Mechanisms for the Reactions of Nitrones with Aroyl Chlorides

Article abstract of DOI:10.1021/ja00377a025

Reaction of nitrones with equivalent quatities of aroyl chlorides in anhydrous dioxane containing triethylamine aields N,N-diacylamines.Treatment of nitrons with 18O-labeled benzoyl chloride under these conditions forms N,N-diacylamines with the 18O label distributed equally between the two acyl groups.Reaction of nitrones with equivalent or excess amounts of aroyl chlorides in anhydrous dioxane in the absence of triethylamine brings about isomerization of the nitrones to amides. α-Phenyl-N-(p-tolyl)nitrone treated with <18O>benzoyl chloride leads to an amide containing 50percent of the 18O label.Both reactions can be rationalized on the basis of the formation of aroyloxy(benzylidene)ammonium chlorides which undergo elimination of acid anions or acid to yield nitrillium ions.Addition of the acid anions or acids to the nitrillium ions affords the precursors to the N,N-diacylamines or isomerized amides, respectively.