3-Bromopyridine → 4-Benzothiazol-2-YL-5-pyridin-3-YL-1H-pyrazol-3-ylamine

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A yellow suspension of 3-pyridinyl lithium in THF was prepared according to the literature (Cama, L. D.; Wildonger, K. J.; Guthikonda, R.; Ratcliffe, R. W.; Christensen, B. G. Tetrahedron (1983), 39, 2531) by adding n-BuLi (0.25 mL of a 2 M solution in cyclohexane, 0.5 mmol) to a solution of 3-bromopyridine (87 mg, 0.5 mmol) in anhydrous ether (3 mL) at −78° C. To this slurry was rapidly added 2-benzothiazol-2-yl-3,3-bismethylsulfanylacrylonitrile (140 mg, 0.5 mmol) in anhydrous THF (5 mL) under argon. The resulting mixture was stirred at −78° C. for 1 hour, and then slowly warmed up to room temperature and stirred at that temperature for 2 hours. Upon completion of the reaction, the mixture was poured into a saturated NH4Cl aqueous solution. The aqueous phase was extracted with ethyl acetate. The organic phase was washed with brine, dried over magnesium sulfate, filtered and evaporated. The crude material was then purified by flash chromatography eluting with CH2Cl2:MeOH=1:0-19:1 to yield 100 mg (65%) of the desired product as a brown oil. MS (m/z, ES+): 310 (M+1, 25%), 263 (M−46, 100%).

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