Synthesis, characterization and DFT calculations of new ethynyl-bridged C60 derivatives

Article abstract of DOI:10.1016/j.tet.2010.03.092

A new series of soluble C₆₀ derivatives for organic electronic application has been synthesized by ethynylation reaction using different electron-donating and electron-withdrawing groups of varying length.

Full text of DOI:10.1016/j.tet.2010.03.092

Tetrahedron 66 (2010) 4230–4242
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis, characterization and DFT calculations of new ethynyl-bridged
C60 derivatives
a
b
a
b
´
Simon Rondeau-Gagne , Carles Curutchet , François Grenier , Gregory D. Scholes ,
,
Jean-François Morin a
*
a
´
´
´
´
´
´
´
Departement de chimie, Centre de recherche sur les materiaux avances, Universite Laval, 1045 Ave. de la Medecine, Quebec, Quebec, Canada G1V 0A6
b Department of Chemistry, University of Toronto, 80 George Street, Toronto, Ontario, Canada M5S 3H6
a r t i c l e i n f o
a b s t r a c t
Article history:
A new series of soluble C60 derivatives for organic electronic application has been synthesized by
Received 22 January 2010
Received in revised form 22 March 2010
Accepted 23 March 2010
ethynylation reaction using different electron-donating and electron-withdrawing groups of varying
length.
Ó 2010 Elsevier Ltd. All rights reserved.
Available online 30 March 2010
Keywords:
Fullerene
OPE
DFT Calculations
Electrochemistry
1. Introduction
substituent and the C60 cage, do not allow direct through-bond
conjugation, making modulation of the electronic properties
Fullerenes play a fundamental role in the development of
organic electronics. The relative low cost, ease of functionalization
and remarkable electrochemical properties of C60 has led it to
become one of the most used n-type materials for the development
of efficient and stable opto-electronic devices, especially for solar
cells1 and molecular electronic2 applications. Because pristine C60 is
difficult to process owing to its poor solubility in common organic
solvents, solubilizing substituents have to be attached to it through
covalent bond formation. In the past two decades, a lot of reactions
have been developed to efficiently functionalize the C60 cage. These
include, among others, direct arylation through organometallic
precursors3 and radical reactions,4 cyclopropanation (Bingel
reaction),5 [2þ2],6 [3þ2]7 and [4þ2]8 cycloaddition.
rather difficult.1d,e The modulation of the LUMO energy level of C60
is particularly important for organic electronic application (e.g.,
polymer solar cells) as a difference of few tenth of eV could have
a significant impact on the device efficiency.11 Thus, a synthetic
strategy enabling the modulation of the electronic properties of C60
still needs to be developed.
Ethynylation reaction has proven to be very useful to bridge the
C60 with different substituents in moderate to good yields.12 This
reaction has been used recently to prepare surface nanomachines,13
electro- and photoactive materials14 and NLO active molecules.15
Although electrochemical characterization of few alkynyl-bridge
C60 derivatives has been reported in the recent literature,14a,15a no
systematic study of the influence of the nature of the alkyne
derivatives on the electronic properties of C60 has been performed.
For the purpose of the LUMO energy level modulation, ethynylation
reaction is expected to be particularly interesting since the electron
density can be tuned through the substituent bearing the terminal
alkyne (R) but also through the electrophilic species (E) used to
quench the reaction (Scheme 1). Moreover, an ethynyl moiety
directly attached to the C60 participates in a through-space p-orbital
overlapping, called ‘periconjugation’, thus indirectly increasing the
electronic communication between C60 and the R group.15a,16
Herein we report the synthesis, optical and electrochemical
In addition to increased the solubility of C60, properly designed
functional groups have the ability to modulate the electronic
properties of C60, particularly the LUMO energy level, either by
through-bond1d,9 or through-space interactions.10 The ability of
such functional groups to modulate the electronic density on the
C60 cage strongly rely on the type of linker used to attach it to the
C60. For example, cyclopropanation and cycloaddition reactions,
which lead to the formation of two sp3 carbons between the
properties and DFT calculations of
a series of thirteen C60
* Corresponding author. E-mail address: jean-francois.morin@chm.ulaval.ca
(J.-F. Morin).
derivatives prepared by ethynylation reaction using different
0040-4020/$ – see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.03.092

S. Rondeau-Gagne´ et al. / Tetrahedron 66 (2010) 4230–4242
4231
The starting aryl iodides (17a,b) have been prepared using
well-established protocols18,19 while derivatives 17c–e were
purchased. For the carbazole derivatives, the synthesis is depicted
in Scheme 2. First, a standard Sonogashira coupling between
triisopropylsilylacetylene (TIPSA) and the commercially available
2-(trifluoromethanesulfonyl)-carbazole was performed to provide
compound 14 in good yield. It is noteworthy that TIPSA was used
rather than trimethylsilylacetylene (TMSA) since the TMS-
protected alkyne on carbazole is not stable enough under the
alkylation conditions. Compound 14 was then alkylated with octyl
iodide using sodium hydride (NaH) in DMF to give compound 15.
Then, the TIPS-protected alkyne was cleaved using tetrabutyl-
ammonium fluoride (TBAF) in THF to provide compound 16 in
excellent yield.
TIPSA, Pd(PPh3)2Cl2
CuI, Et3N
OTf
TIPS
THF, rt
83%
N
H
N
H
14
1) NaH, DMF
TBAF, THF
93%
◦
0 C
TIPS
N
C8H17
2) C8H17I, rt
79%
15
N
C8H17
16
TMSA, Pd(PPh3)2Cl2
CuI, Et3N
R
TMS
R
X
THF, rt
Scheme 1. Ethynyl-bridged C60 derivatives.
18a, 98%
18b, 84%
18c, 79%
17a, R = 4-(N,N-dibutyl)aniline
17b, R = 4-(octyloxy)phenyl
17c, R = 4-nitrophenyl
KOH
electron-donor and electron-acceptor groups in order to determine
the ability of such groups to modulate the LUMO level of C60 using
an ethynyl bridge (Scheme 1). This work is the first step of a project
aiming at developing new C60 derivatives for solar cells application.
R
H
THF/MeOH
19a, 55%
19b, 96%
19c, 73%
TMSA, Pd(PhCN)2Cl2
P(t-Bu)3, CuI, Et3N
19d, 75%
19e, 74%
R
X
R
TMS
THF, rt
2. Results and discussion
17d, R = 3-hexylthiophene
17e, R = 5-hexylthiophene
18d, 97%
18e, 39%
All the C60 derivatives synthesized in this study are presented in
Scheme 1. Different electron-donating and electron-withdrawing
groups were used for the purpose of this study, namely
substituted thiophene, carbazole and phenyl rings bearing het-
eroatoms (N, O). Thiophene and carbazole rings have been chosen
because those are important building blocks in organic semi-
conductors, especially in conjugated polymers for solar cell appli-
cation.17 Phenyl group was used for its ease of functionalization in
different positions. All these units have been substituted with alkyl
chains to enhance the solubility of the resulting derivatives. As
electrophiles, proton was used in all cases, except for 13 in which
unsubstituted benzoyl group was used to study its effect on the
1, 25%
2, 60%
3, 24%
4, 73%
5, 24%
6, 62%
1) C60 (excess), LHMDS,
THF, rt
19a-e
16
R
2) TFA
H
Scheme 2. Synthesis of compounds 1–6.
