Selective syntheses of novel polyether fullerene multiple adducts

Article abstract of DOI:10.1021/jo034542l

We have applied a modified macrocyclic tether approach to control multiple additions to C₆₀. The technique of ³He NMR was used to confirm the selective formation of specific C₆₀ multiple adducts by the macrocyclic tether approach. An oligoglycol was used as a flexible linker to produce macrocyclic polyether-linked malonates 5, 6, 8, and 9 under solid-liquid PTC (phase-transfer-catalysis) conditions. The formation of a single C₆₀ tris-adduct, 3, from macrocyclic malonate 1 and ³He@C₆₀ was proven by ³He NMR. Similarly, multiple additions to C₆₀ of macrocyclic polyether malonate 5 gave C₆₀ bis-adduct 10 selectively, while the reaction of C₆₀ with macrocyclic malonate 8 gave bis-adducts 11 and 12. A similar process with macrocyclic malonate 6 gave tris-adduct 13 with high selectivity as well. Saponification of these C₆₀ multiple adducts gives the corresponding polyacids that are potentially useful in biological applications. Macrocyclic polyether fullerenes are a new class of ionophores, which could be interesting for molecular recognition and for the development of biosensors.

Full text of DOI:10.1021/jo034542l

Selective Syn th eses of Novel P olyeth er F u ller en e Mu ltip le
Ad d u cts
Zhiguo Zhou, David I. Schuster, and Stephen R. Wilson*
Department of Chemistry, New York University, 100 Washington Square East,
New York, New York 10003
steve.wilson@nyu.edu
Received April 28, 2003
We have applied a modified macrocyclic tether approach to control multiple additions to C60. The
technique of 3He NMR was used to confirm the selective formation of specific C60 multiple adducts
by the macrocyclic tether approach. An oligoglycol was used as a flexible linker to produce
macrocyclic polyether-linked malonates 5, 6, 8, and 9 under solid-liquid PTC (phase-transfer-
catalysis) conditions. The formation of a single C60 tris-adduct, 3, from macrocyclic malonate 1 and
3
3He@C60 was proven by He NMR. Similarly, multiple additions to C60 of macrocyclic polyether
malonate 5 gave C60 bis-adduct 10 selectively, while the reaction of C60 with macrocyclic malonate
8 gave bis-adducts 11 and 12. A similar process with macrocyclic malonate 6 gave tris-adduct 13
with high selectivity as well. Saponification of these C60 multiple adducts gives the corresponding
polyacids that are potentially useful in biological applications. Macrocyclic polyether fullerenes
are a new class of ionophores, which could be interesting for molecular recognition and for the
development of biosensors.
In tr od u ction
leads to a mixture of eight bis-isomers. Although the
equatorial and trans-3 bis-adducts are favored, the
selectivity is quite poor. Further addition to certain bis-
adducts shows higher selectivity, but chromatographic
separation of isomers becomes increasingly more difficult.
To overcome these difficulties, several research groups
have independently developed synthetic methods to
produce isomeric bis- and tris-adducts with higher
selectivity.13-15 Recently, Hirsch and co-workers have
come up with a tether-directed approach, in which
macrocyclic malonates incorporating alkyldiols as linkers
between the malonate groups were used to control
multiple additions to C60.16
We are interested in designing and developing C60
multiple adducts with defined three-dimensional struc-
tures, which have poly-oxygen binding sites for complex-
ation with biologically relevant substances, such as metal
cations and alkylammonium ions. We modified Hirsch’s
approach for the selective preparation of polyether
fullerene bis- and tris-adducts, using macrocyclic poly-
ether malonates to control the remote multifunctional-
ization of C60. The technique of 3He NMR has been found
to be a powerful and reliable tool for characterization of
C60 multiple adducts,17,18 and it was used to confirm the
Since the discovery of C60, syntheses and properties of
its derivatives have become the focus of intensive study.1
C60 multiple adducts have been widely used in a variety
of fields of science. In particular, multiple adducts with
a defined three-dimensional structure are of increasing
interest with respect to their electrochemical,2 chiropti-
cal,3 spectroscopic,4 biological,5-8 and material proper-
ties.9-11 The usual method for syntheses of C60 multiple
adducts is stepwise addition. For the widely used Bingel-
Hirsch reaction,12 the second addition of diethyl malonate
(1) Wilson, S. R.; Schuster, D. I.; Nuber, B.; Meier, M. S.; Maggini,
M.; Prato, M.; Taylor, R. Fullerenes: Chemistry, Physics, and Technol-
ogy, Kadish, K. M., Ruoff, R. S., Eds.; Wiley-Interscience: New York,
2000; pp 91-176.
