Chemical Stability of the Peroxide Bond Enables Diversified Synthesis of Potent Tetraoxane Antimalarials

The development of widespread drug resistance to chloroquine (CQ(a)) has resulted in severe health issues for countries in malaria endemic regions. The antimalarial properties of artemisinin 2 and of other peroxides, such as 1,2,4,5-tetraoxacy-cloalkanes (tetraoxanes), have recently begun to be exploited in the development of new approaches to fighting CQ-resistant strains of malaria. New tetraoxanes employing a steroidal backbone have now been prepared that are highly active, are inexpensive, and demonstrate low toXieity.(5,6) A part of our research in this field is focused on the development of a new type of tetraoxane with nonidentical substituents(6) that utilize a steroid and small cyclohexylidene carriers possessing secondary amide bonds. Also, during our work in this field we discovered that tetraoxanes are unusually stable, even. at pH 1.6,(6c) a characteristic that subsequently allowed the synthesis of many interesting derivatives. This communication encompasses the synthesis of various amino-functionalized antimalarials based on the appreciable stability of the tetraoxane moiety to reaction conditions such as reductive amination and LiAlH4 reduction. Their respective antimalarial activities and the pronounced antiproliferative activity of certain products are reported along with in vitro metabolism studies.