Reaktion #7812

Reaktionsgleichung

p-toluenesulfonic acid

3-hydroxy-4-methylbenzoic acid

SOCl2

2-aminophenol

triethylamine

→

5-(1,3-benzoxazol-2-yl)-2-methylphenol

Lösungsmittel

toluene

EtOAc

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThis reaction was refluxed for 30 min
2. 2
   Sonstigethe excess SOCl2 removed in vacuo
3. 3
   workup.DISSOLUTIONThe oily acid chloride was dissolved in THF (15 mL)
4. 4
   Sonstigethe precipitate was removed by filtration
5. 5
   EinengenThe filtrate was concentrated
6. 6
   Sonstigedried in vacuo
7. 7
   TemperaturThe reaction was refluxed overnight
8. 8
   Temperaturcooled to rt
9. 9
   WaschenThe EtOAc solution was washed with H2O (3×5 mL)
10. 10
    Trocknendried (MgSO4)
11. 11
    Filtrationfiltered
12. 12
    Einengenconcentrated in vacuo
13. 13
    SonstigeThe residue was recrystallized in EtOAc

Vorschrift

To a 100 mL round-bottom flask with 3-hydroxy-4-methylbenzoic acid (2.5 g, 16.4 mmol) was added SOCl2 (15 mL) dropwise. This reaction was refluxed for 30 min, cooled to rt and the excess SOCl2 removed in vacuo. The oily acid chloride was dissolved in THF (15 mL) and the solution was added dropwise to a mixture of 2-aminophenol (1.8 g, 16.4 mmol), triethylamine (1.7 g, 16.4 mmol) in THF (30 mL) at 0° C. The reaction was then brought to rt for 0.5 h and the precipitate was removed by filtration. The filtrate was concentrated and dried in vacuo. To the dark brown solid residue was added toluene (20 mL) and p-toluenesulfonic acid (15.6 g, 82 mmol). The reaction was refluxed overnight, cooled to rt and dissolved in EtOAc (500 mL). The EtOAc solution was washed with H2O (3×5 mL), dried (MgSO4), filtered, and concentrated in vacuo. The residue was recrystallized in EtOAc to afford 5-(1,3-benzoxazol-2-yl)-2-methylphenol as a light yellow solid. MS (ESI) 226 (M+H)+.

Quelle