[Synthesis]
GENERAL STEPS: 2-chloro-3-iodopyridine (2.39 g, 9.98 mmol), cyclopropylboronic acid (860 mg, 10 mmol) and potassium carbonate (4.14 g, 30.0 mmol) were suspended in 1,4-dioxane (50 mL) under nitrogen protection. Tetrakis(triphenylphosphine)palladium(0) (1.16 g, 1.00 mmol) was subsequently added as a catalyst. The reaction mixture was stirred vigorously in an oil bath at 120°C for 4 hours. Upon completion of the reaction, the mixture was cooled to room temperature, diluted with ethyl acetate (50 mL) and filtered through a diatomaceous earth pad to remove insoluble impurities. The filtrate was concentrated under reduced pressure and the crude product obtained was purified by silica gel column chromatography (elution gradient: 10% to 30% petroleum ether solution of ethyl acetate) to give 2-chloro-3-cyclopropylpyridine as a colorless oil. Yield: 1 g (6 mmol, 60% yield). The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 8.20 (dd, J = 4.7, 1.8 Hz, 1H), 7.24-7.28 (m, 1H), 7.14 (br dd, J = 7.6, 4.8 Hz, 1H), 2.12-2.21 (m, 1H), 1.04-1.11 (m, 2H), 0.67 -0.72 (m, 2H). |