4-nitro-1H-pyrazole-3-carboxylic acid (2-amino-4,5-dimethoxy-phenyl)-amide → 5,6-Dimethoxy-2-(4-nitro-1,2-dihydro-3H-pyrazol-3-ylidene)-2H-benzimidazole

HRID 1012144Notes

Reaction equation

[NH2:1][C:2]1[CH:7]=[C:6]([O:8][CH3:9])[C:5]([O:10][CH3:11])=[CH:4][C:3]=1[NH:12][C:13]([C:15]1[C:19]([N+:20]([O-:22])=[O:21])=[CH:18][NH:17][N:16]=1)=O>C(O)(=O)C>[CH3:11][O:10][C:5]1[C:6]([O:8][CH3:9])=[CH:7][C:2]2[NH:1][C:13]([C:15]3[C:19]([N+:20]([O-:22])=[O:21])=[CH:18][NH:17][N:16]=3)=[N:12][C:3]=2[CH:4]=1

Participants

Conditions

Temperature: 140 °C

Procedure

4-Nitro-1H-pyrazole-3-carboxylic acid (2-amino-4,5-dimethoxy-phenyl)-amide (2.35 g, 7.65 mmol) was dissolved in acetic acid (150 ml) and refluxed at 140° C. for 5 hours. The solution was left to cool and the solvent removed in vacuo. The resulting solid was partitioned between ethyl acetate (25 ml) and brine (25 ml). The organic layer was separated, dried (MgSO4), filtered and the solvent removed in vacuo to yield 5,6-dimethoxy-2-(4-nitro-1H-pyrazol-3-yl)-1H-benzimidazole (2.08 g, 94%).

Workup

waitThe solution was left
temperatureto cool
customthe solvent removed in vacuo
customThe resulting solid was partitioned between ethyl acetate (25 ml) and brine (25 ml)
customThe organic layer was separated
dry with materialdried (MgSO4)
filtrationfiltered
customthe solvent removed in vacuo

Sources & evidence

ORD record: ord-818dabe71927476091df741f37588387
Source dataset: uspto-grants-2011_07
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07977477B2

Reaction notes

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