P(Cl)(Cl)(Cl)=O.[CH3:6][C:7]1[CH:15]=[C:10]2[CH:11]=[CH:12][CH:13]=[CH:14][N:9]2[N:8]=1.[C:16](=O)([O-])[O-:17].[K+].[K+]>CN(C)C=O>[CH:16]([C:15]1[C:7]([CH3:6])=[N:8][N:9]2[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=12)=[O:17]To 116.6 ml of dimethylformamide was added 105 ml of phosphorus oxychloride, followed by 99 g of 2-methylpyrazolo[1,5-a]pyridine under stirring at keeping the temperature below 20° C. The reaction mixture was stirred at 50°-60° C. for 1 hours, then poured into ice water. Acidic aqueous solution was neutralized with potassium carbonate, then extracted with dichloromethane, washed with salt water, dried over anhydrous sodium sulfate and then concentrated. The resulting residue was recrystallized from methanol to give the title compound in a yield of 54.8 g (46%) as colorless crystals, mp 77°-79° C.
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