- Regiospecifically Fluorinated Polycyclic Aromatic Hydrocarbons via Julia-Kocienski Olefination and Oxidative Photocyclization. Effect of Fluorine Atom Substitution on Molecular Shape
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A modular synthesis of regiospecifically fluorinated polycyclic aromatic hydrocarbons (PAHs) is described. 1,2-Diarylfluoroalkenes, synthesized via Julia-Kocienski olefination (70-99% yields), were converted to isomeric 5- and 6-fluorobenzo[c]phenanthrene, 5-and 6-fluorochrysene, and 9- and 10-benzo[g]chrysene (66-83% yields) by oxidative photocyclization. Photocyclization to 6-fluorochrysene proceeded more slowly than conversion of 1-styrylnaphthalene to chrysene. Higher fluoroalkene dilution led to a more rapid cyclization. Therefore, photocyclizations were performed at higher dilutions. To evaluate the effect of fluorine atom on molecular shapes, X-ray data for 5- and 6-fluorobenzo[c]phenanthrene, 6-fluorochrysene, 9- and 10-fluorobenzo[g]chrysene, and unfluorinated chrysene as well as benzo[g]chrysene were obtained and compared. The fluorine atom caused a small deviation from planarity in the chrysene series and decreased nonplanarity in the benzo[c]phenanthrene derivatives, but its influence was most pronounced in the benzo[g]chrysene series. A remarkable flattening of the molecule was observed in 9-fluorobenzo[g]chrysene, where the short 2.055 ? interatomic distance between bay-region F-9 and H-8, downfield shift of H-8, and a 26.1 Hz coupling between F-9 and C-8 indicate a possible F-9···H-8 hydrogen bond. In addition, in 9-fluorobenzo[g]chrysene, the stacking distance is short at 3.365 ? and there is an additional interaction between the C-11-H and C-10a of a nearby molecule that is almost perpendicular.
- Banerjee, Shaibal,Sinha, Saikat,Pradhan, Padmanava,Caruso, Alessio,Liebowitz, Daniel,Parrish, Damon,Rossi, Miriam,Zajc, Barbara
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p. 3983 - 3993
(2016/06/09)
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- Pinpoint-fluorinated phenacenes: New synthesis and solubility enhancement strategies
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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.
- Fuchibe, Kohei,Morikawa, Toshiyuki,Shigeno, Kento,Fujita, Takeshi,Ichikawa, Junji
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supporting information
p. 1126 - 1129
(2015/03/14)
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- Domino synthesis of fluorine-substituted polycyclic aromatic hydrocarbons: 1,1-difluoroallenes as synthetic platforms
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Rather crafty: 1,1-Difluoroallenes bearing an aryl group and a cyclopentene moiety undergo indium(III)-catalyzed Friedel-Crafts-type cyclization with subsequent ring expansion and dehydrogenation to afford fluorinated polycyclic aromatic hydrocarbons in high yields. The introduction of an Ar group was effected by in situ halogenation of the intermediary indium species and a subsequent Suzuki-Miyaura reaction. Copyright
- Fuchibe, Kohei,Mayumi, Yuka,Zhao, Nan,Watanabe, Shumpei,Yokota, Misaki,Ichikawa, Junji
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supporting information
p. 7825 - 7828
(2013/08/23)
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