Several 9-substituted derivatives of the antimalarial drug artemisinin have been prepared by functionalizing the double bond of artemisitene and related compounds. Stereochemical assignments for these compounds were made using a combination of NMR experiments, an X-ray diffraction study of one compound, and chemical correlations of several other compounds with this one compound of unambiguous structure and with its epimer. The compounds synthesized show a wide variation in in vitro antimalarial activity.