Chloro compounds silanes

Jones and coworkers developed a new method of generating silenes based on the addition-elimination reaction. Addition of t-BuLi to an appropriately substituted chloro(vinyl)silane produces a neopentyl-substituted silene67,68. Among many reactions, it has been shown that the transient silene adds to anthracene to afford stereoisomers, 40a and 40b, as isolable compounds (Scheme 11). Fractional crystallization of the adduct 40 from hexane gave pure 40a, leaving a 69/31 mixture of 40a and 40b. 

Tris(dimethylphenylsilyl)silane originates from me2SiLi and ClsSiH183. The tertiary Si-H group in these substances has been investigated in detail (UV, IR, NMR) and was found very reactive and slightly oxidizable. The chloro compound initially formed undergoes further reactions ... 

A solution of compound 182 (55.3 mg, 0.13 mmol) [Eq. (13)], (bromomethyl)chloro dimethyl silane (23 p,L, 0.17 mmol), and triethylamine (35 p,L, 0.26 mmol) in 1 mL of dry CH Clj was stirred for 3 h at room temperature, and then the solvent was evaporated under reduced pressure. The residue was rapidly eluted from a column of basic silica gel (hexane-EtOAc, 3 1) to afford an unstable syrup. This silyl ether was dissolved under argon in 2 mL of dry degased benzene. This solution was heated under reflux, and a solution of tributyltin hydride (56 mg, 0.2 mmol) and AIBN (2%) in 1 mL of benzene was added dropwise over 1 h. The heating was continued for 3 h, and benzene was evaporated. Methanol (0.2 mL), THE (0.2 mL), 30% HjOj (0.3 mL), and NajCOj (16 mg) were added to the residue. The mixture was refluxed for 4 h. Evaporation and column chromatography (hexanes-EtOAc, 1 1) gave the diol 60 (40 mg, 71%) as a gum [a]j, —12° (c 1, CHCI3). 

Neu5 Ac-o2Me methyl ester 3a is the starting product. Compound 3a has been selectively sUylated with r-butyl-chloro-dimethyl-silane in pyridine and... 

Summary The synthesis of the first silicon complexes with the tridentate diketoamine HN[CH2C(rBu)=0]2 (1) is described. The reaction of YSiXs (X = Cl, Br Y = H, Cl, Br, Ph, Vinyl) with 5-aza-2,2,8,8-tetramethylnonane-3,7-dione (1) in the presence of NEtj as an auxiliary base furnished the unusual dinuclear silicon complexes (6-11) having pentacoordinate silicon centers. Theoretical calculations (B3LYP/6-31G ) carried out for the monomeric chloro-substituted silane 7A are consistent with a folded structure and a relatively short and highly polarized Si-N bond (1.742 A Charge Si 0.96 N -0.53). The calculated value for the dimerization energy of 7A is -29 kcal/mol, reflecting the presence of a partial Si-N it-bond. Thus, the novel dimeric silicon compound 7 is the result of a head-to-tail dimerization of formally two Si=N bonds in 7A. 

Oxygenated Silanes. Controlled introduction of oxygen substituents onto silicon is an interesting special case, since several syntheses are possible. For mono-oxygenated compounds, one can simply react a chloro-(chloromethyl)silane with two equivalents of triazole and then displace the labile silicon-bound triazole with water or an alcohol. However, a better alternative in practice is to introduce first an alcohol and then triazole. In this case, the hydroxy compound can be prepared by hydrolysis of the silyl ether with aqueous acid. Scheme II outlines these options. 

Lithium 1-alkynylboronates are attacked by many electrophiles at the position P to the boron atom. The subsequent rearrangement gives a variety of functionalized 1-alkenylboronanes (eq (28)). The stereochemistry can be either " or Z, or a mixture of the two [15]. The reaction with chloro(diethyl)borane or chloro(trimethyl)silane and -stanane stereoselectively produces c /5-bimetallic compounds [41]. 

The chloro(cyclopentadienyl)silanes Cp SiH/Tb. (y = 0, 1) 1-4 and pentachloro(cyclopenta-dienyl)disilanes Cp Si2Cl5 5-8 are synthesized via metathesis reaction of the cyclopentadienyl lithium salts and trichlorosilane, tetrachlorosilane or hexachlorodisilane in THF or hexane (Scheme 1). Treatment of 1-8 with LiAlH4 leads under Cl-H exchange to the corresponding hydridosilyl 9-11 and hydridodisilanyl 12-15 compounds in good yields. 

Phenylthiomethyl)trimethylsilyl carbene (10) has been generated via two independent methods, either from the diazo compound through copper catalysis (eq 14), or from the chloro-(phenylthiomethyl)silane by base-induced o -elimination. The generation of carbene 10 was verified by [2 +1] cycloadditions with olefins affording cyclopropanes (eq 15) in low to moderate yields (12-61%). ... 

The versatility of lithium aluminum hydride permits synthesis of alkyl, alkenyl, and arylsilanes. Silanes containing functional groups, such as chloro, amino, and alkoxyl in the organic substituents, can also be prepared. Mixed compounds containing both SiCl and SiH cannot be prepared from organopolyhalosilanes using lithium aluminum hydride. Reduction is invariably complete. 

