This application discloses provides a process for the introduction of nitro-group functionality into a compound which contains also a site of unsaturation and/or oxygen functionality by direct (one step) oxidation of an oxime functional group mediated by a molybdenum VI/VII peroxo complex, the process comprising: (a) providing a substrate of Formula I containing an oxime functional group;  wherein R1 and R2 are selected independently from linear, branched or cyclic alkyl and linear, branched or cyclic alkenyl groups, optionally substituted, with the proviso that at least one of R1 or R2 contains a carbon/carbon double bond; and (b) contacting said substrate of Formula I with a molybdenum oxidation complex, thereby oxidizing said oxime functional group to a nitro functional group to yield the structure of Formula III. Where R1 and R2 are as defined above.