Reaktion #7802

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
   SonstigeThe resulting reaction mixture
5. 5
   Sonstigethe resulting precipitate was removed by filtration
6. 6
   EinengenThe filtrate was concentrated
7. 7
   Sonstigedried under vacuum
8. 8
   workup.DISSOLUTIONThe resulting dark brown solid residue was dissolved in toluene (20 mL)
9. 9
   TemperaturThe reaction was refluxed overnight
10. 10
    Temperaturcooled at rt
11. 11
    WaschenThe EtOAc 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 dropwise SOCl2 (15 mL). The reaction was refluxed for 30 min and cooled to rt. The excess of SOCl2 was removed in vacuo and the oily acid chloride was dissolved in THF (15 mL). This resulting 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 resulting reaction mixture was then brought to rt for 30 min and the resulting precipitate was removed by filtration. The filtrate was concentrated and dried under vacuum. The resulting 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 at rt and EtOAc (500 mL) was added. The EtOAc 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