For the synthesis of compounds 18a–c, the corresponding aryl
iodides have been coupled to TMSA using standard Sonogashira
coupling at room temperature with good to excellent yield (79–
98%). For the 2-bromothiophene derivatives, the standard Sono-
gashira conditions lead to only very low yield of the desired
product, even at high temperature (65 ꢀC). Thus, we applied the
conditions developed by Buchwald and co-workers using
PdCl2(PhCN)2 and a hindered ligand (P(t-Bu)3) specially designed
for unactivated aryl bromides.20 These conditions were very suc-
cessful for the synthesis of 18d (3-hexylthiophene) (97% yield) but
not for the synthesis of 18e (39% yield). This difference of re-
activity has not been investigated in the course of this study. All
the TMS-protected alkyne (18a–e) were then desilylated in basic
LUMO energy level of C60
.
In order to study the conjugation path in ethynyl-bridged C60
derivatives, the substituents have been directly attached to the C60
(compounds 1–6) or placed in a face-to-face configuration (ortho
position) (compounds 10–12) relative to the C60 cage. In the former
case, a through-bond mechanism is expected to dominate while in
the later case, a through-space interaction is more likely to take
place. The effect of the substituents length has also been studied in
the linear derivatives by adding a phenyl linker between the
substituents and the C60 cage (compounds 7–9). The synthesis of
the precursors and their C60 derivatives is outlined in Scheme 2–5.

4232
S. Rondeau-Gagne´ et al. / Tetrahedron 66 (2010) 4230–4242
conditions in a mixture of THF and methanol to provide the ter-
minal alkyne 19a–e in moderate to excellent yields (55–93%). The
lower yield for the N,N-dibutylaniline derivative (19a) can be
explained by the poor stability of this compound. Partial
decomposition has been observed during the purification by
column chromatography on silica gel.
The ethynylation reactions on C60 were conducted using a slightly
modified procedure reported by Tour and co-workers14 Terminal
alkyne precursor and C60 were added in dry THF and sonicated for
three hours before LHMDS (lithium bis(trimethylsilyl)amide) was
added.Afterfewminutesofstirringatroomtemperature,thereaction
was quenched with trifluoroacetic acid (TFA) and the solvent was
immediately removed under vacuum. All the derivatives have been
purified by usual column chromatography on silica gel. The success
of the ethynylation reaction of C60 has been assessed by the
appearance of a peak at around 7.1 ppm in the 1H NMR, which
15b
corresponds to the presence of a proton directly attached to C60
.
Moreover, a set of peaks appears between 140 and 160 ppm in the
13C NMR spectra upon attachment of C60, which corresponds to the
carbon of the C60 cage.
For the ethynylation reaction, the yield of reaction is very de-
pendent on the solubility and ease of purification. For example, the
reaction yields for 1 (25%) and 5 (24%) were found to be much lower
than for 4 (73%) and 6 (62%) since they are much less soluble.
Nonetheless, the reaction yields obtained for the soluble derivatives
are slightly better than those published previously,13–15 probably
due to the better solubility of our derivatives but also to careful time
monitoring for each reaction steps.
In order to study the influence of the length of the linker between
the substituents and the C60 cage, oligo(phenylene ethynylene)
(OPE) based on the alkoxyphenyl, carbazole and nitrophenyl have
been synthesized and their preparation is outlined in Scheme 3.
Compounds 19b–c and 16 were coupled to 4-(trimethylsilylethy-
nyl)iodobenzene21 under standard Sonogashira conditions to pro-
vide 20b–d in moderate to excellent yield (66–97%). Then, the
alkyne were deprotected and coupled to the C60 using the same
conditions described above to provide compounds 7–9 in moderate
yields (44–59%).
Scheme 4. Synthesis of compounds 10–12.
TMSA group was selectively attached at the 2 position using
standard Sonogashira coupling conditions to provide compound
22 in good yield. In order to ensure the regioselectivity of this
coupling, the reaction was initiated at 0 ꢀC before it was warmed
at room temperature for several hours. Then, the bromine was
changed to an iodine atom using tert-butyllithium followed by
1,2-diiodoethane to afford compound 23 in 92% yield. Although
Sonogashira coupling can be performed directly on the bromine
derivative under standard conditions, the replacement of the
bromine by the iodine has been achieved in order to be able to
perform the next step at room temperature since 1,2-dialkynyl
benzene derivatives are known to be unstable at elevated tem-
perature (required for Sonogashira coupling on
a bromine
derivative) because they can undergo radical-promoted cycliza-
tion.22 Compound 23 was then coupled to 19b–c and 16 using
Sonogashira coupling in moderate to good yield (49–85%) and
the alkyne were deprotected using KOH to afford the precursors
25b–d. Those were then attached to the C60 as previously
described in moderate to poor yield (12–57%). The lower yields
obtained for the ortho derivatives can be attributed to the diffi-
culty to form the acetylide using LHMDS compared to the other
derivatives. In fact, more LHMDS was necessary to efficiently
deprotonate the precursors of compounds 10–12 than usually
required for other precursors (2 equiv).
For the benzoylation reaction (Scheme 5), compound 16 was
dissolved in THF and treated with LHMDS before a large excess of
benzoyl chloride was added. The low yield (22%) of this reaction is
attributed to the formation of a significant amount of unknown
polar side products.
Scheme 3. Synthesis of compounds 7–9.
Derivatives in which the electron-rich or electron-poor sub-
stituent is facing the C60 cage owing to an ortho linker were also
synthesized (Scheme 4). Starting from 2-iodobromobenzene, one

S. Rondeau-Gagne´ et al. / Tetrahedron 66 (2010) 4230–4242
4233
can be attributed to a more efficient conjugation through a para
linker.24 Interestingly, the difference inthe lmax values forcompounds
2 and 10 is only 2 nm, compared to 12 and 15 nm for the 3/11 and 6/12
pairs, respectively. This could be an indication that through-space
ground state interaction takes place between the C60 cage and the
octyloxyphenyl substituent in ortho position. Nierengarten and
co-workers reported recently a bathochromic shift, related to an
intramolecular through-space interaction, of the absorption band of
Scheme 5. Synthesis of compound 13.
OPEs lying close to a C60.
