Ethyl Acetate → 3-(2,4-Dichloro-phenyl)-6-ethyl-2-methyl-pyrazolo[5,1-b]oxazole

HRID 1671331Notes

Reaction equation

HRID 1671331 reaction equation
[Cl:1][C:2]1[CH:7]=[C:6]([Cl:8])[CH:5]=[CH:4][C:3]=1[C:9](=O)[CH:10]([O:12][C:13]1[NH:14][N:15]=[C:16]([CH2:18][CH3:19])[CH:17]=1)[CH3:11].[NH4+].[Cl-].C([O-])([O-])=O.[Na+].[Na+].CCOC(C)=O>ClCCCl.[Ti](Cl)(Cl)(Cl)Cl>[Cl:1][C:2]1[CH:7]=[C:6]([Cl:8])[CH:5]=[CH:4][C:3]=1[C:9]1[N:14]2[N:15]=[C:16]([CH2:18][CH3:19])[CH:17]=[C:13]2[O:12][C:10]=1[CH3:11]

Participants

7

Reactant 4

HCID 8857Ethyl AcetateHCID 10340Sodium CarbonateHCID 25517Ammonium ChlorideHCID 178436885HCID 178436885, compound

Product 1

HCID 591860723-(2,4-Dichloro-phenyl)-6-ethyl-2-methyl-pyrazolo[5,1-b]oxazole

Reagents, catalysts & solvents 2

HCID 24193Titanium TetrachlorideCatalystHCID 111,2-DichloroethaneSolvent

Conditions

Temperature
80 °C

Procedure

To a pale yellow solution of 1-(2,4-dichloro-phenyl)-2-(5-ethyl-2H-pyrazol-3-yloxy)-propan-1-one (9.00 g, 28.7 mmol) in 1,2-dichloroethane (125 ml) is slowly added via syringe titanium tetrachloride (3.80 ml, 34.5 mmol) generating a dark red solution. The reaction mixture is heated at 80° C. for 3 hours and allowed to cool to RT. The reaction mixture is poured slowly into NH4Cl (200 ml) and basified (pH 8) using Na2CO3 (200 ml). EtOAc (300 ml) is added and the biphasic solution is filtered through Celite® 521 (filter material) to remove titanium salts. The solution is extracted with EtOAc (3×75 ml) and the combined organics washed with H2O (1×100 ml), and brine (100 ml), dried (Na2SO4), filtered and concentrated in vacuo to yield an amber solid. The residue is crystallized from hot EtOAc/iso-hexane (1:5, 30 ml) to yield white solid: The mother liquor is purified using a Flashmaster (SiO2 150 ml/70 g column) eluting with 3:1 iso-hexane/EtOAc to yield a yellow solid which is crystallized from hot EtOAc/iso-hexane (1:8, 30 ml) to yield the title compound as a pale yellow solid; MS: m/z 295.15 [M+H]+

Workup

  1. temperatureto cool to RT
  2. filtrationthe biphasic solution is filtered through Celite® 521 (filter material)
  3. customto remove titanium salts
  4. extractionThe solution is extracted with EtOAc (3×75 ml)
  5. washthe combined organics washed with H2O (1×100 ml), and brine (100 ml)
  6. dry with materialdried (Na2SO4)
  7. filtrationfiltered
  8. concentrationconcentrated in vacuo
  9. customto yield an amber solid
  10. customThe residue is crystallized from hot EtOAc/iso-hexane (1:5, 30 ml)
  11. customto yield white solid
  12. customThe mother liquor is purified
  13. washeluting with 3:1 iso-hexane/EtOAc
  14. customto yield a yellow solid which
  15. customis crystallized from hot EtOAc/iso-hexane (1:8, 30 ml)

Sources & evidence

ORD record
ord-4e130233b0e5450b9f1d339bfb0bb0bb
Source dataset
uspto-grants-2011_08
Patent number
US07994203B2

Reaction notes

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