Glyoxal → 6-Bromoquinoxaline

HRID 729488Notes

Reaction equation

HRID 729488 reaction equation
[Br:1][C:2]1[CH:3]=[C:4]([NH2:9])[C:5]([NH2:8])=[CH:6][CH:7]=1.[CH:10]([CH:12]=O)=O>CO>[Br:1][C:2]1[CH:3]=[C:4]2[C:5](=[CH:6][CH:7]=1)[N:8]=[CH:12][CH:10]=[N:9]2

Participants

4

Reactant 2

HCID 7860GlyoxalHCID 3235934-Bromobenzene-1,2-diamine

Product 1

HCID 6109396-BromoquinoxalineYield 51%

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Procedure

In a round bottom flask under nitrogen was combined 4-bromo-benzene-1,2-diamine (2.01 g, 10.7 mmol), methanol (50 mL), and glyoxal (40% by wt. 3.1 mL, 26.9 mmol) and the resulting solution stirred overnight. The reaction was then concentrated in vacuo and purified by flash column chromatography on silica gel using 5-10% ethyl acetate in dichloromethane as eluant to yield 1.14 g (50% yield) of 6-Bromo-quinoxaline as a yellow-orange solid. 1H NMR (DMSO-d6): 9.00 (d,2H,J=2.8 Hz), 8.36 (d,1H,J=2.2 Hz), 8.07 (d,1H,J=9.0 Hz), 8.02 (dd,1H,J=8.8,2.1 Hz). CHN for C8H5BrN2: calc. C 45.97, H 2.41, N 13.4; found C 45.99, H 2.09, N 13.09. LC/MS (Method A): r.t.=1.10 min., purity=99%, calculated mass=208, [M+H]+=209/211. HPLC (Method B): r.t.=7.4 min., purity=98.52% at 210-370 and 98.8% at 322 nm.

Workup

  1. customIn a round bottom flask under nitrogen was combined
  2. concentrationThe reaction was then concentrated in vacuo
  3. custompurified by flash column chromatography on silica gel using 5-10% ethyl acetate in dichloromethane as eluant

Sources & evidence

ORD record
ord-8a9fe57f35364f40bef8b1ee8a7326a9
Source dataset
uspto-grants-2009_09
Patent number
US07582636B2

Reaction notes

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