Aminopurine and aminoquinazoline scaffolds for development of potential dengue virus inhibitors.

Previous efforts led to dicarboxamide derivatives like 1.3, comprising either an imidazole, pyrazine or fenyl ring as the central scaffold, with many congeners displaying strong inhibitory effects against dengue virus (DENV) in cell-based assays. Following up on some literature reports, the rationale was borne out to preserve the pending groups, now attached to either a 2,6-diaminopurine or 2,4-diaminoquinazoline scaffold. Synthetic efforts turned out less straightforward than expected, but yielded some new derivatives with low micromolar anti-DENV activity, albeit not devoid of cellular toxicity. The purine 14 proved the most potent compound for this series with an EC50 of 1.9 μM and a selectivity index of 58, while the quinazoline 18a displayed an EC50 of 2.6 μM with SI of only 2.