Synthesis of fullerene building blocks bearing alkyne or azide groups and their subsequent functionalization by the copper mediated Huisgen 1,3-dipolar cycloaddition

Article abstract of DOI:10.1016/j.tet.2008.09.047

C₆₀ derivatives bearing either terminal alkyne or azide functional groups have been prepared and used as building blocks under the copper mediated Huisgen 1,3-dipolar cycloaddition conditions. In general, the reactivity of C₆₀ toward

Full text of DOI:10.1016/j.tet.2008.09.047

Tetrahedron 64 (2008) 11409–11419
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Synthesis of fullerene building blocks bearing alkyne or azide groups and their
subsequent functionalization by the copper mediated Huisgen 1,3-dipolar
cycloaddition
a
b
c
b,
*
´
Rossimiriam Pereira de Freitas , Julien Iehl , Beatrice Delavaux-Nicot , Jean-François Nierengarten
a Universidade Federal de Minas Gerais, Departamento de Qu´ımica, Av. Antoˆnio Carlos, 6627, 31270901 Belo Horizonte, MG, Brazil
b Laboratoire de Chimie des Mate´riaux Mole´culaires, Universite´ Louis Pasteur et CNRS (UMR 7509), Ecole Europe´enne de Chimie, Polym`eres et Mate´riaux (ECPM),
25 rue Becquerel, 67087 Strasbourg Cedex 2, France
c Laboratoire de Chimie de Coordination du CNRS (UPR 8241), 205 route de Narbonne, 31077 Toulouse Cedex 4, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 31 July 2008
Received in revised form 5 September 2008
Accepted 12 September 2008
Available online 26 September 2008
C60 derivatives bearing either terminal alkyne or azide functional groups have been prepared and used as
building blocks under the copper mediated Huisgen 1,3-dipolar cycloaddition conditions. In general, the
reactivity of C60 toward azides does not significantly compete with the cycloaddition leading to the
desired 1,2,3-triazole derivatives and good yields can be obtained when fullerene derivatives with rea-
sonable solubility are used as starting materials. The electrochemical properties of the new fullerene
derivatives have also been investigated by cyclic voltammetry (CV) and Osteryoung Square Wave Vol-
tammetry (OSWV).
Keywords:
Alkynes
Azides
Ó 2008 Elsevier Ltd. All rights reserved.
Cycloadditions
Fullerene
Triazoles
1. Introduction
limited. Approaches which use the most common meth-
anofullerene derivatives4 as synthetic intermediates frequently
Following the discovery of the macroscopic-scale [60]fullerene
synthesis, the chemistry of this fascinating spherical molecule has
been intensively investigated.1 The chemical reactivity of C60 is
now well established and a large number of fullerene derivatives
have been prepared.1 Owing to their facile multiple reducibility,
optical non-linearity and/or efficient singlet oxygen photosensiti-
zation, fullerene-containing compounds have found applications
in materials science2 and biology.3 Whereas most of the fullerene
derivatives reported to date have been prepared by the direct
functionalization of C60 in the final step, the use of fullerene
building blocks in multi-step synthesis has been much scarcely
considered. This is mainly associated with the chemical reactivity
of the fullerene moiety. Effectively, C60 derivatives react readily
with radicals, various nucleophiles, carbenes, and participate as
involve reactions carried out under neutral or acid conditions.
Examples are cleavage of protecting groups,5 activation of car-
boxylic acid derivatives for subsequent esterification or prepara-
tion of amides,6 construction of porphyrins,7 and condensation
reactions.8 As a part of our research program on fullerene de-
rivatives, we have recently evaluated the potential of click
chemistry9 to functionalize fullerene derivatives.10,11 Such chem-
istry appears to be an attractive tool for fullerene chemistry as
click reactions are modular, tolerant to a wide range of functional
groups, and high yielding. The copper mediated Huisgen 1,3-di-
polar cycloaddition of organic azides and alkynes12 to give 1,2,3-
triazoles is without any doubts the most useful member of this
family of reactions. However, whereas this click reaction has
proven to be powerful for a large variety of building blocks,13 its
compatibility with fullerene derivatives was not obvious, as or-
ganic azides may also undergo [3þ2] cycloadditions to the [6,6]
double bonds of fullerenes.14 In this paper, we report a full ac-
count on our results concerning the use of the copper mediated
Huisgen 1,3-dipolar cycloaddition starting from fullerene building
blocks bearing either terminal alkyne or azide functional groups.
In addition, the electrochemical properties of the resulting ful-
lerene derivatives are described.
reactive 2
p
components in a variety of cycloaddition reactions.1
Thus the range of reactions that can be used for the further
transformations of fullerene derivatives appears to be quite
* Corresponding author.
E-mail addresses: rossipdf@yahoo.com.br (R. Pereira de Freitas), bea-
trice.delavaux-nicot@lcc-toulouse.fr (B. Delavaux-Nicot), nierengarten@chi-
mie.u-strasbg.fr (J.-F. Nierengarten).
0040-4020/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.09.047

11410
R. Pereira de Freitas et al. / Tetrahedron 64 (2008) 11409–11419
2. Results and discussion
achieved under optimized concentration conditions. Compound 9
was thus obtained in a good yield (80%), thus showing that the
reactivity of the fullerene moiety with organic azides plays only
a minor role under copper mediated Huisgen 1,3-dipolar cycload-
dition conditions.
2.1. Synthesis
The first series of click reactions have been performed from
fullerene derivatives functionalized with terminal alkyne groups.
The preparation of alkyne 4 is depicted in Scheme 1. Reaction of
commercial malonyl dichloride (2) with 4-pentyn-1-ol (1) in the
presence of pyridine afforded malonate 3 in 77% yield. The reaction
of compound 3 with C60, iodine, and 1,8-diazabicyclo[5.4.0]undec-
7-ene (DBU) under Bingel conditions15 gave methanofullerene 4 in
44% yield. Treatment of 4 (1 equiv) with benzyl azide (3 equiv),
CuSO4$5H2O (0.1 equiv), and sodium ascorbate (0.3 equiv) in
CH2Cl2/H2O under vigorous stirring at room temperature for 96 h
gave the cycloaddition product 5 in a moderate yield (48%). The
solubility of compound 4 is quite low and all the starting material
was not dissolved under the copper mediated Huisgen reaction
conditions. Thus, the reaction was slow and side reactions, most
probably cycloaddition of benzyl azides to the fullerene core, were
observed. To solve this problem, we decided to prepare a more
soluble methanofullerene-alkyne derivative bearing a 3,5-didode-
cyloxybenzyl group. N,N0-Dicyclohexylcarbodiimide (DCC)-medi-
ated esterification of 1 with carboxylic acid 6 yielded malonate 7.
Subsequent treatment with C60, iodine, and DBU afforded meth-
anofullerene 8. Owing to the good solubility of alkyne 8, the re-
action of this compound with benzyl azide in the presence of
CuSO4$5H2O and sodium ascorbate in CH2Cl2/H2O could be
To further decrease the reactivity of the C60 moiety toward the
azide reagents in the click reactions, we have decided to prepare
a fullerene bis-adduct bearing two terminal alkyne groups. It is well
known that the reactivity of the fullerene unit is decreased by in-
creasing the number of substituents on the carbon cage.16 The
synthesis of building block 12 is depicted in Scheme 2. Treatment of
diacid 10 with 4-pentyn-1-ol (1) and DCC in the presence of
4-dimethylaminopyridine (DMAP) and 1-hydroxybenzotriazole
(HOBt) gave bis-malonate 11 in 58% yield. Fullerene derivative 12
was then prepared by taking advantage of the versatile regiose-
lective reaction developed by Diederich et al.,17 which led to mac-
rocyclic bis-adducts of C60 by a cyclization reaction at the carbon
sphere with bis-malonate derivatives in a double Bingel15 cyclo-
propanation. Reaction of 11 with C60, I2, and DBU in toluene at room
temperature afforded the desired cyclization product 12 in 44%
yield. The relative position of the two cyclopropane rings in 12 on
the C60 core has been determined based on the molecular sym-
metry (Cs) deduced from the 1H and 13C NMR spectra. It is also well
established that the 1,3-phenylenebis(methylene)-tethered bis-
malonates produce regioselectively the Cs symmetrical cis-2 addi-
17,18
tion pattern at C60
.
