Pinpoint-Fluorinated Phenacenes: New Synthesis and Solubility Enhancement Strategies

Abstract

The Pd(II)-catalyzed cyclizations of 2,2-difluorovinylated biaryls, following a Friedel-Crafts-type mechanism, provide a new route to pinpoint-fluorinated phenacenes. The single fluorine substituent stabilized the synthesized fluoropicenes (fluoro[5]phenacenes) toward aerial oxidation and contributed to their solubility in organic solvents. For example, 6- and 13-fluoropicenes were 25- and 15-fold more soluble in THF than nonfluorinated picene. X-ray crystal structure analysis revealed that the fluorine substituent did not alter molecular planarity.

Regiospecifically Fluorinated Polycyclic Aromatic Hydrocarbons via Julia–Kocienski Olefination and Oxidative Photocyclization. Effect of Fluorine Atom Substitution on Molecular Shape

“…16c However, in the present cases, we have observed that fluorine-atom substitution does elicit influence on the shapes of the molecules when compared to their unfluorinated analogues. A small deviation from planarity was observed for 6-F-Ch in comparison to chrysene, which is planar, and deviation from planarity increased in 5-F-Ch containing a bay-region fluorine atom.…”

“…On the other hand, synthesis of the isomeric 5-fluorobenzo[ c ]phenanthrene required a completely different approach. 11a Transition-metal-catalyzed introduction of fluorine atom into aromatics has been the focus of recent research and in the context of PAHs, synthesis of 4-aza-10-fluorophenanthrene, 16a 9-fluorophenanthrene, 16b 5-and 6-fluorochrysenes, and fluorinated phenacenes 16c has been reported. Several fluorinated PAHs (F-PAHs) were synthesized via indium(III)-catalyzed cyclization of aryl- and cyclopentene-substituted 1,1-difluoroallenes, followed by ring expansion and dehydrogenation.…”

“…Several fluorinated PAHs (F-PAHs) were synthesized via indium(III)-catalyzed cyclization of aryl- and cyclopentene-substituted 1,1-difluoroallenes, followed by ring expansion and dehydrogenation. 17 Whereas the latter two methods 16c,17 are mechanistically interesting, one potential limitation is a substrate-dependent formation of isomeric monofluoro PAHs.…”

Ni‐Catalyzed Synthesis of Fluoroarenes via [2+2+2] Cycloaddition Involving α‐Fluorine Elimination

“…(2)]. 23 The resulting pinpoint‐fluorinated planar π‐conjugated system can be a promising candidate as organic electronic material 24 …”

“…[23] The resulting pinpoint-fluorinated planar p-conjugated system can be ap romising candidate as organic electronic material. [24] In summary,w eh ave developedanickel-catalyzedm ethod for directs ynthesis of fluoroarenes via a-fluorine elimination. This method for fluoroarene synthesis complements conventional methods, which install fluorine on preformed benzene rings.…”