(2) Kessinger, R.; Gomez-Lopez, M.; Boudon, C.; Gisselbrechet, J .-
P.; Gross, M.; Echegoyen, L.; Diederich, F. J . Am. Chem. Soc. 1998,
120, 8545.
(3) Djojo, F.; Hirsch, A.; Grimme, S. Eur. J . Org. Chem. 1999, 11,
3027.
(4) Guldi, D. M.; Hungerbuhler, H.; Asmus, K. D. J . Phys. Chem.
1995, 99, 9380.
(5) Wilson, S. R. Fullerenes: Chemistry, Physics and Technology;
Kadish, K. M., Ruoff, R. S., Eds.; Wiley-Interscience: New York, 2000;
pp 437-465.
(6) Dugan, L. L.; Turetsky, D. M.; Du, C.; Lobner, D.; Wheeler, M.;
Almli, C. R.; Shen, C. K. F.; Luh, K. Y.; Choi, D. W.; Lin, T. S. Proc.
Natl. Acad. Sci. U.S.A. 1997, 94, 9434.
(7) Wolff, D. J .; Mialkowski, K.; Richardson, C. F.; Wilson, S. R.
Biochemistry 2001, 40, 37.
(8) Wolff, D. J .; Barbieri, C. M.; Richardson, C. F.; Schuster, D. I.;
Wilson, S. R. Arch. Biochem. Biophys. 2002, 399, 130.
(9) Wilson, S. R.; Cayetano, V.; Yurchenko, M. Tetrahedron 2002,
58, 4041.
(10) Wilson, S. R.; Yurchenko, M.; Schuster, D. I.; Yurchenko, E.
N.; Sokolova, O.; Braslavsky, S. E.; Klihm, G. J . Am. Chem. Soc. 2002,
124, 1977.
(12) Hirsch, A.; Lamparth, I.; Karfunkel, H. R. Angew. Chem., Int.
Ed. Engl. 1994, 33, 437.
(13) Diederich, F.; Kessinger, R. Acc. Chem. Res. 1999, 32, 537.
(14) van Eis, M. J .; Alvarado, R. J .; Echegoyen, L.; Seiler, P.;
Diederich, F. Chem. Commun. 2000, 19, 1859.
(15) Taki, M.; Sugita, S.; Nakamura, Y.; Kasashima, E.; Yashima,
E.; Okamoto, Y.; Nishimura, J . J . Am. Chem. Soc. 1997, 119, 926.
(16) Reuther, U.; Brandmu¨ller, T.; Donaubauer, W.; Hampel, F.;
Hirsch, A. Chem. Eur. J . 2002, 8, 2261.
(11) Wilson, S. R.; Yurchenko, M.; Schuster, D. I.; Khong, A.;
Saunders: M. J . Org. Chem. 2000, 65, 2619.
(17) Saunders: M.; Cross, R. J .; J imenez-Vazquez, H. A.; Shimshi,
R.; Khong, A. Science 1996, 271, 1693.
10.1021/jo034542l CCC: $25.00 © 2003 American Chemical Society
Published on Web 09/06/2003
7612
J . Org. Chem. 2003, 68, 7612-7617

Syntheses of Novel Polyether Fullerene Multiple Adducts
F IGURE 1. 3He NMR spectrum of reaction mixture of 1 with 3He@C60 (the peak at -0.001 ppm is gaseous 3He).
