One-Pot Synthesis of Coumarin-Based Oxazabicyclic and Oxazatricyclic Compounds and Their Fluorescence Redox Switching Properties

An oxazabicycle and an oxazatricycle were efficiently synthesized by coupling of coumarins and N-alkylquinolium or isoquinolium salt to investigate their fluorescence redox-switching properties. Chemical reduction of the strongly fluorescent oxazabicycle and oxazatricycle results in the ring-opened products with a distinct decrease in emission intensity. Both resulting ring-opened species can be swiftly reverted to the original ring-closed forms by oxidation.