Synthesis, iron(II)-induced cleavage and in vivo antimalarial efficacy of 10-(2-hydroxy-1-naphthyl)-deoxoqinghaosu (-deoxoartemisinin)

Abstract

A convenient methodology for attaching an acid-stable UV chromophore onto the qinghaosu (artemisinin) framework with readily available dihydroqinghaosu acetate as the starting material is presented. The resulting derivatives of deoxoqinghaosu may be used as a sensitive probe in the mechanistic and biological/pharmacological investigations. As the first application of the present methodology, naphth-2-ol is attached to qinghaosu nucleus through a carbon–carbon single bond by a boron trifluoride-catalyzed Friedel–Crafts alkylation. A previously undetected racemization at C-9 mediated by an enol ether under the reaction conditions (BF₃·OEt₂, CH₂Cl₂) that have been widely used for preparing C-10 derivatives of dihydroqinghaosu is observed. The knowledge gained from the present work may assist the rational design of new trioxane-type antimalarial agents.