Hydrochloric Acid → 1-(6,7-Dichloro-2,3-dimethoxyquinoxalin-5-yl)-3-hydroxypropyl methyl sulphone

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Reaction Steps

Ozone was bubbled through a solution of 1-(6,7-dichloro-2,3-dimethoxyquinoxalin-5-yl)-3-butenyl methyl sulphone (50 mg, 0.128 mmol) [Example 93(a)] in dry dichloromethane (1.3 ml) at -78° C. until a blue colour developed. The mixture was stirred for 5 minutes and was then purged with a stream of oxygen and then nitrogen. Methanol (1.3 ml) was added and the mixture allowed to equilibrate at -78° C. before sodium borohydride (12 mg, 0.319 mmol) was added in two portions. The mixture was stirred for 5 mins and was then allowed to warm to room temperature. The mixture was poured into 2M hydrochloric acid (20 ml) and extracted with dichloromethane (2×20 ml). The combined extracts were washed with brine (20 ml), dried (MgSO4) and concentrated under reduced pressure. The residue was purified by flash chromatography (eluting with 1:1 hexane:ethyl acetate) to give 1-(6,7-dichloro-2,3-dimethoxyquinoxalin-5-yl)-3-hydroxypropyl methyl sulphone (35.6 mg, 70%) as a white foam.

Provenance & Evidence