Direct synthesis of trimethyl(2-phenoxyethyl)silanes from aromatic fluorides

A direct synthesis of trimethyl(2-phenoxyethyl)silanes from the corresponding aromatic fluorides and 2-(trimethylsilyl)ethanol was developed. A variety of substituents were tolerated and a substitution reaction using 1-bromo-3-chloro-5-fluorobenzene was demonstrated.     

Synthesis and Cytotoxicity of 3-(Hetarylthio)-1-propynyl(trimethyl)silanes

We have developed a two-step method for synthesis of 3-(hetarylthio)-1-propynyl(trimethyl)silanes from thiols in a phase-transfer catalysis system HCCCH₂Br-solid K₂CO₃-18-crown-6-toluene followed by reaction with n-BuLi-Me₃SiCl in ether or THF. We have observed that 3-[1,3-bis(trimethylsilyl)-2-propynyl]thioindole displays high cytotoxicity in HT-1080 and MG-22A tumor cell lines.     

Oxidative cross-coupling of allyl(trimethyl)silanes with aryl boronic acids by palladium catalysis

The first oxidative cross-coupling of allylsilanes with aryl boronic acids has been developed by palladium catalysis. The reaction between β-substituted allyl(trimethyl)silanes and a wide range of aryl boronic acids afforded allylarenes in moderate to good yields and excellent selectivity. On the basis of experimental results and literature reports, it was suggested that the reaction might start from transmetalation of aryl boronic acid with AgOAc followed by transmetalation with Pd(II) to give an arylpalladium acetate complex as a key intermediate. This intermediate underwent either electrophilic addition/desilylation or transmetalation with allylsilane and subsequent reductive elimination to give the final product.     

Silver-promoted cross-coupling of substituted allyl(trimethyl)silanes with aryl iodides by palladium catalysis

A ligand-free Pd-catalyzed cross-coupling of substituted allyl(trimethyl)silanes with aryl iodides enabled by silver salts was developed. This reaction delivered allylic arenes chemoselectively and regioselectively. The study suggested that the reaction might proceed through oxidative addition of ArI to Pd(0) followed by halide abstraction to give an electrophilic complex ArPdX, which further reacted with allyl(trimethyl)silanes via electrophilic addition/desilylation/reductive elimination to afford the allyl-aryl coupling products.     

Radical Reactions of Tricyclo[4.1.0.02,7]heptane Derivatives with Arenesulfonylethynyl(trimethyl)silanes

Russian Journal of Organic Chemistry - Photochemically or thermally initiated reactions of arenesulfonylethynyl(trimethyl)silanes ArSO2C≡CSiMe3 (Ar = Ph, 4-MeC6H4) with...     

Trimethyl(trihalomethyl)silanes as dihalomethylene transfer agents

Trimethyl(trichloromethyl)silane and trimethyl(tribromomethyl)silane react with anhydrous potassium fluoride in diglyme to give good yields of CX₂ transfer products (dihalocyclopropanes) with olefins. Catalysis by 18-crown-6 ether is observed.     

Alkoxy(acyloxy)silanes

Conclusions Alkoxychlorosilanes react with trimethylacyloxysilanes to give the difficultly accessible alkoxy(acyloxy)silanes of general formula (RO)_nSi(OCOR)_4-n (n=1–3) in 60–80% yields.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 671–674, March, 1989.     

Lewis acids as co-reagents in sulfenylation reactions

Russian Journal of Organic Chemistry -     

Titanium(IV)-catalyzed enantioselective sulfenylation of beta-ketoesters

A [Ti(TADDOLato)] complex (1) catalyzes the enantioselective sulfenylation of beta-ketoesters using phenylsulfenyl chloride, giving ees of up to 88% and yields of up to 95%. The reaction does not require the presence of a base. [reaction: see text]     

Some trimethyl phosphine and trimethyl phosphite complexes of tungsten(IV)

Direct reduction of WCl₆ with PMe₃ in toluene at 120°C in a sealed tube affords the complexes [WCl₄(PMe₃)_x] (x = 2, 3). [WCl₄(PMe₃)₃] abstracts oxygen from equimolar amounts of water in wet acetone or tetrahydrofuran to give [WOCl₂(PMe₃)₃] in very high yields. This procedure has been successfully applied to the high yield synthesis of other known oxotungsten(IV) complexes, [WOCl₂(PR₃)₃] (PR₃ = PMe₂Ph and PMePh₂). Metathesis reactions of [WOCl₂(PMe₃)₃] with NaX give [WOX₂(PMe₃)₃] (X = NCO, NCS) and [WOX₂(PMe₃)] (X = Me₂NCS₂). The synthesis of the trimethylphosphite analogue, [WOCl₂(P(OMe)₃)₃], is also described and the structures of the new complexes assigned on the basis of IR and ¹H and ³¹P NMR spectroscopy.     

Synthesis of (diorgano)chloro(4-chlorobutoxy)silanes

Some novel (diorgano)chloro(4-chlorobutoxy)silanes were obtained by the reaction of dichlorodiorganosilanes with tetra hydrofuran in the presence of chloroplatinic acid.Translated fromIzvestiva Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 943–945, April, 1996.     

Ti(IV)-catalyzed asymmetric sulfenylation of 1,3-dicarbonyl compounds

The electrophilic enantioselective sulfenylation of 1,3-dicarbonyl compounds with phenylsulfenyl chloride is effectively catalyzed by [Ti(TADDOLato)] complexes. The corresponding products are obtained in moderate to high yields. The highest ee values (up to 97 %) are obtained in toluene at room temperature and with a typical catalyst loading of 5 mol %. Bulky ester groups and sterically undemanding substituents at the alpha-position were found to be crucial structural features of the starting materials in order to assure high enantioselectivity. The absolute configuration of one of the chiral products has been determined. The stereochemical course of the reaction is similar to that of analogous [Ti(TADDOLato)]-catalyzed atom-transfer reactions. A common side-reaction the sulfenylated products undergo is a deacylation leading to racemic alpha-sulfenylated esters.     

NaY zeolite as host for the selective heterogeneous oxidation of silanes and olefins with hydrogen peroxide catalyzed by methyltrioxorhenium

The methyltrioxorhenium(MTO)-catalyzed oxidation of silanes to silanols and the epoxidation of various olefins by aqueous 85% H(2)O(2) proceed in high yields and excellent product selectivities (no disiloxanes, diols) in the presence of the zeolite NaY. The oxidative species is located inside the 12-A supercages. This prevents the bimolecular condensation of the silanol to disiloxane by steric means and the Lewis-acid assisted hydrolysis of the epoxide to the diol.     

Poly(guanidyl)silanes as a new class of chelating, N-based ligand

The series of poly(guanidyl)silanes RnSi[hpp](4-n) [hpp = 1,3,4,6,7,8-hexahydro-2Hpyrimido[1,2-a]pyrimidinate; R = Me, n= 1, 2; R = Ph, n= 1] have been synthesised and their coordination behaviour at copper(I) halides investigated.     

Hexakis(trimethylsilylmethyl)ditungsten as catalyst for metathesis reactions of olefins

Conclusions W₂[CH₂Si(CH₃)₃]₆ initiates the polymerization of cyclic olefins, and in combination with WCl₆ is active in the metathesis of both linear and cyclic olefins.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1403–1404, June, 1979.