Radical initiated reactions of artemisinin derivatives

Abstract

Heating the propynyldihydroartemisinin derivatives 4 and 5 with Bu₃SnH–AIBN in toluene gave the stereoisomers 18 and 20 (5-exo trig products) respectively. The allyl ether 6 gave 21, a 1,2-cis 1,5-trans product under similar conditions, whereas the ether 7 gave two compounds, 22 (1,2-cis 1,5-cis) and 23 (1,2-cis 1,5-trans). The bromo ethers 8–12 gave their corresponding debrominated products whereas the bromo ether 14 and the bromo sulfides 15 and 16 gave the olefin 30.