Desulfonylative radical ring closure onto aromatics. A modular route to benzazepin-2-ones and 5-arylpiperidin-2-ones

Adducts from the intermolecular radical addition of N-xanthylacetyl-N-methanesulfanilides to Boc-protected allylamine undergo ring closure with loss of a methanesulfonyl radical to give benzazepin-2-ones. Upon deprotection and exposure to triethylamine, these compounds rearrange into 5-aryl-2-piperidones. This approach also represents a useful route to benzazepin-2-ones unsubstituted on the nitrogen atom of the azepinone ring.