SCHEME 1
selectivity of the new tether-directed approach and to
identify the formation of specific C60 bis- and tris-adducts.
Instead of alkyldiols, triethylene glycol and tetraethylene
glycol were used as flexible linkers to produce macrocyclic
malonates with two or three Bingel reacting species.
These macrocyclic malonates gave specific bis- or tris-
addition to C60 depending on the length and flexibility of
the linkers incorporated between the malonate groups.
One advantage of this approach is that the saponification
of the C60 multiple adducts gives the corresponding tetra-
acids or hexa-acids with defined three-dimensional struc-
tures. These fullerene polyacids are very important from
the point of biological applications, which are landmarked
by the discovery of the neuroprotective properties of
water-soluble C3- and D3-C60 hexa-acids by Dugan.6 In
addition, macrocyclic polyether fullerenes represent a
new class of ionophores, which are potentially size-
selective synthetic receptors in molecular recognition for
alkali metal cations and biologically relevant alkylam-
monium ions, including protonated amines, guanidinium
ions, amino acids, and dendritic oligoamines. Therefore,
macrocyclic polyether fullerenes could be of interest for
the development of biosensors.19
reaction mixture from 1 and 3He@C60 was directly
3
subjected to 3He NMR analysis. The He NMR spectrum
afforded only one sharp peak at -12.085 ppm, which is
3
the precise He chemical shift for a C60 tris-adduct with
the e,e,e addition pattern (Figure 1).18 Therefore, 3He
NMR was used to monitor the selectivity of our modified
tether-directed approach.
P r ep a r a tion a n d Ch a r a cter iza tion of Ma cr ocyclic
P olyeth er Ma lon a tes. Macrocycles 5 and 6 with two
and three identical linkers, respectively, were prepared
from the condensation of malonyl dichloride with trieth-
ylene glycol under solid-liquid phase-transfer-catalysis
(PTC) conditions using KF as base and template, triethyl-
(benzyl)ammonium chloride (TEBA) as catalyst, and
dichloromethane as solvent (Scheme 2).20 Macrocycles
with different ring size were separated by flash chroma-
tography. Macrocycles with more than three malonate
units were also obtained. The yields of 5 and 6 were
improved, compared with those in the absence of PTC
conditions. Macrocycles 5 and 6 were fully characterized
Resu lts a n d Discu ssion
3
Syn th esis a n d He NMR Ch a r a cter iza tion of e,e,e
3
C60 Tr is-a d d u ct. The technique of He NMR has been
found to be a reliable and convenient tool for character-
ization of C60 bis- and tris-adducts.17,18 We employed this
technique to confirm the selective formation of specific
C60 multiple adducts by the tether-directed approach.
1
by H NMR, 13C NMR, and mass spectrometry.
Similarly, the condensation of tetraethylene glycol with
malonyl dichloride under PTC conditions afforded a
series of macrocycles with identical linkers in different
ring sizes. Macrocycle 7 with one malonate unit, 8 with
two malonate units, and 9 with three malonate units
were separated in pure form and fully characterized, but
the yields of 8 and 9 were lower than those of 5 and 6,
respectively (Scheme 3).
P r ep a r a tion a n d Ch a r a cter iza tion of Ma cr ocyclic
P olyeth er F u ller en es. Macrocycle 5 reacted cleanly
with C60 to produce only one bis-adduct 10, with the cis-3
addition pattern, in the presence of I2 and DBU in toluene
(Scheme 4). Compound 10 was obtained in pure form in
3
First, we used He NMR to determine the selectivity of
Hirsch’s tether approach. Macrocyclic malonate 1 was
prepared following the reported procedure, by condensa-
tion of octanediol with malonyl dichloride.16 Reaction of
macrocyclic malonate 1 with C60 under Bingel conditions
gave only one isomer of tris-adduct 2, identified as the
e,e,e tris-adduct with C3 symmetry based on 13C NMR,
MS, and UV-vis data.16 Similarly, the reaction of mac-
3
rocyclic malonate 1 with He@C60 in place of pristine C60
under Bingel conditions produced one single isomer of
tris-adduct 3 (Scheme 1). Without any purification, the
(18) Cross, R. J .; J imenez-Vazquez, H. A.; Lu, Q.; Saunders: M.;
Schuster, D. I.; Wilson, S. R.; Zhao, H. J . Am. Chem. Soc. 1996, 118,
11454.
