Dimethyl acetylenedicarboxylate → 5-Hydroxy-1H-pyrazole-3-carboxylic acid methyl ester

HRID 644824Notes

Reaction equation

HRID 644824 reaction equation
O.[NH2:2][NH2:3].[C:4]([C:10]([O:12][CH3:13])=[O:11])#[C:5][C:6](OC)=[O:7]>C1(C)C=CC=CC=1>[OH:7][C:6]1[CH:5]=[C:4]([C:10]([O:12][CH3:13])=[O:11])[NH:3][N:2]=1

Participants

4

Reactant 2

HCID 12980Dimethyl acetylenedicarboxylateHCID 24654Hydrazine hydrate (1:1)

Product 1

HCID 1784986025-Hydroxy-1H-pyrazole-3-carboxylic acid methyl esterYield 73.8%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

Hydrazine monohydrate (6.7 g, 210 mmol) was added to a solution of dimethyl acetylenedicarboxylate (24.7 g, 175 mmol) in toluene (90 ml) at 0° C., and the thus-obtained mixture was gradually temperature-increased up to room temperature, stirred for 2 hours and further stirred under heating at 130° C. for 4 hours. After completion of the reaction, a precipitated solid was filtered and washed with diethyl ether, to give a white solid of methyl 3-hydroxypyrazole-5-carboxylate (18.2 g, yield: 73.8%). mp: 229-231° C.; 1H-NMR (DMSO-d6, DMSO, ppm): δ 3.79 (s, 3H), 5.91 (s, 1H), 10.10-10.45 (br s, 1H). (Hydroxy proton was not assigned.)

Workup

  1. stirringfurther stirred
  2. temperatureunder heating at 130° C. for 4 hours
  3. customAfter completion of the reaction
  4. filtrationa precipitated solid was filtered
  5. washwashed with diethyl ether

Sources & evidence

ORD record
ord-0e1e48f1d6284ac99c57a9d2f1281415
Source dataset
uspto-grants-2010_04
Patent number
US07700786B2

Reaction notes

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