Reaction of 12 with benzyl azide under the
conditions optimized for the preparation of compound 9 gave bis-
HO
H
O
O
1
RO
O
O
O
O
OH
Cl
Cl
O
6
R = C12H25
2
(i)
(ii)
OR
O
O
O
RO
RO
O
O
O
O
O
H
H
H
H
H
3
OR
7 R = C12H25
(iii)
O
(iii)
O
O
O
O
O
H
OR
4
8 R = C12H25
(iv)
O
(iv)
O
O
O
RO
N
N
N
N
N
O
O
O
O
N
N
N
N
Ph
Ph
Ph
OR
5
9
R = C12H25
Scheme 1. Reagents and conditions: (i) CH2Cl2, pyridine, rt (77%); (ii) DCC, DMAP, HOBt, CH2Cl2, 0 ꢀC to rt (59%); (iii) C60, DBU, I2, PhMe, rt (4: 44%, 8: 31%); (iv) benzyl azide,
CuSO4$5H2O, sodium ascorbate, CH2Cl2/H2O, rt (5: 48%, 9: 80%).

R. Pereira de Freitas et al. / Tetrahedron 64 (2008) 11409–11419
11411
1,2,3-triazole 13 in 70% yield. When compared to the preparation of
compound 5 from methanofullerene 4, the increased yield can be
explained by both the higher solubility of the starting terminal
alkyne and the decreased reactivity of the bis-substituted fullerene
group.
end, the synthesis of methanofullerene derivatives substituted with
one or two azide groups was attempted. Unfortunately, these
compounds were found to be very unstable in the solid state al-
though reasonably stable in solution. Most probably, in-
termolecular cycloaddition reactions between the C60 and the azide
groups led to complex mixtures of polymeric compounds. Actually,
only fullerene bis-adducts were sufficiently stable to be used as
synthetic intermediates in click reactions. This observation con-
firms the decreased reactivity of the fullerene moiety by increasing
the number of substituents on the carbon cage. The preparation of
the building block 23 is depicted in Scheme 4. Reaction of bis-
malonic acid 10 with alcohol 20 under esterification conditions
(DCC, DMAP, HOBt) yielded bis-malonate 21. Subsequent treatment
with sodium azide in DMF at room temperature gave 22 in 76%
yield. Bis-adduct 23 was then obtained in 16% yield by reaction of
22 with C60, I2, and DBU in toluene at room temperature. Upon
purification, diazide 23 should be used for the click reactions within
the next 4 h to obtain good yields. Reaction of 23 with phenyl-
acetylene under optimized conditions afforded bis-1,2,3-triazole 24
in 78% yield. The structure of compound 24 was confirmed by its 1H
and 13C NMR spectrum as well as by mass spectrometry. Inspection
of the 1H NMR spectra clearly indicates the disappearance of the
O
O
O
O
O
O
O
O
(i)
O
O
O
O
O
O
10
11
HO
OH
H
H
O
O
O
O
O
(ii)
O
CH2-azide signal at
of 24 shows the typical singlet of the 1,2,3-triazole unit at
7.75 ppm as well as the signal corresponding to the CH2-triazole
protons at 4.42 ppm. The click reaction conditions were also used
d
3.41 ppm. Importantly, the 1H NMR spectrum
H
O
O
d
d
to produce derivative 25 from terminal alkyne 8 and bis-azide 23.
The structure of 25 was confirmed by MALDI-TOF mass spectrom-
etry showing the expected molecular ion peak at m/z 3889 ([MH]þ,
calcd for C278H145N6O20: 3889.24).
12
H
O
Finally, it was also possible to prepare a bis-methanofullerene
bearing four azide groups that was stable enough to be used in
click reactions. The synthesis of compound 30 is shown in
Scheme 5. Tosylation of azide-alcohol 26 followed by alkylation of
3,5-dihydroxybenzyl alcohol gave compound 28 in 40% yield. Bis-
malonate 29 was obtained in 48% yield by reaction between diacid
10 and alcohol 28 under esterification conditions (DCC, DMAP,
HOBt). The preparation of fullerene bis-adduct 30 from bis-
malonate 29 under Diederich conditions17 was then achieved in
10% yield. Compound 31 resulting from four simultaneous click
reactions between tetra-azide 30 and terminal alkyne 8 was then
obtained in 34% yield. Owing to the presence of two pendant alkyl
chains per peripheral fullerene moiety, compound 31 is well sol-
uble in common organic solvents such as CH2Cl2, CHCl3, THF or
toluene, and spectroscopic characterization was easily achieved.
The 1H NMR spectrum of 31 shows the typical pattern of the
central 1,3-phenylenebis(methylene)-bridged fullerene bis-adduct
with the expected additional signals arising from the four equiv-
alent substituted methanofullerenes. The integration ratios are
also consistent with the proposed molecular structure. Finally, the
expected molecular ion peak is observed at m/z 6994.5 ([MH]þ,
calcd for C496H291N12O36: 6994.83) in the MALDI-TOF mass spec-
trum of 31.
O
O
O
O
N
(iii)
O
O
N
N
O
Ph
N
13
N
N
Ph
Scheme 2. Reagents and conditions: (i) 1, DCC, DMAP, HOBt, CH2Cl2, 0 ꢀC to rt (58%);
(ii) C60, DBU, I2, PhMe, rt (44%); (iii) benzyl azide, CuSO4$5H2O, sodium ascorbate,
CH2Cl2/H2O, rt (70%).
These results prompted us to further investigate the synthesis of
a fullerene bis-adduct bearing four terminal alkyne groups allowing
the simultaneous grafting of four azide derivatives under click
conditions. The synthesis of fullerene derivative 18 is depicted in
Scheme 3. Conversion of 4-pentyn-1-ol (1) to the corresponding
tosylate was easily carried out under classic conditions and gave
compound 14 in 73% yield. Alkylation of commercial methyl-3,5-
dihydroxybenzoate with 14 afforded intermediate 15 in 81% yield.
Subsequent treatment of 15 with LAH gave benzylic alcohol 16 in
83% yield. The reaction of diacid 10 with alcohol 16 and DCC in the
presence of DMAP and HOBt gave bis-malonate 17 in 74% yield. A
double Bingel15 cyclopropanation was used to prepare fullerene
bis-adduct derivative 18. Reaction of 17 with C60, I2, and DBU in
toluene at room temperature afforded the desired cyclization
product 18 in 39% yield. The copper mediated Huisgen 1,3-dipolar
cycloaddition reaction of 18 with benzyl azide gave tetra-1,2,3-
triazole 19 in a moderate yield (39%).
2.2. Electrochemistry
The electrochemical properties of compounds 8, 9, 12, 13, 18, 19,
and 24 were determined by cyclic voltammetry (CV) and Oster-
young Square Wave Voltammetry (OSWV). All the experiments
were performed at room temperature in CH2Cl2 solutions con-
taining tetra-n-butylammonium tetrafluoroborate (0.1 M) as sup-
porting electrolyte and ferrocene (Fc) as internal reference, with
a Pt wire as the working electrode and a saturated calomel elec-
trode (SCE) as a reference. Potential data for all of the compounds
are collected in Table 1. As typical examples, the cyclic voltammo-
grams obtained from 8 and 13 are shown in Figure 1.
In a second series of click reactions, we have evaluated the use of
fullerene building blocks functionalized with azide groups. To this

11412
R. Pereira de Freitas et al. / Tetrahedron 64 (2008) 11409–11419
R
(i)
(ii)
(iv)
O
O
1
TsO
H
14
H
H
15 R = CO2Me
16 R = CH2OH
(iii)
O
O
O
O
O
O
O
O
O
O
O
(v)
O
O
O
O
O
O
O
O
O
O
O
O
O
H
H
H
H
H
H
H
H
17
18
O
O
O
O
O
O
O
(vi)
O
O
O
O
O
N
N
N
N
N
N
Ph
Ph
N
N
N
N
N
N
19
Ph
Ph
Scheme 3. Reagents and conditions: (i) TsCl, pyridine, CH2Cl2, 0 ꢀC to rt (73%); (ii) methyl-3,5-dihydroxybenzoate, K2CO3, LiBr, DMF, 80 ꢀC (81%); (iii) LiAlH4, THF, 0 ꢀC (83%); (iv) 10,
DCC, DMAP, HOBt, CH2Cl2, 0 ꢀC to rt (74%); (v) C60, DBU, I2, PhMe, rt (39%); (vi) benzyl azide, CuSO4$5H2O, sodium ascorbate, CH2Cl2/H2O, rt (39%).
