4-Amino-6,7-dihydro-6-oxo-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester → 4-amino-1-phenyl-7H-pyrazolo[5,4-b]pyridin-6-one

HRID 1263493Notes

Reaction equation

HRID 1263493 reaction equation
C(OC([C:6]1[C:11](=[O:12])[NH:10][C:9]2[N:13]([C:16]3[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=3)[N:14]=[CH:15][C:8]=2[C:7]=1[NH2:22])=O)C>[OH-].[Na+].O>[NH2:22][C:7]1[C:8]2[CH:15]=[N:14][N:13]([C:16]3[CH:17]=[CH:18][CH:19]=[CH:20][CH:21]=3)[C:9]=2[NH:10][C:11](=[O:12])[CH:6]=1

Participants

4

Reactant 1

HCID 1359572564-Amino-6,7-dihydro-6-oxo-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester

Product 1

HCID 1358542794-amino-1-phenyl-7H-pyrazolo[5,4-b]pyridin-6-oneYield 63%

Reagents, catalysts & solvents 2

HCID 962WaterSolventHCID 14798Sodium HydroxideSolvent

Procedure

4-Amino-6,7-dihydro-6-oxo-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester (0.68 g, 2.28 mmol) was heated at reflux in sodium hydroxide solution (12 ml of a 15 wt. % solution in water). After 6 h, the mixture was allowed to cool to room temperature and was then transferred to a fridge and kept there for 19 h. The white precipitate was filtered off and the filtrate set aside. The solid was dissolved in water and acidified to pH 5 by dropwise addition of concentrated hydrochloric acid. The product was extracted into ethyl acetate (×2) and the combined organic layers washed with brine before being dried (MgSO4) and concentrated. 4-Amino-1,7-dihydro-1-phenylpyrazolo[3,4-b]pyridin-6-one (324 mg, 63%) was obtained as a white solid. The filtrate which had been set aside was acidified to pH 5 and extracted with ethyl acetate (×2). The combined organic extracts were washed with saturated aqueous sodium hydrogencarbonate solution and then brine before being dried (MgSO4) and concentrated. This afforded a second crop of the product (145 mg, total yield 91%), m.p. 223-225° C. δH (400 MHz; DMSO) 5.58 (1H, s), 6.76 (2H, br s), 7.23-7.27 (1H, m), 7.46-7.50 (2H, m), 8.16 (1H, s), 8.21-8.24 (2H; m), 11.16 (1H, br s); m/z (ES+) 227 (M+H+).

Workup

  1. waitkept there for 19 h
  2. filtrationThe white precipitate was filtered off
  3. dissolutionThe solid was dissolved in water
  4. additionacidified to pH 5 by dropwise addition of concentrated hydrochloric acid
  5. extractionThe product was extracted into ethyl acetate (×2)
  6. washthe combined organic layers washed with brine
  7. dry with materialbefore being dried (MgSO4)
  8. concentrationconcentrated

Sources & evidence

ORD record
ord-57de8313eaf046579e495572d7925903
Source dataset
uspto-grants-2003_04
Patent number
US06541484B2

Reaction notes

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