Influence of an additional amino group on the potency of aminoadamantanes against influenza virus A. II - Synthesis of spiropiperazines and in vitro activity against influenza A H3N2 virus.

Spiro[piperidine-2,2'-adamantane] 4 is one of the most potent synthetic anti-influenza A aminoadamantanes or other cage structure amines tested so far. Based on previous results Tataridis et al. (2007) [5h] which demonstrate the boost of in vitro potency by the presence of an additional amino group, we examined whether the incorporation of a second amino group into this heterocycle would increase the anti-influenza A virus activity. The new synthetic molecules 5-7 are capable of forming two hydrogen bonds within the receptor. We identified the diamino derivatives 5 and 6, which are active against influenza A H3N2 virus although less potent than amantadine and its equipotent spiropiperidine 4.