E
K. Yamada et al.
Cluster
Synlett
(7) A fulvene derivative containing a TBF unit has been reported;
see: (a) Ramage, R.; Gilles, R. Tetrahedron Lett. 1992, 33, 385.
(b) Brown, A. R.; Irving, S. L.; Ramage, R.; Gilles, R. Tetrahedron
1995, 51, 11815.
(8) For recent studies on direct oxidation of fluorene to fluorenone,
see: (a) Artamkina, G. A.; Grinfel’d, A. A.; Beletskaya, I. P. Bull.
Acad. Sci. USSR, Div. Chem. Sci. (Engl. Transl.) 1983, 32, 345.
(b) Noureldin, N. A.; Zhao, D.; Lee, D. G. J. Org. Chem. 1997, 62,
8767. (c) Zheng, G.; Liu, C.; Wang, Q.; Wang, M.; Yang, G. Adv.
Synth. Catal. 2009, 351, 2638. (d) Jacques, M. Synth. Commun.
1989, 19, 2061. (e) Gershonov, E.; Katz, E.; Karton, Y.; Zafrani, Y.
Tetrahedron 2007, 63, 3762.
Figure 5 Cyclic voltammograms of 7 in DMF at r.t.
(9) 17H-Tetrabenzo[a,c,g,i]fluoren-17-one (4)
In conclusion, we have developed an effective prepara-
tion of 17H-tetrabenzo[a,c,g,i]fluoren-17-one (4) and we
have described the synthesis and physicochemical proper-
ties of the fulvalene derivatives 5–7. Crystallographic analy-
sis revealed a helicene-like nonplanar structure for 4.
Whereas compounds 4—6 are stable dark-red or purple
crystals, the symmetric fulvalene 7 is a rather-air-sensitive
blue solid. Electrochemical measurements revealed that the
fulvalenes presented here are new and efficient electron ac-
ceptors. In particular, 7 acts as a five-stage redox system
with high electron affinity. The novel electronic properties
of 7 are explained in terms of its highly twisted structure as
well as its extended π-electron system, as predicted by DFT
calculations.17 Further studies are underway on the appli-
cability of tetrabenzofluorene derivatives in the design of
other π-conjugated systems, as well as on their potential
use in organic electronic materials.
Dark-red prisms; yield: 256 mg (70%); mp 284.0–286 °C (Lit.2
295 °C). IR (KBr): 3072w, 3057w, 1697s, 1425m, 1095m, 748s,
729s, 718s cm–1. 1H NMR (500 MHz, CDCl3): δ = 7.64–7.84 (m, 8
H), 8.31 (d, J = 8.2 Hz, 2 H), 8.69 (d, J = 7.9 Hz, 2 H), 8.78 (d, J =
8.6 Hz, 2 H), 9.23 (d, J = 8.6 Hz, 2 H). 13C NMR (125.8 MHz,
CDCl3): δ = 122.75, 123.95, 124.85, 125.88, 126.46, 126.58,
126.95, 127.63, 128.46, 128.55, 128.94, 131.60, 134.71, 146.93,
197.44. MS (EI): m/z (%): 380 [M+] (100), 352 [M–CO]+ (35), 350
(38). UV/Vis (CH2Cl2): λmax (ε, M−1·cm−1) = 321 (29500), 336
(33500), 423 (2320), 530 (900) nm.
3,5-Di-tert-butyl-4-(17H-tetrabenzo[a,c,g,i]fluoren-17-
ylidene)cyclohexa-2,5-dien-1-one (5)
Black-red prisms; yield: 15 mg (10%); mp 293–294 °C. FT-IR
(KBr): 719s, 747s, 870m, 1256m, 1364m, 1456w, 1620s (C=O),
2859w, 2947m, 3077w cm–1 1H NMR (500 MHz, CDCl3):
.
δ = 1.18 (s, 18 H), 7.61–7.66 (m, 6 H), 7.73 (t, J = 7.8 Hz, 2 H),
7.90 (s, 2 H), 8.22 (t, J = 8.3 Hz, 2 H), 8.48 (d, J = 8.3 Hz, 2 H), 8.74
(t, J = 8.3 Hz, 2 H), 8.77 (d, J = 8.3 Hz, 2 H). MS (EI): m/z (%): 570
[M + 2]+ (100), 569 [M + 1]+ (10), 568 [M+] (20). HRMS (ESI): m/z
[M + 1]+ calcd for C43H37O: 569.2839; found: 569.2851. UV/Vis
(CH2Cl2): λ (ε, M−1·cm−1) = 301 (26500), 358 (27000), 452
(20500), 529 (6300) nm. 13C NMR spectra for 5–7 could not be
recorded because of the low solubilities of these compounds.
