Reaktion #7804

Reaktionsgleichung

2-aminophenol

triethylamine

3-hydroxy-4-methylbenzoic acid

SOCl2

p-toluenesulfonic acid

→

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

Lösungsmittel

THF

EtOAc

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThe reaction was refluxed for 30 min
2. 2
   Sonstigethe excess of SOCl2 was removed in vacuo
3. 3
   workup.DISSOLUTIONThe oily acid chloride was dissolved in THF (15 mL)
4. 4
   TemperaturThe reaction was then warmed to rt for 1 h
5. 5
   Sonstigethe precipitate was removed by filtration
6. 6
   EinengenThe filtrate was concentrated
7. 7
   Sonstigedried in vacuo
8. 8
   workup.DISSOLUTIONthe dark brown solid residue was dissolved in toluene (20 mL)
9. 9
   TemperaturThe reaction was refluxed overnight
10. 10
    Temperaturcooled to rt
11. 11
    WaschenThe organic solution was washed with brine (3×50 mL)
12. 12
    Trocknendried (MgSO4)
13. 13
    Filtrationfiltered
14. 14
    Einengenconcentrated in vacuo
15. 15
    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. The reaction was refluxed for 30 min, cooled to rt and the excess of SOCl2 was 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) and THF (30 mL) at 0° C. The reaction was then warmed to rt for 1 h and the precipitate was removed by filtration. The filtrate was concentrated and dried in vacuo and the dark brown solid residue was dissolved in toluene (20 mL) and p-toluenesulfonic acid (15.6 g, 82 mmol) was added. The reaction was refluxed overnight, cooled to rt and dissolved in EtOAc (500 mL). The organic solution was washed with brine (3×50 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