[CH2:1]([C:3]1[CH:8]=[CH:7][N:6]2[N:9]=[CH:10][CH:11]=[C:5]2[CH:4]=1)[CH3:2].C1C(=O)N([Br:19])C(=O)C1.O>ClCCl>[Br:19][C:11]1[CH:10]=[N:9][N:6]2[CH:7]=[CH:8][C:3]([CH2:1][CH3:2])=[CH:4][C:5]=12To a stirred solution of 5-ethylpyrazolo[1,5-a]pyridine (1.1 g, 0.008 mmol) in dichloromethane (10 mL) at 0° C. was added NBS (1.75 g, 0.009 mmol) and reaction mixture was stirred at room temperature for 5 min. Subsequently, water was added and the reaction mixture was extracted with dichloromethane (2×10 mL). The organic layer was washed with water (1×30 mL), sat. NaHCO3 solution (1×10 mL), brine (1×10 mL), dried over Na2SO4 and concentrated to afford 2.1 g (84%) of 3-bromo-5-ethylpyrazolo[1,5-a]pyridine (I-17) as a brownish highly viscous liquid. The crude was progressed to next step without any further purification. ESI-LC/MS (m/z): [M+H]+ 225.0, [(M+2)+H]+227.0, RT 2.50 min.
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