ORGANIC
LETTERS
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Vol. 8, No. 9
775-1778
Novel Methodology for the Preparation
of Five-, Seven-, and Nine-Membered
Fused Rings on C60
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Maria Hatzimarinaki and Michael Orfanopoulos*
Department of Chemistry, UniVersity of Crete, Iraklion, Voutes 71003, Crete, Greece
Received January 12, 2006
ABSTRACT
The photocycloaddition of dienyl cyclopropanes to C60 gives a new synthetic approach to yield stereospecifically five-, seven-, and nine-
membered [60]fullerene adducts. Our results suggest the formation of a biradical intermediate between the dienyl substrate and C60. An
electron transfer between the triplet excited state of C60 and the dienyl substrate precedes the formation of the intermediate.
Many reactions for the functionalization of [60]fullerene have
been developed on the basis of its electron-deficient behav-
ior. Photoinduced functionalization of [60]fullerene has
from -0.42 V vs SCE of the ground state to close to 1.14 V
vs SCE of the triplet state. Previously, we reported the [2
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+ 2] functionalization of C60 with moderately electron-rich
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attracted considerable interest because photoexcited C60
p-methoxyarylalkenes as well as with the less-electron-rich
exhibits more electrophilicity than the ground state of C60.2
alkyl-substituted 1,3-butadienes. Stereochemical and sec-
4
3
[
60]Fullerene can easily be excited into its triplet state, C60
,
ondary kinetic isotope effects studies showed that the first
(rate-determining) step of the reaction involves the formation
in quantum yield near unity, elevating the reduction potential
of an open intermediate (dipolar or biradical) between the
(
1) For reviews on fullerene functionalization, see: (a) Wudl, F. In
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C60 and the unsaturated substrate. Moreover, in the case of
Buckminsterfullerenes; Billups, W. E., Ciufolini, M. A., Eds.; VCH
Publishers: New York, 1993; Chapter 13. (b) The Chemistry of Fullerenes;
Taylor, R., Ed.; World, Scientific: Singapore, 1995. (c) Diederich, F.; Isaacs,
L.; Philp, D. Chem. Soc. ReV. 1994, 243. (d) Prato, M.; Maggini, M. Acc.
Chem. Res. 1998, 31, 519. (e) Hirsch, A.; Brettreich, M. Fullerenes; Wiley-
VCH Verlag Gmbh & Co. KGaA: 2005. (f) Komatsu, K.; Murata, M.;
Murata, Y. Science 2005, 307, 238.
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,4-hexadienes, it is noteworthy that the stereochemical
studies favor the involvement of a biradical rather than a
dipolar intermediate.
During the course of our studies on the mechanism of
photocycloadditions of dienes and alkenes to C60, we have
developed a new synthetic approach to prepare functionalized
(2) (a) Akasaka, T.; Ando, W. J. Am. Chem. Soc. 1993, 115, 10366. (b)
Liou, K.-F.; Cheng, C.-H. Chem. Commun. 1996, 1423. (c) Lawson, G. E.;
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(3) (a) Arbogast, J. W.; Darmanyan, A. O.; Foote, C. S.; Rubin, Y.;
Diederich, F. N.; Alvarez, M. M.; Anz, S. J.; Whetten, R. L. J. Phys. Chem.
1991, 95, 11. (b) Arbogast, J. W.; Foote, C. S.; Kao, M. J. Am. Chem. Soc.
1992, 114, 2277.
(4) (a) Vassilikogiannakis, G.; Orfanopoulos, M. Tetrahedron Lett. 1997,
24, 4323. (b) Vassilikogiannakis, G.; Orfanopoulos, M. J. Am. Chem. Soc.
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ulos, M. J. Org. Chem. 2000, 65, 8180. (d) Vassilikogiannakis, G.;
Chronakis, N.; Orfanopoulos, M. J. Am. Chem. Soc. 1998, 120, 9911.
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999, 1, 1509. (e) Mokami, K.; Matsumoto, S.; Okubo, Y.; Fujitsuka, M.;
Ito, O.; Suenobu, T.; Fukuzumi, S. J. Am. Chem. Soc. 2000, 122, 2236. (f)
Akasaka, T.; Maeda, Y.; Wakahara, T.; Mizushima, T.; Ando, W.; W a¨ lchli,
M.; Suzuki, T.; Kobayashi, K.; Nagase, S.; Kako, M.; Nakadaira, Y.;
Fujitsuka, M.; Ito, O.; Sasaki, Y.; Yamamoto, K.; Erata, T. Org. Lett. 2000,
, 2671. (g) Imahori, H.; Tamaki, K.; Araki, Y.; Sekiguchi, Y.; Ito, O.;
Sakata, Y.; Fukuzumi, S. J. Am. Chem. Soc. 2002, 124, 5165.
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0.1021/ol0600887 CCC: $33.50
© 2006 American Chemical Society
Published on Web 04/07/2006