Silylated and germylated cyclopropanones

The synthesis of trimethylsilyl- and germyl-cyclopropanones, by treating diazomethane with the corresponding trimethyl ketene, and their ring expansion to cyclobutanones are described.     

Peripherally Silylated Porphyrins

Silylation of peripherally lithiated porphyrins with silyl electrophiles has realized the first synthesis of a series of directly silyl‐substituted porphyrins. The meso‐silyl group underwent facile protodesilylation, whereas the β‐silyl group was entirely compatible with standard work‐up and purification on silica gel. The meso‐silyl group caused larger substituent effects to the porphyrin compared with the β‐silyl group. Silylation of β‐lithiated porphyrins with 1,2‐dichlorodisilane furnished β‐to‐β disilane‐bridged porphyrin dimers. A doubly β‐to‐β disilane‐bridged Ni^II‐porphyrin dimer was also synthesized from a β,β‐dilithiated Ni^II‐porphyrin and characterized by X‐ray crystallographic analysis to take a steplike structure favorable for interporphyrinic interaction. Denickelation of β‐silylporphyrins was achieved upon treatment with a 4‐tolylmagnesium bromide to yield the corresponding freebase porphyrins.     

Silylated derivatives of arabinonucleosides

Procedure have been developed which allow for the selective derivatization of arabinonucleosides at the 5′? or 2′? and 5′? or 3′? and 5′? positions.     

Silylated derivatives of azasilacyclopentanes

Catalytic intramolecular cyclization of 3-aminopropylalkoxysilanes and 3-aminopropylalkoxydisiloxanes in the presence of hexamethyldisilazane has been studied; structure and reactivity of the formed azasilacyclopentanes have been investigated. In particular, the prepared cyclic azasilanes were studied by ¹H, ²⁹Si, and ¹³C NMR spectroscopy. Possibility of catalytic co-condensation of the compounds containing methoxy and trimethylsiloxy groups with preservation of azasilacyclopentane structure has been demonstrated. Depending on temperature and the reactants ratio, the interaction of 3-aminopropylmethyldimethoxysilane with hexamethyldisilazane can yield 1-(trimethylsilyl)-2-methyl-2-methoxy-1-aza-2-silacyclopentane or the polymer bearing azasilacyclopentane fragments in the main chain.     

可湿气固化的硅烷化聚醚的研究

以聚醚多元醇为原料 ,通过聚氨酯预聚体的方法制得了可湿气固化的硅烷化聚醚 ,研究了温度和时间对反应的影响 ,以及不同NCO/OH比值对固化物力学性能的影响。结果表明 ,固化后形成的弹性体的不同力学性能可通过调节不同NCO/OH的比值而获得     

Preparation of Bicyclic Secondary and Tertiary Phosphines from Radical Addition of Phosphine and Primary Phosphines to Limonene

Abstract

In the presence of a free radical initiator, limonene combines with a primary phosphine to yield a 1:1 adduct (I). Initially the addition takes place at the isopropenyl moiety. The resulting secondary phosphine subsequently undergoes an intramolecular addition to produce two isomeric 2-alkyl-4,8-dimethyl-3-phosphabicyclo [3.3.1]nonanes (II, III) in >85% yield. Analogous bicyclic secondary phosphines are formed by free radical addition of phosphine to limonene. Yields are slightly lower due to the addition of the reactive secondary phosphines to a second mole of limonene.     

Stacking-Conformations in Functionally Substituted Phosphines

The methods of synthesis and space structure of phosphorus-containing compounds, in which stacking conformation is realized, are considered. It is shown that intramolecular stacking can be observed in monoheterocyclic compounds, bi-and polycyclic compounds, complexes of metals and acyclic compounds.     

Silylated bis(o-aminophenols)

Conclusions Silyl derivatives of a series of bis(o-aminophenols) have been described.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 920–922, April, 1976.     

Phosphorylated and Silylated Derivatives of Alfa-Mercaptocarbonyl Compounds

Abstract

The phosphorylation and silylation of α-mercaptocarbonyl compounds have been investigated. Novel different cyclic and linear silicon(phosphorus) containing derivatives have been obtained.     

Silylated Cyclohexadienes in Radical Chain Hydrosilylations

A new method for the mild radical hydrosilylation of alkenes and alkynes is described. Silylated cyclohexadienes that can be readily prepared on large scale are used as radical hydrosilylating reagents. Non‐activated alkenes and alkynes are hydrosilylated in high yields. The reaction can be combined with C C bond formation, as demonstrated for the preparation of silylated cycloalkanes from the corresponding dienes. Furthermore, radical hydrosilylations in combination with β‐fragmentation reactions for the synthesis of allylsilanes and hydrosilylations of aldehydes and ketones providing protected alcohols can be readily performed by this strategy.     

