Methylglyoxal → 6-Bromo-2-methylquinoxaline

Participants

Reaction Steps

The product from Example 61A (9.4 g, 50 mmol) in acetonitrile (100 mL) was treated with 40% aqueous pyruvic aldehyde (11.0 mL, 60 mmol) dropwise. After stirring at room temperature for 2 hours, the mixture was concentrated and the residue was suspended in IPAc (100 mL) and filtered. The filtrate was washed with 20% brine, dried with Na2SO4, filtered, and the filtrate was concentrated. The residue was purified by silica gel column chromatography eluting with heptane:EtOH:MeOH (8:2:1) to provide the title compounds. MS 224 (M+H)+; 1H NMR (400 MHz, CDCl3) δ 8.73 (s, 1H), 8.72 (s, 1H), 8.23 (d, J=2.2 Hz, 1H), 8.18 (d, J=2.1 Hz, 1H), 7.75-7.93 (m, 4H), 2.78 (s, 3H), 2.76 (s, 3H); 13C NMR (400 MHz, CDCl3) δ 154.32, 153.73, 146.34, 145.83, 142.28, 141.17, 140.45, 139.34, 133.17, 132.15, 131.15, 130.75, 130.16, 129.71, 123.66, 122.38, 22.89.

Provenance & Evidence