The mild epoxidation of strained alkenes using (DMPO)(2)MnCI catalyst (DMPO= 1,2-dimethy1-4(1H)pyridinone-3-olate) in the presence of various oxidants was studied. Hydrogen peroxide and monopersulfate were found to be the best oxidants when used with imidazole in acetonitrile at 4 degrees C, with up to 94% conversion. Dismutation of hydrogen peroxide was also observed when used as an oxidant. The epoxidation using hydrogen peroxide or monoperoxysulfate appears to be mild and very selective for strained alkenes. A mechanism is proposed where imidazole is required for activation of the oxidant and where a detected Mn-v = 0 species is proposed as the active species. Competitive reaction between H2O2 and the substrate for the active species is proposed and homolytic vs heterolytic scissions of the O-O bond of the oxidant are discussed. (C) 2014 Elsevier B.V. All rights reserved.