Water → 7-Chloro-2-(4-methoxyphenyl)pyrazolo[1,5-A]pyridine

Temperature

15 °C

To a solution of 2-(6-chloro-2-pyridinyl)-1-(4-methoxyphenyl)ethanone oxime (38.7 g, 140 mmol) in 1,2-dimethoxyethane (150 mL) at 0° C. was added trifluoroacetic anhydride (20 mL 140 mmol), keeping the temperature below 10° C. during the addition. After the addition was complete, the reaction was warmed to 15° C. The solution was then cooled to 4° C. and a solution of triethylamine (39 mL, 280 mmol) in 1,2-dimethoxyethane (15 mL) was added over a period of 0.5 hours. The mixture was allowed to warm to room temperature and was stirred at room temperature for 1.5 hours. To this mixture was added iron(II) chloride (0.18 g, 1.4 mmol) and the reaction was heated at 75° C. for 15 hours. The reaction mixture was poured into water (300 mL). The resulting suspension was extracted with ethyl acetate. The organic phase was dried (magnesium sulfate), filtered and concentrated to a solid. This solid was recrystallized from methanol to give 7-chloro-2-(4-methoxyphenyl)pyrazolo[1,5-α]pyridine (18.7 g, 52%) as pale yellow needles. 1H NMR (CDCl3): δ 7.91 (d, 2H), 7.43 (d, 1H), 7.01 (t,1H), 6.95 (d, 2H), 6.81 (d, 1H), 6.80 (s, 1H), 3.83 (s, 3H); MS m/z 259 (M+1).

1. customthe temperature below 10° C.
2. additionduring the addition
3. additionAfter the addition
4. temperatureThe solution was then cooled to 4° C.
5. temperatureto warm to room temperature
6. temperaturethe reaction was heated at 75° C. for 15 hours
7. extractionThe resulting suspension was extracted with ethyl acetate
8. dry with materialThe organic phase was dried (magnesium sulfate)
9. filtrationfiltered
10. concentrationconcentrated to a solid
11. customThis solid was recrystallized from methanol

ORD record

ord-b86e4e9e8cda43fe90f56cc4905fd7e5

Source dataset

uspto-grants-2007_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07160897B2