Rearrangement of tertiary amine oxides—XI : Solvent effects on the reactions of 2- and 4-picoline N-oxides with acetic anhydride

Abstract

The reactions of 2- and 4-picoline N-oxides with acetic anhydride uniformly labelled with 18O have been studied in three different solvents and the products subjectd to 18O analyses. With 2-picoline N-oxide, the change of solvent did not effect the 18O distribution of the resulting main product, 2-acetoxymethylpyridine. The reaction proceeds via “radical cage process”, similar to the previous experiment with no solvent. In the case of 4-picoline N-oxide, the reaction in the sovlents appears to be different, the concentration of 18O in the resulting ester mixture, i.e., 3-acetoyx-4-methylpyridine and 4-acetoxymethylpyridine approaching the value that is expected from the radical pair process. The effect of solvent and the nature of these rearrangements are briefly discussed.