Circulene

A circulene is a macrocyclic arene in which a central n-sided polygon is completely surrounded and fused by benzenoids.^[1] [5]circulene (corannulene), [6]circulene (coronene), [7]circulene,^[2][3][4][5] and [12]circulene (kekulene) have all been synthesized in the laboratory. These compounds belong to a larger class of geodesic polyarenes. Whereas [5]circulene is bowl-shaped and [6]circulene is planar, [7]circulene has a unique saddle-shaped structure (compare to cones and partial cones in calixarenes). Conceptually related compounds are the helicenes.

Quadrannulene

The isolation of quadrannulene or tetrabenzo[4]circulene has been reported.^[6]

[8]Circulenes

The isolation of the [8]circulene derivative 2,5,6,9,10,13,14-octamethyl-3,4,7,8,11,12,15,16-octa(4-tolyl)[8]circulene has been reported ^[7]

Hetrocyclic circulenes

Hetrocyclic circulene is a macrocyclic arene in which a central n-sided polygon is completely surrounded and fused by heterocycle. Sulflower is a stable heterocyclic octacirculene based on thiophene.

Gallery

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  Corannulene ([5]circulene)

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  Coronene ([6]circulene)

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  [7]circulene

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  Sulflower, an octacirculene

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  Kekulene ([12]circulene)

References

1. Dopper, J.H.; Wynberg, Hans (1972). "Heterocirculenes a new class of polycyclic aromatic hydrocarbons". Tetrahedron Letters. 13 (9): 763–766. doi:10.1016/S0040-4039(01)84432-4.
2. Yamamoto, Koji; Harada, Tadashi; Nakazaki, Masao; Naka, Takuo; Kai, Yasushi; Harada, Shigeharu; Kasai, Nobutami (1983). "Synthesis and characterization of [7]circulene". Journal of the American Chemical Society. 105 (24): 7171–7172. doi:10.1021/ja00362a025.
3. Koji, Yamamoto; Tadashi, Harada; Yoshio, Okamoto; Hiroaki, Chikamatsu; Masao, Nakazaki; Yasushi, Kai; Takuo, Nakao; Mitsuya, Tanaka; Shigeharu, Harada; Nobutami, Kasai (1988). "Synthesis and molecular structure of [7]circulene". Journal of the American Chemical Society. 110 (11): 3578–3584. doi:10.1021/ja00219a036.
4. Yamamoto, K.; Sonobe, H.; Matsubara, H.; Sato, M.; Okamoto, S.; Kitaura, K. (1996). "Convenient New Synthesis of [7]Circulene". Angew. Chem. Int. Ed. Engl. 35: 69–70. doi:10.1002/anie.199600691.
5. Extended systems of closed helicene. Synthesis and characterization of [7] and [7.7]-circulene Koji Yamamoto Pure & Appl. Chem., Vol. 65, No. 1, pp. 157-163, 1993. Online article
6. Bharat, Bhola; Bally, T.; Valente, A.; Cyrański, Michał K.; Dobrzycki, Ł.; Spain, Stephen M.; Rempała, P.; Chin, Matthew R.; King, Benjamin T. (2010). "Quadrannulene: A Nonclassical Fullerene Fragment". Angew. Chem. Int. Ed. 49: 399–402. doi:10.1002/anie.200905633.
7. Feng, C.-N.; Kuo, M.-Y.; Wu, Y.-T. (2013). "Synthesis, Structural Analysis, and Properties of [8]Circulenes". Angew. Chem. Int. Ed. 52: 7791–7794. doi:10.1002/anie.201303875.