[[(1-Ethyl-3-methyl-5-pyrazolyl)amino]methylene]malonic acid diethyl ester → 1-ethyl-4-hydroxy-3-methyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester
Reaction equation
C(O[C:4](=[O:21])[C:5](=[CH:11][NH:12][C:13]1[N:17]([CH2:18][CH3:19])[N:16]=[C:15]([CH3:20])[CH:14]=1)[C:6]([O:8][CH2:9][CH3:10])=[O:7])C>C1(OC2C=CC=CC=2)C=CC=CC=1>[CH2:9]([O:8][C:6]([C:5]1[C:4]([OH:21])=[C:14]2[C:15]([CH3:20])=[N:16][N:17]([CH2:18][CH3:19])[C:13]2=[N:12][CH:11]=1)=[O:7])[CH3:10]Participants
Procedure
14.8 g of [[(1-ethyl-3-methyl-5-pyrazolyl)amino]methylene]malonic acid diethyl ester (0.05 mol) is dissolved in 50 g of diphenyl ether. The reaction mixture is heated to 235°-250° (bath temperature) and allowed to react at this temperature for 1 to 2 hours, while continuously distilling off the resulting ethanol. The last part of the alcohol is removed by means of a water aspirator. The diphenyl ether is separated by distillation with a fractionation column in vacuo. The 1-ethyl-4-hydroxy-3-methyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester is obtained at b.p.0.1-0.5 125°-129°, yield 10.7 g = 86% of theory, m.p. 91-93°. The compound is recrystallized from ligroin (90°-100°), and has a melting point of 93°-94°. Hydrolysis of this product with aqueous sodium hydroxide yields 1-ethyl-4-hydroxy-3-methyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid, m.p. 212°-213°.
Workup
- temperatureThe reaction mixture is heated to 235°-250° (bath temperature)
- customto react at this temperature for 1 to 2 hours
- distillationwhile continuously distilling off the resulting ethanol
- customThe last part of the alcohol is removed by means of a water aspirator
- customThe diphenyl ether is separated by distillation with a fractionation column in vacuo
Sources & evidence
- ORD record
- ord-023e181b63ac419aafc75f91fc8188e7
- Source dataset
- uspto-grants-1976_06
- Patent number
- US03966746
Reaction notes
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