Substituted Nitrogen-Bridged Diazocines

Novel nitrogen bridged diazocines (triazocines) were synthesized that carry a formyl or an acetyl group at the CH 2 NR- bridge and bromo- or iodo substituents at the distant phenyl ring. The photophysical properties were investigated in acetonitrile and water. As compared to previous approaches the yields of the intramolecular azo cyclizations were increased (from ~40 to 60%) by an oxidative approach starting from the corresponding aniline precursors. The Z → E photoconversion yields in acetonitrile are 80-85% and the thermal half-lives of the metastable E configurations are 31-74 min. Particularly, the high photoconversion yields (~70%) of the water-soluble diazocines are noteworthy, which makes them promising candidates for applications in photopharmacology. The halogen substituents allow further functionalization via cross-coupling reactions.