Lawesson's reagent → 6,7-Dichloro-2,3-dimethoxy-5-thioacetamidoquinoxaline

Participants

Reaction Steps

5-Acetamido-6,7-dichloro-2,3-dimethoxyquinoxaline (20.49 g, 64.8 mmol) was added to a stirred suspension of 2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulphide (Lawesson's reagent) (15.7 g, 38.9 mmol) in toluene (432 ml) at room temperature under nitrogen. The mixture was warmed to the reflux temperature 25 minutes and was maintained at that temperature for a further 90 minutes. After being cooled the mixture was concentrated under reduced pressure and the residue purified by flash chromatography on silica gel, eluting with dichloromethane. 6,7-Dichloro-2,3-dimethoxy-5-thioacetamidoquinoxaline (17.54 g, 81%) was obtained as a yellow foam.

Provenance & Evidence