(19) Kirschner, A. N.; Richardson, C. F.; Wilson, S. R. Abstr. Pap.
- Am. Chem. Soc. 2001, 221st, IEC-234.
(20) Zhou, Z,; Schuster, D. I.; Wilson, S. R. In The Exciting World
of Nanocages and Nanotubes; Kamat, P. V.; Guildi, D. M., Kadish, K.
M., Eds.; 2002; ECS Proceedings Vol. 12, pp 215-224.
J . Org. Chem, Vol. 68, No. 20, 2003 7613

Zhou et al.
SCHEME 2
SCHEME 3
to that of the cis-3 bis-adduct of diethyl malonate to C60.12
3He NMR analysis confirmed the formation of a single
bis-adduct with the cis-3 addition pattern. The 3He NMR
spectrum of the crude reaction mixture from 5 and
3He@C60 showed only one sharp peak for bis-adducts at
-10.236 ppm (Figure 2), which is the precise chemical
shift for the cis-3 C60 bis-adduct of diethyl malonate.18
SCHEME 4
Similarly, macrocyclic polyether malonate 8 reacted
with C60 under Bingel conditions selectively to produce
two isomeric C60 bis-adducts. Bis-adduct 11 with the cis-3
addition pattern and bis-adduct 12 with the equatorial
addition pattern were separated by flash chromatography
over silica gel and were obtained in pure form in a ratio
of 3.5:1 (Scheme 5). Both isomers were characterized by
NMR and mass data. The UV-vis spectrum of 11, shown
up to 60% yield after unreacted C60 and oligomeric
products were removed by flash chromatography. Poly-
ether fullerene 10 was characterized by 1H NMR, 13C
NMR, 3He NMR, MS, and UV-vis spectral data. The
UV-vis spectrum of 10, shown in Figure 4, is identical
3
F IGURE 2. 3He NMR spectrum of reaction mixture of 5 with He@C60 showing a peak at -10.236 ppm for the cis-3 bis-adduct.18
(Note: the peak at -0.009 is gaseous 3He, the peak at -6.371 is 3He@C60, and the peak at -8.018 ppm is a mono-adduct).
SCHEME 5
7614 J . Org. Chem., Vol. 68, No. 20, 2003

Syntheses of Novel Polyether Fullerene Multiple Adducts
F IGURE 3. 3He NMR spectrum of reaction mixture of 6 with 3He@C60. The peak at -12.040 corresponds to the expected C3
tris-adduct.18 (Note: peak at -0.009 is gaseous 3He, the peak at -6.373 is unreacted 3He@C60, and the peak at -8.016 ppm
corresponds to an unknown mono-adduct).
bis-adduct 10. Tentatively, the structure of tris-adduct
13 can be assigned as trans-4, cis-3, cis-3. Compound 13
was characterized by NMR, MS, and UV-vis. Its UV-
vis spectrum did not match that of any previously
3
reported tris-adduct of C60. The He NMR spectrum of
3
the crude reaction mixture of 6 and He@C60 confirmed
the formation of only one tris-adduct, which showed a
sharp peak at -12.040 ppm (Figure 3). But polyether tris-
malonate 9 did not react with C60 under similar condi-
tions, which could be explained by the highly polar nature
of tris-malonate 9.
Con clu sion s
F IGURE 4. UV-vis spectra of C60 bis-adducts (10, 11, and
12 from bottom to top) in the region of 400-700 nm.