In the anodic region, all the studied compounds present at
least one irreversible peak at ca. þ1.1–1.4 V versus Fc/Fcþ, which
can be likely attributed to the oxidation of the dialkyloxyphenyl
and/or dialkylphenyl units.19 In the cathodic region, fullerene
derivatives 8, 9, 12, 13, 18, 19, and 24 essentially retain the elec-
trochemical pattern of the parent fullerene but the reduction
potentials of all of these species are shifted to more negative
values when compared to those of pristine C60. This is the classical
behavior observed for most fullerene derivatives, the cyclic vol-
tammograms of which are typically characterized by small shifts
to more negative potentials as the saturation of a double bond on
the C60 surfaces causes a partial loss of ‘conjugation’.20 There are,
however, no significant differences between the reduction po-
tentials of mono-adducts 8 and 9 when compared to those of the
cis-2 bis-adducts 12, 13, 18, 19, and 24. Whereas the first reduction
observed at ca. ꢁ1.05 to ꢁ1.10 V versus Fc/Fcþ is always reversible,
the second is irreversible at low scan rates (0.1 V sꢁ1) but becomes
reversible at scan rates higher than 2 V sꢁ1 in accordance with
already reported observations on other C60 derivatives.21 The third
wave gradually disappears when the second one becomes re-
versible, so that it probably implies reduction of the product
formed after the second reduction. It is worth mentioning that
this effect is relatively limited for mono-adducts 8 and 9 but be-
comes important for bis-adducts 12, 13, 18, 19, and 24 (Fig. 2).
While CV experiments were unable to detect clearly the next re-
duction waves, OSWV revealed such processes easily (Fig. 3). The
reduction observed at ca. ꢁ1.88 to ꢁ1.92 V versus Fc/Fcþ corre-
3ꢁ 2ꢁ
sponds to the redox couple C /C and the wave at ca. –2.06 to
60 60
ꢁ2.11 V versus Fc/Fcþ to the reduction of an electrogenerated
species.21 Finally, the reduction seen at ca. ꢁ2.28 to ꢁ2.45 V ver-
4ꢁ 3ꢁ
sus Fc/Fcþ is ascribed to the C /C redox couple.
60 60
The electrochemical properties of compounds 25 and 31 were
also investigated. The electrochemical behavior of 25 and 31 in both
CV and OSWV (Figs. 1 and 3) appears to be similar to that of com-
pounds 8, 9, 12, 13, 18, 19, and 24. The reduction potentials are also
quite similar (Table 1). This seems to indicate that the different
fullerene units in 25 and 31 behave as independent redox centers.
The electrochemical behavior of the two kinds of fullerene subunits

R. Pereira de Freitas et al. / Tetrahedron 64 (2008) 11409–11419
11413
O
O
O
O
O
O
(i)
(iii)
HO
Br
O
O
20
R
R
O
21 R = Br
22 R = N3
(ii)
O
O
O
O
O
O
O
N
N
(iv)
N
O
O
O
O
N3
O
O
O
O
23
24
N
N
N3
N
(v)
O
O
O
O
O
O
O
N
N
O
N
O
O
O
N
O
N
N
RO
OR
O
O
O
O
25 R = C12H25
RO
OR
Scheme 4. Reagents and conditions: (i) 10, DCC, DMAP, HOBt, CH2Cl2, 0 ꢀC to rt (46%); (ii) NaN3, DMF, rt (76%); (iii) C60, DBU, I2, PhMe, rt (16%); (iv) phenylacetylene, CuSO4$5H2O,
sodium ascorbate, CH2Cl2/H2O, rt (78%); (v) 8, CuSO4$5H2O, sodium ascorbate, CH2Cl2/H2O, rt (50%).
present in both 25 and 31, i.e., mono- and bis-adducts, is similar and
it was not possible to observe separate waves for both of them.
more complex fullerene derivatives. Work in this direction is now
under investigation in our laboratory.
3. Conclusions
4. Experimental
4.1. General
To sum up, we have shown that click chemistry is an interesting
tool for the functionalization of fullerene building blocks. The
chemical transformation of fullerene derivatives bearing azides and
alkynes under the copper mediated Huisgen 1,3-dipolar cycload-
dition conditions was demonstrated. Whereas the preparation of
fullerene azide derivatives is difficult due to their fast de-
composition, fullerene alkyne building blocks are easy to produce.
In general, the reactivity of C60 toward azides is not significantly
competing with the cycloaddition leading to the desired 1,2,3-tri-
azole derivatives and good yields can be obtained when fullerene
derivatives with reasonable solubility are used as starting mate-
rials. In particular, bis-adduct derivatives bearing alkyne groups
appear to be the most promising building blocks for the synthesis of
Reagents and solvents were purchased as reagent grade and
used without further purification. THF was distilled over sodium
benzophenone ketyl. All reactions were performed in standard
glassware under an inert Ar atmosphere. Evaporation and con-
centration were done at water aspirator pressure and drying in
vacuo at 10ꢁ2 Torr. Column chromatography: silica gel 60 (230–400
mesh, 0.040–0.063 mm) was purchased from E. Merck. Thin layer
chromatography (TLC) was performed on glass sheets coated with
silica gel 60 F254 purchased from E. Merck, visualization by UV light.
IR spectra (cmꢁ1) were measured on an ATI Mattson Genesis Series
FTIR instrument. NMR spectra were recorded on a Bruker AC 300

11414
R. Pereira de Freitas et al. / Tetrahedron 64 (2008) 11409–11419
OH
(i)
(ii)
(iii)
OTs
N3
OH
N3
O
O
26
27
28
N3
O
N3
O
O
O
O
O
O
O
O
O
O
O
O
O
(iv)
O
O
O
O
N3
N3
O
O
O
O
O
O
29
30
N3
N3
N3
N3
N3
N3
O
O
O
O
O
O
O
O
(v)
O
O
N
N
O
O
N
N
N
N
O
O
N
N
N
N
N
O
O
O
N
O
O
O
O
O
O
O
RO
OR
OR
O
O
RO
O
O
RO
OR
RO
OR
31 R = C12H25
Scheme 5. Reagents and conditions: (i) TsCl, Et3N, CH2Cl2, 0 ꢀC to rt (75%); (ii) 3,5-dihydroxybenzyl alcohol, K2CO3, LiBr, DMF, 80 ꢀC (40%); (iii) 10, DCC, DMAP, HOBt, CH2Cl2, 0 ꢀC to
rt (48%); (iv) C60, DBU, I2, PhMe, rt (10%); (v) 8, CuSO4$5H2O, sodium ascorbate, CH2Cl2/H2O, rt (34%).
with solvent peaks as reference. Mass measurement was carried
out on a ZA HF instrument (FAB) with 4-nitrobenzyl alcohol as
matrix or on a Bruker BIFLEXÔ matrix-assisted laser desorption
time-of-flight mass spectrometer (MALDI-TOF) with 1,8,9-trihy-
droxyanthracene (dithranol) as matrix. Elemental analysis were
performed by the analytical service at the Laboratoire de Chimie de
Coordination (Toulouse, France).
(0.5 mm diameter). The supporting electrolyte n-Bu4NBF4 (Fluka,
99% electrochemical grade) was used as received and simply
degassed under argon. Dichloromethane was freshly distilled over
CaH2 prior to use. The solutions used during the electrochemical
studies were typically 10ꢁ3 M in compound and 0.1 M in supporting
electrolyte. Before each measurement, the solutions were degassed
by bubbling Ar and the working electrode was polished with a pol-
ishing machine (Presi P230). Under these experimental conditions,
Fc/Fcþ is observed at þ0.54ꢂ0.01 V versus SCE.
4.2. Electrochemistry
4.2.1. Compound 3
The electrochemical measurements were carried out with
a potentiostat Autolab PGSTAT100. Experiments were performed at
room temperature in a homemade airtight three-electrode cell
connected toavacuum/argon line. The reference electrode consisted
ofa saturated calomelelectrode (SCE)separated fromthe solutionby
a bridge compartment. The counter electrode was a platinumwire of
ca.1 cm2 apparent surface. Theworkingelectrode was a Pt microdisk
Malonyl dichloride (350 mg, 2.48 mmol) was added to a stirred
solution of 4-pentyn-1-ol (420 mg, 4.96 mmol) and pyridine
(0.4 mL, 4.96 mmol) in CH2Cl2 (30 mL) at 0 ꢀC. After 1 h, the mix-
ture was allowed to warm up to room temperature (within 1 h) and
stirred for 24 h. The organic layer was washed with water, dried
over MgSO4, and concentrated. Column chromatography (SiO2,

R. Pereira de Freitas et al. / Tetrahedron 64 (2008) 11409–11419
11415
Table 1
Electrochemical data of 8, 9,12, 13, 18,19, 24, 25, and 31 determined by OSWV on a Pt
working electrode in CH2Cl2þ0.1 M n-Bu4NBF4 at room temperature in the presence
of ferrocene used as internal referencea,b
0.0
Oxidation
Reduction
E1
E1
E2
E3
E4
E5
E6
8
9
þ1.11
þ1.10
þ1.18
þ1.29
þ1.12
þ1.38
þ1.29
þ1.27
þ1.16
ꢁ1.07
ꢁ1.05
ꢁ1.08
ꢁ1.07
ꢁ1.10
ꢁ1.06
ꢁ1.05
ꢁ1.05
ꢁ1.10
ꢁ1.46
ꢁ1.43
ꢁ1.39
ꢁ1.39
ꢁ1.40
ꢁ1.38
ꢁ1.37
ꢁ1.40
ꢁ1.39
ꢁ1.68c
ꢁ1.67c
ꢁ1.68c
ꢁ1.68c
ꢁ1.70c
ꢁ1.68c
ꢁ1.66c
ꢁ1.68c
ꢁ1.58c
ꢁ1.91
ꢁ1.90
ꢁ1.88
ꢁ1.89
ꢁ1.92
ꢁ1.90
ꢁ1.88
ꢁ1.90
ꢁ1.90
ꢁ2.11c
ꢁ2.10c
ꢁ2.07c
ꢁ2.08c
ꢁ2.09c
ꢁ2.10c
ꢁ2.06c
ꢁ2.09c
ꢁ2.09c
ꢁ2.33
ꢁ2.32
ꢁ2.28
ꢁ2.38
ꢁ2.45
ꢁ2.42
ꢁ2.40
ꢁ2.28
d
12
13
18
19
24
25
31
-0.5
8
a
-1.0
0.0
OSWVs were obtained using a sweep width of 20 mV, a frequency of 10 Hz, and
a step potential of 5 mV.
b
Values in V versus Fc/Fcþ
.
c
Waves corresponding to an electrogenerated species obtained after the second
reduction step.
