Fluoro-artemisinins: When a gem-difluoroethylene replaces a carbonyl group

Exo gem-difluoromethylene-artemisinins (8) has been designed to mimic artemisinin. The classical Wittig olefination reaction applied to artemisinin failed. An alternative reaction involving the generation of an α-CF3 carbanion, from the corresponding bromide 6, allowed the access to the target compound 8, and could also be exemplified in sugar series. The replacement of the carbonyl function by a difluoroethylene moiety resulted in a better antimalarial activity.