An approach for directed selective syntheses of mul-
tiple adducts of C60 employing macrocyclic bis- and tris-
malonates incorporating flexible polyether linkers was
explored, and 3He NMR spectrometry was used to
confirm the selective formation of specific C60 multiple
adducts. Macrocyclic malonate 1 gave only one isomeric
tris-adduct with the e,e,e addition pattern, identified
SCHEME 6
3
using He NMR. A polyether macrocycle with two mal-
onate units, 5, afforded exclusively the C2-symmetric cis-3
bis-adduct 10 in high yield. However, its analogue 8 gave
two isomeric bis-adducts, 11 with a C2-symmetric cis-3
addition pattern and 12 with a Cs-symmetric equatorial
addition pattern. The specific bis-addition patterns de-
pend on the distance between the two malonate groups,
which is governed by the length and flexibility of the
linkers, and the symmetry of the respective bis-addition
patterns. Similarly, an analogous polyether macrocycle
6 with three malonate units led to the specific formation
of a single tris-adduct, 13 in high yield, but polyether
tris-malonates 9 did not react with C60 under similar
conditions. All the polyether fullerene multiple adducts
and the corresponding precursors were characterized
in Figure 4, matches the UV-vis spectrum of C60 bis-
adducts with the same addition pattern, such as com-
pound 10. Compound 12 shows the characteristic UV-
vis absorption spectrum of a C60 bis-adduct with the
equatorial addition pattern in the region of 400-700 nm
(Figure 4).12
The specific addition patterns of C60 bis-adducts pre-
pared by our tether-directed method depend on the
distance between the two malonate groups that is deter-
mined by the length and flexibility of the linkers incor-
porated between the two malonate groups. Macrocyclic
bis-malonates bearing two identical linkers prefer to give
C2-symmetric bis-addition patterns, while those bearing
two proper different-length linkers prefer to give Cs-
symmetric bis-addition patterns to avoid introducing ring
strains.16 In our study, only identical linkers were used,
so the macrocyclic bis-malonates preferably generated
bis-adducts with C2 symmetry, which explained the lower
yield of Cs-symmetric bis-adduct 12 in the ratio of 1:3.5
to C2-symmetric bis-adduct 11.
using H NMR, 13C NMR, He NMR, UV-vis spectros-
copy, and mass spectrometry. Saponification of our C60
multiple adducts results in the corresponding fullerene
polyacids that are potentially biological active.6 Macro-
cyclic polyether fullerenes also represent a new class of
ionophores, which can noncovalently bind with biologi-
cally relevant species including metal cations and alkyl-
ammonium ions.20 Therefore, they could be interesting
for the development of biosensors and for molecular
recognition.21 The approach provides a facile access to
functionalized polyether fullerenes with specific three-
1
3
Tris-malonate macrocycle 6 reacted with C60 to afford
only one tris-adduct isomer, 13, in the presence of I2 and
DBU in toluene at room temperature (Scheme 6). The
isolated yield was about 51%, slightly lower than that of
(21) Singh, H.; Kumar, M.; Singh, P.; Kumar, S. J . Chem. Res.,
Synop. 1998, 4, 132.
J . Org. Chem, Vol. 68, No. 20, 2003 7615

Zhou et al.
organic layers were combined, washed with brine, dried over
anhydrous Na2SO4, and concentrated under reduced pressure.
The crude reaction mixture was separated by flash chroma-
tography over silica gel by using ethyl acetate to give initial
fractions containing compound 7, followed by elution using
ethyl acetate/methanol (96/4) to give compound 8 (0.345 g,
11.4%) and finally elution with ethyl acetate/methanol
(90/10) to give compound 9 (0.202 g, 6.6%): 1H NMR of 8
(CDCl3) δ 3.41 (4 H, s), 3.59 (16 H, m), 3.66 (8 H, t), 4.24 (8 H,
t); 13C NMR of 8 (CDCl3) δ 42.3, 65.6, 69.8, 71.6, 71.7, 167.5;
dimensional structures, which could be interesting for the
construction of self-assembled nanoscale architectures.
