Phosphorus oxychloride → 7-Bromo-2-chloroquinoxaline

HRID 751278

Reaction equation

HRID 751278 reaction equation
[Br:1][C:2]1[CH:11]=[C:10]2[C:5]([N:6]=[CH:7][C:8](=O)[NH:9]2)=[CH:4][CH:3]=1.O=P(Cl)(Cl)[Cl:15]>C(Cl)(Cl)Cl.C(O)(C)C>[Br:1][C:2]1[CH:11]=[C:10]2[C:5]([N:6]=[CH:7][C:8]([Cl:15])=[N:9]2)=[CH:4][CH:3]=1

Participants

4

Reactant 2

HCID 24813Phosphorus oxychloride2×HCID 49132647-bromo-1H-quinoxalin-2-one

Product 1

HCID 49132537-Bromo-2-chloroquinoxalineYield 58%

Reagents, catalysts & solvents 1

HCID 21906603Chloroform isopropyl alcoholSolvent

Procedure

Heat benzene-1,2-diamine (7.5 g, 69 mmol) and oxo-acetic acid ethyl ester (20 mL) in ethanol (100 mL) at 120° C. for 18 h. Cool, filter the resulting precipitate, and wash with dry ether to give 1H-quinoxalin-2-one (6.7 g). Dissolve 1H-quinoxalin-2-one in acetic acid (300 mL), add bromine (5 mL), and stir the reaction mixture for 1 h. Filter the resulting crystals and wash with ether to afford 7-bromo-1H-quinoxalin-2-one (7.2 g). Reflux 7-bromo-1H-quinoxalin-2-one in POCl3 (30 mL) for 18 h. Remove POCl3 in vacuo, dissolve the product in 3:1 chloroform/isopropyl alcohol, and wash the organic phase with saturated sodium bicarbonate. Dry over sodium sulfate and purify by silica gel flash chromatography eluting with dichloromethane to 10% methanol/90% dichloromethane to afford the title compound as a yellow solid (4.5 g, 58%). MS (electrospray, m/z) 243.0 and 245.0 (M+1).

Workup

  1. washwash the organic phase with saturated sodium bicarbonate
  2. dry with materialDry over sodium sulfate
  3. custompurify by silica gel flash chromatography
  4. washeluting with dichloromethane to 10% methanol/90% dichloromethane

Sources & evidence

ORD record
ord-6cc32df0ad024daab1dd79d38d468d8e
Source dataset
uspto-grants-2008_07
Patent number
US07405299B2

Linked notes

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