Nine dihydroartemisinin acetal dimers (6–14) with diversely functionalized linker units were synthesized and tested for in vitro antiprotozoal, anticancer and antimicrobial activity. Compounds 6, 7 and 11 [IC50: 3.0–6.7 nM (D6) and 4.2–5.9 nM (W2)] were appreciably more active than artemisinin (1) [IC50: 32.9 nM (D6) and 42.5 nM (W2)] against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of the malaria parasite, Plasmodium falciparum. Compounds 10, 13 and 14 displayed enhanced anticancer activity in a number of cell lines compared to the control drug, doxorubicin. The antifungal activity of 7 and 12 against Cryptococcus neoformans (IC50: 0.16 and 0.55 μM, respectively) was also higher compared to the control drug, amphotericin B. The antileishmanial and antibacterial activities were marginal. A number of dihydroartemisinin acetal monomers (15–17) and a trimer (18) were isolated as byproducts from the dimer synthesis and were also tested for biological activity.Nine dihydroartemisinin acetal dimers with diversely functionalized linker units were synthesized and tested for in vitro antiprotozoal, anticancer and antimicrobial activity. Full spectroscopic data are given for the title compounds.

Circular dichroism is a powerful tool for establishing the absolute configuration of flavonoids and proanthocyanidin analogues. It has been utilized to study the configuration of flavanones, dihydroflavonols (3-hydroxyflavanones), flavan-3-ols, flavan-4-ols, flavan-3,4-diols, flavans, isoflavans, isoflavanones, pterocarpans, 6a-hydroxypterocarpans, rotenoids, 12a-hydroxyrotenoids, neoflavonoids, 3,4-dihydro-4-arylcoumarins, 4-arylflavan-3-ols, auronols, homoisoflavanones, proanthocyanidins, and various classes of biflavonoids. Results relevant to the correlation of circular dichroic data and the absolute configuration of the diastereoisomers of some of the above classes of compounds will be discussed.Application of circular dichroism to definition of the absolute configuration of flavanones, dihydroflavonols, flavan-3-ols, flavan-4-ols, flavan-3,4-diols, flavans, isoflavans, isoflavanones, pterocarpans, neoflavonoids, and 4-arylflavan-3-ols is discussed.

Covering: January 1999 to December 2001. Previous review: 2000, 17, 193.