tert-Butyl 4-(5-bromo-3-((1-(hydroxyamino)ethylidene)amino)pyrazin-2-yl)piperazine-1-carboxylate → 5-Bromo-2-methyl-8-(piperazin-1-yl)-[1,2,4]triazolo[1,5-a]pyrazine

Participants

Reaction Steps

In a 50 mL round bottom flask, tert-butyl 4-(5-bromo-3-((1-(hydroxyamino)ethylidene)amino)pyrazin-2-yl)piperazine-1-carboxylate (2.3 g, 5.5 mmol) was treated with polyphosphoric acid (10 g) at 50° C. for 1 h then at 75° C. for 1.75 h. Work-up: the mixture was carefully neutralized with saturated aqueous NaHCO3 (300 mL) and extracted with CH2Cl2 (100 mL×3). The combined organic layers were dried over anhydrous Na2SO4 and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel with 5% EtOAc in CH2Cl2 (containing 2% Et3N), to afford 1.0 g (61%) of the product as a white solid. MS m/z: 297 (M+H+).

Provenance & Evidence