CH2Cl2) gave 3 (450 mg, 77%) as a colorless oil. 1H NMR (CDCl3,
300 MHz):
d
1.80 (m, 4H), 1.91 (t, J¼3 Hz, 2H), 2.20 (m, 4H), 3.30 (s,
2H), 4.17 (t, J¼6 Hz, 4H).
-0.2
4.2.2. Compound 4
DBU (0.25 mL, 1.72 mmol) was added to a stirred solution of C60
(500 mg, 0.69 mmol), I2 (260 mg, 1.03 mmol), and 3 (163 mg,
0.69 mmol) in toluene (500 mL) at room temperature. The resulting
solution was stirred for 6 h, then filtered through a short plug of
SiO2 (CH2Cl2) and evaporated. Column chromatography (SiO2, tol-
uene) gave 4 (290 mg, 44%) as a dark-red glassy product. 1H NMR
13
-0.4
0.0
(CDCl3, 300 MHz):
d
2.07 (m, 6H), 2.42 (m, 4H), 4.62 (t, J¼6 Hz, 4H).
13C NMR (CDCl3, 75 MHz):
d
15.2, 27.3, 52.0, 65.8, 67.6, 69.7, 71.5,
82.4, 139.0, 141.0, 141.9, 142.2, 143.0, 143.0, 143.1, 143.9, 144.6, 144.7,
144.9, 145.1, 145.2, 145.3, 163.5. Anal. Calcd for C73H14O4$2/3CH2Cl2:
C, 87.93; H, 1.53. Found: C, 87.79; H, 1.48. FABMS: 955 ([M]þ, calcd
for C73H14O4: 954.91).
-0.1
-0.2
4.2.3. Compound 5
To a mixture of 4 (92 mg, 0.096 mmol) and benzyl azide (39 mg,
0.293 mmol) in CH2Cl2 (2 mL) and H2O (2 mL) were added
CuSO4$5H2O (2 mg, 0.012 mmol) and sodium ascorbate (6 mg,
0.030 mmol). The reaction mixture was stirred for 96 h. The organic
layer was diluted with CH2Cl2, washed with water, dried over
MgSO4, and concentrated. Column chromatography (SiO2, toluene/
AcOEt 7:3) gave 5 (75 mg, 48%) as a dark-red glassy product. IR
25
(neat): 1738 (C]O). 1H NMR (CDCl3, 300 MHz):
d 2.22 (m, 4H), 2.85
-1.0
-0.5
E / V vs. SCE
0.0
0.5
(t, J¼7 Hz, 4H), 4.52 (t, J¼6 Hz, 4H), 5.48 (s, 4H), 7.29 (m, 12H). 13C
NMR (CDCl3, 75 MHz):
d
¼22.1, 28.1, 50.9, 54.0, 66.5, 67.2, 71.5, 121.0,
Figure 1. Cyclic voltammograms showing the two first reductions of 8, 13, and 25 on
a Pt electrode at v¼0.1 V sꢁ1 in CH2Cl2þ0.1 M n-Bu4NBF4.
128.0, 128.7, 129.1, 134.8, 138.9, 140.9, 141.8, 142.2, 142.9, 143.0,
143.1, 143.9, 144.5, 144.6, 144.7, 144.9, 145.1, 145.2, 145.2, 145.3,
146.8, 163.5. Anal. Calcd for C87H28N6O4$CH2Cl2: C, 80.92; H, 2.32;
N, 6.43. Found: C, 81.04; H, 2.94; N, 6.50. FABMS: 1221 ([M]þ, calcd
for C87H28N6O4: 1221.22).
29.6, 29.6, 29.7, 31.9, 41.5, 64.0, 67.2, 68.0, 69.1, 82.7, 101.1, 106.5,
137.2, 160.5, 166.2, 166.3.
4.2.4. Compound 7
4.2.5. Compound 8
DCC (1.10 g, 5.34 mmol), HOBt (cat), and DMAP (75 mg,
0.71 mmol) were added to a solution of 4-pentyn-1-ol (86 mg,
1.96 mmol) and 6 (1.10 g, 1.78 mmol), in CH2Cl2 (50 mL) at 0 ꢀC.
After 1 h, the mixture was allowed to warm slowly to room tem-
perature, and was then stirred for 22 h, filtered, and evaporated.
DBU (0.19 mL, 1.27 mmol) was added to a stirred solution of C60
(458 mg, 0.64 mmol), I2 (193 mg, 0.76 mmol), and 7 (400 mg,
0.64 mmol) in toluene (450 mL) at room temperature. The resulting
solution was stirred for 6 h, then filtered through a short plug of
SiO2 (CH2Cl2) and evaporated. Column chromatography (SiO2,
hexanes/CH2Cl2 80:20) gave 8 (529 mg, 31%) as a dark-red solid. IR
Column chromatography (SiO2, CH2Cl2/hexanes 1:1) gave
7
(697 mg, 59%) as a colorless oil. 1H NMR (CDCl3, 300 MHz):
d
0.88 (t,
(neat): n
3309 (^C–H), 1745 (C]O). 1H NMR (CDCl3, 300 MHz):
J¼7 Hz, 6H), 1.26–1.46 (m, 36H), 1.71–1.90 (m, 6H), 1.96 (t, J¼2 Hz,
1H), 2.26 (m, 2H), 3.43 (s, 2H), 3.92 (t, J¼6 Hz, 4H), 4.26 (t, J¼6 Hz,
2H), 5.10 (s, 2H), 6.41 (t, J¼2 Hz, 1H), 6.46 (d, J¼2 Hz, 2H). 13C NMR
d
0.88 (t, J¼7 Hz, 6H), 1.20–1.41 (m, 36H), 1.75 (m, 4H), 2.02 (m, 3H),
2.36 (m, 2H), 3.90 (t, J¼7 Hz, 4H), 4.58 (t, J¼7 Hz, 2H), 5.43 (s, 2H),
6.42 (t, J¼2 Hz, 1H), 6.60 (d, J¼2 Hz, 2H). 13C NMR (CDCl3, 75 MHz):
(CDCl3, 75 MHz):
d
14.1, 15.0, 22.7, 26.0, 27.3, 29.2, 29.3, 29.4, 29.5,
d 14.1, 15.1, 22.7, 26.1, 27.2, 29.2, 29.3, 29.4, 29.6, 29.6, 29.7, 31.9, 51.9,

11416
R. Pereira de Freitas et al. / Tetrahedron 64 (2008) 11409–11419
0.0
0.0
13
-0.2
-0.4
-0.5
-0.6
12
-1.0
0.0
0.0
-0.5
-1.0
E/ V vs. SCE
-1.5
0.0
-0.5
-1.0
25
-0.2
8
-0.4
-1.5
-1.0
-0.5
E / V vs. SCE
0.0
0.5
-0.6
Figure 2. Cyclic voltammograms showing the three first reductions of 8 and 12 on a Pt
electrode at v¼0.1 V sꢁ1 in CH2Cl2þ0.1 M n-Bu4NBF4.
0.0
-0.5
-1.0
E/ V vs. SCE
-1.5
65.7, 68.1, 68.9, 69.6, 71.4, 82.5, 101.7,107.2, 136.4, 138.7,139.3, 140.8,
140.9, 141.8, 141.9, 142.1, 142.2, 142.8, 142.9, 143.0, 143.7, 143.8,
144.4, 144.5, 144.6, 144.8, 144.9, 145.0, 145.0, 145.1, 145.2, 160.5,
163.3, 163.4. Anal. Calcd for C99H62O6$1/2 CHCl3: C, 84.92; H, 4.48.
