Bromovinyl trimethylsilane

InChl = 1S/C5H1 lBrSi/cl-5(6)7(2,3)4/hlH2,2-4H3 InChIKey = VVDJVCJVVHHCIB-UHFFFAOYSA-N 

Alternate Names l-(trimethylsilyl)vinyl bromide 1-bromo-l-(tiimethylsilyl)ethylene. 

Physical Data bp 124 °Cy745 mmHg d 1.156 g cm. Solubility completely miscible with THF and Et20. 

Analysis of Reagent Purity H and NMR can be used. Preparative Methods prepared, in good yield, from the reaction of vinyltrimethylsilane with bromine at low temperature followed by dehydrohalogenation in the presence of an amine base. Alternative s)mtheses and reagents, i.e. (1-bromovinyl)-triphenylsilane and (l-bromovinyl)tiiethylsilane, are also known. 

Vinyltrimethylsilane Metal. l-TrimethylsUylvinyl metal species are mostly used as acyl anion equivalents and as hindered vinyl anion substitutes. l-(trimethylsilyl)vinyllithium is easily accessible from (l-bromovinyl)trimethylsilane by treatment with n-butyllithium at —78°C in ether (eq 1). Other solvents and alkyllithiums can also be used for the metal-halogen exchange. The use of (l-chlorovinyl)trimethylsilane or the direct reaction of (l-bromovinyl)trimethylsilane with lithium metal are not proper methods for generating the lithium species.  

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CYCLOPENTENONES Aluminum chloride. 2-(Bromovinyl)trimethylsilane. Di-fjL-carbonylhexacarbonyldicobalt. lodotrimethylsilane. Potassium hydroxide. l-(Trimethylsilyl)-l-(phenylthio)ethylene. 

I-Bromo-2.2-dichloro-l-trimelhylsilylcyclopropane A suspension of (I-bromovinyl)trimethylsilane (34.9 g, 0.195 mol) and sodium trichloroacetate (36.2 g, 0.195 mol) in DMH/2-methoxyethyl ether (10 1. 25 mL) was stirred under Nj at 80-90 C until CO, evolution ceased (ca. 10 h). The resulting dark solution was cooled to 25 C and diluted with pentane (100 mL) and H O (100 mL). After stirring for 0.5 h, the mixture was filtered through glass wool and the residue washed with pentane (200 mL). The aqueous phase from... 

The (2-bromovinyl)trimethylsilane reacts with dialkyl phosphites in toluene at 50°C in the presence of catalytic amounts of PdtPPh iyht N to give Z/az .v-dialkyl 2-(trimethylsilyl)vinylphosphonates in 76-80% yields. This coupling reaction is very sensitive to the steric hindrance of the substrate. The dialkyl 2-(trimethylsilyl)vinylphosphonatcs so obtained have been used in a Diels-Alder reaction with cyclopentadiene. ... 

This reagent is prepared from (l-bromovinyl)trimethylsilane by metal-luilogcn exchange with r-butyllithium. 

Palladium-Catalyzed Reactions. Numerous nucleophiles react with (l-bromovinyl)trimethylsilane in the presence of palladium complexes. The bromine has been substituted by phenylthio, vinyl, and aryl groups. This approach gives reasonable yields of the desired products. However, the substitution reactions sometimes lack regiospecificity. For example, a mixture of regioisomers was obtained in eq 6. Two mechanisms have been proposed for the formation of the -substituted product. One involves an elimination step to give trimethylsilylacetylene as an intermediate, which then undergoes catalyzed additions with the nucleophile at either the a- or positions. The other mechanism involves the formation of a pentacoordinated palladium intermediate, leading to the formation of isomeric products. ... 

Substrate for Cyclopropanation. Dichlorocar-bene adds to vinyltrimethylsilane, and the adduct is a source of 1-chlorocyclopropene, a reactive dienophile for Diels-Alder reactions. Dichlorocarbene also reacts with (l-bromovinyl)trimethylsilane to form (l-bromo-2-dichlorocyclopropyl)trimethylsilane. 8-Elimination in the presence of tetra-n-butylammonium fluoride gives l-bromo-2-chlorocyclopropene, another reactive dienophile (eq 7). 

Preparative Methods prepared by the reaction of [E)-2-(trimethylsilyl)vinyllithium with methyl chloroformate or by carbonation of the corresponding Grignard reagent prepared from (l-bromovinyl)trimethylsilane, giving 2-trimethyl-silylacrylic acid. The methyl ester is prepared from the acid by direct esterification with absolute methanol in the presence of mineral acid, by reaction with diazomethane at low temperature, or by treatment with BF3-MeOH complex. For preparation of various trialkylsilylacrylic acid esters and f-butyl 2-trimethylsilylcrotonate, see the cited references. 

Preparative Methods attempts to produce synthetically useful quantities of ( )-2-(trimethylsilyl)vinyllithium (1) by reaction of lithium metal with (2-bromovinyl)trimethylsilane (2) failed because of concomitant metalation-elimination processes involving (1) and ) However, the transmetalation process between (2) and excess f-butyllithium has been effectively used to provide (1) (eq 1). An alternative route to (1) employs the transmetalation of a l-(trimethylsilyl)-2-stannylethylene with organolithium reagents (eqs 2 and 3). ... 

Related Reagents. (2-Bromovinyl)trimethylsilane Lithio-2-tributylstannylethylene ( )- l-Tri- -butylstannyl-2-trimethylsilylethylene. 

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