Synthesis and Characterization of Hepta[5][5]circulene as a Subunit of C70 Fullerene

Abstract

The polycyclic aromatic compound with a S-shaped circular arrangement of seven benzene rings, hepta[5][5]circulene 11, was prepared by FVP of bis(1-chlorovinyl)acenaphthofluoranthene 9. The structure and electrochemical properties were also reported.

Cycloaromatization of Open and Masked 1,3-Hexadien-5-ynes − Mechanistic and Synthetic Aspects

“…Instead of the bowl-shaped 72, the nearly planar 8 was isolated in 20% yield and calculated to be more stable than 72 by 28 kcal mol Ϫ1 (Scheme 18, top). [5] Similar observations were made by Rabideau et al [49] Their unsuccessful efforts to synthesize the dimethylbenzcorannulene 74 from 73 at 1000°C resulted predominantly in the formation of the planar 75 (Scheme 18, bottom). Both examples clearly show that the formation, by means of 1,6-C,H insertions of vinylidenecarbenes, of highly strained compounds with curved, bowl-like architecture only has a chance of occurring if alternative cyclizations to more or less planar cycloaromatization products can be precluded by a lack of structural prerequisites.…”

“…Scott's first high-energy approach to corannulene (4) This route to a hydrocarbon, possessing the minimal structure of a C 5v -symmetrical fullerene subunit, was an incentive to prepare further PAHs of this kind, such as, for example, the fullerene fragments 6, [4] 8 [5] (see Scheme 2), 70, [47] and 71 [48] (Scheme 17), albeit that 8 is a planar PAH.…”

“…Stimulated by the spectacular high-temperature gasphase syntheses of medium-sized and large nonalternating PAHs Ϫ such as, for example, of 4 from 3, [3] 6 from 5, [4] or 8 from 7 [5] (Scheme 2) Ϫ further, analogous cycloaromatizations of different 1,3-hexadien-5-ynes or of compounds incorporating such a substructure were studied at different temperatures and in different reactor systems (ampoule, flow and flash vacuum techniques).…”

Spectroscopy of Dibenzorubicene: Experimental Data for a Search in Interstellar Spectra

“…Moreover, the carbon skeleton of DBR is a subunit of C 70 , which has been detected recently in space 5. The synthesis of DBR, which is also known as hepta[5][5]circulene, was first reported by Matsuda et al4 With the exception of two theoretical studies that used semiempirical models,6, 7 the literature is lacking data on DBR, which strengthens the motivation for the present work.…”

“…Dibenzo[ cde , opq ]rubicene (DBR, C 30 H 14 , CAS 175289‐30‐2) is a PAH that shows absorption bands at 424 and 448 nm in a 1,4‐dioxane solution 4. The close proximity between the latter wavelength and the position of one of the strongest DIBs that was found at 442.8 nm has prompted us to the present study 1.…”