(Dibromomethyl)trimethylsilane

bp 49.5–51.5°C/12 mmHg; d 1.519 g cm?3.

Reaction of (dibromomethyl)- trimethylsilane with n-butyllithium at ?110°C results in the formation of trimethylsilylbromomethyllithium. The silane and the n-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(trimethylsilylbromomethyl) mercury, respectively. If the lithium reagent is allowed to warm in the presence of cyclohexene, the only reaction observed is an alkylation with the n-butyl bromide formed in the exchange reaction. The alkylated product is formed in 89% yield.

to a dry, 1.0 L three-neck flask, equipped with a mechanical stirrer, a pentane thermometer, a nitrogen inlet tube, and a pressure-equalizing addition funnel, was added 62.0 g (0.245 mol) of bromoform and 300 mL of dry THF. The reaction was cooled to ?90°C and 0.25 mol of isopropylmagnesium chloride in 200 mL of THF was added during 30 min at such a rate that the temperature was kept at ?80°C or below. The reaction was stirred at ?90°C for 15 min and then 0.25 mol of chlorotrimethylsilane in 100 mL of THF was added at such a rate that the temperature did not exceed?80°C. After 1 h, the reaction was allowed to warm to rt. The reaction mixture was hydrolyzed with saturated NH4Cl solution until large lumps of salt cake formed. The organic layer was poured off, dried over anhydrous Na2SO4, and distilled at atmospheric pressure to remove most of the THF. A trap-to-trap distillation of the residue at 0.1 mmHg was followed by distillation through an 11 in. Vigreux column. The fraction boiling at 49.5–51.5°C/12 mmHg was collected, affording 47.9 g (79%) of (dibromomethyl)trimethylsilane.