Found: C, 85.17; H, 4.66.
Figure 3. OSWVs (cathodic scan) of compounds 13 and 25 on a Pt electrode in
CH2Cl2þ0.1 M n-Bu4NBF4 at room temperature.
After 1 h, the mixture was allowed to warm slowly to room tem-
perature, and was then stirred for 60 h, filtered, and evaporated.
Column chromatography (SiO2, CH2Cl2/AcOEt 1:1) gave 11 (390 mg,
4.2.6. Compound 9
To a mixture of 8 (114 mg, 0.084 mmol) and benzyl azide
(22 mg, 0.165 mmol) in CH2Cl2 (2 mL) and H2O (2 mL) were added
CuSO4$5H2O (1 mg, 0.006 mmol) and sodium ascorbate (4 mg,
0.02 mmol). The reaction mixture was stirred for 4 h. The organic
layer was diluted with CH2Cl2, washed with water, dried over
MgSO4, and concentrated. Column chromatography (SiO2, hexane/
CH2Cl2/MeOH 49:49:2) gave 9 (99 mg, 80%) as a dark-red glassy
58%) as a yellow oil. 1H NMR (CDCl3, 300 MHz):
d 1.85 (m, 4H), 1.98
(t, J¼3 Hz, 2H), 2.24 (m, 4H), 3.44 (s, 4H), 4.25 (t, J¼6 Hz, 4H), 5.19 (s,
4H), 7.31–7.39 (m, 4H).
4.2.8. Compound 12
DBU (0.30 mL, 1.91 mmol) was added to a stirred solution of C60
(300 mg, 0.42 mmol), I2 (264 mg, 1.04 mmol), and 11 (183 mg,
0.42 mmol) in toluene (600 mL) at room temperature. The resulting
solution was stirred for 6 h, then filtered through a short plug of SiO2
(CH2Cl2) and evaporated. Column chromatography (SiO2, hexane/
CH2Cl2 50:50) gave 12 (206 mg, 44%) as a dark-red solid. 1H NMR
product. IR (neat): 1735 (C]O). 1H NMR (CDCl3, 300 MHz):
d 0.88 (t,
J¼7 Hz, 6H), 1.22–1.45 (m, 36H), 1.73 (m, 4H), 2.20 (m, 2H), 2.84 (t,
J¼7 Hz, 2H), 3.87 (t, J¼7 Hz, 4H), 4.50 (t, J¼6 Hz, 2H), 5.42 (s, 2H),
5.49 (s, 2H), 6.38 (t, J¼2 Hz, 1H), 6.58 (d, J¼2 Hz, 2H), 7.37 (m, 6H).
13C NMR (CDCl3, 75 MHz):
d
14.1, 22.1, 22.7, 26.1, 29.3, 29.4, 29.5,
(CDCl3, 300 MHz): d 1.94–2.00 (m, 6H), 2.32 (m, 4H), 4.39–4.57 (m,
29.6, 29.7, 29.7, 31.9, 51.9, 66.5, 68.2, 68.9, 71.4, 101.6, 107.2, 121.0,
128.0, 128.7, 129.1, 136.8, 138.7, 139.2, 140.8, 141.8, 142.2, 143.0,
143.8,144.4,144.5,144.6,144.8,145.0,145.1,145.2, 45.3,160.5,163.3,
163.3. Anal. Calcd for C106H69N3O6$1.3 CH2Cl2: C, 81.05; H, 4.64; N,
2.74. Found: C, 80.82; H, 4.88; N, 3.00. FABMS: 1481 ([M]þ, calcd for
C106H69N3O6: 1480.73).
4H), 5.2 (d, J¼12 Hz, 2H), 5.9 (d, J¼12 Hz, 2H), 7.30–7.54 (m, 4H). 13C
NMR(CDCl3, 75 MHz):d15.1, 27.2, 49.2,65.5,67.0,67.5, 69.6,70.6, 82.4,
123.9, 126.8, 128.7, 134.6, 135.9, 136.3, 136.6, 137.8, 140.0, 141.1, 141.4,
142.4, 142.9, 143.4, 143.6, 143.8, 144.1, 144.2, 144.3, 144.4, 144.7, 145.1,
145.3, 145.4, 145.7, 145.8, 145.8, 146.0, 146.1, 147.4, 147.5, 147.6, 148.7,
162.8,162.9. Anal. Calcd for C84H22O8$CH2Cl2: C, 82.07; H,1.94. Found:
C, 81.82; H, 2.19. FABMS: 1159 ([M]þ, calcd for C84H22O8: 1159.09).
4.2.7. Compound 11
DCC (627 mg, 3.07 mmol), HOBt (cat), and DMAP (75 mg,
0.61 mmol) were added to a solution of 4-pentyn-1-ol (270 mg,
3.22 mmol) and 10 (476 mg, 1.54 mmol) in CH2Cl2 (20 mL) at 0 ꢀC.
4.2.9. Compound 13
To a mixture of 12 (75 mg, 0.06 mmol) and benzyl azide (26 mg,
0.19 mmol) in CH2Cl2 (2 mL) and H2O (2 mL) were added

R. Pereira de Freitas et al. / Tetrahedron 64 (2008) 11409–11419
11417
CuSO4$5H2O (1 mg, 0.006 mmol) and sodium ascorbate (4 mg,
0.02 mmol). The reaction mixture was stirred for 60 h. The organic
layer was diluted with CH2Cl2, washed with water, dried over
MgSO4, and concentrated. Column chromatography (SiO2, toluene/
AcOEt 7:3) gave 13 (64 mg, 70%) as a dark-red glassy product. 1H
chromatography (SiO2, CH2Cl2/methanol 99.8:0.2) gave 17 (1.43 g,
74%) as a yellow oil. IR (neat):
3289 (^C–H), 1731 (C]O). 1H NMR
(CDCl3, 300 MHz):
n
d
1.97 (t, J¼3 Hz, 4H), 1.98 (m, 8H), 2.38 (m, 8H),
3.48 (s, 4H), 4.02 (t, J¼6 Hz, 8H), 5.09 (d, J¼3.5 Hz, 4H), 5.16 (s, 4H),
6.42 (t, J¼2 Hz, 2H), 6.48 (d, J¼2 Hz, 4H), 7.31 (m, 4H). 13C NMR
NMR (CDCl3, 300 MHz):
4H), 5.20 (d, J¼12 Hz, 2H), 5.47 (s, 4H), 5.80 (d, J¼12 Hz, 2H), 7.15
(m, 15H), 7.30 (s, 1H). 13C NMR (CDCl3, 75 MHz):
21.9, 28.1, 49.3,
d
2.10 (m, 4H), 2.80 (t, J¼7 Hz, 4H), 4.38 (m,
(CDCl3, 75 MHz): d 15.1, 28.0, 41.4, 66.1, 66.8, 67.0, 68.9, 83.3, 101.2,
106.5, 106.6, 127.8, 128.1, 128.9, 135.6, 137.3, 160.1, 166.1. Anal. Calcd
for C48H50O12: C, 70.40; H, 6.15. Found: C, 69.74; H, 6.31.
d
54.0, 66.2, 67.0, 67.5, 70.7, 120.9, 123.9, 126.8, 128.0, 128.7, 129.1,
130.0, 134.8, 135.8, 136.2, 136.6, 140.0, 140.9, 141.3, 142.3, 143.0,
143.3, 143.6, 143.8, 144.0, 144.2, 144.3, 144.4, 144.7, 145.0, 145.2,
145.3, 145.4, 145.7, 145.8, 145.8, 146.1, 146.8, 147.4, 147.6, 148.6,
162.8, 162.9. Anal. Calcd for C98H36N6O8$4.8CH2Cl2: C, 67.36; H,
2.51; N, 4.50. Found: C, 67.43; H, 2.93; N, 4.52. MALDI-TOF: 1426
([MH]þ, calcd for C98H37N6O8: 1426.41).
