膦配合物, 并测试其对特定有机化学反应的催化性能. 硅氢加成反应是有机硅化学中的重要反应, 多种过渡金属包括铂、钯、铑、钌等的膦配合物对于硅氢加成反应均有催化活性. 综述了近几年来过渡金属膦配合物在硅氢加成反应中的应用进展.     

Structure-reactivity relationships in organosilicon chemistry revisited

Available quantitative data of the reactivity of organosilicon compounds were subjected to correlation analysis. As an alternative to the carbon chemistry values, the scale of steric constants E _S (Si) can be used for organosilicon compounds and the inductive effect is best expressed by two terms, involving the parameter of electronegativity of substituents. Alkyl substituents contribute to the reactivity exclusively through their steric effects, steric and polar effects in silicon compounds are additive and the resonance effect is insignificant. The correlation analysis can be employed in investigations of organosilicon reactions along with other methods.      

Kinetic models for the chemisorption of organic compounds on oxide surfaces

A kinetic equation for chemisorption on amorphous oxide surfaces is proposed, and activation energies, pre-exponential factors for reactions of various organosilicon compounds with Si, Ti and Al oxide active sites are calculated. Relationships between the kinetic parameters and reagent structure were established.     

Silicon-based cross-coupling reaction: an environmentally benign version

Much attention has been paid to the cross-coupling reaction of organosilicon compounds due to their stability, non-toxicity, and natural abundance of silicon. In addition, the silicon-based cross-coupling has many advantages over other cross-coupling protocols. Successful examples of the silicon-based cross-coupling reaction are reviewed, focusing especially on the advances made in the last decade. Having had a number of highly effective palladium catalysts developed mainly for other cross-coupling reactions, the development of the silicon-based protocol owes heavily to the design of organosilicon reagents which effectively undergo transmetalation, a key elemental step of the silicon-based cross-coupling reaction. This tutorial review thus classifies various organosilicon reagents depending on substituents on silicon and surveys their cross-coupling reactions with various electrophiles.     

Chromatographic separation of asymmetric organosilicon compounds on cellulose and amylose stationary phases. The stereochemistry of functional transformation reactions

Summary Silicon compounds, especially silanes, have been separated on cellulose carbamate and amylose carbamate stationary phases. Reasonable recognition is achieved in the separation of organosilicon compounds on cellulose carbamate. Stereoselectivity at the asymmetric silicon center in functional transformation reactions is discussed.     

有机硅化合物的不对称合成反应

介绍了“碳中心”手性有机硅化合物的合成,以及在烯丙基硅烷与醛的Hosomi-Sakurai反应和α-烯丙基硅碳负离子与醛的反应中的应用。提出并实践了两条提高对映选择性的途径。烯基硅醇的不对称环氧化反应扩展了Sharpless反应的适用范围,为合成光活性的具简单结构的环氧化合物提供了一条简易的途径。     

Control of the stereochemical structure of silicon‐containing polymers

Various optically pure organosilicon compounds were synthesized or separated on HPLC. Stereoregular silicon‐containing polymers, poly(carbosilane)s, poly(carbosiloxane)s and poly(siloxane)s were synthesized from these compounds as monomer. Stereochemistry of the elementary reactions to give stereoregular polymers was elucidated.     

Unusual Behavior of Nitrogen-Containing Organosilicon Compounds in the Reactions with Isocyanates

Russian Journal of General Chemistry - The behavior of organic and organosilicon nitrogen-containing compounds such as N-(trimethylsilyl)N-(2-{2-[(trimethylsilyl)oxy]ethoxy]}ethyl)amine and...     

具有生物活性的有机硅化合物研究近况

生物有机硅化合物的研究进展迅速,而且越来越受到人们的重视。实际上,它是有机硅化学的一个新的分支。本文对有机硅化合物的毒理学、有机硅药物化学以及有机硅农药作了简要的论述。