Phosphorus oxychloride → 5-Bromo-3-chloro-2-methylquinoxaline

HRID 1055953

Reaktionsgleichung

Reaktionsgleichung von HRID 1055953
[Br:1][C:2]1[CH:3]=[CH:4][CH:5]=[C:6]2[C:11]=1[NH:10][C:9](=O)[C:8]([CH3:13])=[N:7]2.P(Cl)(Cl)([Cl:16])=O>O>[Br:1][C:2]1[CH:3]=[CH:4][CH:5]=[C:6]2[C:11]=1[N:10]=[C:9]([Cl:16])[C:8]([CH3:13])=[N:7]2

Komponenten

4

Edukt 2

HCID 24813Phosphorus oxychlorideHCID 71295542HCID 71295542, Verbindung

Produkt 1

HCID 894288875-Bromo-3-chloro-2-methylquinoxalineAusbeute 75 %

Reagenzien, Katalysatoren, Lösungsmittel 1

HCID 962WaterLösungsmittel

Reaktionsbedingungen

Temperatur
0 °C

Versuchsvorschrift

A slurry of 8-bromo-3-methylquinoxalin-2(1H)-one (6.33 g, 26.5 mmol) in phosphorus oxychloride (20 mL, 219 mmol) was heated at reflux for 1.5 h in a round-bottomed flask fitted with a water-cooled reflux condenser and drying tube. Excess POCl3 was removed in vacuo (16 Torr, 36° C.), and the residue was taken up in DCM (50 mL), transferred to an Erlenmeyer flask, cooled to 0° C., and saturated aq. NaHCO3 (ca. 80 mL) was added (cautiously, with rapid stirring). The resulting biphasic mixture was stirred rapidly for 5 min. Upon cessation of gas evolution, the mixture was extracted with DCM (3×200 mL), and the combined extracts were dried over Na2SO4, filtered, and concentrated onto silica gel. Chromatographic purification of the residue (silica gel, 0-30% EtOAc/hexanes) furnished 5-bromo-3-chloro-2-methylquinoxaline (126e; 5.12 g, 19.85 mmol, 75% yield) as a light-yellow solid: 1H NMR (400 MHz, CDCl3) δ ppm 8.02 (1H, d, J=7.6 Hz), 8.00 (1H, dd, J=8.4, 1.2 Hz), 7.60 (1H, t, J=7.9 Hz), 2.87 (3H, s). m/z (ESI, +ve) 256.9 (M+H)+.

Aufarbeitung

  1. temperatureat reflux for 1.5 h in a round-bottomed flask
  2. temperaturecooled
  3. temperaturereflux condenser
  4. customdrying tube
  5. customExcess POCl3 was removed in vacuo (16 Torr, 36° C.)
  6. additionsaturated aq. NaHCO3 (ca. 80 mL) was added (cautiously,
  7. stirringThe resulting biphasic mixture was stirred rapidly for 5 min
  8. extractionUpon cessation of gas evolution, the mixture was extracted with DCM (3×200 mL)
  9. dry with materialthe combined extracts were dried over Na2SO4
  10. filtrationfiltered
  11. concentrationconcentrated onto silica gel
  12. customChromatographic purification of the residue (silica gel, 0-30% EtOAc/hexanes)

Quellen und Nachweise

ORD-Eintrag
ord-d6f55763d26e403fbe2c4516c4456189
Quelldatensatz
uspto-grants-2016_07
Patentnummer
US09394297B2

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