Potassium Hydroxide → 5-(2,4-Bis-benzyloxy-phenyl)-1H-pyrazole-3-carboxylic acid

HRID 322850Notes

Reaction equation

HRID 322850 reaction equation
[CH2:1]([O:8][C:9]1[CH:14]=[C:13]([O:15][CH2:16][C:17]2[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=2)[CH:12]=[CH:11][C:10]=1[C:23]1[CH:27]=[C:26]([C:28]([O:30]CC)=[O:29])[NH:25][N:24]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[OH-].[K+]>CO.C1COCC1>[CH2:1]([O:8][C:9]1[CH:14]=[C:13]([O:15][CH2:16][C:17]2[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=2)[CH:12]=[CH:11][C:10]=1[C:23]1[CH:27]=[C:26]([C:28]([OH:30])=[O:29])[NH:25][N:24]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1

Participants

5

Reactant 2

HCID 14797Potassium HydroxideHCID 10502648HCID 10502648, compound

Product 1

HCID 45681585-(2,4-Bis-benzyloxy-phenyl)-1H-pyrazole-3-carboxylic acidYield 9.3%

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 8028TetrahydrofuranSolvent

Procedure

A solution of ethyl 3-(2,4-dibenzyloxyphenyl)-pyrazole-5-carboxylate (1.5 g) in methanol (20 mL) and THF(10 mL) is treated with aqueous 10% KOH (7.5 mL) and refluxed for 2 hours. The solution is evaporated, brought to pH 1 with 1 M HCl, and the precipitate filtered. The solid is purified by flash chromatography on silica, eluting with dichloromethane/methanol (98:2). Fractions homogeneous in the required product are combined and evaporated. The residue is recrystallized from ethyl acetate to give 3-(2,4-dibenzyloxyphenyl)-pyrazole-5-carboxylic acid as colourless crystals (0.13 g), m.p. 218-219° C. 1H NMR (CDCl3) 5.1 (2H,s), 5.2(2H,s), 6.68(1H,d), 6.72(1H,s), 7.3-7.5(11H,m), 7.7(1H,d).

Workup

  1. temperaturerefluxed for 2 hours
  2. customThe solution is evaporated
  3. filtrationthe precipitate filtered
  4. customThe solid is purified by flash chromatography on silica
  5. washeluting with dichloromethane/methanol (98:2)
  6. customevaporated
  7. customThe residue is recrystallized from ethyl acetate

Sources & evidence

ORD record
ord-4c31393d779246878980cd1a069f50d1
Source dataset
uspto-grants-2001_04
Patent number
US06211234B1

Reaction notes

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