4.2.14. Compound 18
DBU (0.38 mL, 2.55 mmol) was added to a stirred solution of C60
(400 mg, 0.55 mmol), I2 (352 mg, 1.39 mmol), and 17 (454 mg,
0.55 mmol) in toluene (800 mL). The resulting solution was stirred
for 12 h, then filtered through a short plug of SiO2 (CH2Cl2) and
concentrated. Column chromatography (SiO2, CH2Cl2/hexane 1:1)
followed by gel permeation chromatography (Biobeads SX-1,
CH2Cl2) gave 18 (332 mg, 39%) as a dark-orange glassy product. IR
4.2.10. Compound 14
To a solution of 4-pentyn-1-ol (10 g, 0.119 mol) and pyridine
(9.62 mL, 0.119 mol) in CH2Cl2 (100 mL) at 0 ꢀC were added tosyl
chloride (25 g, 0.131 mol) and DMAP (2.9 g, 0.238 mol). After 1 h,
the mixture was allowed to warm slowly to room temperature,
then stirred for 18 h, filtered, and evaporated. The organic layer was
diluted with CH2Cl2, washed with water, then brine, dried with
MgSO4, and concentrated in vacuo. The crude product was purified
by column chromatography (SiO2, CH2Cl2/hexane 1:1) to give 14
(neat): n
3292 (^C–H), 1744 (C]O). 1H NMR (CDCl3, 300 MHz):
d
1.96 (m, 12H), 2.37 (m, 8H), 3.99 (t, J¼6 Hz, 8H), 5.05 (d, J¼13 Hz,
2H), 5.22 (d, J¼12 Hz, 2H), 5.36 (d, J¼12 Hz, 2H), 5.83 (d, J¼13 Hz,
2H), 6.40 (t, J¼2 Hz, 2H), 6.51 (d, J¼2 Hz, 4H), 7.26 (m, 1H), 7.28 (m,
1H), 7.40 (m, 1H), 7.49 (s, 1H). 13C NMR (CDCl3, 75 MHz):
d 17.0, 28.1,
49.0, 66.2, 66.9, 67.4, 68.5, 69.0, 70.6, 83.4, 101.6, 107.3, 123.6, 125.2,
126.6, 128.2, 128.6, 129.0, 134.4, 135.8, 136.1, 136.6, 136.7, 137.8,
139.9, 141.0, 141.2, 142.3, 142.7, 143.2, 143.6, 143.8, 143.9, 144.1,
144.2, 144.3, 144.6, 144.9, 145.0, 145.2, 145.3, 145.6, 145.7, 145.8,
146.0, 147.3, 147.4, 148.6, 160.1, 162.6, 162.7. Anal. Calcd for
(20.73 g, 73%) as a colorless oil. IR (neat):
(CDCl3, 300 MHz):
1.85 (m, 2H), 1.88 (t, J¼3 Hz, 1H), 2.26 (m, 2H),
2.44 (s, 3H), 4.14 (t, J¼6 Hz, 2H), 7.34 (d, J¼8 Hz, 2H), 7.79 (d, J¼8 Hz,
2H). 13C NMR (CDCl3, 75 MHz):
14.9, 21.6, 27.7, 68.7, 69.4, 82.1,
n
3289 (^C–H). 1H NMR
d
C108H46O12$2CH2Cl2: C, 77.47; H, 2.96. Found: C, 77.27; H, 2.57.
d
FABMS: 1535 ([M]þ, calcd for C108H46O12: 1535.55).
127.9, 129.8, 132.9, 144.8. Anal. Calcd for C12H14O3S: C, 60.48; H,
5.92. Found: C, 60.51; H, 5.58.
4.2.15. Compound 19
To a mixture of 18 (65 mg, 0.042 mmol) and benzyl azide
(28 mg, 0.21 mmol) in CH2Cl2 (1 mL) and H2O (1 mL) were added
CuSO4$5H2O (1 mg, 0.006 mmol) and sodium ascorbate (4 mg,
0.02 mmol). The reaction mixture was stirred for 20 h. The organic
layer was diluted with CH2Cl2, washed with water, dried over
MgSO4, and concentrated. Column chromatography (SiO2, CH2Cl2/
MeOH 99:1) gave 19 (34 mg, 39%) as a dark-red glassy product. IR
4.2.11. Compound 15
A
mixture
of
methyl-3,5-dihydroxybenzoate
(0.88 g,
5.24 mmol), 14 (2.49 g, 10.47 mmol), K2CO3 (3.98 g, 28.82 mmol),
and LiBr (0.682 g, 7.86 mmol) in dry DMF (10 mL) was stirred at
80 ꢀC for 60 h. The mixture was cooled to room temperature, fil-
tered, and evaporated. The crude product was then purified by
column chromatography (SiO2, CH2Cl2/hexane 70:30) to give 15
(neat):
n d 2.09 (m, 8H),
1744 (C]O). 1H NMR (CDCl3, 300 MHz):
(1.28 g, 81%) as a white solid. IR (neat):
n
3289 (^C–H), 1713 (C]O).
2.83 (t, J¼7 Hz, 8H), 3.90 (t, J¼6 Hz, 8H), 5.04 (d, J¼13 Hz, 2H), 5.19
(d, J¼12 Hz, 2H), 5.30 (d, J¼12 Hz, 2H), 5.47 (s, 8H), 5.81 (d, J¼13 Hz,
2H), 6.32 (t, J¼2 Hz, 2H), 6.44 (d, J¼2 Hz, 4H), 7.23 (m, 13H), 7.33 (m,
1H NMR (CDCl3, 300 MHz):
d
1.97 (t, J¼3 Hz, 2H), 2.00 (m, 4H), 2.40
(m, 4H), 3.89 (s, 3H), 4.08 (t, J¼6 Hz, 4H), 6.65 (t, J¼2 Hz,1H), 7.18 (d,
J¼2 Hz, 2H). 13C NMR (CDCl3, 75 MHz):
d
15.1, 28.0, 52.2, 66.4, 68.9,
14H), 7.47 (t, J¼2 Hz, 1H). 13C NMR (CDCl3, 75 MHz):
d 22.2, 28.8,
83.3, 106.6, 107.8, 131.9, 159.9, 166.8. Anal. Calcd for C18H20O4: C,
71.98; H, 6.71. Found: C, 71.84; H, 6.58.
29.7, 49.1, 54.0, 67.0, 68.5, 70.6, 101.5, 107.1, 120.8, 123.5, 126.6,
128.0, 128.6, 129.1, 134.4, 134.8, 135.7, 136.1, 136.6, 136.7, 137.7, 140.0,
141.1, 142.3, 142.7, 143.1, 143.5, 143.7, 143.9, 144.1, 144.2, 144.3, 144.6,
144.8,144.9,145.1,145.3, 145.5, 145.6, 145.7,146.0, 147.3,147.4,147.6,
4.2.12. Compound 16
A 1 M LAH solution in THF (3 mL, 3 mmol) was added dropwise
to a stirred solution of 15 (1.28 g, 4.26 mmol) in THF (20 mL) at 0 ꢀC.
The resulting mixture was stirred for 6 h at 0 ꢀC, then MeOH was
carefully added. The organic layer (diluted with CH2Cl2) was
washed with water, then brine, dried over MgSO4, and concen-
trated. Column chromatography (SiO2, CH2Cl2/methanol 99.5:0.5)
148.6, 160.1, 162.5, 162.7. Anal. Calcd for C136H74N12O12$3/2CHCl3: C,
73.49; H, 3.39; N, 7.48. Found: C, 73.46; H, 3.83; N, 7.05. MALDI-MS:
2068.6 ([M]þ, calcd for C136H74O12N12: 2068.16).
4.2.16. Compound 21
DCC (2 g, 9.82 mmol), HOBt (cat), and DMAP (0.23 g, 1.87 mmol)
wereadded toa solution of 3-bromopropan-1-ol (1.36 g, 9.82 mmol)
and 10 (1.45 g, 4.68 mmol) in CH2Cl2 (50 mL) at 0 ꢀC. After 1 h, the
mixture was allowed to warm slowly to room temperature, and was
then stirred for 90 h, filtered, and evaporated. Column chromatog-
raphy (SiO2, CH2Cl2/hexane 90:10) gave 21 (1.183 g, 46%) as a yellow
gave 16 (0.967 g, 83%) as a yellow oil. IR (neat):
n 3400 (O–H), 3290
(^C–H). 1H NMR (CDCl3, 300 MHz):
d
1.97 (t, J¼3 Hz, 2H), 1.98 (m,
4H), 2.39 (m, 4H), 4.03 (t, J¼6 Hz, 4H), 4.59 (s, 2H), 6.38 (t, J¼2 Hz,
1H), 6.50 (d, J¼2 Hz, 2H). 13C NMR (CDCl3, 75 MHz):
d 15.1, 28.1,
65.2, 66.1, 68.9, 83.4, 100.5, 105.2, 143.3, 160.2. Anal. Calcd for
C17H20O3: C, 74.97; H, 7.40. Found: C, 74.54; H, 7.11.
oil. IR (neat):
n d 2.15 (m,
1728 (C]O). 1H NMR (CDCl3, 300 MHz):
4H), 3.39 (t, J¼6.5 Hz, 4H), 3.44 (s, 4H), 4.28 (t, J¼6 Hz, 4H), 5.18 (s,
4.2.13. Compound 17
4H), 7.34 (m, 4H); 13C NMR (CDCl3, 75 MHz):
66.8, 128.1, 128.4, 128.9, 135.6, 166.1.
d 29.05, 31.3, 41.4, 63.1,
DCC (1.01 g, 4.97 mmol), HOBt (cat), and DMAP (0.116 g,
0.948 mmol) were added to a solution of 16 (1.35 g, 4.97 mmol) and
10 (0.73 g, 2.37 mmol) in CH2Cl2 (25 mL) at 0 ꢀC. After 1 h, the
mixture was allowed to warm slowly to room temperature, and was
then stirred for 90 h, filtered, and evaporated. Column
4.2.17. Compound 22
A
mixture of 21 (1.016 g, 1.84 mmol) and NaN3 (0.718 g,
11.04 mmol) in dry DMF (5 mL) was stirred at room temperature for

11418
R. Pereira de Freitas et al. / Tetrahedron 64 (2008) 11409–11419
16 h. The organic layer was diluted with Et2O, washed with water
then brine, dried over MgSO4, and concentrated. Column chroma-
tography (SiO2, CH2Cl2) gave 22 (668 mg, 76%) as a yellow oil. IR
N, 2.04. Found: C, 81.60; H, 3.15; N, 2.22. MALDI-TOF-MS: 3889
([MH]þ, calcd for C278H145N6O20: 3889.24).
