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A 43-member 1,2-dioxolane library was synthesized by coupling a 1,2-dioxolane-3-acetic acid derivative to a range of amines. Ten compounds had EC(50)s30nM against Plasmodium falciparum 3D7 and Dd2 strains, and another 15 compounds had EC(50)s50nM against both 3D7 and Dd2. The library was then subjected to a range of in vitro DMPK assays, which revealed that side chains with a heteroatom were required for favorable solubility, LogD and membrane permeability. CYP450 inhibition was isoform dependent, with 2C19 and 3A4 particularly susceptible, and the majority of compounds tested against rat and human microsomes were metabolized rapidly.

Artemisinin-derived compounds play an integral role in current malaria chemotherapy. Given the virtual certainty of emerging resistance, we have investigated spiro-1,2-dioxolanes as an alternative scaffold. The endoperoxide functionality was generated by the SnCl(4)-mediated annulation of a bis-silylperoxide and an alkene. The first set of eight analogs gave EC(50) values of 50-150 nM against Plasmodium falciparum 3D7 and Dd2 strains, except for the carboxylic acid analog. A second series, synthesized by coupling a spiro-1,2-dioxolane carboxylic acid to four separate amines, afforded the most potent compound (EC(50) approximately 5 nM).