The rearrangements of the nitrones of simple cyclic conjugated ketones

Abstract

The ring expansions of N-methyl nitrones formed from cyclic conjugated ketones have been investigated.  Low yields of cyclic amides were obtained. In general, the best conditions for the rearrangementinvolved using p-toluenesulfonyl chloride and polyphosphoric acid in tetrahydrofuran. The parent ketone and, in some cases, an N-aryl sulfonamide were also obtained; mechanisms for their formation are discussed.