Phosphorus oxychloride → Ethyl 4-chloro-1,5-dimethyl-6-oxo-1,6-dihydropyridazine-3-carboxylate

HRID 421908Notes

Reaction equation

HRID 421908 reaction equation
O[C:2]1[C:3]([C:11]([O:13][CH2:14][CH3:15])=[O:12])=[N:4][N:5]([CH3:10])[C:6](=[O:9])[C:7]=1[CH3:8].O=P(Cl)(Cl)[Cl:18]>>[Cl:18][C:2]1[C:3]([C:11]([O:13][CH2:14][CH3:15])=[O:12])=[N:4][N:5]([CH3:10])[C:6](=[O:9])[C:7]=1[CH3:8]

Participants

3

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 66673242Ethyl 4-hydroxy-1,5-dimethyl-6-oxo-1,6-dihydropyridazine-3-carboxylate

Product 1

HCID 66674070Ethyl 4-chloro-1,5-dimethyl-6-oxo-1,6-dihydropyridazine-3-carboxylateYield 86%

Conditions

Temperature
85 °C

Procedure

A mixture of ethyl 4-hydroxy-1,5-dimethyl-6-oxo-1,6-dihydropyridazine-3-carboxylate (1.85 g, 8.72 mmol) and POCl3 (9 mL) was heated for 16 hours at 85° C. POCl3 was removed under reduced pressure. Then the crude material was quenched with ice-water. The mixture was neutralized with saturated aqueous NaHCO3 (pH ˜6 to 7) and extracted with EtOAc (3×). The combined organic layers were dried over MgSO4, filtered, and concentrated under reduced pressure to give the crude material that was purified by silica gel flash column chromatography (100% hexanes to 5 to 10 to 20% EtOAc in hexanes) to afford 1.72 g (86%) of the desired product.

Workup

  1. customPOCl3 was removed under reduced pressure
  2. customThen the crude material was quenched with ice-water
  3. extractionextracted with EtOAc (3×)
  4. dry with materialThe combined organic layers were dried over MgSO4
  5. filtrationfiltered
  6. concentrationconcentrated under reduced pressure
  7. customto give the crude material that
  8. customwas purified by silica gel flash column chromatography (100% hexanes to 5 to 10 to 20% EtOAc in hexanes)

Sources & evidence

ORD record
ord-1e45f1f4ea004375816c2ef19395bc07
Source dataset
uspto-grants-2012_01
Patent number
US08101611B2

Reaction notes

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