Hydrochloric Acid → 1-(1,4-Dihydro-6,7-dichloro-2,3-dioxoquinoxaline-5-yl)-3-butenyl methyl sulphone

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Reaction Conditions

Reaction Steps

A mixture of 1-(6,7-dichloro-2,3-dimethoxyquinoxalin-5-yl)-3-butenyl methyl sulphone (from step (a), 27 mg, 0.069 mmol), 2M hydrochoric acid (0.5 ml) and dioxane (1 ml) was warmed at 90° C. for 15 h, cooled and concentrated under reduced pressure. The residue was sonicated with ether and a few drops of methanol and the resulting white solid was collected by filtration, washed with ether and dried to afford the title compound (17 mg, 68%) as a white powder, m.p. 270.5-272° C.

Provenance & Evidence