Reaktion #7808

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
   Filtrationafter which time, the precipitate was filtered
5. 5
   EinengenThe filtrate was concentrated
6. 6
   Sonstigedried in vacuo
7. 7
   workup.DISSOLUTIONThe dark brown solid residue was dissolved in toluene (20 mL)
8. 8
   TemperaturThe mixture was refluxed overnight
9. 9
   Temperaturcooled to rt
10. 10
    WaschenThe EtOAc solution was washed with brine (3×50 mL)
11. 11
    Trocknendried (MgSO4)
12. 12
    Filtrationfiltered
13. 13
    Einengenconcentrated in vacuo
14. 14
    SonstigeThe residue was recrystallized in EtOAc

Vorschrift

To a 10 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. The excess of SOCl2 was removed in vacuo and the oily acid chloride was dissolved in THF (15 mL). The 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 reaction mixture was brought to rt for 30 min, after which time, the precipitate was filtered. The filtrate was concentrated and dried in vacuo. The dark brown solid residue was dissolved in toluene (20 mL) and p-toluenesulfonic acid (15.6 g, 82 mmol) was added. The mixture was refluxed overnight, cooled to 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