Photocyclodehydrofluorination (PCDHF) - A synthetic method for fluorinated polynuclear aromatic hydrocarbons

The Mallory type photocyclization involves a series of photoreactions of stilbenes and stilbene-like derivatives which undergo intramolecular cyclization, forming dihydrophenanthrenes and their derivatives under appropriate UV irradiation. In typical Mallory photocyclizations, appropriate oxidants or leaving groups are usually needed to accomplish the overall process. In our research, the fluorine atom functions as an unusual leaving group, introducing a new type of Mallory type photocyclization reaction [special characters omitted] the photocyclodehydrofluorination (PCDHF). Fluorinated stilbenes and their derivatives undergo ring closures, which could be a very useful to produce a large range of fluorinated polynuclear aromatic hydrocarbons that possess a phenanthrene (or heterocyclic analogue of phenanthrene) substructure. This PCDHF method could permit the construction of more extensive structures with high crystal cofaciality and close packing of interest as high mobility organic semiconductors. This methodology, when coupled with other complementary approaches to produce highly fluorinated aromatics and the functionalization of existing perfluoroaromatics should become a formidable arsenal to prepare such materials.