硅甲基接枝改性MCM-48的结构特征及表面性质

本文利用三甲基氯硅烷与未焙烧MCM-48反应,实现对MCM-48的表面硅甲基接枝改性。结果表明:原未焙烧MCM-48孔道内的CTAB模板剂被脱除,三甲基氯硅烷与表面羟基反应,将硅甲基官能团接枝到MCM-48的内外表面。改性后MCM-48具有良好的长程有序结构,较窄的孔径分布,较大的孔体积和较高的比表面积,相对于未焙烧MCM-48,硅甲基接枝改性MCM-48的表面亲水性降低,亲油性得到提高。     

CO2 Capture with Silylated Ethanolamines and Piperazines

Amine treatment is commonly used to capture CO₂ from exhaust gases and from ambient air. The Si−N bond in aminosilanes is capable of reacting with CO₂ more readily than amines. In the current study we have synthesized trimethylsilylated ethanolamines, diethanolamines and piperazines and investigated their reaction toward CO₂. All products were characterized by ¹H, ¹³C, and ²⁹Si NMR, RAMAN spectroscopy as well as mass spectrometry. The product of a twofold CO₂-insertion into bis-trimethylsilylated piperazine was analysed by single-crystal X-ray diffraction. Furthermore, quantum chemical calculations (DFT) were used to supplement the experimental results. Geometry optimizations and NBO calculations for each starting material were carried out at the B3LYP level with different basis sets. DFT calculations at the B3LYP, WB97XD and M062x level were conducted for geometry optimization and frequency calculations to examine the thermochemical data. The calculations were carried out both for the gas phase and in solvent environment. The calculated reaction enthalpies varied between −37 and −107 kJ mol⁻¹, while experimental values around −100 kJ mol⁻¹ were determined.     

Intramolecular Interaction in Heterocyclic Phosphines

Some specific features of space structure, reactivity, complex formation and unusual physical properties of organic and organophosphorus compounds are due to univalent intramolecular interactions. Several intramolecular interactions observed in heterocyclic phosphines will be discussed in this current paper.     

Anionic Access to Silylated and Germylated Binuclear Heterocycles

A simple access to silylated and germylated binuclear heterocycles, based on an original anionic rearrangement, is described. A set of electron‐rich and electron‐poor silylated aromatic and heteroaromatic substrates were tested to understand the mechanism and the factors controlling this rearrangement, in particular its regioselectivity. This parameter was shown to follow the rules proposed before from a few examples. Then, the effect of the substituents borne by the silicon itself, in particular the selectivity of the ligand transfer, was studied. Additionally, this chemistry was extended to germylated substrates. A hypervalent germanium species, comparable to the putative intermediate proposed with silicon, seems to be involved. However, a pathway implicating the elimination of LiCH₂Cl was observed for the first time with this element, leading to unexpected products of the benzo‐oxa (or benzo‐aza) germol‐type.     

Reaction of 1,2,3-Selenadiazoles with Phosphines

Nucleophilic attack of tributyl- and triphenylphosphines on 4-phenyl- and 5-ethoxycarbonyl-4-methyl-1,2,3-selenadiazoles leads to the quantitative formation of selenophosphoranes and substituted acetylenes. The molecular structure of 4-phenyl-1,2,3-selenadiazole was confirmed by X-ray crystallography.     

Synthesis and Structure of Tetraethynylsilane and Its Silylated Derivatives

The known tetrakis((trimethylsilyl)ethynyl)silane was prepared and deprotected. By using trifluoromethanesulfonic acid, the smooth stepwise desilylation of the starting material was achieved, and all of the partially protected and the fully deprotected species were isolated by sublimation. Crystal structures of all of the partially and the fully deprotected species were obtained. None of the compounds is thermally sensitive. Attempts to explosively decompose these species upon heating failed.     

Binaphthyl-Substituted Chiral Phosphines and Oxides from Binaphthophooles and Nucleophiles

Binaphthophospholes 1 are the starting compounds for the synthesis of chiral phosphine oxides 3 or phosphines 4 via reaction of phospholium salts 2 with nucleophiles. The binaphthyl residue acts as a stereochemical probe for monitoring the integrity of the phosphorus stereocenter.