A simple synthesis of C-10 substituted deoxoartemisinin and 9-epi-deoxoartemisinin with various organozinc reagents

A direct substitution reaction of 10α- or 10β-benzenesulfonyl dihydroartemisinin, prepared from dihydroartemisinin with thiophenol in the presence of BF3Et2O and consecutive oxidation with H2O2/urea complex, with organozinc reagents derived from allyl, benzyl, phenyl, vinyl and n-butyl Grignard reagents stereoselectively produced C-10 substituted deoxoartemisinins in good to moderate yields. The same reaction of 10β-benzenesulfonyl-9-epi-dihydroartemisinin gave corresponding 9-epi-deoxoartemisinin derivatives.