[Cl:1][C:2]1[N:7]=[C:6]([CH2:8][C:9]([C:12]2[O:13][CH:14]=[CH:15][C:16]=2[CH3:17])=[N:10]O)[CH:5]=[CH:4][CH:3]=1.FC(F)(F)C(OC(=O)C(F)(F)F)=O.C(N(CC)CC)C>COCCOC.[Fe](Cl)Cl>[Cl:1][C:2]1[N:7]2[N:10]=[C:9]([C:12]3[O:13][CH:14]=[CH:15][C:16]=3[CH3:17])[CH:8]=[C:6]2[CH:5]=[CH:4][CH:3]=1
To a solution of 2-(6-chloro-2-pyridinyl)-1-(3-methyl-2-furyl)ethanone oxime (24.5 g, 97.7 mmol) in 1,2-dimethoxyethane (200 mL) at 0° C. was added trifluoroacetic anhydride (14.5 mL, 103 mmol), while keeping the temperature below 10° C. After the addition was complete, the reaction was warmed to 15° C. The solution was then cooled to 0–5° C. and a solution of triethylamine (28.6 mL, 205 mmol) in 1,2-dimethoxyethane (30 mL) was added over 0.5 hours. The reaction mixture was allowed to warm to room temperature and was stirred for 2 hours. To this mixture was added iron(II) chloride (0.62 g, 4.9 mmol) and the reaction was heated at 75° C. for 15 hours. The reaction was concentrated, then ethyl acetate and water were added. The organic phase was separated, washed with water, dried (magnesium sulfate), filtered and concentrated. Purification by silica gel chromatography (9:1 hexanes:ethyl acetate) gave 7-chloro-2-(3-methyl-2-furyl)pyrazolo[1,5-a]pyridine (14.6 g, 640%) as yellow oil. 1H NMR (CDCl3): δ 7.52 (d, 1H), 7.48 (d, 1H), 7.10 (t, 1H), 6.92 (d, 1H), 6.86 (s, 1H), 6.42 (d, 1H), 2.49 (s, 3H). MS m/233 (M+1).
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