Facile Synthesis of Azahelicenes and Diaza[8]circulenes through the Intramolecular Scholl Reaction |
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Authors: | Dr. Chihiro Maeda Shuichi Nomoto Koki Akiyama Dr. Takayuki Tanaka Prof. Tadashi Ema |
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Affiliation: | 1. Division of Applied Chemistry Graduate School of Natural Science and Technology, Okayama University Tsushima, Okayama, 700-8530 Japan;2. Department of Chemistry Graduate School of Science, Kyoto University Sakyo-ku, Kyoto, 606-8502 Japan |
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Abstract: | Carbazole-based aza[7]helicenes and hetero[9]helicenes were successfully obtained via the intramolecular Scholl reaction of 3,6-bis(biphenyl-2-yl)carbazole congeners, while the reaction of 3,6-bis(naphthylphenyl)-appended carbazole gave a triple helicene via an unexpected simultaneous double aryl rearrangement. DFT calculations suggested that the rearrangement proceeded via an arenium cation intermediate. In addition, the reaction of methoxy-appended substrate gave an azahepta[8]circulene via the concurrent C−C bond formation. These helical dyes showed circularly polarized luminescence. The azahepta[8]circulene was further transformed into deeply saddle-distorted dibenzodiaza[8]circulenes as the first example of its solution-based synthesis and unambiguous structural determination. |
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Keywords: | carbazoles circularly polarized luminescence circulenes dyes helicenes |
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