Aza-Ring Expansion of cis-Bicyclooctanones and Related Compounds. A Regiospecific Synthesis of cis-Octahydroindolones

Article abstract of DOI:10.1021/jo00141a014

The aza-ring expansion of a series of 1-substituted cis-bicyclo<4.2.0>octan-7-ones and related compounds has been examined.Beckmann rearrangement of oximes of the ketones 2, 6, and 7 under acid conditions affords as the major products the corresponding octahydroisoindolones 4, 8, and 9, respectively.In contrast to the Beckmann transformation, the N-methylnitrones derived from 2, 6, and 7 on treatment with p-toluenesulfonyl chloride undergo a regio- and stereospecific rearrangement to the respective cis-octahydroindolones 13, 14, and 20.The factors responsible for controling the different regiochemistry exhibited by the Beckmann and nitrone rearrangements in cis-bicyclo<4.2.0>octanones and analogous systems are discussed.