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

The regiochemistry of the intramolecular Schmidt reaction of 2-substituted ketones has proved susceptible to control by the placement of an aromatic group at an adjacent position, permitting the selective formation of a series of bridged bicyclic lactams from these substrates. This phenomenon is ascribed to the presence of stabilizing through-space interactions between the positively charged leaving group and the aromatic substituents in a key azidohydrin intermediate.