(neat):
(m, 4H), 3.33 (t, J¼6 Hz, 4H), 3.44 (s, 4H), 4.22 (t, J¼6 Hz, 4H), 5.18 (s,
4H), 7.34 (m, 4H). 13C NMR (CDCl3, 75 MHz):
27.9, 41.3, 47.8, 62.3,
n
2095 (–N3), 1728 (C]O). 1H NMR (CDCl3, 300 MHz):
d
1.88
4.2.21. Compound 28
A mixture of 3,5-dihydroxybenzyl alcohol (0.549 g, 3.917 mmol),
27 (2 g, 7.835 mmol), K2CO3 (2.97 g, 21.54 mmol), and LiBr (0.51 g,
5.87 mmol) in dry DMF (10 mL) was stirred at 80 ꢀC for 60 h. The
mixture was cooled to room temperature, filtered, and evaporated.
Column chromatography (SiO2, CH2Cl2) gave 28 (480 mg, 40%) as
d
66.8, 128.1, 128.3, 128.9, 135.6, 166.1. Anal. Calcd for C20H24N6O8: C,
50.42; H, 5.08. Found: C, 50.79; H, 4.97.
4.2.18. Compound 23
a yellow oil. IR (neat):
300 MHz):
n
2091 (–N3), 3362 (O–H). 1H NMR (CDCl3,
DBU (0.76 mL, 3.10 mmol) was added to a stirred solution of C60
(800 mg, 1.1 mmol), I2 (704 mg, 1.39 mmol), and 22 (908 mg,
1.1 mmol) in toluene (1600 mL). The resulting solution was stirred
for 12 h, then filtered through a short plug of SiO2 (CH2Cl2) and
evaporated. Column chromatography (SiO2, CH2Cl2/hexane 60:40)
followed by gel permeation chromatography (Biobeads SX-1,
CH2Cl2) gave 23 (214 mg, 16%) as a dark-orange glassy product. IR
d
2.03 (m, 4H), 3.49 (t, J¼6.5 Hz, 4H), 4.02 (t, J¼6 Hz, 4H),
4.60 (s, 2H), 6.37 (t, J¼2 Hz,1H), 6.51 (d, J¼2 Hz, 2H).13C NMR (CDCl3,
75 MHz): d 28.7, 48.2, 64.5, 65.1,100.6,105.2,143.5,159.9. Anal. Calcd
for C13H18N6O3: C, 50.97; H, 5.92. Found: C, 50.77; H, 5.57.
4.2.22. Compound 29
DCC (695 mg, 3.4 mmol), HOBt (cat), and DMAP (79 mg,
0.65 mmol) were added to a solution of 28 (990 mg, 3.23 mmol) and
10 (501 mg, 1.62 mmol) in CH2Cl2 (20 mL) at 0 ꢀC. After 1 h, the mix-
ture was allowed to warm slowly to room temperature, and was then
stirred for 72 h, filtered, and evaporated. Column chromatography
(SiO2, CH2Cl2/methanol 99.5:0.5) gave 29 (694 mg, 48%) as a yellow
(neat): n d 2.00
2094 (–N3), 1739 (C]O). 1H NMR (CDCl3, 300 MHz):
(m, 4H), 3.41 (t, J¼6 Hz, 4H), 4.44 (m, 4H), 5.19 (d, J¼13 Hz, 2H), 5.87
(d, J¼13 Hz, 2H), 7.30–7.44 (m, 3H), 7.53 (s, 1H). 13C NMR (CDCl3,
75 MHz):
d 28.0, 29.6, 47.9, 49.0, 49.2, 63.9, 66.9, 67.5, 70.5, 124.1,
126.9, 128.7, 135.8, 136.1, 136.5, 140.0, 141.0, 141.4, 142.3, 142.8,
143.3, 143.6, 143.8, 144.0, 144.2, 144.3, 144.4, 144.7, 145.0, 145.3,
145.4, 145.7, 145, 146.0, 146.1, 147.4, 147.5, 147.6, 148.5, 162.7, 162.9.
oil. IR (neat):
2.02 (m, 8H), 3.49 (t, J¼6 Hz, 8H), 3.49 (s, 4H), 4.01 (t, J¼6 Hz, 8H),
5.10 (s, 4H), 5.16 (s, 4H), 6.41 (t, J¼2 Hz, 2H), 6.49 (d, J¼2 Hz, 4H), 7.31
(m, 4H). 13C NMR (CDCl3, 75 MHz):
28.6, 41.4, 48.1, 64.6, 66.8, 66.9,
n
2093 (–N3), 1731 (C]O). 1H NMR (CDCl3, 300 MHz):
d
4.2.19. Compound 24
d
A mixture of 23 (84 mg, 0.07 mmol), phenylacetylene (15.8 mg,
0.15 mmol), CuSO4$5H2O (1 mg, 0.006 mmol), and sodium ascor-
bate (4 mg, 0.02 mmol) in CH2Cl2 (3 mL) and H2O (3 mL) was stirred
at room temperature for 24 h. The organic layer was diluted with
CH2Cl2, washed with water, dried over MgSO4, and concentrated.
Column chromatography (SiO2, CH2Cl2/methanol 99.5:0.5) gave 24
101.2, 106.6, 127.7, 128.1, 128.9, 135.6, 137.5, 159.9, 166.1, 166.15. Anal.
Calcd for C40H46N12O12: C, 70.40; H, 6.15. Found: C, 69.74; H, 6.31.
4.2.23. Compound 30
DBU (0.38 mL, 2.55 mmol) was added to a stirred solution of C60
(400 mg, 0.55 mmol), I2 (352 mg, 1.39 mmol), and 29 (492 mg,
0.55 mmol) in toluene (800 mL). The resulting solution was stirred
for 12 h, then filtered through a short plug of SiO2 (CH2Cl2) and
evaporated. Column chromatography (SiO2, CH2Cl2/hexane 80:20)
followed by gel permeation chromatography (Biobeads SX-1
CH2Cl2) gave 30 (88 mg, 10%) as a dark-orange glassy product. IR
(80 mg, 78%) as a dark-orange glassy product. IR (neat):
n 1742
(C]O). 1H NMR (CDCl3, 300 MHz):
d
2.41 (m, 4H), 4.42 (m, 4H), 4.50
(t, J¼7 Hz, 4H), 5.30 (d, J¼13 Hz, 2H), 5.87 (d, J¼13 Hz, 2H), 7.30–
7.44 (m, 9H), 7.55 (s, 1H), 7.75 (s, 2H), 7.77–7.84 (m, 4H). 13C NMR
(CDCl3, 75 MHz):
d 29.3, 29.6, 30.9, 46.7, 63.4, 67.7, 119.9, 124.5,
125.7,127.2,128.2, 128.8, 130.4,135.6,135.8,136.5,138.1,140.1,141.0,
141.4, 142.3, 142.8, 143.4, 143.6, 143.9, 144.1, 144.2, 144.4, 144.7,
144.9, 145.0, 145.1, 145.3, 145.4, 145.5, 145.7, 145.8, 146.0, 146.1,
146.2, 147.6, 147.9, 148.4, 162.7, 163.0. Anal. Calcd for
C96H32N6O8$CHCl3: C, 76.88; H, 2.20; N, 5.55. Found: C, 76.31; H,
2.19; N, 5.20. FABMS: 1397 ([M]þ, calcd for C96H32N6O8: 1397.35).
