Acetic Anhydride → 7-(2,4-dichloro-phenyl)-1H-pyrazolo[3,4-c]pyridine

To a mixture of N-[2-(2,4-dichloro-phenyl)-4-methyl-pyridin-3-yl]-acetamide (30; 0.787 g, 2.67 mmol), 30 mL of benzene, acetic anhydride (0.780 mL, 8.27 mmol), and potassium acetate (0.330 g, 3.36 mmol) at 78° C. was added isoamyl nitrite (0.572 mL, 4.27 mmol), and the yellow mixture was stirred for 22 h. After cooling, the mixture was filtered and concentrated to an orange oil. To the oil was added 21 mL of ethanol, 7 mL of water, and lithium hydroxide monohydrate (0.339 g, 8.80 mmol). The orange mixture was stirred for 3 h, then concentrated to remove ethanol. The orange residue was partitioned between 50 mL of diethyl ether and 50 mL of a 10% aqueous NaOH solution, and the aqueous layer was extracted with 50 mL of diethyl ether. The combined organic layers were washed with 100 mL of a saturated aqueous NaCl solution, dried over MgSO4, filtered, loaded onto silica gel and concentrated. Column chromatography (0→20% EtOAc/hexanes) afforded of 7-(2,4-dichloro-phenyl)-1H-pyrazolo[3,4-c]pyridine (31; 0.484 g; 67%) as a foamy pale yellow solid.

1. temperatureAfter cooling
2. filtrationthe mixture was filtered
3. concentrationconcentrated to an orange oil
4. stirringThe orange mixture was stirred for 3 h
5. concentrationconcentrated
6. customto remove ethanol
7. customThe orange residue was partitioned between 50 mL of diethyl ether and 50 mL of a 10% aqueous NaOH solution
8. extractionthe aqueous layer was extracted with 50 mL of diethyl ether
9. washThe combined organic layers were washed with 100 mL of a saturated aqueous NaCl solution
10. dry with materialdried over MgSO4
11. filtrationfiltered
12. concentrationconcentrated

ORD record

ord-0edab7bcbfbc462e9edcc05eb5f305f9

Source dataset

uspto-grants-2008_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07365211B2