Phosphorus oxychloride → 2-Chloro-5-methyl-1,3-benzoxazole

HRID 563719Notes

Reaction equation

HRID 563719 reaction equation
[CH3:1][C:2]1[CH:3]=[CH:4][C:5]2[O:9][C:8](S)=[N:7][C:6]=2[CH:11]=1.P(Cl)(Cl)([Cl:14])=O.P(Cl)(Cl)(Cl)(Cl)Cl>C(Cl)Cl>[Cl:14][C:8]1[O:9][C:5]2[CH:4]=[CH:3][C:2]([CH3:1])=[CH:11][C:6]=2[N:7]=1

Participants

5

Reactant 3

HCID 24813Phosphorus oxychlorideHCID 24819Phosphorus pentachlorideHCID 178423563HCID 178423563, compound

Product 1

HCID 99896072-Chloro-5-methyl-1,3-benzoxazole

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

5-Methyl-benzooxazole-2-thiol (5.0 g, 30.2 mmol), phosphorus oxychloride (25.0 mL, 269.4 mmol), and phosphorus pentachloride (7.56 g, 36.3 mmol) were combined in CH2Cl2 (30 mL), and the reaction was stirred at room temperature overnight. The mixture was concentrated several times from fresh CH2Cl2 to remove traces of phosphorus oxychloride, and the residue was treated with saturated aqueous Na2CO3 to adjust to pH 8. The aqueous layer was extracted twice with CH2Cl2, and the combined organic layers were washed with H2O and brine, and then dried over Na2SO4, decanted, and concentrated. The crude material was purified by silica gel chromatography (0-100% EtOAc in hexanes) to give the title compound.

Workup

  1. concentrationThe mixture was concentrated several times from fresh CH2Cl2
  2. customto remove traces of phosphorus oxychloride
  3. additionthe residue was treated with saturated aqueous Na2CO3
  4. extractionThe aqueous layer was extracted twice with CH2Cl2
  5. washthe combined organic layers were washed with H2O and brine
  6. dry with materialdried over Na2SO4
  7. customdecanted
  8. concentrationconcentrated
  9. customThe crude material was purified by silica gel chromatography (0-100% EtOAc in hexanes)

Sources & evidence

ORD record
ord-35365d21e69b463cb7e461ec1face7ed
Source dataset
uspto-grants-2011_11
Patent number
US08067445B2

Reaction notes

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