Hydrazine → 5-Chloro-1H-pyrazolo[3,4-b]pyridine

Temperature

65 °C

To a solution of 5-chloro-2-fluoro-3-(4,4,5,5-tetramethyl-1,3-dioxolan-2-yl)pyridine, 28, (14.5 g, 55.8 mmol) and N,N-diisopropylethylamine (19.5 mL, 112.0 mmol) in isopropanol (200 mL) was added hydrazine (12.0 mL, 382.3 mmol). The mixture was heated to 65° C. overnight. LC-MS indicates desired hydrazine compound formed and the mixture was concentrated in vacuo. The crude residue was taken up in 300 mL of water and 120 mL of EtOH followed by 50 mL of 6N HCl. The resulting mixture was warmed to 45° C. overnight. Once LC-MS indicated completion of the reaction, the mixture was neutralized with 6N NaOH and the pH adjusted to 8. The mixture was concentrated in vacuo to remove volatile EtOH and extracted with EtOAc (3×). The combined organic layer was dried over Na2SO4, filtered through a plug of silica and concentrated in vacuo. Trituration with 10% aqueous acetonitrile provided the desired product (6.15 g, 72% yield, 90% purity by NMR): 1H NMR (300.0 MHz, CDCl3) δ 11.43 (s, 1H), 8.55 (d, J=2.2 Hz, 1H), 8.10 (d, J=2.2 Hz, 1H) and 8.08 (s, 1H) ppm; LC/MS Gradient 10-90%, 0.1% formic 5 min, C18/ACN, RT=2.05 min (M+H) 153.91.

1. customformed
2. concentrationthe mixture was concentrated in vacuo
3. temperatureThe resulting mixture was warmed to 45° C. overnight
4. customcompletion of the reaction
5. concentrationThe mixture was concentrated in vacuo
6. customto remove volatile EtOH
7. extractionextracted with EtOAc (3×)
8. dry with materialThe combined organic layer was dried over Na2SO4
9. filtrationfiltered through a plug of silica
10. concentrationconcentrated in vacuo

ORD record

ord-6d8c40a8032b4c3797a77ec2405410ee

Source dataset

uspto-grants-2014_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08871774B2