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Diindenopyrenes: Extended 1,6- and 1,8-Pyrenoquinodimethanes with Singlet Diradical Characters
Daijiro Hibi1, Kenichi Kitabayashi1, Kazuya Fujita1
1Division of Frontier Materials Science, Graduate School of Engineering Science, Osaka University , 1-3 Machikaneyama, Toyonaka 560-8531, Japan.
Abstract:
Diindenopyrene 4b and its diastereomer, which are extended homologues of 1,6- and 1,8-pyrenoquinodimethanes fused by indene units, respectively, were synthesized by reaction of 1,4,5,8-tetrakis(mesitylethynyl)naphthalene (7) with bis(2,4,6-trimethylpyridine)iodine(I) hexafluorophosphate via cationic cyclization mechanisms at both centers of reaction. Unexpectedly, reaction of 7 with iodine, a reagent that typically gives products of cationic cyclization, gave cycloheptapentalenoindenophenalene derivative 9b and its diastereomer incorporating an azulene unit at one end of the π framework, via two different modes (radical and cationic) of cyclization at each reaction site. The physical properties of the products are presented, and the dual modes of cyclization of 7 and its model compound with only one reaction center are discussed.
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