Their applications in biological aspect and molecular
recognition are currently under investigation.
Exp er im en ta l Section
P r ep a r a tion of Ma cr ocycle 1. To a stirred solution of
octanediol (6.7 mmol, 1.0 g) in 500 mL of dry dichloromethane
was added pyridine (1.1 mL, 13.5 mmol). Then a solution of
malonyl dichloride (6.9 mmol, 1.0 g) in 250 mL of dry
dichloromethane was slowly added to the above mixture over
8 h, under N2 at room temperature. Upon completion of
addition, the solution was stirred for an additional 3 h.
Saturated NaHCO3 solution was added to the reaction mix-
ture, and the organic layer was separated and dried over
anhydrous MgSO4. After removal of solvents, the crude reac-
tion mixture was separated by flash chromatography over
silica gel by using ethyl acetate/hexanes (1/5) to give initial
fractions, followed by elution using ethyl acetate/hexanes (1/
3) to give compound 1 (0.119 g, 8.1%): 1H NMR of 1 (CDCl3)
δ 1.32 (24 H, m), 1.64 (12 H, m), 3.37 (6 H, s), 4.15 (12 H, t);
13C NMR of 1 (CDCl3) δ 26.1, 28.8, 29.4, 42.2, 65.9, 167.1; m/z
643.2 (M + 1).
1
m/z 547.4 (M + Na+); H NMR of 9 (CDCl3) δ 3.42 (6 H, s),
3.66 (24 H, m), 3.72 (12 H, t), 4.31 (12 H, t); 13C NMR of 9
(CDCl3) δ 41.9, 65.2, 69.3, 71.1, 71.2, 166.8; m/z 809.5
(M + Na+).
P r ep a r a tion of C60 Bis-a d d u ct 10. To a stirred solution
of C60 (72.0 mg, 0.1 mmol), 5 (43.6 mg, 0.1 mmol), and iodine
(50.8 mg, 0.2 mmol) in 100 mL of dry toluene was dropwise
added a solution of DBU (76.0 mg, 0.5 mmol) in 25 mL of dry
toluene under argon at room temperature. Upon completion
of addition, the resulting reaction mixture was stirred for 30
min. The reaction mixture was washed twice with water and
then dried over anhydrous MgSO4. The raw mixture was
subjected to flash chromatography on silica gel. Unreacted C60
was removed by using toluene, and then the eluant was
changed to toluene/ethyl acetate/methanol (60/30/10) to give
10 (69.1 mg, 60%): 1H NMR of 10 (CDCl3) δ 3.53 (2 H, m),
3.64 (4 H, m), 3.80 (6 H, m), 3.92 (4 H, m), 4.41 (4 H, m), 4.68
(2 H, m), 4.84 (2 H, m); 13C NMR of 10 (CDCl3) δ 50.2, 66.2,
66.6, 68.6, 69.5, 69.7, 70.4, 70.8, 71.4, 140.9, 141.2, 141.3, 142.4,
143.2, 143.5, 143.6, 143.6, 144.2, 144.3, 144.4, 144.5, 144.7,
145.0, 145.1, 145.3, 145.4, 145.6, 145.8, 146.1, 146.2, 147.3,
147.4, 147.5, 147.8, 148.3, 163.3, 163.5; m/z 1175 (M + Na+);
UV-vis spectrum, see Figure 4; 3He NMR of 3He@10 δ -0.009
(gaseous 3He), -6.371 (3He@C60), -8.016 (3He@C60 mono-
adduct), -10.236 (3He@10) ppm.
P r ep a r a tion of C60 Bis-a d d u cts 11 a n d 12. To a stirred
solution of C60 (72.0 mg, 0.1 mmol), 8 (52.4 mg, 0.1 mmol),
and iodine (50.8 mg, 0.2 mmol) in 100 mL of dry toluene was
dropwise added a solution of DBU (76.0 mg, 0.5 mmol) in 25
mL of dry toluene under argon at room temperature. Upon
completion of the addition, the resulting reaction mixture was
stirred for 30 min. The reaction mixture was washed twice
with water and then dried over anhydrous MgSO4. The raw
mixture was subjected to flash chromatography on silica gel.
