Sulfuric Acid → 3-Ethyl-7,8-dihydro-3H-pyrazolo[4',3':5,6]pyrido[3,4-d]pyridazine-6,9-dione

HRID 429047Notes

Reaction equation

HRID 429047 reaction equation
N[C:2]1[C:3]2[C:12]3[CH:13]=[N:14][N:15]([CH2:16][CH3:17])[C:11]=3[N:10]=[CH:9][C:4]=2[C:5](=[O:8])[NH:6][N:7]=1.N([O-])=[O:19].[Na+].S(=O)(=O)(O)O.[N]=O.[N+]([O-])=O>O>[CH2:16]([N:15]1[C:11]2[N:10]=[CH:9][C:4]3[C:5](=[O:8])[NH:6][NH:7][C:2](=[O:19])[C:3]=3[C:12]=2[CH:13]=[N:14]1)[CH3:17]

Participants

6

Reactant 4

HCID 1118Sulfuric Acid2×HCID 183543209-Amino-3-ethyl-3H-pyrazolo[4',3':5,6]pyrido[3,4-d]pyridazin-6(7H)-oneHCID 23668193Sodium NitriteHCID 178526922HCID 178526922, compound

Product 1

HCID 109880883-Ethyl-7,8-dihydro-3H-pyrazolo[4',3':5,6]pyrido[3,4-d]pyridazine-6,9-dione

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

To a suspension of 9-amino-3-ethyl-3H-pyrazolo[4′,3′:5,6]pyrido[3,4-d]pyridazin-6(7H)-one (5.0 g, 21.7 mmol) and sodium nitrite (15.0 g, 10 eq) in water (200 mL) was added concentrated sulfuric acid until the pH was <2. The suspension was stirred vigorously and some nitric oxide—nitrogen dioxide was evolved. This suspension was then placed on a hot plate and heated to boiling. The pH of the reaction was maintained at pH>2 with the addition of sulfuric acid as necessary. When the reaction was judged complete by HPLC, the resulting reaction mixture was cooled to rt. The precipitated white solid was collected by filtration, washed with water thoroughly and dried under vacuum to afford the title compound as an off white solid (4.6 g, 92%, purity >95% as judged by HPLC).

Workup

  1. temperatureheated to boiling
  2. customthe resulting reaction mixture
  3. filtrationThe precipitated white solid was collected by filtration
  4. washwashed with water thoroughly
  5. customdried under vacuum

Sources & evidence

ORD record
ord-a0731cdd1b364246be0875f4b8deaddf
Source dataset
uspto-grants-2001_11
Patent number
US06316438B1

Reaction notes

Loading…