34236-47-0Relevant academic research and scientific papers
Fluorinated Phenanthrenes as Aryne Precursors: PAH Synthesis Based on Domino Ring Assembly Using 1,1-Difluoroallenes
Abe, Masashi,Fuchibe, Kohei,Ichikawa, Junji,Idate, Hiroto
, (2020/03/05)
On treatment with the catalyst InBr3, 1,1-difluoroallenes that bear a cyclopentene moiety and an aryl group underwent domino ring assembly in the presence or absence of N-bromosuccinimide or N-iodosuccinimide to afford aryne precursors such as three-ringed ortho-fluoro(halo)phenanthrenes, four-ringed ortho-fluoro(halo)tetraphenes, ortho-fluoro(halo)chrysenes and fluoro[4]helicenes. Metalation of the aryne precursors followed by elimination of the fluoride resulted in the unprecedented systematic generation of arynes bearing π-extended systems. Diels?Alder reactions of these arynes with isobenzofurans afforded the corresponding cycloadducts whose reductive aromatisation in an SnCl2/HBr system furnished fully aromatised benzotriphenylenes. In addition, oxidative aryl?aryl coupling (the Scholl reaction) of these benzotriphenylenes facilitated the synthesis of ‘half HBCs’ (hexabenzocoronenes).
Regiospecifically Fluorinated Polycyclic Aromatic Hydrocarbons via Julia-Kocienski Olefination and Oxidative Photocyclization. Effect of Fluorine Atom Substitution on Molecular Shape
Banerjee, Shaibal,Sinha, Saikat,Pradhan, Padmanava,Caruso, Alessio,Liebowitz, Daniel,Parrish, Damon,Rossi, Miriam,Zajc, Barbara
, p. 3983 - 3993 (2016/06/09)
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.
Domino synthesis of fluorine-substituted polycyclic aromatic hydrocarbons: 1,1-difluoroallenes as synthetic platforms
Fuchibe, Kohei,Mayumi, Yuka,Zhao, Nan,Watanabe, Shumpei,Yokota, Misaki,Ichikawa, Junji
, p. 7825 - 7828 (2013/08/23)
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
Synthesis of the K-Region Monofluoro- and Difluorobenzophenanthrenes
Mirsadeghi, Seid,Prasad, Ganesh K. B.,Whittaker, Noel,Thakker, Dhiren R.
, p. 3091 - 3096 (2007/10/02)
Polycyclic aromatic hydrocarbons are metabolically activated by cytochromes P-450 an epoxide hydrolase to ultimate mutagens and carcinogens.Substitution by fluorine at specific positions has been used to elucidate metabolic activation and detoxication pathways of polycyclic aromatic hydrocarbons.Substitution by fluorine at the K-region C-6 position of the weak carcinogen benzophenanthrene (1) causes a >4-fold increase in its tumorigenicity.Out of the six possible monofluorobenzophenanthrenes, only 5-fluorobenzophenanthrene (8a) has not been evaluated as a carcinogen, presumably because a convenient synthetic method for the 5-fluoro derivative has not been available.Hence, a new method has been developed for the synthesis of 8a from readily available starting materials.The method consists of selective bromination of benzophenanthrene (1) to 5-bromobenzophenanthrene (3), substitution of bromine by an amino group, and a modified Schiemann reaction of 5-aminobenzophenanthrene (6a) to yield 5-fluorobenzophenanthrene (8a).An improved method for the synthesis of 6-fluorobenzophenanthrene (19) has also been developed which consist of bromofluorination of β-naphthylstyrene, followed by selective dehydrobromination and photocyclization of the fluorostyrene to the 6-fluoro derivative 19.The above methods, with minor modifications, also provided synthetic routes for the preparation of the difluoro derivatives 5,7-, 5,8-, and 6,7-difluorobenzophenanthrenes.
SYNTHESIS OF MONOFLUOROBENZOPHENANTHRENES
Ittah,Yitzhak,Jerina, Donald M.
, p. 137 - 144 (2007/10/02)
Synthesis of 1-, 2-, 3- and 4-fluorobenzophenanthrenes by photocyclization of appropriate β-naphth-1-yl fluorostyrene is described.An improved synthesis of 6-fluorobenzophenanthrene was developed.Partial photochemical debromination occured upon cycl
