Ruthenium tetroxide oxidation of N-acylated alkylamines : A new general synthesis of imides.

Oxidation of various N-acylalkylamines with ruthenium tetroxide (RuO4) was systematically investigated. N-Acylalkylamines having an electron-donating group at the α-or β-position with respect to amide nitrogen or an electron-donating alkyl function in the acyl group were smoothly oxidized to the corresponding imides in excellent yields. On the other hand, N-acylalkylamines having an electron-withdrawing group were not oxidized at all, and most of the starting material was recovered. It appears that the reactivity of N-acylalkylamines is closely correlated with the acidity of the carboxylic acid from which the N-acyl group is derived, and also with the electron density at the methylene moiety adjacent to the amide nitrogen atom.