Hydrazine → 2-Hydrazino-6,7-difluoroquinoxaline

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Reaction Steps

The foregoing methodology was followed starting with 2-chloro-6,7-difluoroquinoxaline. This compound (4.00 g, 19.9 mmol) was dissolved in 100 ml of absolute EtOH. Hydrazine (1.4 ml, 44 mmol) was added, and the mixture heated at reflux for 21/2 hours. The mixture was cooled and allowed to stand overnight before collecting the resulting precipitate, yielding 3.80 g of an orange, solid 2-hydrazino-6,7-difluoroquinoxaline. This product (3.8 g, 19.4 mmol) was stirred in 30 ml triethylorthoformate and heated at reflux (100° C.) for 5 hours. The resulting product was cooled to room temperature, filtered and dried, yielding 2.63 g of 7,8-difluoro-1,2,4-triazolo[4,3-a]quinoxaline (13). The difluoro compound (13) (1.81 g 8.78 mmol) was added to glacial AcOH (25 ml) and treated with 80% monoperoxyphthalic acid Mg salt.6H2O (2.88 g, 4.66 mmol). The mixture was heated at 60°-70° C. overnight and initially went into solution, then a precipitate formed after 1-2 hours. This was allowed to cool, before pouring onto H2O. The precipitate was collected by filtration and air dried to yield 7,8-difluoro-1,2,4-triazolo[4,3-a]quinoxalin-4(5H)-one (14).

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