Methanesulfonic Acid → Ethyl 5,6,7,8-tetrahydropyrazolo[5,1-b][1,3]benzoxazole-2-carboxylate

HRID 1744989Notes

Reaction equation

HRID 1744989 reaction equation
[CH2:1]([O:3][C:4]([C:6]1[CH:10]=[C:9]([O:11][CH:12]2[CH2:17][CH2:16][CH2:15][CH2:14][C:13]2=O)[NH:8][N:7]=1)=[O:5])[CH3:2].CS(O)(=O)=O>C(O)(=O)C.C1(C)C=CC=CC=1>[N:7]1[N:8]2[C:9]([O:11][C:12]3[CH2:17][CH2:16][CH2:15][CH2:14][C:13]=32)=[CH:10][C:6]=1[C:4]([O:3][CH2:1][CH3:2])=[O:5]

Participants

5

Reactant 2

HCID 6395Methanesulfonic AcidHCID 178469286ethyl-5-[(2-oxocyclohexyl)oxy]-1H-pyrazole-3-carboxylate

Product 1

HCID 22224483Ethyl 5,6,7,8-tetrahydropyrazolo[5,1-b][1,3]benzoxazole-2-carboxylateYield 59.5%

Reagents, catalysts & solvents 2

HCID 176Acetic AcidSolventHCID 1140TolueneSolvent

Procedure

A mixture of ethyl-5-[(2-oxocyclohexyl)oxy]-1H-pyrazole-3-carboxylate (127.6 mg, 0.5 mmol) and methane sulfonic acid (95 mg) in 5 ml of acetic acid and toluene (50 ml) was refluxed for 18 hours using a Dean-Stark trap to remove water. The reaction mixture was allowed to cool to room temperature. The reaction mixture was filtered. The filtrate was concentrated to an oil. The residue was dissolved in ethyl acetate and aqueous bicarbonate solution. The organic layer was washed with water and dried over MgSO4. After removal of the ethyl acetate, the residue was purified by silica gel chromatography eluting with 1:1 ethyl acetate/hexane to give 69.7 mg (59%) of the desired product as white solid. Mp; 55–57° C.; Electrospray-MS m/z 235.0 (M+H)+

Workup

  1. temperaturewas refluxed for 18 hours
  2. customto remove water
  3. filtrationThe reaction mixture was filtered
  4. concentrationThe filtrate was concentrated to an oil
  5. dissolutionThe residue was dissolved in ethyl acetate
  6. washThe organic layer was washed with water
  7. dry with materialdried over MgSO4
  8. customAfter removal of the ethyl acetate
  9. customthe residue was purified by silica gel chromatography
  10. washeluting with 1:1 ethyl acetate/hexane

Sources & evidence

ORD record
ord-cae0fa80c6eb4be1b3d22c6bc7e805d8
Source dataset
uspto-grants-2006_03
Patent number
US07018997B2

Reaction notes

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