25 However, UV-visible experiments cannot
UV-visible spectra of the phenylalkoxy-, carbazole and
nitrobenzene derivatives with and without the C60 have been
taken in dilute solution and the results are presented in Table 1
(see Supplementary data for all the spectra). All those com-
pounds and their acetylenic precursors absorb light in the UV
region (290–339 nm), which is consistent with other OPEs
be used to study such interaction in our derivatives since the C60 and
the OPE UV-visible bands overlap in the 300–340 region.
To study the influence of electron-donating and electron-
withdrawing units on the LUMO level of C60, cyclic voltammetry
measurements were performed in solution in cathodic regime and
the results are summarized in Table 2 (see Supplementary data for
all the CVs). All proton-substituted derivatives (compound 1–12)
show at least two quasi-reversible reduction waves between 0 and
ꢁ2.5 V versus Fc/Fcþ as usually observed for C60 derivatives. The
Table 1
Optical properties of compounds 2, 3, 6–12
a
Compound
lmax (nm)
3
b (mmolꢁ1 cm2)
2
3
5
6
7
8
9
10
11
12
263, 307
259, 314
261, 327
270, 315
262, 320
260, 333
268, 337
260, 309
260, 326
268, 330
Table 2
Cyclic voltammetry data of C60, PCBM and compounds 1–13a
38,800
Compound
Ered1 (V)
Exp. LUMO (eV)b
Theo. LUMO (eV)
C60
PCBM
1
2
3
4
5
6
7
8
9
10
11
12
13
ꢁ0.824
ꢁ0.921
ꢁ0.873
ꢁ0.876
ꢁ0.847
ꢁ0.855
ꢁ0.877
ꢁ0.864
ꢁ0.862
ꢁ0.856
ꢁ0.854
ꢁ0.859
ꢁ0.845
ꢁ0.847
ꢁ0.838
ꢁ3.980
ꢁ3.880
ꢁ3.927
ꢁ3.924
ꢁ3.953
ꢁ3.945
ꢁ3.923
ꢁ3.936
ꢁ3.938
ꢁ3.944
ꢁ3.946
ꢁ3.941
ꢁ3.955
ꢁ3.953
ꢁ3.962
ꢁ3.744
ꢁ3.590
ꢁ3.630
ꢁ3.592
ꢁ3.810
ꢁ3.649
ꢁ3.620
ꢁ3.624
ꢁ3.620
ꢁ3.750
ꢁ3.636
ꢁ3.644
ꢁ3.740
ꢁ3.602
ꢁ3.624
10,780
19,100
a
The first value correspond to the most intense band in the spectrum while the
second value correspond to the p–p transition.
*
b
Calculated in a 1 cm quartz cell with a concentration of 5,0ꢂ10ꢁ6 mol/L at 25 ꢀC.
reported in the literature.14a,23 Compared to compounds 2, 3 and
6, UV-visible spectra of compounds 7, 8 and 9 were shifted
bathochromically (13, 17 and 22 nm, respectively) because of the
extended conjugation length (see example in Fig. 1). On the
other hand, the ortho derivatives 10–12 are also red shifted
compared to compounds 2, 3 and 6, but at a lesser extent. This
a
Potential versus ferrocene/ferrocinium measured with cyclic voltammetry at
a scan rate of 200 mV/s in a degassed mixture of o-DCB/MeCN (4:1) containing
Bu4NPF6 (0.1 M) as a supporting electrolyte. Platinum wires were used as working
and counter electrodes and Ag/Agþ electrode was used as reference electrode.
b
Values estimated using the following equation; ELUMO¼ꢁ(Ered1þ4.8) eV.26
LUMO levels of the C60 derivatives were calculated from the
potential of the first reduction wave (Ered1) using the equation
ELUMO¼ꢁ(Ered1þ4.8) eV.26 It is noteworthy that the values of potential
at the peak maximum give us much more better reproducibility
than the values of the half-wave potential typically used for the cal-
culation of the ELUMO. Thus, our values are not absolute ones, but they
are used to establish comparison between our derivatives and
the well-studied [6,6] phenyl-C61-butyric acid methyl ester (PCBM).
Compared to PCBM, the introduction of an ethynyl bridge
between the substituents and C60 lowered the ELUMO value. As
expected, the highest LUMO levels have been calculated for
compound1 and 2 that contain strongelectron-donating units in the
para position relative to the alkyne, a dialkylamine (ꢁ3.927 eV) and
an alkoxy (ꢁ3.924 eV), respectively (Fig. 2). In the opposite,
compound 3 shows the lower ELUMO value (ꢁ3.953 eV) owing to the
presence of a strong electro-withdrawing nitro group (Fig. 2). Those
results show that modulation of the LUMO energy level of C60
through an alkyne bridge is feasible, but not trivial. The modulation
of 50 meV between different derivatives is in the same order of
magnitude as that observed in other reports.1 Interestingly the
substitution pattern on the thiophene ring has a significant
influence on the electrochemical properties of the C60 derivatives. In
fact, the hexyl chain in position 3 of the thiophene ring makes the
ELUMO value of C60 lower (ꢁ3.945 eV) than its 5-hexylthiophene
homologue (ꢁ3.923 eV). This small difference can be attributed to
not only solvent effects but also to an electronic interaction between
Figure 1. UV-visible spectra of (a) compounds 3 and 8 and (b) compounds 6 and 9 in
chloroform (10ꢁ6 M).

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S. Rondeau-Gagne´ et al. / Tetrahedron 66 (2010) 4230–4242
Figure 2. Cyclic voltamogram of compounds 1, 2 and 3 in 0.1 M Bu4NPF6 at a scan rate
of 0.1 V sꢁ1 at room temperature.
Figure 3. Cyclic voltamogram of compounds 6 and 13 in 0.1 M Bu4NPF6 at a scan rate
of 0.1 V sꢁ1 at room temperature.
the alkyl chain and the C60 cage. The DFT-optimized geometries of
the derivatives showed that the alkyl chain in compound 4 (vide
infra) is much more closer to the fullerene than in compound 5,
which translates into a significant smaller dipole. The dþ charge
carried by this proximate alkyl chain has better ability to stabilize
a negative charge on the C60 cage, thus decreasing the Ered1 value.
The addition of a phenyl group between the electro-donating/
withdrawing substituent and the C60 cage is responsible for a par-
tial loss of the electronic communication between them. Indeed,
there is almost no difference in the ELUMO values between
compounds 7 (ꢁ3.938 eV) and 8 (ꢁ3.944 eV) containing the
alkoxyphenyl and the nitrophenyl group, respectively. Thus, the
electro-donating/withdrawing units have to be close to the C60 cage
to have influence on its electronic properties.