Unreacted C60 was removed by using toluene, and then the
eluant was changed to toluene/ethyl acetate/methanol (60/38/
2) to give 12 (10.0 mg, 8.1%), followed by the elution using
toluene/ethyl acetate/methanol (60/35/5) to give 11 (34.8 mg,
28.1%): 1H NMR of 11 (CDCl3) δ 3.60-3.80 (20 H, m), 3.94
(4 H, t), 4.30 (2 H, m), 4.56 (2 H, m), 4.70 (2 H, m), 4.84 (2 H,
m); 13C NMR of 11 (CDCl3) δ 49.5, 66.2, 66.3, 66.8, 67.6, 69.2,
70.2, 70.5, 70.9, 71.2, 71.5, 136.8, 137.2, 137.6, 137.8, 140.0,
141.0, 141.2, 142.4, 142.5, 143.4, 143.6, 143.7, 144.2, 144.3,
144.4, 144.5, 144.7, 145.0, 145.1, 145.3, 145.4, 145.7, 146.0,
146.2, 147.2, 147.3, 148.4, 162.9, 163.6; m/z 1262.2 (M + Na+);
UV-vis spectrum, see Figure 4; 1H NMR of 12 (CDCl3) δ 3.02
(1 H, m), 3.35-4.00 (22 H, m), 4.19 (3 H, m), 4.45 (1 H, m),
4.68 (1 H, m), 4.70 (2 H, m), 5.02 (2 H, m); m/z 1262.3
(M + Na+); UV-vis spectrum, see Figure 4.
P r ep a r a tion of C60 Tr is-a d d u ct 2. To a stirred solution
of C60 (72.0 mg, 0.1 mmol), 1 (64.2 mg, 0.1 mmol), and iodine
(76.2 mg, 0.3 mmol) in 100 mL of dry toluene was dropwise
added a solution of DBU (114.0 mg, 0.75 mmol) in 25 mL of
dry toluene under argon at room temperature. Upon comple-
tion of addition, the resulting reaction mixture was stirred for
0.5 h. The reaction mixture was washed twice with water and
then dried over anhydrous MgSO4. The raw mixture was
subjected to flash chromatography on silica gel. Unreacted C60
was removed by using toluene, and then the eluant was
changed to toluene/ethyl acetate (98/2) to give 2 (80.5 mg,
59%): 13C NMR of 2 (CDCl3) δ 25.6, 26.3, 28.9, 29.0, 29.1, 29.3,
54.4, 66.3, 67.1, 70.5, 71.3, 140.9, 141.1, 141.7, 142.5, 142.7,
143.6, 143.8, 144.4, 144.5, 145.5, 145.5, 146.3, 146.4, 146.4,
146.5, 146.6, 146.7, 147.9, 162.5, 162.8; m/z 1357 (M + 1); 3He
3
NMR of 3, He@2 δ -0.001 (gaseous 3He), -6.363 (3He@C60),
-12.085 (3He@2) ppm.
P r ep a r a tion of Ma cr ocycles 5 a n d 6. To a stirred
solution of triethylene glycol (7.5 mmol, 1.13 g), KF (30.0 mmol,
1.74 g), and TEBA (0.3 mmol, 60.0 mg) in 50 mL of dry
dichloromethane was added dropwise a solution of malonyl
dichloride (15.0 mmol, 2.12 g) in dry dichloromethane under
N2 at room temperature. Upon completion of addition, the
solution was stirred for 4 h. Water was added to the reaction
mixture, and the organic layer was separated. The aqueous
phase was extracted three times with chloroform, and the
organic layers were combined, washed with water, dried over
anhydrous MgSO4, and concentrated under reduced pressure.
