ASYMMETRIC SYNTHESIS--STRUCTURE, STEREOCHEMISTRY AND NMR

Diabetes, Digestive, Kidney Diseases

Investigators

Abstract

Two series of N-substitutited 11-azaartemisinins were prepared and a new synthesis of 10b-alkyldeoxoartemisinis was developed. Many of the compounds were four or seven times more active in vitro against drug resistant strains of Plasmodium falciparum than the lead compound artemisinin. The first series involved a base catalyzed addition of olefins conjugated with a variety of electron withdrawing groups to 11-azaartemisinin. The second involved a dimethylaminopyridine catalyzed addition of terminal acetylenes conjugated to electron withdrawing groups to 11-azaartemisinin. The new synthesis of 10b-alkyldeoxoartemisinins from artemisinin was also developed. The synthesis involves redution of artemisinin by diisobutyl aluminum hydride followed by acetylation. The latter acetyl derivative was treated with titanium tetrachloride and a series of trimethylsiloxyl enol ethers to produce a series of 10b-alkyldeoxoartemisinins. The antimalarial activities of all new compounds were determined. A third series of compounds were prepared by acid catlyzed Michael additions to artemisitene. The compounds were four to seven times more active than artemisinin.