反应详情

温度

0 °C

A solution of NaNO2 (110.4 g, 1.6 mol, 8 eq) in water (200 mL) was added dropwise to a solution of 5-bromoindole (IX) (39.2 g, 0.2 mol, 1 eq) in acetone (1000 mL) stirred at −10→0° C., while adding NaNO2 the solution temperature was maintained below 20° C. An aqueous 2N HCl solution (480 mL) was added slowly to the solution with vigorously stirring while keeping the internal temperature between 0 and 20° C. The solution was further stirred at 20° C. for 3 h after the addition. The solution was concentrated under reduced pressure to remove acetone while keeping the temperature below 35° C. The solid was collected by filtration and transferred to a flask. Cold (−10° C.) DCM (200 mL) was added and stirred for 30 min at −5° C., the solids were filtered and dried under vacuum at 40° C. to get 5-bromo-1H-indazole-3-carbaldehyde (X) (34.0 g, 151 mmol, 76% yield) as a brown solid. ESIMS found for C8H5BrN2O m/z 225 (M+H).

1. temperaturewas maintained below 20° C
2. stirringwith vigorously stirring
3. customthe internal temperature between 0 and 20° C
4. stirringThe solution was further stirred at 20° C. for 3 h
5. additionafter the addition
6. concentrationThe solution was concentrated under reduced pressure
7. customto remove acetone
8. customthe temperature below 35° C
9. filtrationThe solid was collected by filtration
10. customtransferred to a flask
11. additionCold (−10° C.) DCM (200 mL) was added
12. stirringstirred for 30 min at −5° C.
13. filtrationthe solids were filtered
14. customdried under vacuum at 40° C.