To study a possible through-space interaction between the C60
and the substituent, ortho OPEs were tested. By comparing
compounds 10, 11 and 12, it is clear that the electronic nature of the
substituent has little or no effect on the LUMO energy level of C60
with values ranging from ꢁ3.941 to ꢁ3.955 eV. Interestingly, the
ELUMO values calculated for the nitrophenyl derivatives substituted
in para position (3) and that in ortho position (11) are almost
identical (w ꢁ3.954 eV). This result is quite surprising given that
compound 11 has one more phenyl group between the nitrophenyl
and the C60 cage. Although it is too premature to attribute this to
a direct through-space interaction, this hypothesis is the most
likely in regard to the data collected so far. However, the through-
space interaction in compounds 10–12 is expected to be minimal
since the distance between the substituent and the C60 cage
(calculated on the optimized geometries) is ca. 5.7 Å, which is too
high to allow efficient intramolecular interaction.
functional has become the standard method to study organic
chemistry because it constitutes a good compromise between
computational cost and accuracy in the prediction of a variety of
molecular properties.29 Moreover, Zhan and co-workers demon-
strated that the ionization potentials, electron affinities and elec-
tronic excitation energies of a variety of organic and inorganic
compounds can be linearly correlated with the HOMO, LUMO and
HOMO/LUMO gap energies calculated at the B3LYP level.30 Because
of the size of the molecules, initial geometry optimizations and
vibrational frequency analysis were performed at the B3LYP/STO-
3 G level adopting all-trans conformations for the alkyl chains. After
the structures were confirmed to be true minima, the geometries
were refined using the split-valence double-zeta 6-31G(d) basis set,
and subsequent single-point calculations used to evaluate HOMO
and LUMO energies were performed adopting an enlarged split-
valence triple-zeta 6-311þG(d,p) basis set.
An interesting result from our calculations is that HOMO
energies along the series of ethynyl-bridged derivatives can be
modulated over a significant range of w0.6 eV, while modulation of
LUMO levels appears to be more moderate spanning a range of
w0.2 eV. Thus, the differences predicted for the HOMO/LUMO gaps
are largely originated by changes in the HOMO levels. A visual
inspection of the molecular orbitals, as shown in Figure 4 for
selected derivatives, explains this observation. Thus, while the
LUMO orbitals reside exclusively in the fullerene cage, only in the
compounds 1, 3, 4, 8 and 11 we have localization of the HOMO on
As shown in Figure 3, the presence of an electron-withdrawing
benzoyl group on the C60 (compound 13) decreases the first
reduction potential substantially (ꢁ0.838 V) with respect to its
protonated counterpart (6, ꢁ0.864 V). Also, compound 13 is not as
stable as the proton-substituted ones upon reduction as shown by
the irreversibility of the reduction wave. Nonetheless, these results
show that using different electrophilic species in the course of the
reaction can significantly perturb the LUMO energy level of C60
.
The electronic structure of pristine C60, PCBM, and the series of
ethynyl-bridged C60 derivatives were investigated by performing
extensive density functional theory (DFT) calculations. Our basic
aim is to understand how different substituents modulate the
levels of the highest occupied molecular orbital (HOMO) and the
lowest unoccupied molecular orbital (LUMO), which can be directly
related to the optical and electrochemical properties of these
materials. DFT calculations were performed using the B3LYP hybrid
functional,27 which mixes the Lee, Yang, and Parr functional for the
correlation part and Becke’s three-parameter functional for the
exchange, as implemented in the Gaussian 03 code.28 The B3LYP
Figure 4. Visual representation of the HOMO and LUMO molecular orbitals for selected
ethynyl-bridged C60 derivatives. The corresponding HOMO/LUMO orbital energies in eV
are ꢁ6.125/ꢁ3.630 for compound 1, ꢁ6.076/ꢁ3.592 for compound 2, and ꢁ5.889/ꢁ3.624
for compound 6.

S. Rondeau-Gagne´ et al. / Tetrahedron 66 (2010) 4230–4242
4235
the fullerene unit. In other derivatives, the HOMO is partially
delocalized over the substituent (compounds 2 and 5), and in most
cases it completely resides in it. This degree of localization trans-
lates into HOMO levels over w5.7–5.9 eV when the orbital resides
in the substituent, whereas, a complete or partial localization over
the fullerene cage translates into larger values (w6.0–6.3 eV) much
closer to pristine C60 (6.45 eV) or PCBM (6.11 eV).
Ontheotherhand,theorderingofHOMOlevelsfollowsreasonably
well the electron-donating ability of the substituents: –Ph–NO2<–
Ph–NBu2 w –hexyl-tiophene w –Ph–O–Oct<N-octyl-carbazole. The
same ordering is observed for the LUMO levels, except that LUMO
values from carbazole derivatives are in this case much closer to the
energies obtained for the other molecules. Overall, the substitution of
a Solvent Purifier System (SPS). Other solvents were used as re-
ceived. Tetrahydrofuran (THF) and triethylamine (TEA) used for
Sonogashira reactions were degassed for 30 min prior to use.
LHMDS (1 M solution in THF) was used. All anhydrous and air
sensitive reactions were performed in oven-dried glassware under
positive argon pressure. Analytical thin-layer chromatography was
performed with silica gel 60 F254, 0.25 mm pre-coated TLC plates.
Compounds were visualised using 254 nm and/or 365 nm UV
wavelength and/or aqueous sulfuric acid solution of ammonium
heptamolybdate tetrahydrate (10 g/100 mL H2SO4þ900 mL H2O).
Flash column chromatographies were performed on 230–400 mesh
silica gel R10030B. Nuclear magnetic resonance (NMR) spectra
were recorded at 400 MHz (1H) and 100 MHz (13C). Signals are
reported as m (multiplet), s (singlet), d (doublet), dd (doublet of
doublet), t (triplet), q (quadruplet) and br s (broad singlet) and
coupling constants are reported in hertz (Hz). The chemical shifts
the C60 unit and the corresponding decrease in p-delocalization leads
in general to a decrease in the absolute value of the LUMO levels and
thusintheelectronacceptingabilityoffullerenetowardsvaluescloser
to PCBM. This effect together with the strong modulation of the
HOMO energies leads to a significant range of values w2.11–2.50 eV
for the HOMO/LUMO gaps, which are smaller than those predicted for
pristine C60 (2.71 eV) or PCBM (2.52 eV).
are reported in ppm (d) relative to residual solvent peak. High-
resolution mass spectra (HRMS) were recorded with an apparatus
equipped with an ESI or APPI ion source. IR spectra were recorded
using a Nicolet Magna 850 Fourier transform infrared spectrometer
(Thermo Scientific, Madison, WI) with a liquid nitrogen cooled
narrow-band mercury cadmium telluride (MCT) detector and
a Golden Gate ATR accessory (Specac Ltd., London, UK). Each
spectrum was obtained from 64 scans at a resolution of 4 cmꢁ1
Finally, we investigated the ability of our calculations to predict
quantitatively the LUMO energy levels of the C60 derivatives. A least
squares fit between experimental and theoretical LUMO energies
LUMO
LUMO
DFT
ðE
¼ A ꢃ E
þ BÞ leads to a moderate degree of correlation
exp
(Pearson’s coefficient r¼0.43). However, restricting the fit to the
compounds bearing a –H in the electron-withdrawing position (i.e.,
all except compound 13), the results show to a better correlation
(r¼0.61). Moreover, if we focus the analysis on the structurally
related compounds 1–6, which differ only in the group connected
to the terminal alkyne (R) and thus share the same basic skeleton,
we obtain a significantly improved correlation between theory and
experiment (r¼0.83). This analysis suggests that DFT can be used as
a useful tool to understand and qualitatively predict the changes in
LUMO levels for structurally related C60 derivatives, but points also
to the difficulties in correlating these changes when the differences
between derivatives are not limited to a single group but affect the
overall structure of the substituent.
