Glyoxal → 6-Bromoquinoxaline

Participants

Reaction Steps

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. Upon arrival the reaction was concentrated to dryness on a rotary evaporator 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): δ=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), rt=1.10 mins., purity=99%, calculated mass=208, [M+H]+=209/21. HPLC (Method C): rt=7.4 mins., purity=98.52% @ 210-370 nm and 98.8% @ 322 nm.

Provenance & Evidence