Methyl 3,5-diaminopyrazine-2-carboxylate → Methyl 3,5-diamino-6-fluoropyrazinoate

Participants

Reaction Conditions

Reaction Steps

In a Kel-FR reactor cooled to -78° C in an acetone-dry ice bath is placed methyl 3,5-diaminopyrazinoate (6g.) and liquid hydrogen fluoride (70 ml.). A stream of fluorine-helium mixture (1:4 v/v) is passed through the solution for 51/2 hours at -78° C. followed by a vigorous stream of nitrogen to remove the solvent. The reaction residue is treated with conc. hydrochloric acid (60 ml.), evaporated to dryness, dissolved in water (75 ml.) and neutralized with aqueous sodium hydroxide to give methyl 3,5-diamino-6-fluoropyrazinoate (5 g.) which is purified by sublimation (140°-50° C., 0.05 mm Hg.) and recrystallization from 2-propanol.

Provenance & Evidence