反应详情

2,4-Bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulphide (Lawesson's reagent) (19.5 g, 48.2 mmol) was added to a solution of 6,7-dichloro-2,3-dimethoxy-5-methoxyacetamidoquinoxaline (27 g, 78 mmol) in tetrahydrofuran (480 ml) and the mixture was stirred for 18 hours at room temperature, then evaporated under reduced pressure. The residue was purified by flash chromatography on silica gel by gradient elution using hexane:dichloromethane (1:1 changing to 1:4, by volume) as the eluent to give 6,7-dichloro-2,3-dimethoxy-5-methoxythioacetamidoquinoxaline (29.1 g, >100%) as a white solid, mp 198-200° C., containing a minor impurity.

1. customevaporated under reduced pressure
2. customThe residue was purified by flash chromatography on silica gel by gradient elution