Synthesis and antimalarial activities of structurally simplified 1,2,4‐trioxanes related to artemisinin

Eleven derivatives of the clinically useful, antimalarial, 1,2,4‐trioxane artemisinin have been synthesized in only several steps from commercial cyclohexanones. Of these simple, tricyclic 1,2,4‐trioxanes, 10 showed considerable in vitro antimalarial activity, with one being as potent as artemisinin. Some structure‐activity relationship generalizations are made from this series of artemisinin analogs. Triethylsilyl hydrotrioxide (Et 3 SiOOOH), prepared in situ from ozone and triethylsilane, is shown to be a mild, fastacting, and effective dioxetane‐forming reagent with vinyl ethers and with a vinyl thioether on relatively small (50–100 mg) scale.