4.2. General procedure for addition of C60 to terminal alkynes
To a round bottom flask equipped with a magnetic stir bar was
added the terminal alkyne, C60 (2 equiv per terminal alkyne H) and
THF (5 mM) under argon atmosphere. The reaction mixture was
sonicated for 3 h and LHMDS (2 equiv per terminal alkyne H) was
then added at room temperature to the greenish-brown solution
formed after sonication. During the addition of LHMDS, small
aliquots from the reaction were extracted and quenched with
trifluoroacetic acid (TFA) for TLC analysis. After the addition of
LHMDS, the reaction was stirred for 5 min and quenched with TFA
(20 equiv). After removal of solvent under vacuo, the crude product
was diluted with CH2Cl2 and the organic layer was filtered under
vacuum to remove excess of unreacted C60. The solvent was
removed under reduced pressure and the crude product was
purified by flash chromatography on silica gel with a mixture of
CS2/hexanes to afford the desired compound.
3. Conclusion
In conclusion, a new series of soluble C60 derivatives for organic
electronic application has been synthesized by ethynylation re-
action using different electron-donating and electron-withdrawing
groups of varying length. We show that electronic communication
between the C60 and the substituent can take place via the alkyne
bridge. We also show that depending on the electronic nature of the
substituent attached to the C60, materials with different absorption
bands can be obtained. However, only slight modification of the
LUMO energy level is observed when the electronic nature of the
substituent is changed. DFTcalculations of the LUMO energy level of
the derivatives synthesized show good correlation with those
measured by electrochemistry. Further experiments will include,
among others, the attachment of new electrophiles (other than
proton and benzoyl) to assess the ability of such groups to modulate
the LUMO energy level through to the position next to the alkyne on
the C60 cage. More electron-donating and electron-withdrawing
units will also be synthesized to study a potential through-space
interaction between the C60 cage and the substituent attached to it.
4.2.1. N,N-Dibutyl-4-iodoaniline(17a). A 50 mL round bottom flask
equipped with a magnetic stir bar was charged with 4-iodoaniline
(2.00 g, 9.13 mmol), anhydrous DMF (18.2 mL) and NaH (650 mg,
27.1 mmol) under argon atmosphere. The reaction mixture was
cooled to 0 ꢀC, stirred for 30 min and butyl iodide (4.15 mL,
36.5 mmol) was then added. The temperature was raised to room
temperature and the solution was stirred overnight. MeOH was
carefully added, followed by H2O and the mixture was extracted
with CH2Cl2. The organic layer was washed with H2O (4ꢂ), dried
over Na2SO4 and the solvent was removed under reduced
pressure. The crude product was purified by flash chromatography
on silica gel with hexanes as eluent to afford the desired com-
pound 17a (1.08 g, 35% yield) as a yellow oil. 1H NMR (CDCl3,
400 MHz): 7.40 (d, J¼8.9 Hz, 2H), 6.40 (d, J¼8.9 Hz, 2H), 3.21 (t,
J¼7.7 Hz, 4H), 1.53 (m, 4H), 1.32 (m, 4H), 0.94 (t, J¼7.3 Hz, 6H); 13C
NMR (CDCl3, 100 MHz): 147.6, 137.6, 114.0, 75.3, 50.7, 29.2, 20.3,
13.9; HRMS (ESI-TOF) m/z calcd for C14H22IN [MþH]þ: 332.0873,
found 332.0873. FT IR (ATR): 2962m, 2593w, 2208w, 1605w,
1458m, 1264s, 764m.
4. Experimental
4.1. General remarks
4.2.2. N,N-dibutyl-4-((trimethylsilyl)ethynyl)aniline(18a). A 50 mL
round bottom flask equipped with a magnetic stir bar was charged
with 17a (1.00 g, 3.02 mmol), THF (15 mL), triethylamine (1.66 mL,
[60]Fullerene (99% pure) was used as received. Solvents used for
organic synthesis (THF, CH2Cl2, DMF) were dried and purified with

4236
S. Rondeau-Gagne´ et al. / Tetrahedron 66 (2010) 4230–4242
12.1 mmol), PdCl2(PPh3)2 (42 mg, 0.06 mmol), CuI (11.5 mg,
0.06 mmol) and trimethylsilylacetylene (0.85 mL, 6.04 mmol) un-
der argon atmosphere. The reaction mixture was stirred overnight
at room temperature, diluted in CH2Cl2, washed with NH4Cl (3ꢂ)
and dried over Na2SO4. The solvent was removed under reduced
pressure and the crude product was purified by flash chromatog-
raphy on silica gel with hexanes to 1% EtOAc/hexanes as eluent to
afford the desired compound 18a (907 mg, 98% yield) as a dark
orange oil. 1H NMR (CDCl3, 400 MHz): 7.28 (d, J¼8.6 Hz, 2H), 6.50
(d, J¼8.7 Hz, 2H), 3.25 (t, J¼7.6 Hz, 4H), 1.55 (m, 4H), 1.33 (m, 4H),
0.94 (t, J¼7.3 Hz, 6H), 0.22 (s, 9H); 13C NMR (CDCl3, 100 MHz): 148.1,
133.3, 110.9, 108.5, 106.8, 90.8, 50.6, 29.3, 20.3, 14.0, 0.26; HRMS
(APPI-TOF) m/z calcd for C19H31NSi [MþH]þ: 302.2299, found
302.2317. FT IR (ATR): 2956m, 2897w, 2147s, 1605s, 1515s, 1367m,
1247m, 1186m, 839s, 760m.
22.9, 14.4, 0.29; HRMS (APPI-TOF) m/z calcd for C15H24SSi [MþH]þ:
265.1441, found 265.1436. FT IR (ATR): 2925w, 2856w, 2143w,
1248m, 836s, 757m.
4.2.5. 2-Ethynyl-3-hexylthiophene (19d). A 25 mL round bottom
flask equipped with a magnetic stir bar was charged with 18d
(750 mg, 2.84 mmol), KOH (796 mg,14.2 mmol), THF (7.0 mL), MeOH
(7.0 mL) and water (1.0 mL). The reaction mixture was stirred for 2 h,
diluted with CH2Cl2, washed with water (3ꢂ) and dried over Na2SO4.
