Methylglyoxal → 7-Chloro-2-methyl-8-nitro-quinoxaline

HRID 505236Notes

Reaction equation

O=[C:2]([CH3:5])[CH:3]=O.[Cl:6][C:7]1[C:8]([N+:15]([O-:17])=[O:16])=[C:9]([NH2:14])[C:10]([NH2:13])=[CH:11][CH:12]=1>C1COCC1.Cl>[Cl:6][C:7]1[C:8]([N+:15]([O-:17])=[O:16])=[C:9]2[C:10]([N:13]=[CH:3][C:2]([CH3:5])=[N:14]2)=[CH:11][CH:12]=1

Participants

Conditions

Temperature: 65 °C

Procedure

At room temperature, 2-oxo-propionaldehyde (40% aqueous solution, 3.03 ml, 20.15 mmol, 1.0 equiv) was added to a solution of 4-chloro-3-nitro-benzene-1,2-diamine (3.78 g, 20.15 mmol) in THF (600 ml) and aqueous HCl (5N, 9.5 ml). The mixture was warmed to 65° C. for 10 minutes, then it was concentrated to approximately 200 ml and extracted with EtOAc. The combined organic layers were washed with dilute aqueous NaHCO3 solution and brine, dried over Na2SO4, filtered and concentrated in vacuo. The residue was purified via flash chromatography (gradient of hexane/EtOAc 9:1 to 7:3) to afford the title compound (3.86 g, 81%, 92:8 mixture of 7-chloro-2-methyl-8-nitro-quinoxaline and 6-chloro-2-methyl-5-nitro-quinoxaline). 1H NMR (400 MHz, CDCl3): δ=8.81 (s, 1H), 8.15 (d, J=9.1 Hz, 1H), 7.74 (d, J=9.1 Hz, 1H), 2.79 (s, 3H). MS (ES+): 224 (M+H)+.

Workup

concentrationit was concentrated to approximately 200 ml
extractionextracted with EtOAc
washThe combined organic layers were washed with dilute aqueous NaHCO3 solution and brine
dry with materialdried over Na2SO4
filtrationfiltered
concentrationconcentrated in vacuo
customThe residue was purified via flash chromatography (gradient of hexane/EtOAc 9:1 to 7:3)

Sources & evidence

ORD record: ord-ac7dd6816ffc4b79b870fd635ddb7a84
Source dataset: uspto-grants-2010_08
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07781438B2

Reaction notes

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