17-(9H-Fluoren-9-ylidene)-17H-tetrabenzo[a,c,g,i]fluorene
(6)
Acknowledgment
This study was supported by Hyogo prefecture and a JSPS Grant-in-
Aid for Scientific Research (C) (No. 25410209).
Black-violet prisms; yield: 7 mg (5%); mp >300 °C. FT-IR (KBr):
733s, 1429w, 1447m, 3034w, 3064w cm–1 1H NMR (500 MHz,
.
Supporting Information
CDCl3): δ = 6.90 (t, J = 7.2 Hz, 2 H), 7.09 (t, J = 7.2 Hz, 2 H), 7.15
(t, J = 7.6 Hz, 2 H), 7.38 (t, J = 7.6 Hz, 2 H), 7.42 (d, J = 7.6 Hz, 2 H),
7.56 (t, J = 7.6 Hz, 2 H), 7.65 (d, J = 7.7 Hz, 2 H), 7.69 (t, J = 7.6 Hz,
2 H), 7.93 (d, J = 8.3 Hz, 2 H), 8.33 (d, J = 8.3 Hz, 2 H), 8.59 (d, J =
8.1 Hz, 2 H), 8.68 (d, J = 8.1 Hz, 2 H). HRMS (ESI): m/z [M+] calcd
for C42H24: 528.1881; found: 528.1873. UV/Vis (CH2Cl2): λ (ε,
Supporting information for this article is available online at
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References and Notes
M−1·cm−1
(13600) nm.
) = 303 (29600), 342 (13100), 359 (12100), 545
(1) (a) Hopf, H. Classics in Hydrocarbon Chemistry: Syntheses, Con-
cepts, Perspectives; Wiley-VCH: Weinheim, 2000. (b) Cross Con-
jugation: Modern Dendralene, Radialene and Fulvene Chemistry;
Hopf, H.; Sherburn, M. S., Eds.; Wiley-VCH: Weinheim, 2016.
(2) Brunetti, F. G.; Gong, X.; Tong, M.; Heeger, A. J.; Wudl, F. Angew.
Chem. Int. Ed. 2010, 49, 532.
(3) De Ridder, R.; Martin, R. H. Bull. Soc. Chim. Belg. 1960, 69, 534.
(4) Schröder, K.; Haase, D.; Saak, W.; Lützen, A.; Beckhaus, R.;
Wichmann, S.; Schellenberg, J. Organometallics 2006, 25, 3824.
(5) Kitamura, C.; Tanigawa, Y.; Kurata, H.; Kobayashi, T.; Naito, H.;
Kawase, T. Tetrahedron 2012, 68, 1688.
17-Bromo-17H-tetrabenzo[a,c,g,i]fluorene (12)
Dark-red prisms; yield: 267 mg (60%); mp 255–256 °C. FT-IR
(KBr): 1125, 1157, 1435, 1447, 3069 cm–1 1H NMR (270 MHz,
.
CDCl3): δ = 6.58 (s, 1 H), 7.62–7.81 (m, 4 H), 8.43 (d, J = 7.6 Hz, 4
H), 8.64 (d, J = 7.9 Hz, 4 H), 8.81 (t, J = 7.6 Hz, 4 H). 13C NMR
(125.8 MHz, CDCl3): δ = 44.35, 123.35, 123.78, 124.81, 125.48,
126.80 (2C), 127.01, 127.71, 127.79, 128.05, 131.00, 132.48,
136.40, 140.04.
The structure was confirmed by the X-ray crystallographic
analysis; see Figure S3 in the Supporting Information.
17,17′-Bi(17H-tetrabenzo[a,c,g,i]fluorenylidene) (7)
Dark-blue leaflets; yield: 40 mg (50%); mp >300 °C. IR (KBr):
(6) Ueda, Y.; Tanigawa, Y.; Kitamura, C.; Ikeda, H.; Yoshimoto, Y.;
Tanaka, M.; Mizuno, K.; Kurata, H.; Kawase, T. Chem. Asian J.
2013, 8, 392.
1
1495, 1564, 1607, 2851, 2920, 2957, 3038, 3073 cm–1. H NMR
(500 MHz, CDCl3): δ = 6.72 (t, J = 7.7 Hz, 4 H), 7.64–7.71 (m, 12
H), 7.96 (d, J = 8.2 Hz, 4 H), 8.42 (d, J = 8.2 Hz, 4 H), 8.49 (d, J =
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–F