The solvent was removed under reduced pressure and the crude
product was purified by flash chromatography on silica gel with
hexanes as eluent to afford compound 19d (488 mg, 75% yield) as
a yellow oil. 1H NMR (CDCl3, 400 MHz): 7.14 (d, J¼5.1 Hz,1H), 6.84 (d,
J¼5.1 Hz,1H), 3.42 (s,1H), 2.70 (t, J¼7.6 Hz, 2H), 1.60 (m, 2H), 1.31 (m,
6H), 0.88 (t, J¼6.5 Hz, 3H); 13C NMR (CDCl3, 100 MHz): 149.1, 128.0,
126.2,116.9, 83.1, 31.6, 30.2, 29.4, 28.9, 22.6,14.1; HRMS (ESI-TOF) m/z
calcd for C12H16S [MþH]þ: 193.1045, found 193.1050. FT IR (ATR):
3309m, 2924s, 2855s, 2100w, 1664m, 1465m, 1410s, 1294w, 838m.
Compound 4. See the general procedure for addition of C60 to
terminal alkynes. The materials used were 19d (40 mg, 0.21 mmol),
C60 (300 mg, 0.42 mmol) THF (83 mL), LHMDS (0.5 mL, 0.42 mmol)
and TFA (0.3 mL, 4.36 mmol). The crude product was purified by
flash chromatography on silica gel with hexanes to 10% CS2/hex-
anes as eluent to afford compound 4 (140 mg, 73% yield) as a brown
powder: mp>300 ꢀC; 1H NMR (CDCl3, 400 MHz): 7.28 (d, J¼5.0 Hz,
1H), 7.07 (s, 1H), 6.96 (d, J¼5.2 Hz, 1H), 2.95 (t, J¼7.6 Hz, 2H), 1.80
(m, 2H), 1.35 (m, 6H), 0.87 (t, J¼6.7 Hz, 3H); 13C NMR (CDCl3,
100 MHz): 151.3, 151.1, 149.1, 147.5, 147.3, 146.5, 146.3, 146.1, 145.7,
145.6, 145.5, 145.4, 145.3, 145.2, 144.6, 144.4, 143.1, 142.9, 142.5,
142.0, 141.9 (2C), 141.8, 141.6, 141.5, 140.4, 140.3, 136.0, 135.1 (29
signals from sp2-C in the C60 core), 128.3 (–C], Ar),126.8 (–C], Ar),
117.4 (–C^), 98.1 (–C^), 61.7 (CH in the C60 core), 53.3 (quaternary
sp3-C in the C60 core), 31.8 (CH2), 30.5 (CH2), 29.9 (CH2), 29.2 (CH2),
4.2.3. N,N-Dibutyl-4-ethynylaniline (19a). A 25 mL round bottom
flask equipped with a magnetic stir bar was charged with 18a
(750 mg, 2.49 mmol), KOH (558 mg, 9.95 mmol), THF (6.0 mL),
MeOH (6.0 mL) and water (1.0 mL). The reaction mixture was
stirred for 2 h, diluted with CH2Cl2, washed with H2O (3ꢂ) and
dried over Na2SO4. The solvent were removed under reduced
pressure and the crude product was purified by flash chromato-
graphy on silica gel with hexanes to 1% EtOAc/hexanes as eluents
to afford compound 19a (311 mg, 55% yield) as a dark orange oil.
1H NMR (CDCl3, 400 MHz): 7.32 (d, J¼8.4 Hz, 2H), 6.53 (d,
J¼8.5 Hz, 2H), 3.26 (t, J¼7.6 Hz, 4H), 2.95 (s, 1H), 1.53 (m, 4H), 1.34
(m, 4H), 0.95 (t, J¼7.3 Hz, 6H); 13C NMR (CDCl3, 100 MHz): 148.2,
133.3, 111.0, 107.4, 85.1, 74.4, 50.7, 29.3, 20.3, 13.9; HRMS (ESI-TOF)
m/z calcd for C16H23N [MþH]þ: 230.1903, found 230.1905. FT IR
(ATR): 3305w, 2956m, 2896w, 2099m, 1606s, 1514s, 1366m,
1180m, 812s.
Compound 1. See the general procedure for addition of C60 to
terminal alkynes. The materials used were 19a (50 mg, 0.22 mmol),
C60 (314 mg, 0.43 mmol), THF (87 mL), LHMDS (0.5 mL, 0.42 mmol)
and TFA (0.3 mL, 4.36 mmol). The crude product was purified by
flash chromatography on silica gel with hexanes to 20% CS2/hex-
anes as eluents to afford compound 1 (51 mg, 25% yield) as a brown
powder: mp>300 ꢀC; 1H NMR (CDCl3, 400 MHz): 7.63 (d, J¼8.1 Hz,
2H), 7.13 (s, 1H), 6.69 (d, J¼8.4 Hz, 2H), 3.35 (t, J¼7.1 Hz, 4H), 1.64
(m, 4H), 1.41 (m, 4H), 1.00 (t, J¼7.2 Hz, 6H); 13C NMR (CDCl3,
100 MHz): 152.2, 151.9, 148.3, 147.6, 147.3, 146.7, 146.4, 146.2, 145.9,
145.6, 145.5, 145.4 (2C), 144.7, 144.6, 143.2, 143.0, 142.5, 142.2, 142.0
(2C), 141.7, 141.6, 140.4, 140.2, 136.3, 135.0 (27 signals from sp2-C in
the C60 core), 133.4 (–C], Ar), 111.3 (–C], Ar), 107.7 (–C], Ar), 90.1
(–C^), 85.2 (–C^), 62.1 (CH in the C60 core), 55.4 (quaternary sp3-C
in the C60 core), 50.7 (CH2), 29.4 (CH2), 20.5 (CH2), 14.1 (CH3); HRMS
22.9 (CH2), 14.4 (CH3); HRMS (APPI-TOF) m/z calcd for C72H16
S
[MþH]þ: 913.1045, found 913.1055. FT IR (ATR): 2915s, 2848s,
2327w, 2213w, 1717m, 1426s, 1181s, 1013s, 805m, 767s.
