Chlorotrimethylsilane-Lithium bromide

ALKYL BROMIDES Bromine. Bromo-triniethylsilane. Chlorotrimethylsilane-Lithium bromide. 

The synthesis of 2-trimethylsilyoxy-l,3-butadiene by treatment of methyl vinyl ketone with chlorotrimethylsilane, lithium bromide and triethylamine in tetrahydrofuran was discussed in section 12.5.6. It was discussed how the stoichiometry of the reaction was determined by canonical analysis of the response surface model, and how this analysis made it possible to establish experimental conditions which afforded a quantitative conversion. However, before the response surface model could be established it was necessary to find a reaction system worth optimizing. 

Chlorotrimethylsilane (2.7 g, 25 mmol) (1) (CAUTION) is added to a solution of lithium bromide (1.74g, 20 mmol) in dry acetonitrile (20 ml) (2) with good stirring under a nitrogen atmosphere. Cinnamyl alcohol (1.34 g, 10 mmol) is then added and the reaction mixture heated under reflux for 12 hours. The progress of the reaction is monitored by t.l.c. on silica gel plates with hexane as the eluant. On completion of the reaction (12 hours), the reaction mixture is taken up in ether (50 ml), washed successively with water (2 x 25 ml), sodium hydrogen carbonate solution (10%, 50 ml) and finally brine, and dried over anhydrous sodium sulphate. Evaporation of the ether affords the pure bromide in 93 per cent yield. The product may be recrystallised from ethanol and has m.p. 31-32 °C CAUTION this compound is lachrymatory. 

It was found that methyl vinyl ketone could be converted into 2-trimethylsilyl-1,3-butadiene by reaction with chlorotrimethylsilane (TMSC1) in the presence of triethylamie (TEA) and lithium bromide in tetrahydrofuran solution [33]. 

A screening experiment with different types of electrophilic additives showed that a promising procedure for future development was to treat methyl vinyl ketone (MVK) with chlorotrimethylsilane (TMSCl) in the presence of triethylamine (TEA) and lithium bromide in tetrahydrofuran. 

Chlorotrimethylsilane Silane, chlorotrimethyl- (8,9) (75-77>4) Tetrachlorosilane Silicon chloride (8) Silane, tetrachloro- (9) (10026-04-7) Methyllithium-lithium bromide complex Lithium, methyl- (8,9) (917-54-4)... 

In many, but not all, cases iodotrimethylsilane can be replaced by chlorotrimethylsilane plus sodium iodide without changing the course of the reaction. Bromotrimethylsilane and chlorotrimethylsilane plus sodium bromide gave rise to the formation of y-bromides, chlorotrimethylsilane plus lithium chloride yielded y-chlorides. The cyanide ion could not substitute the halides in these reactions. When 1-acetyl-2,2-dimethylcyclopropane (3) was... 

Lithium-Halogen Exchange. Reaction of (dibromomethyl)-trimethylsilane with n-butyllithium at — 110°C results in the formation of trimethylsilylbromomethyllithium. The silane and the -BuLi are added simultaneously in order to suppress side reactions. Treatment of the intermediate lithium reagent with chlorotrimethylsilane (eq 1) or mercury(II) bromide (eq 2) affords bis(trimethylsilyl)bromomethane or bis(trimethylsilyl-bromDmethyl)mercury, respectively. If the lithium reagent is... 

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