The crude reaction mixture was separated by flash chroma-
tography over silica gel by using ethyl acetate/hexanes (4/1)
to give initial fractions containing compound 4, followed by
elution using ethyl acetate to give compound 5 (0.266 g, 16.2%)
and finally elution with ethyl acetate /methanol (98/2) to give
compound 6 (0.151 g, 9.2%): 1H NMR of 5 (CDCl3) δ 3.41 (4
H, s), 3.62 (8 H, s), 3.72 (8 H, t), 4.32 (8 H, t); 13C NMR of 5
(CDCl3) δ 41.9, 65.2, 69.3, 71.1, 167.5; m/z 459 (M + Na+); 1H
NMR of 6 (CDCl3) δ 3.48 (6 H, s), 3.66 (12 H, s), 3.73 (12 H, t),
4.33 (12 H, t); 13C NMR of 6 (CDCl3) δ 42.8, 64.7, 68.9, 69.8,
166.6; m/z 677 (M + Na+).
P r ep a r a tion of Ma cr ocycles 8 a n d 9. To a stirred
solution of tetraethylene glycol (11.6 mmol, 2.3 g), KF (25.0
mmol, 1.5 g), and TEBA (0.3 mmol, 65.0 mg) in 50 mL of dry
dichloromethane was added dropwise a solution of malonyl
dichloride (17.4 mmol, 2.5 g) in dry dichloromethane under
N2 at room temperature. Upon completion of addition, the
solution was stirred for 5 h. Water was added to the reaction
mixture, and the organic layer was separated. The aqueous
phase was extracted three times with chloroform, and the
P r ep a r a tion of C60 Tr is-a d d u ct 13. To a stirred solution
of C60 (72.0 mg, 0.1 mmol), 6 (65.4 mg, 0.1 mmol), and iodine
(76.2 mg, 0.3 mmol) in 100 mL of dry toluene was dropwise
added a solution of DBU (114.0 mg, 0.75 mmol) in 25 mL of
dry toluene under argon at room temperature. Upon comple-
tion of addition, the resulting reaction mixture was stirred for
30 min. The reaction mixture was washed twice with water
and then dried over anhydrous MgSO4. The raw mixture was
subjected to flash chromatography on silica gel. Unreacted C60
was removed by using toluene, and then the eluant was
changed to toluene/ethyl acetate/methanol (50/40/10) to give
13 (70.1 mg, 51%): 1H NMR of 13 (CDCl3) δ 3.12 (2 H, m),
3.42 (7 H, m), 3.70 (13 H, m), 3.92 (2 H, m), 4.28 (3 H, m),
7616 J . Org. Chem., Vol. 68, No. 20, 2003

Syntheses of Novel Polyether Fullerene Multiple Adducts
4.52 (6 H, m), 4.68 (2 H, m), 5.00 (1 H, m); 13C NMR of 13
(CDCl3) δ 53.5, 54.0, 65.7, 65.8, 68.2, 68.6, 69.2, 69.8, 70.8,
70.2, 140.6, 141.0, 141.8, 141.9, 142.2, 143.0, 143.3, 143.6,
143.9, 144.4, 144.6, 144.7, 144.9, 145.1, 145.2, 145.3, 145.5,
145.8, 146.3, 146.4, 146.5, 146.6, 146.7, 146.8, 148.5, 162.9,
164.0; m/z 1391 (M + Na+); 3He NMR of 3He@13 δ -0.009 ppm
thank Professors Martin Saunders and R. J ames Cross
and Dr. Anthony Khong (Yale University) for samples
of He@C60 and for He NMR spectra.
3
3
Su p p or tin g In for m a tion Ava ila ble: Spectral data for
compounds 1, 2, 5, and 6-13. This material is available free
of charge via the Internet at http://pubs.acs.org.
3
(gaseous He), -6.373 ppm (3He@C60), -8.018 (3He@C60 mono-
adduct), -12.040 ppm (3He@13).
Ack n ow led gm en t. This work was supported by the
National Science Foundation (No. CHE-009789). We
J O034542L
J . Org. Chem, Vol. 68, No. 20, 2003 7617