Bowl-shaped fragments of fullerenes, so-called buckybowls, are useful precursors for the synthesis of fullerenes and also have interesting properties themselves. Some fragments of C60, such as corannulene, are well studied. In contrast, there is a lack of methods for the synthesis of bowl-shaped C70 fragments.
Jishan Wu, National University of Singapore and Tianjin University, Fuzhou, China, and colleagues have synthesized a bowl-shaped arylated derivative of a C70 fragment, dicyclopenta[4,3,2,1-ghi:4′,3′,2′,1′-pqr]perylene (pictured). The team used a solution-phase synthesis starting from 3-formylperylene. Friedel–Crafts alkylations were used close the five-membered rings and brominations followed by Suzuki couplings were used to introduce stabilizing aryl substituents.
The resulting arylated C70-fragment is stable and has a bowl shape, which was shown using X-ray crystallography. NMR spectroscopy showed that the compound has an overall antiaromatic character, which is unusual for a buckybowl. The NMR measurements also showed that the bowl undergoes rapid inversion at room temperature.
- Dicyclopenta[4,3,2,1-ghi:4′,3′,2′,1′-pqr]perylene: A Bowl-Shaped Fragment of Fullerene C70 with Global Antiaromaticity,
Ya Zou, Wangdong Zeng, Tullimilli Y. Gopalakrishna, Yi Han, Qing Jiang, Jishan Wu,
J. Am. Chem. Soc. 2019.