Synthesis
The general procedure for synthesizing 3-methyl-2-(tributyltin)pyridine from tributyltin chloride was as follows: with reference to Example 195, 2-bromo-3-methylpyridine (1.0 g) was dissolved in tetrahydrofuran (10 mL) and cooled to -70°C. At this temperature, a hexane solution of 1.6 mol/L n-butyllithium (4.0 mL) was slowly added dropwise. After keeping the reaction at -70°C and stirring for 15 minutes, tributyltin chloride (2.2 g) was slowly added. Stirring was continued at the same temperature for 1 hour. After completion of the reaction, water was added to the reaction mixture and extracted with ethyl acetate. The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent. The resulting crude product was purified by silica gel column chromatography with hexane-ethyl acetate (19:1, v/v) as eluent to afford the target compound 3-methyl-2-(tributylstannyl)pyridine (1.75 g, 79% yield) in colorless oily form. The structure of the product was confirmed by 1H-NMR (CDCl3), δ: 0.85-0.95 (9H, m), 1.11-1.17 (6H, m), 1.29-1.37 (6H, m), 1.49-1.57 (6H, m), 2.36 (3H, s), 6.99-7.03 (1H, m), 7.31-7.34 (1H, m). 8.52-8.54 (1H, m).
