Two-step reduction of the O-methyloxime group in the antibiotic cefetamet

Most oximes as well as their N-alkyl and O-alkyl derivatives are electrochemically reduced in a single four-electron step to the amine. Some exceptions have been reported, where the reduction occurs in two two-electron steps. The reduction of the O-methyloxime grouping in the antibiotic cefetamet occurs at pH 5–9 in two steps, corresponding to a reduction to the imine and amine, respectively. It has been shown that the separation of the two two-electron processes is caused by differences in position and rate of establishment of acid–base equilibria resulting in protonations of the oxime and imino grouping.