Triethylamine → 3-Chloro-5-methyl-1,2-benzoxazole

HRID 1725576Notes

Reaction equation

HRID 1725576 reaction equation
O[C:2]1[C:6]2[CH:7]=[C:8]([CH3:11])[CH:9]=[CH:10][C:5]=2[O:4][N:3]=1.C(N(CC)CC)C.O=P(Cl)(Cl)[Cl:21]>O>[Cl:21][C:2]1[C:6]2[CH:7]=[C:8]([CH3:11])[CH:9]=[CH:10][C:5]=2[O:4][N:3]=1

Participants

5

Reactant 3

HCID 8471TriethylamineHCID 24813Phosphorus oxychloride3×HCID 178423564HCID 178423564, compound

Product 1

HCID 154539903-Chloro-5-methyl-1,2-benzoxazoleYield 87%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

3-Hydroxy-5-methyl-1,2-benzisoxazole (15.0 g, 100.6 mmol; preparation: Australian Journal of Chemistry (1977), 30(8), 1847-50) were suspended in triethylamine (15.4 ml, 110.6 mmol), and phosphorus oxytrichloride (37.0 g, 22.5 ml, 241.4 mmol) was added dropwise with cooling to this mixture at room temperature. Since stirring of the reaction mixture became almost impossible after about half the amount of phosphorus oxytrichloride had been added dropwise, the temperature was raised to 50° C. After dropwise addition of the total amount of phosphorus oxytrichloride, the reaction mixture was heated at 130° C. for 5 h, after which the reaction was complete according to TLC. After cooling, the mixture was slowly added dropwise to water (200 ml) while cooling, the aqueous phase was extracted 3 times with MtB ether, the organic phases were washed with water, dried over magnesium sulfate and concentrated in vacuo. This resulted in 14.6 g of 3-chloro-5-methyl-1,2-benzisoxazole (yield: 87%) as viscous oil which solidified overnight. MS (MSD) m/z 168 [M+H+].

Workup

  1. additionhad been added dropwise
  2. temperaturethe temperature was raised to 50° C
  3. temperaturethe reaction mixture was heated at 130° C. for 5 h
  4. temperatureAfter cooling
  5. temperaturewhile cooling
  6. extractionthe aqueous phase was extracted 3 times with MtB ether
  7. washthe organic phases were washed with water
  8. dry with materialdried over magnesium sulfate
  9. concentrationconcentrated in vacuo

Sources & evidence

ORD record
ord-35350b15cc014a49a4345dc391df15ad
Source dataset
uspto-grants-2009_02
Patent number
US07491729B2

Reaction notes

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