Intramolecular/Intermolecular Sequential Cyclization Accompanied by Double C–F Bond Cleavage: Access to Tricyclic Fluorine-Containing Pyrano[3,2-<i>c</i>]chromenes

Defluorinative cyclization of CF₃-alkenes has emerged as a reliable strategy for crafting intricate polycyclic frameworks. In this study, a facile defluorinative bicyclization approach was developed for the construction of 4<i>H</i>,5<i>H</i>-pyrano[3,2-<i>c</i>]chromenes under mild conditions involving a sequence of intramolecular cyclization and intermolecular defluoroheterocyclization. A variety of polysubstituted 4<i>H</i>,5<i>H</i>-pyrano[3,2-<i>c</i>]chromenes featuring C2-fluorine could be synthesized in good yields with excellent tolerance toward various functional groups. Moreover, the introduction of a C-F bond provides additional possibilities for further modification of this skeleton. The product features aggregation-induced emission (AIE) characteristics after simple modification, which is promising for chemical and biomedical imaging.