The preparation of D-ring-contracted analogues of Qinghaosu (Artemisinin) from Qinghao (Artemisinic) acid and their In vitro activity against Plasmodium falciparum

Qinghao (Artemisinic) acid was converted into dihydroqinghao aldehyde and then submitted to copper(II)-catalysed oxidative deformylation. The resulting ketone was reduced to the diastereomeric alcohols which were submitted to photooxygenation, and then cleavage-oxygenation-cyclisation, catalysed by Cu(II)(OSO₂CF₃)₂, to give the title compounds. In vitro testing results for antimalarial activity indicated a remarkable dependence on the stereochemistry of the 9-methyl-substituent