Synthesis and SAR evaluation of oxadiazolopyrazines as selective Haemophilus influenzae antibacterial agents

The parallel synthesis and antibacterial activity of 5-hydroxy[1,2,5] oxadiazolo[3,4-b]pyrazines is reported. The compounds were synthesized by condensing diaminofurazan with α-keto acids to give a variety of aryl-substituted analogues. Halogenated phenyl groups at C-6 give rise to the greatest Haemophilus influenzae antibacterial activity.