4.2.6. 2-((Trimethylsilyl)ethynyl)-5-hexylthiophene (18e). A 25 mL
round bottom flask equipped with a magnetic stir bar was charged
with 5-bromo-2-hexylthiophene (500 mg, 2.02 mmol), THF (7 mL),
triethylamine (1.1 mL, 8.10 mmol), PdCl2(PhCN)2 (23 mg, 0.06 mmol),
CuI (8 mg, 0.04 mmol), P(t-Bu)3 (0.06 mL, 0.06 mmol) and trime-
thylsilylacetylene (0.6 mL, 4.05 mmol) under argon atmosphere. The
reaction mixture was stirred overnight at room temperature, diluted
in CH2Cl2, washed with NH4Cl (3ꢂ) and dried over Na2SO4. The
solvent was removed under reduced pressure and the crude product
was purified by flash chromatography on silica gel with hexanes as
eluent to afford compound 18e (208 mg, 39% yield) as a yellow oil. 1H
NMR (CDCl3, 400 MHz): 7.03 (d, J¼3.6 Hz, 1H), 6.59 (d, J¼3.5 Hz, 1H),
2.74 (t, J¼7.6 Hz, 2H),1.63 (m, 2H),1.31 (m, 6H), 0.87 (t, J¼6.5 Hz, 3H),
0.23(s, 9H);13C NMR (CDCl3,100 MHz):148.6,132.9,124.2,120.7, 98.4,
97.9, 31.8, 30.4, 28.9, 22.8, 14.3, 0.17; HRMS (APPI-TOF) m/z calcd for
C15H24SSi [MþH]þ: 265.1441, found 265.1441. FT IR (ATR): 3308m,
2927s, 2855m, 2107w, 1459m, 1378w, 799s.
(APPI-TOF) m/z calcd for C76H23
950.1910. FT IR (ATR): 2920m, 2852m, 2212w, 1603s, 1515s, 1363m,
1185s, 830s, 766s.
N
[MþH]þ: 950.1903, found
4.2.4. 2-((Trimethylsilyl)ethynyl)-3-hexylthiophene (18d). A 25 mL
round bottom flask equipped with a magnetic stir bar was charged
with 2-bromo-3-hexylthiophene (750 mg, 3.03 mmol), THF
(10 mL), triethylamine (1.7 mL, 12.1 mmol), PdCl2(PhCN)2 (35 mg,
0.09 mmol), CuI (12 mg, 0.06 mmol), P(t-bu)3 (0.09 mL, 0.09 mmol)
and trimethylsilylacetylene (0.8 mL, 6.07 mmol) under argon
atmosphere. The reaction mixture was stirred overnight at room
temperature, diluted in CH2Cl2, washed with NH4Cl (3ꢂ) and dried
over Na2SO4. The solvent was removed under reduced pressure and
the crude product was purified by flash chromatography on silica
gel with hexanes as eluent to afford compound 18d (779 mg, 97%
yield) as a yellow oil. 1H NMR (CDCl3, 400 MHz): 7.05 (d, J¼5.1 Hz,
1H), 6.77 (d, J¼5.1 Hz, 1H), 2.67 (t, J¼7.6 Hz, 2H), 1.59 (m, 2H), 1.30
(m, 6H), 0.88 (t, J¼6.5 Hz, 3H), 0.23 (s, 9H); 13C NMR (CDCl3,
100 MHz): 148.9,128.3,126.1,118.6,100.8, 97.9, 31.9, 30.4, 29.7, 29.2,
4.2.7. 2-Ethynyl-5-hexylthiophene (19e). A 25 mL round bottom
flask equipped with a magnetic stir bar was charged with 18e
(350 mg, 1.32 mmol), KOH (371 mg, 6.62 mmol), THF (3.0 mL),
MeOH (3.0 mL) and water (1.0 mL). The reaction mixture was stir-
red for 2 h, diluted with CH2Cl2, washed with water (3ꢂ) and dried
over Na2SO4. The solvent was removed under reduced pressure and
the crude product was purified by flash chromatography on silica
gel with hexanes as eluent to afford compound 19e (223 mg, 74%
yield) as a yellow oil. 1H NMR (CDCl3, 400 MHz): 7.07 (d, J¼3.5 Hz,
1H), 6.61 (d, J¼3.5 Hz, 1H), 3.27 (s, 1H), 2.75 (t, J¼7.6 Hz, 2H), 1.64
(m, 2H), 1.29 (m, 6H), 0.88 (t, J¼6.6 Hz, 3H); 13C NMR (CDCl3,

S. Rondeau-Gagne´ et al. / Tetrahedron 66 (2010) 4230–4242
4237
100 MHz): 148.6, 133.1, 123.9, 119.2, 80.4, 77.5, 31.5, 30.1, 28.7, 22.6,
14.1; HRMS (APPI-TOF) m/z calcd for C12H16S [MþH]þ: 193.1045,
found 193.0973. FT IR (ATR): 3311m, 2927s, 2858s, 2108w, 1664m,
1466m, 1412m, 1295w, 836m.
(500 mg, 1.09 mmol), tetrabutylammonium fluoride (1.6 mL,
1.63 mmol) and THF (5.4 mL). The reaction mixture was stirred for
30 min, diluted with CH2Cl2, washed with water (3ꢂ) and dried
over Na2SO4. The solvent was removed under reduced pressure and
the crude product was purified by flash chromatography on silica
gel with hexanes to 1% EtOAc/hexanes as eluents to afford com-
pound 16 (308 mg, 93% yield) as a yellow oil. 1H NMR (CDCl3,
400 MHz): 8.01 (d, J¼7.9 Hz, 1H), 7.96 (d, J¼7.9 Hz, 1H), 7.51 (s, 1H),
7.42 (t, J¼7.5 Hz, 1H), 7.32 (t, J¼8.7 Hz, 2H), 7.18 (t, J¼7.4 Hz, 1H),
4.14 (t, J¼7.3 Hz, 2H), 3.11 (s, 1H), 1.76 (m, 2H), 1.19 (m, 10H), 0.84 (t,
J¼7.1 Hz, 3H); 13C NMR (CDCl3, 100 MHz): 141.0, 139.8, 126.2, 123.3,
122.8, 122.3, 120.6, 120.2, 119.1, 118.6, 112.5, 108.8, 85.1, 76.5, 43.0,
31.8, 29.3, 29.1, 28.9, 27.2, 22.6, 14.1; HRMS (APPI-TOF) m/z calcd for
C22H25N [MþH]þ: 304.2060, found 304.2060. FT IR (ATR): 3308m,
3290m, 2954m, 2926s, 2854m, 2104w, 1598w, 1455s, 1441m,1326s.
