Sodium Carbonate → 6-hydroxy-1H-indazole

Temperature

2.5 °C

To a stirred suspension of 6-aminoindazole (20 mmol) in concentrated HCl (6 mL) at 0° C. was added a solution of NaNO2 (22 mmol) in water (12 mL) in portions. During the addition, the temperature of the reaction mixture was maintained at 0-5° C., and the stirring continued for additional 45 min. The contents were then added into a flask containing 1% aqueous HCl (200 mL), and heated at 100° C. The reaction mixture was then stirred at 100° C. for 5 h. The contents were cooled to RT, neutralized to pH 7 using 5% aqueous Na2CO3, and extracted with EtOAc (2×70 mL). Combined organic layers were washed with brine and dried over anhydrous Na2SO4. Removal of solvent under vacuum provided 6-hydroxyindazole as dark brown solid, which was used for further transformation without any purification.

1. additionDuring the addition
2. additionThe contents were then added into a flask
3. temperatureheated at 100° C
4. temperatureThe contents were cooled to RT
5. extractionextracted with EtOAc (2×70 mL)
6. washCombined organic layers were washed with brine
7. dry with materialdried over anhydrous Na2SO4
8. customRemoval of solvent under vacuum

ORD record

ord-fb7bf5521dd2494a8fd1b2dcc0a854d1

Source dataset

uspto-grants-2013_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08377983B2