Useful stereoselective syntheses of ( )- and (Z)-2-butenyl(trifluoro)silanes have been reported. The (Z)-isomer is available by hydrosilation of butadiene, the (E)-compound being prepared by displacement of chloride from ( )-l-chloro-2-butene37. 

Among the Friedel-Crafts alkylations of aromatic compounds with (chlorinated alkyl)silanes, the alkylation of benzene with (tt>-chloroalkyl)silanes in the presence of aluminum chloride catalyst was generally affected by two factors the spacer length between the Cl and silicon and the electronic nature of substituents on the silicon atom of (w-chloroalkyl)silanes. As the spacer length between the C—Cl and silicon increases from (chloromethyl)silane to (/i-chloroethyl)silane to (/-chloropropyl)silane, the reactivity of the silanes increases. As the number of chloro-groups on the silicon decreases from (chloromethyl)trichlorosilanes to (chloromethyl)methyldichlorosilanes to (chloromethyl)trimethylsilanes, the... 

There are two gereral routes to mikto-arm star polymers. The first method makes use of the stepwise addition of living polymers to multifunctional chloro-silane compounds [59-62], The Athens group uses the sequential addition of living polymers to multifunctional chlorosilane compounds under tight stoichiometric control [63, 64],... 

The first cyclopnict(V)azane, reported by Roesky and coworkers in 1983, was the arsenic compound 33, obtained by oxidative addition of CI2 and concomitant trimethyl(chloro)-silane elimination from a bis(trimethylsilyl)amidoAs(III) precursor. Equation (10.11). Each As atom in crystalline 33 is in a trigonal bipyramidal environment (Cl and axial) there is a rhomboidal (AsN)2 core, with the As—longer than the As-Neq bonds [a feature which is replicated in the (Sb N)2 compounds 34, 35, and 36, but differs from the (M N)2 compounds of Section 10.3.1]. Thermolysis of 33 yielded the crystalline compounds [As(CF3)2(p-N)] ,. (v = 3 or 4). ... 

Adsorbed films of ethykriethoxysilane and vinyltriethoxy-silane were formed on silica and alumina by retraction from hydrocarbon solution and their wettabilities and water-stabilities determined. The vinyltriethoxysilane films were generally more oleophobic, more hydrophobic and more resistant to contact with water than the films formed by the ethyl analog. Neither adsorbate formed stable films on a-alumina. The addition of low molecular weight organic acids or bases to the adsorbate solution resulted in both the ethyl and vinyl compound forming hydrophobic and water-stable films on silica and ot-alumina. Films of p-chloro-phenyl-ft-ethyltrichloro, -trimethoxy, and -triethoxysilane were also studied and found to be water-stable and to have wettabilities characteristic of a surface comprised of closely-spaced p-chlorophenyl groups. 

Vinylchlorosilanes undergo Friedel-Crafts alkylation with aromatic compounds in the presence of Lewis acids to give 2-(chlorosilyl)ethylarenes [Eq. (17)].lb 32,33 The reactivity of vinylchlorosilanes for the alkylation of aromatic compounds is slightly lower than that of allylchlorosilanes.lb 3,32 The reactivity of vinylsilanes for alkylation depends on the substituents on the silicon of the vinylsilane. The reactivity of vinylchlorosilanes decreases in the following order dichloro(methyl)vinyl-silane > trichlorovinylsilane > chloro(dimethyl)vinylsilane. The alkylation of mono-substituted benzenes such as toluene, chlorobenzene, and biphenyl with di-chloro(methyl)vinylsilane (lc) at 75-80 °C for 2h affords alkylated products in 50-63% yields.32... 

The formation of the expected 2,4,6-trisilaalkanes 2 can be explained by the 2 1 reaction of (chloromethyl)silanes 1 and elemental silicon. The byproducts, 1,3-disilaalkanes 3, were obtained from the reaction of (chloromethyl)silane reactant 1 and hydrogen chloride (or chlorine) with the same silicon atom, as methyldichlorosilane (or methyltrichlorosilane) was obtained from the methyl chloride reaction. This result indicates that some of the (chloromethyl)silane reactant decomposed under the reaction conditions and acted as a chlorine or hydrogen chloride source. In the direct reaction of (chloromethyl)dimethylchlorosilane (lc), a significant amount of starting material was recovered at temperatures below 300 °C, but the reaction went to completion above 320 °C. 2,6-Dimethyl-2,4,4,6-tetra-chloro-2,4,6-trisilaheptane (2c) was obtained in much higher yields than 3-methyl-l,l,l,3-tetrachloro-l,3-disilabutane (3c) at reaction temperatures ranging from 280 to 320 °C, but the ratio of both compounds reversed above 340 °C. 

In the reaction using cadmium promoter, the selectivity for tris(chloro-silyl)methane 8b was the highest among the four tris(chlorosilyl)methanes 7b-10b and about 73% in the distribution of their four compounds. These are consistent with the results observed for the direct reactions of silicon with (chloromethyl)silanes,20,21 allyl chloride,27 methylene chloride,22 and chloroform.23... 

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