Sulfuric Acid → 6-Methoxyphthalazin-1-ol

HRID 2268827Notes

Reaction equation

HRID 2268827 reaction equation
CC1(C)C[O:5][C:4]([C:7]2[CH:14]=[CH:13][C:12]([O:15][CH3:16])=[CH:11][C:8]=2[CH:9]=O)=[N:3]1.OS(O)(=O)=O.O.[NH2:24]N.C([O-])(O)=O.[Na+]>C(O)(=O)C.O.C(O)C>[CH3:16][O:15][C:12]1[CH:11]=[C:8]2[C:7](=[CH:14][CH:13]=1)[C:4](=[O:5])[NH:3][N:24]=[CH:9]2

Participants

8

Reactant 4

HCID 1118Sulfuric AcidHCID 24654Hydrazine hydrate (1:1)HCID 516892Sodium BicarbonateHCID 122201362-(4,4-Dimethyl-4,5-dihydro-oxazol-2-yl)-5-methoxy-benzaldehyde

Product 1

HCID 122985436-Methoxyphthalazin-1-olYield 73.4%

Reagents, catalysts & solvents 3

HCID 176Acetic AcidSolventHCID 702EthanolSolvent2×HCID 962WaterSolvent2×

Procedure

A solution of 2-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-5-methoxy-benzaldehyde (2 g, 8.58 mmoles), prepared as described in example 2, in 30 ml of a mixture of water (5 ml), ethanol (50 ml) and concentrated H2SO4 (4 ml) up to 100 ml with ethanol, was stirred under reflux for 20 hours, then concentrated to small volume, taken up in water, extracted with ethyl ether and the organic phase was washed with water, anhydrified and brought to dryness. The resultant oil was dissolved in acetic acid (14 ml) and dropwise added, under N2, with hydrazine monohydrate (1.25 ml, 25.7 mmoles) dissolved in acetic acid (6 ml). The mixture was stirred for 3.5 hours at room temperature, then at 80° C. for 4 hours, then cooled, brought to almost complete dryness, taken up in water, neutralised with NaHCO3, extracted more times with CH2Cl2. The organic phases were washed with water, anhydrified and concentrated. The residue was triturated in CH2Cl2 (10 ml) and filtered to give 1.1 g of the title compound (yield: 73.4%). m.p.: 200-205° C.

Workup

  1. temperatureunder reflux for 20 hours
  2. concentrationconcentrated to small volume
  3. extractionextracted with ethyl ether
  4. washthe organic phase was washed with water
  5. dissolutionThe resultant oil was dissolved in acetic acid (14 ml)
  6. stirringThe mixture was stirred for 3.5 hours at room temperature
  7. temperaturecooled
  8. extractionextracted more times with CH2Cl2
  9. washThe organic phases were washed with water, anhydrified
  10. concentrationconcentrated
  11. customThe residue was triturated in CH2Cl2 (10 ml)
  12. filtrationfiltered

Sources & evidence

ORD record
ord-1197a33342fc4737bd43f11760f7da61
Source dataset
uspto-grants-2001_12
Patent number
US06329370B1

Reaction notes

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