Cation-n control of regiochemistry of intramolecular Schmidt reactions en route to bridged bicyclic lactams.

The regiochemistry of the intramolecular Schmidt reaction of 2-azidoalkylketones is controlled by placing a thioether substituent at the position adjacent to the ketone to provide access to a family of unsubstituted medium bridged twisted amides. This outcome is ascribed to the presence of stabilizing through-space interactions between the diazonium cation and the n electrons on heteroatom and does not require a locked conformation of the ketone.