Reaktion #7846

Reaktionsgleichung

2-[4-(bromomethyl)-3-methoxyphenyl]-1,3-benzoxazole

chlorotrimethylsilane

2-bromopyridine

1,2-dibromoethane

→

2-[3-methoxy-4-(pyridin-2-ylmethyl)phenyl]-1,3-benzoxazole

Lösungsmittel

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThe mixture was heated
2. 2
   Temperaturat reflux for 1 h
3. 3
   FiltrationThe resultant organozinc reagent was filtered through a plug of Celite
4. 4
   Sonstigetransferred to a flask
5. 5
   SonstigeThe mixture was degassed with bubbling argon for 15 min
6. 6
   Temperaturheated
7. 7
   Temperaturat reflux for 12 h
8. 8
   workup.ADDITIONThe reaction was poured into H2O (40 mL)
9. 9
   Extraktionextracted with CH2Cl2 (2×30 mL)
10. 10
    TrocknenThe organic extracts were dried (MgSO4)
11. 11
    Einengenconcentrated
12. 12
    Sonstigeto afford a colorless solid
13. 13
    SonstigePurification of the solid by flash chromatography on silica gel (EtOAc:hexanes 3:1)

Vorschrift

A solution of 2-[4-(bromomethyl)-3-methoxyphenyl]-1,3-benzoxazole (320 mg, 1.0 mmol) and THF (10 mL) was treated with Zn powder (activated by grinding with mortar and pestle), a drop of chlorotrimethylsilane, and a drop of 1,2-dibromoethane. The mixture was heated at reflux for 1 h. The resultant organozinc reagent was filtered through a plug of Celite, and transferred to a flask containing 2-bromopyridine (360 mg, 2.0 mmol) and Pd(Ph3P)4 (115 mg, 0.1 mmol). The mixture was degassed with bubbling argon for 15 min, and heated at reflux for 12 h. The reaction was poured into H2O (40 mL) and extracted with CH2Cl2 (2×30 mL). The organic extracts were dried (MgSO4) and concentrated to afford a colorless solid. Purification of the solid by flash chromatography on silica gel (EtOAc:hexanes 3:1) afforded the desired 2-[3-methoxy-4-(pyridin-2-ylmethyl)phenyl]-1,3-benzoxazole as a yellow solid: 1H NMR (CDCl3, 300 MHz) δ 8.55 (d, 1H), 7.76–7.82 (m, 3H), 7.56–7.62 (d, 2H), 7.32–7.36 (m, 3H), 7.11–7.16 (m, 2H), 4.23 (s, 2H), 3.95 (s, 3H). MS (ESI) 317 (M+H)+.

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