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Synthesis, structure and π-expansion of tris(4,5-dehydro-2,3:6,7-dibenzotropone)
Yongming Xiong1, Xue Lin Ma1, Shilong Su1
1Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
Abstract:
The polycyclic skeleton of tris(4,5-dehydro-2,3:6,7-dibenzotropone) is a key structural fragment in carbon schwarzites, a theoretical form of negatively curved carbon allotrope. This report presents a new synthesis of this compound using a Ni-mediated Yamamoto coupling reaction and structural analysis of it with X-ray crystallography. Interestingly, it is observed that tris(4,5-dehydro-2,3:6,7-dibenzotropone) crystallized from its solution in hexane resulting in colorless and yellow crystal polymorphs, where it adopts conformations of approximate C and C 2 symmetry, respectively. Furthermore, expanding its π-skeleton through the Barton-Kellogg and Scholl reactions led to the successful synthesis of a curved polycyclic arene containing three heptagons and two pentagons.
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