3-Bromopyridine → 3-(Trimethylstannyl)pyridine

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Reaction Conditions

Reaction Steps

To a reaction vessel equipped with a mechanically driven agitator, water-cooled condenser, addition funnel, thermometer, and nitrogen inlet was added a solution containing 17.1 g. (0.108 mole) of 3-bromopyridine in 150 cc. of anhydrous ether. The solution was cooled to -50° C. using a dry ice-acetone bath. By a dropwise addition, 40 cc. (0.108 mole) of n-butyllithium in n-hexane was added over 14 minutes. The resulting yellow-orange solution was stirred for an additional 60 minutes. A solution containing 17.9 g. (0.09 mole) of trimethyltin chloride in 150 cc. of anhydrous benzene was added over 40 minutes, followed by a 75 minute stirring period. The dark orange solution was warmed to room temperature and stirred 18 hours before being hydrolyzed with a saturated aqueous solution of ammonium chloride. The aqueous phase was separated from the organic phase and washed with 200 cc. of ether. The organic portions were combined, dried over a quantity of anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. A dark red liquid (16.2 g.) was isolated and distilled under reduced pressure (0.1-0.2 mm.). A clear, colorless liquid fraction boiling at 50°-60° C. was collected and redistilled (6.5 mm.). The fraction boiling at 100°-103° C. was collected and analyzed. The tin content was found to be 48.89%. The calculated tin content for trimethyl-3-pyridyltin is 49.07%. Gas chromatographic analysis indicated a purity of 98% and the refractive index was recorded as 1.5399 at 25° C. The nuclear magnetic resonance spectrum contained a singlet at 0.33 ppm. (CH3 --Sn, 9H's), a complex multiplet centered at 7.2 ppm. (β-pyridyl H, 1H), a doublet of triplets at 7.75 ppm. (γ-pyridyl H, 1H), a doublet of doublets at 8.52 ppm. (γ-pyridyl H on 6 carbon, 1H), and a doublet at 8.65 ppm. (γ-pyridyl H on 2 carbon, 1H) in agreement with the expected structure.

Provenance & Evidence