Hydrochloric Acid → 6-chloro-1H-indazole

Temperature

0 °C

A slurry of 5-chloro-2-methylaniline (1-1, 30 g, 0.21 mol) in water (200 mL) was treated with HCl (12N, 53 mL, 0.64 mol). The resulting solution was cooled to 0° C. and reacted with aqueous solution of sodium nitrite (14.6 g, 0.21 mol). After 30 min. stirring, any insoluble particles were removed by filtration and the filtrate solution was treated at 0° C. with sodium tetrafluoroborate dissolved in water (150 mL). Precipitates so formed was collected by filtration, washed with ice-cold water, cold methanol and then with ethylether. The product (1-2) was dried in vacuo and then suspended in chloroform (500 mL) in the presence of potassium acetate (34 g, 0.35 mol) and 18-crown-6 (2.29 g, 8.67 mmol). The reaction mixture was stirred at the ambient temperature for 1.5 h, partitioned between ethyl acetate and water. The organic layer was washed with brine, separated, dried (MgSO4) and concentrated in vacuo. Trituation with dichloromethane and hexanes afforded the desired product as an orange powder (1-3); 1H NMR (400 MHz, DMSO-d6) δ 13.18 (bs, 1H), 8.11 (s, 1H), 7.79 (d, 1H, J=8.7 Hz), 7.62 (s, 1H), 7.13 (dd, 1H, J=7.9, 1.9 Hz).

1. customany insoluble particles were removed by filtration
2. additionthe filtrate solution was treated at 0° C. with sodium tetrafluoroborate
3. dissolutiondissolved in water (150 mL)
4. customPrecipitates so
5. customformed
6. filtrationwas collected by filtration
7. washwashed with ice-cold water, cold methanol
8. dry with materialThe product (1-2) was dried in vacuo
9. stirringThe reaction mixture was stirred at the ambient temperature for 1.5 h
10. custompartitioned between ethyl acetate and water
11. washThe organic layer was washed with brine
12. customseparated
13. dry with materialdried (MgSO4)
14. concentrationconcentrated in vacuo

ORD record

ord-f880cd936f4341ef95ae97d2d06c9203

Source dataset

uspto-grants-2006_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07101884B2