Intramolecular/Intermolecular\nSequential Cyclization\nAccompanied by Double C–F Bond Cleavage: Access to Tricyclic\nFluorine-Containing Pyrano[3,2‑<i>c</i>]chromenes

Defluorinative\ncyclization of CF<sub>3</sub>-alkenes has emerged\nas a reliable strategy for crafting intricate polycyclic frameworks.\nIn this study, a facile defluorinative bicyclization approach was\ndeveloped for the construction of 4<i>H</i>,5<i>H</i>-pyrano­[3,2-<i>c</i>]­chromenes under mild conditions involving\na sequence of intramolecular cyclization and intermolecular defluoroheterocyclization.\nA variety of polysubstituted 4<i>H</i>,5<i>H</i>-pyrano­[3,2-<i>c</i>]­chromenes featuring C2-fluorine could\nbe synthesized in good yields with excellent tolerance toward various\nfunctional groups. Moreover, the introduction of a C–F bond\nprovides additional possibilities for further modification of this\nskeleton. The product features aggregation-induced emission (AIE)\ncharacteristics after simple modification, which is promising for\nchemical and biomedical imaging.