1-(Pyridin-3-yl)-4,5-dihydro-1H-pyrazol-3-amine → 1-(Pyridin-3-yl)-1H-pyrazol-3-amine

Temperature

60 °C

To a 3-neck, round bottomed flask (100 mL) was charged 1-(pyridin-3-yl)-4,5-dihydro-1H-pyrazol-3-amine (1.00 g, 6.17 mmol) and acetonitrile (20 mL). Manganese(IV) oxide (2.68 g, 30.8 mmol) was added, causing an exotherm from 20° C. to 25° C. The reaction was stirred at 60° C. for 18 hours, after which it was filtered through a Celite® pad and the pad was rinsed with acetonitrile (20 mL). Water (20 mL) was added to the combined filtrates and the resulting mixture was concentrated to 10 mL. Water (20 mL) was added and the resulting mixture was again concentrated to 10 mL. The resulting suspension was stirred at 20° C. for 18 hours and filtered. The filter cake was rinsed with water (2×5 mL) and dried to afford the title compound as a brown solid (0.68 g, 69%): mp 169-172° C.; 1H NMR (400 MHz, DMSO-d6) δ 9.07-8.82 (m, 1H), 8.33 (dd, J=4.6, 1.5 Hz, 1H), 8.24 (d, J=2.6 Hz, 1H), 8.00 (ddd, J=8.4, 2.7, 1.4 Hz, 1H), 7.42 (ddd, J=8.5, 4.6, 0.8 Hz, 1H), 5.80 (d, J=2.6 Hz, 1H), 5.21 (s, 2H); 13C NMR (101 MHz, DMSO-d6) δ 157.67, 144.68, 138.00, 136.22, 128.30, 123.95, 123.17, 97.08; ESIMS m/z 161 ([M+H]+).

1. customfrom 20° C. to 25° C
2. filtrationafter which it was filtered through a Celite® pad
3. washthe pad was rinsed with acetonitrile (20 mL)
4. additionWater (20 mL) was added to the combined filtrates
5. concentrationthe resulting mixture was concentrated to 10 mL
6. additionWater (20 mL) was added
7. concentrationthe resulting mixture was again concentrated to 10 mL
8. stirringThe resulting suspension was stirred at 20° C. for 18 hours
9. filtrationfiltered
10. washThe filter cake was rinsed with water (2×5 mL)
11. customdried

ORD record

ord-791cd723be90469fa70e9eff9fea8911

Source dataset

uspto-grants-2015_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09199964B1