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Microwave-assisted Intramolecular Dehydrogenative Diels-Alder Reactions for the Synthesis of Functionalized Naphthalenes/Solvatochromic Dyes
Published on: April 1, 2013
Thiophene-fused bisdehydro[12]annulene that undergoes transannular alkyne cycloaddition by either light or heat
Aiko Fukazawa1, Hiroya Oshima, Yoshihito Shiota
1Department of Chemistry, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya 464-8602, Japan. aiko@chem.nagoya-u.ac.jp
Abstract:
A new bisdehydro[12]annulene derivative having a thiophene-fused structure has been synthesized. This highly twisted π-conjugated macrocycle with two acetylene moieties in close proximity produces a [2+2]-type alkyne cycloadduct by either photoirradiation or mild heating without any transition metals. Theoretical calculations reveal that the thermal reaction proceeds through successive 8π and 4π electrocyclic reactions, while the photochemical reaction is an asynchronous concerted [2+2] cycloaddition. The fused structure with the less-aromatic thiophene ring is crucial for achieving this reaction. The cycloadduct, thiophene-fused biphenylene, has significant potential as a new polycyclic π-scaffold for electronic applications.
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