Design, synthesis, and biological evaluation of a series of simple and novel potential antimalarial compounds

A series of compounds bearing an endocyclic –N–O– moiety with potential antimalarial activity based on simple derivatives of the tropolone purpurogallin was prepared by means of a hetero Diels–Alder reaction using nitrosobenzene as a dienophile. The rationale behind the design of these compounds is presented, together with the synthetic route to derivatives bearing aromatic and aliphatic esters of the C4′-position hydroxyl group of the purpurogallin framework, as well as biological data obtained from in vitro assays against Plasmodium falciparum and Trypanosoma cruzi. Several of the new compounds have activities in the 3–9 μM range, and provide leads for the development of a novel class of antiparasitic drugs with improved biological and pharmacological properties.