Hydrazine → 4-chloro-1H-pyrazolo[4,3-c]pyridine

To a mixture of 2-chloro-4-iodonicotinaldehyde (1.0 g, 3.7 mmol) in ethanol (6.0 mL) was added 3.0 mL of hydrazine (excess). The mixture was stirred at room temperature for 15 h and then concentrated under reduced pressure. The residue was diluted with water (30 mL) and extracted with dichloromethane (300 mL). The organic extract was washed with brine, dried over Na2SO4, and concentrated under reduced pressure. The residue was dissolved in dichloromethane (5 mL) and stirred for 5 min. The precipitated solid was isolated by filtration and dried to give the desired intermediate 4-chloro-1H-pyrazolo[4,3-c]pyridine as a grey solid (110 mg, 19% yield), which was used in the next step without further purification. LCMS(ESI) m/z: 154.1 [M+H+]

1. concentrationconcentrated under reduced pressure
2. additionThe residue was diluted with water (30 mL)
3. extractionextracted with dichloromethane (300 mL)
4. extractionThe organic extract
5. washwas washed with brine
6. dry with materialdried over Na2SO4
7. concentrationconcentrated under reduced pressure
8. dissolutionThe residue was dissolved in dichloromethane (5 mL)
9. stirringstirred for 5 min
10. customThe precipitated solid was isolated by filtration
11. customdried

ORD record

ord-4e1bbcaa759743a2b6f22608896a7d7d

Source dataset

uspto-grants-2016_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09309240B2