title: Unsymmetric Twofold Scholl Cyclization of a 5,11-Dinaphthyltetracene: Selective Formation of Pentagonal and Hexagonal Rings via Dicationic Intermediates.
abstract: Even though the Scholl reaction is one of the most powerful processes for the synthesis of polycyclic aromatic hydrocarbons (PAHs), its mechanism still remains a subject of discussion. Herein, we report a unique twofold Scholl cyclization of a 5,11-dinaphthyltetracene. Single-crystal X-ray diffraction analysis of the cyclization product revealed that unsymmetric cyclizations of the two naphthyl groups resulted in the formation of fully unsaturated pentagonal and hexagonal rings. The thus obtained product exhibits a twisted π-surface and an absorption band that reaches up to 950 nm. A combined experimental and theoretical study showed that such unsymmetric Scholl cyclizations can be rationalized in terms of a mechanism that involves dicationic intermediates, which stands in contrast to previously reported pathways based on radical cations and arenium ions.
authors.affiliation: Institute for Chemical Research, Kyoto Univeristy, Uji, Kyoto, 611-0011, Japan.
authors.lastname: Chaolumen
authors.affiliation: Institute for Chemical Research, Kyoto Univeristy, Uji, Kyoto, 611-0011, Japan.|PRESTO, Japan) Science and Technology Agency (JST, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
authors.forename: Michihisa
authors.identifier: 0000-0002-5479-2993
authors.initials: M
authors.lastname: Murata
authors.affiliation: Institute for Chemical Research, Kyoto Univeristy, Uji, Kyoto, 611-0011, Japan.
authors.forename: Atsushi
authors.identifier: 0000-0003-1430-0947
authors.initials: A
authors.lastname: Wakamiya
authors.affiliation: Institute for Chemical Research, Kyoto Univeristy, Uji, Kyoto, 611-0011, Japan.
authors.forename: Yasujiro
authors.identifier: 0000-0003-0287-0299
authors.initials: Y
authors.lastname: Murata
keywords: Scholl reaction; X-ray diffraction; fused-ring systems; mechanism; π interactions