Synthesis, structure, and antiviral properties of novel 2-adamantyl-5-aryl-2 H -tetrazoles

The reaction of 5-aryl- NH -tetrazoles with adamantan-1-ol in concentrated sulfuric acid proceeds regioselectively with the formation of the corresponding 2-adamantyl-5-aryl-2 H -tetrazoles. Nitration of these compounds leads to 2-(adamantan-1-yl)-5-(3-nitroaryl)-2 H tetrazoles. The structures and composition of the obtained novel 2-adamantyl-5-aryltetrazoles were proven by IR spectroscopy, 1 H and 13 C NMR spectroscopy, high-resolution mass spectrometry, and also by X-ray structural analysis. According to the simultaneous thermal analysis data, the obtained compounds are thermally stable up to a temperature of about 150°C. In vitro studies have shown that some of the 2-adamantyl-5-aryltetrazoles exhibit moderate inhibitory activity against influenza A (H1N1) virus. The antiviral selectivity index (SI) of 2-[2-(adamantan-1-yl)-2 H -tetrazol-5-yl]-6-bromo-4-nitroaniline is significantly higher (SI 11) than that of the reference drug rimantadine (SI 5).