(neat): 2093 (–N3), 1743 (C]O). 1H NMR (CDCl3, 300 MHz):
d 2.00
(m, 8H), 3.47 (t, J¼6 Hz, 8H), 3.96 (t, J¼6 Hz, 8H), 5.06 (d, J¼13 Hz,
2H), 5.24 (d, J¼12 Hz, 2H), 5.35 (d, J¼12 Hz, 2H), 5.82 (d, J¼13 Hz,
2H), 6.38 (t, J¼2 Hz, 2H), 6.51 (d, J¼2 Hz, 4H), 7.18 (m, 1H), 7.39 (m,
1H), 7.49 (s, 1H). 13C NMR (CDCl3, 75 MHz):
d 28.7, 48.2, 49.0, 63.9,
64.6, 67.4, 68.5, 101.7, 107.4, 107.5, 123.6, 123.8, 125.3, 126.6, 126.7,
128.2, 128.6, 129.0, 134.4, 135.8, 136.1, 136.5, 136.6, 136.8, 137.8,
140.0, 140.9, 141.1, 141.3, 142.3, 142.7, 143.1, 143.6, 143.8, 144.0, 144.1,
144.2, 144.3, 144.6, 144.8, 145.0, 145.2, 145.4, 145.6, 145.7, 145.8,
145.9, 146.0, 147.3, 147.5, 148.6, 148.7, 148.75, 159.9, 162.6, 162.7.
4.2.20. Compound 25
A mixture of 23 (50 mg, 0.031 mmol), 8 (209 mg, 0.15 mmol),
CuSO4$5H2O (0.5 mg, 0.003 mmol), and sodium ascorbate (2 mg,
0.009 mmol) in CH2Cl2 (1 mL) and H2O (1 mL) was stirred at room
temperature for 1 h. The organic layer was diluted with CH2Cl2,
washed with water, dried over MgSO4, and concentrated. Column
chromatography (SiO2, CH2Cl2/methanol 99.5:0.5) gave 25 (81 mg,
4.2.24. Compound 31
To a mixture of 30 (50 mg, 0.031 mmol) and 8 (209.4 mg,
0.15 mmol) in CH2Cl2 (1 mL) and H2O (1 mL) were added
CuSO4$5H2O (0.5 mg, 0.003 mmol) and sodium ascorbate (2 mg,
0.009 mmol). The reaction mixture was stirred for 1 h. The organic
layer was diluted with CH2Cl2, washed with water, dried over MgSO4,
and concentrated. Column chromatography (SiO2, CH2Cl2/methanol
99.5:0.5) gave 31 (34%) as a dark-red glassy product. IR (neat): 1743
50%) as a dark-red glassy product. IR (neat):
(CDCl3, 300 MHz):
n
1743 (C]O). 1H NMR
0.87 (t, J¼7 Hz,12H),1.24 (m, 72H),1.72 (m, 8H),
d
2.20 (m, 4H), 2.35 (m, 4H), 2.86 (t, J¼7 Hz, 4H), 3.87 (t, J¼6 Hz, 8H),
4.38 (m, 4H), 4.42 (t, J¼7 Hz, 4H), 4.50 (t, J¼6 Hz, 4H), 5.27 (d,
J¼13 Hz, 2H), 5.43 (s, 4H), 5.88 (d, J¼13 Hz, 2H), 6.38 (t, J¼2 Hz, 2H),
6.58 (d, J¼2 Hz, 4H), 7.30–7.44 (m, 5H), 7.50 (s, 1H). 13C NMR (CDCl3,
(C]O). 1H NMR (CDCl3, 300 MHz):
d
0.87 (t, J¼7 Hz, 28H), 1.24 (s,
75 MHz):
d
14.1, 21.9, 22.6, 26.1, 28.0, 29.2, 29.3, 29.4, 29.6, 29.7, 31.9,
126H),1.62 (s,14H),1.72 (m,16H), 2.20 (t, J¼6 Hz, 8H), 2.31 (t, J¼6 Hz,
8H), 2.86(m, 8H), 3.87(t, J¼6 Hz,24H), 4.49(m,16H), 5.05(d, J¼13 Hz,
2H), 5.42 (s, 8H), 5.85 (d, J¼13 Hz, 2H), 6.32 (m, 1H), 6.38 (d, J¼2 Hz,
4H), 6.46 (m, 2H), 6.46 (d, J¼2 Hz, 8H), 6.57 (d, J¼2 Hz, 4H), 7.48 (m,
46.5, 49.1, 51.9, 63.4, 66.4, 66.8, 67.7, 68.1, 68.9, 70.5, 71.4,101.7,107.2,
121.4,124.2,127.1,128.8,134.3,135.7,136.0,136.5,138.0,138.6,139.2,
140.1, 140.8, 140.9, 141.0, 141.4, 141.7, 141.8, 142.1, 142.3, 142.8, 142.9,
142.95, 142.97, 142.99, 143.05, 143.3, 143.6, 145.7, 143.8, 143.9, 144.1,
144.2,144.4,144.45,144.5,144.55,144.6,144.62,144.65,144.7,144.8,
144.9, 144.96, 144.97, 145.1, 145.14, 145.19, 145.23, 145.29, 145.5,
145.6, 145.7, 145.9, 146.1, 146.5, 147.3,147.5,147.6, 148.4,160.4, 162.6,
162.9,163.4. Anal. Calcd for C278H144N6O20$2CHCl3: C, 81.54; H, 3.57;
3H), 7.91 (s,1H).13C NMR (CDCl3, 75 MHz):
d 14.1, 21.9, 22.7, 24.9, 25.5,
26.1, 28.0, 29.2, 29.3, 29.4, 29.6, 29.7, 29.9, 31.9, 33.9, 46.9, 64.4, 66.4,
68.1, 69.0, 71.4, 101.7, 107.2, 121.5, 135.7, 136.0, 136.5, 137.1, 138.6, 139.2,
139.6, 140.0, 140.1, 140.3, 140.8, 140.9, 141.0, 141.7, 141.8, 142.1, 142.9,
142.9, 143.6, 143.8, 144.4, 144.5, 144.6, 144.65, 144.8, 144.9, 145.1,

R. Pereira de Freitas et al. / Tetrahedron 64 (2008) 11409–11419
11419
Armaroli, N.; Marconi, G.; Vicinelli, V.; Boudon, C.; Gisselbrecht, J.-P.; Gross, M.;
Hadziioannou, G.; Krasnikov, V.; Ouali, L.; Echegoyen, L.; Liu, S.-G. Carbon 2000,
38, 1587–1598; (c) Nierengarten, J.-F.; Oswald, L.; Nicoud, J.-F. Chem. Commun.
1998, 1545–1546; (d) Urbani, M.; Nierengarten, J.-F. Tetrahedron Lett. 2007, 48,
8111–8115.
8. (a) Hahn, U.; Ge´gout, A.; Duhayon, C.; Coppel, Y.; Saquet, A.; Nierengarten, J.-F.
Chem. Commun. 2007, 516–518; (b) Delavaux-Nicot, B.; Kaeser, A.; Hahn, U.;
Ge´gout, A.; Brandli, P.-E.; Duhayon, C.; Coppel, Y.; Saquet, A.; Nierengarten, J.-F.
J. Mater. Chem. 2008, 18, 1547–1554.
145.2, 145.4, 145.6, 146.1, 146.3, 146.9, 147.4, 147.5, 148.3, 148.5, 159.7,
160.5,162.6,163.4. Anal. Calcd for C496H290N12 36$CHCl3: C, 83.92; H,
O
4.12; N, 2.36. Found: C, 83.67; H, 4.30; N, 2.62. MALDI-TOF: 6994.5
([MH]þ, calcd for C496H291N12O36: 6994.83).
Acknowledgements
9. Kolb, H. C.; Finn, M. G.; Sharpless, K. B. Angew. Chem., Int. Ed. 2001, 40,
2004–2021.
10. Iehl, J.; Pereira de Freitas, R.; Nierengarten, J.-F. Tetrahedron Lett. 2008, 49,
4063–4066.
11. See also: (a) Isobe, H.; Cho, K.; Solin, N.; Werz, D. B.; Seeberger, P. H.; Nakamura, E.
Org. Lett. 2007, 9, 4611–4614; (b) Iehl, J.; Pereira de Freitas, R.; Delavaux-Nicot, B.;
Nierengarten, J.-F. Chem. Commun. 2008, 2450–2452.
This research was supported by the Centre National de la
Recherche Scientifique (UMR 7509), the French Ministry of Research
(doctoral fellowship to J.I.), and the Conselho Nacional de Desen-
´
´
volvimento Cientıfico e Tecnologico (Brazil). We further thank A.
Saquet for the CV and OSWV measurements.
12. (a) Huisgen, R. Pure Appl. Chem. 1989, 61, 613–628; (b) Huisgen, G.; Szeimies,
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Rostovtsev, V. V.; Green, L. G.; Fokin, V. V.; Sharpless, K. B. Angew. Chem., Int. Ed.
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