5,20-Bis(ethoxycarbonyl)-hexaphyrin was synthesized by acid catalyzed cross-condensation of meso-diaryl-substituted tripyrrane and ethyl 2-oxoacetate followed by subsequent oxidation. This hexaphyrin was found to be a stable 28π-antiaromatic compound with a dumbbell-like conformation. Upon oxidization with PbO 2 , this hexaphyrin was converted into an aromatic hexaphyrin with a rectangular shape bearing two ester groups at the edge side. The hexaphyrin can incorporate two Ni II or Cu II metals by using the ester carbonyl groups and three pyrrolic nitrogen atoms to give bis-Ni II and bis-Cu II complexes with essentially the same dumbbell-like structure. The antiaromatic properties of the hexaphyrin and its metal complexes have been well characterized.
Bibliographical noteFunding Information:
This work at Kyoto was supported by Grant-in-Aid from JSPS for Scientific Research (A): 18H03910, Challenging Exploratory Research: 18K19074. The work at Yonsei was supported by the Global Research Laboratory (GRL) Program funded by the Ministry of Science, ICT & Future, Korea (2013K1A1A2A02050183). The authors thank to Prof. Dr. Yorimitsu at Kyoto University for HR-MS measurements, and Prof. Dr. Maeda at Ritsumeikan University for MALDI TOF-MS measurements.
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All Science Journal Classification (ASJC) codes
- Organic Chemistry