Application： A sol-gel process has been developed for the chemical synthesis of ZnS at room temperature using zinc tert-butoxide and H 2 S as precursors in a toluene solution. The key step that enables this zinc-mediated epoxidation to be catalytic may be the equilibrium between zinc peroxide (R)-15 and zinc tert-butoxide (R)-16 in the presence of t-BuOOH. An additional important feature that renders the dual catalytic cycles feasible is the poor reactivity of zinc tert-butoxide toward the iridium-bound cationic intermediate, whereby the requisite deprotonation process is effectively mediated by zinc tert-butoxide.