1(2H)-Pyridazinecarboxylic acid, tetrahydro-, ethyl ester → 2-[7-fluoro-2H-1,4-benzoxazin-3(4H)-on-6-yl]-hexahydro-1H-(1,2,4)-triazolo (1,2-a) pyridazine-1,3-dione

HRID 1381820Notes

Reaction equation

HRID 1381820 reaction equation
[N:1]([C:4]1[C:5]([F:15])=[CH:6][C:7]2[O:12][CH2:11][C:10](=[O:13])[NH:9][C:8]=2[CH:14]=1)=[C:2]=[O:3].C([O:18][C:19]([N:21]1[CH2:26][CH2:25][CH2:24][CH2:23][NH:22]1)=O)C>C(N(CC)CC)C.O1CCOCC1>[F:15][C:5]1[C:4]([N:1]2[C:19](=[O:18])[N:21]3[CH2:26][CH2:25][CH2:24][CH2:23][N:22]3[C:2]2=[O:3])=[CH:14][C:8]2[NH:9][C:10](=[O:13])[CH2:11][O:12][C:7]=2[CH:6]=1

Participants

5

Reactant 2

HCID 30143771(2H)-Pyridazinecarboxylic acid, tetrahydro-, ethyl esterHCID 144028736-isocyanato-7-fluoro-2H-1,4-benzoxazin-3(4H)-one

Product 1

HCID 144028742-[7-fluoro-2H-1,4-benzoxazin-3(4H)-on-6-yl]-hexahydro-1H-(1,2,4)-triazolo (1,2-a) pyridazine-1,3-dioneYield 74.7%

Reagents, catalysts & solvents 2

HCID 8471TriethylamineCatalystHCID 312751,4-DioxaneSolvent

Procedure

A mixture composed of 6-isocyanato-7-fluoro-2H-1,4-benzoxazin-3(4H)-one (2.14 g), 1-ethoxycarbonylhexahydropyridazine (1.62 g) and dioxane (30 ml) is treated with a few drops of triethylamine, stirred at an ambient temperature for 2 hours, and left overnight. The reaction mixture is made free from dioxane by evaporation in vacuo, mixed with methanol (30 ml) containing a catalytic amount of sodium, and refluxed for 2 hours. After removal of methanol by evaporation in vacuo, the resultant solid is collected, and washed with water to obtain an end product 2-[7-fluoro-2H-1,4-benzoxazin-3(4H)-on-6-yl]-hexahydro-1H-(1,2,4)-triazolo (1,2-a) pyridazine-1,3-dione (2.45 g).

Workup

  1. waitleft overnight
  2. customThe reaction mixture is made free from dioxane by evaporation in vacuo
  3. additionmixed with methanol (30 ml)
  4. additioncontaining a catalytic amount of sodium
  5. temperaturerefluxed for 2 hours
  6. customAfter removal of methanol
  7. customby evaporation in vacuo
  8. customthe resultant solid is collected
  9. washwashed with water

Sources & evidence

ORD record
ord-40b3fb53dace4500809f03c4b7c06459
Source dataset
uspto-grants-1989_02
Patent number
US04804394

Reaction notes

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