The oxidation of an allylic alcohol to its hydroperoxides represents a key step in the synthesis of a series of spirobicyclic, antimalarial trioxanes. Herein, we investigate the continuous photo-oxidation of an allylic alcohol with ¹O₂ in scCO₂, as a ‘green’ alternative to conventional methods, and examine the remaining two steps in the synthesis of antimalarial trioxanes from readily available starting materials.