Compound 6. See the general procedure for addition of C60 to
terminal alkynes. The materials used were 16 (50 mg, 0.17 mmol),
C60 (238 mg, 0.33 mmol), THF (66 mL), LHMDS (0.4 mL, 0.33 mmol)
and TFA (0.3 mL, 4.16 mmol). The crude product was purified by
flash chromatography on silica gel with hexanes to 30% CS2/hex-
anes as eluents to afford compound 6 (105 mg, 62% yield) as
a brown powder: mp>300 ꢀC; 1H NMR (CDCl3, 400 MHz): 8.16 (q,
J¼7.7 Hz, 2H), 7.86 (s, 1H), 7.70 (d, J¼6.8 Hz, 1H), 7.49 (m, 2H), 7.25
(m, 2H), 4.37 (s, 2H), 1.96 (s, 2H), 1.27 (m, 10H), 0.87 (m, 3H); 13C
NMR (CDCl3, 100 MHz): 152.0, 151.9, 147.9, 147.1, 146.9, 146.7, 146.6,
146.5, 146.2, 146.1, 145.9, 145.8, 145.7, 145.6, 145.1, 145.0, 144.8,
143.5, 142.8, 142.4, 142.3 (2C), 142.0, 141.9, 141.5, 140.7, 140.6, 140.3
(28 signals from sp2-C in the C60 core), 126.7 (–C], Ar), 123.3 (–C],
Ar), 122.7 (–C], Ar), 121.1 (–C], Ar), 120.8 (–C], Ar), 119.5 (–C],
Ar), 119.2 (–C], Ar), 112.8 (–C], Ar), 110.0 (–C], Ar), 109.2 (–C^),
85.3 (–C^), 62.3 (CH in the C60 core), 55.7 (quaternary sp3-C in the
C60 core), 43.6 (CH2), 32.1 (CH2), 29.7 (CH2), 29.5 (CH2), 29.4 (CH2),
27.6 (CH2), 22.9 (CH2), 14.4 (CH3); HRMS (APPI-TOF) m/z calcd for
C82H25N [MþH]þ: 1024.2060, found 1024.2057. FT IR (ATR): 2916m,
2846m, 2213w, 1719w, 1595m, 1322s, 1119m, 998s, 808s, 763s.
Compound 5. See the general procedure for addition of C60 to
terminal alkynes. The materials used were 19e (40 mg,
0.21 mmol), C60 (300 mg, 0.42 mmol), THF (83 mL), LHMDS
(0.5 mL, 0.42 mmol) and TFA (0.3 mL, 4.16 mmol). The crude
product was purified by flash chromatography on silica gel with
hexanes to 10% CS2/hexanes as eluents to afford compound 5
(45 mg, 24% yield) as a brown powder: mp>300 ꢀC; 1H NMR
(CDCl3, 400 MHz): 7.39 (d, J¼3.7 Hz, 1H), 7.11 (s, 1H), 6.80 (d,
J¼3.3 Hz, 1H), 2.89 (t, J¼7.5 Hz, 2H), 1.74 (m, 2H), 1.36 (m, 6H), 0.90
(m, 3H); 13C NMR (CDCl3, 100 MHz): 151.6, 151.3, 149.3, 147.7, 147.6,
146.7, 146.4, 146.3 (2C), 145.9, 145.8, 145.7, 145.5, 145.4, 144.8,
144.6, 143.3, 142.7, 142.6, 142.2, 142.1 (2C), 141.9, 141.7, 140.4 (2C),
136.1, 135.3 (28 signals from sp2-C in the C60 core), 133.4 (–C],
Ar), 124.4 (–C], Ar), 119.5 (–C^), 95.1 (–C^), 61.7 (CH in the C60
core), 55.4 (quaternary sp3-C in the C60 core), 31.6 (2C, CH2), 30.3
(CH2), 28.7 (CH2), 22.6 (CH2), 14.1 (CH3); HRMS (APPI-TOF) m/z
calcd for C72H16S [MþH]þ: 913.1045, found 913.1021.FT IR (ATR):
2914m, 2844m, 2325w, 1670w, 1425m, 1180m, 1034m, 794s, 767s.
4.2.8. 2-((Triisopropylsilyl)ethynyl)-9H-carbazole (14). A 25 mL
round bottom flask equipped with a magnetic stir bar was
charged with 9H-carbazol-2-yl trifluoromethanesulfonate (500 mg,
1.59 mmol), DMF (8 mL), triethylamine (0.9 mL, 6.34 mmol),
PdCl2(PPh3)2 (45 mg, 0.06 mmol), CuI (6 mg, 0.03 mmol) and triiso-
propylsilylacetylene (0.7 mL, 3.17 mmol) under argon atmosphere.
The reaction mixture was stirred overnight at 100 ꢀC, cooled to room
temperature, diluted in CH2Cl2, washed with NH4Cl (3ꢂ) and dried
over Na2SO4. The solvent was removed under reduced pressure and
the crude product was purified by flash chromatography on silica gel
with hexanes to 6% EtOAc/hexanes as eluents to afford compound 14
(455 mg, 83% yield)asa colourlessoil.1H NMR (CDCl3, 400 MHz): 7.99
(d, J¼8.1 Hz,1H), 7.93 (d, J¼8.1 Hz,1H), 7.79 (s,1H), 7.45 (s,1H), 7.36 (q,
J¼6.5 Hz, 2H), 7.29 (d, J¼8.1 Hz,1H), 7.20 (t, J¼8.1 Hz,1H),1.17 (s, 21H);
13C NMR (CDCl3, 100 MHz): 140.2, 138.9, 126.3, 123.7, 123.3, 122.9,
120.5,120.4,120.0,119.7,114.2,110.7,108.3, 89.9,18.7,11.4; HRMS (ESI-
TOF)m/zcalcdforC23H29NSi[MþH]þ:348.2142, found348.2147. FTIR
(ATR): 2961w, 2866w, 2149w, 1460w, 1325w, 1264s.
4.2.11. 1-Iodo-4-(octyloxy)benzene (17b). A 50 mL round bottom
flask equipped with a magnetic stir bar was charged with 4-iodo-
phenol (2.00 g, 6.80 mmol), DMF (22.7 mL), octyl bromide (1.8 mL,
10.2 mmol) and K2CO3 (2.8 g, 20.5 mmol). The temperature was
raised to 80 ꢀC and the solution was stirred overnight. The reaction
mixture was diluted with CH2Cl2, the organic layer was washed
with H2O (4ꢂ), dried over Na2SO4 and the solvent was removed
under reduced pressure. The crude product was purified by flash
chromatography on silica gel with hexanes as eluent to afford the
desired compound 17b (3.14 g, 98% yield) as yellow oil. 1H NMR
(CDCl3, 400 MHz): 7.54 (d, J¼8.9 Hz, 2H), 6.66 (d, J¼9.4 Hz, 2H), 3.91
(t, J¼6.5 Hz, 2H), 1.76 (m, 2H), 1.33 (m, 10H), 0.89 (m, 3H); 13C NMR
(CDCl3, 100 MHz): 158.2, 132.1 (2C), 116.2 (2C), 112.5, 68.2, 31.8,
29.4, 29.3, 29.2, 26.0, 22.7, 14.1; HRMS (APPI-TOF) m/z calcd for
4.2.9. 9-Octyl-2-((triisopropylsilyl)ethynyl)-9H-carbazole(15). A25 mL
round bottom flask equipped with a magnetic stir bar was charged
with compound 14 (800 mg, 2.30 mmol), DMF (6 mL) and NaH
(110 mg, 4.60 mmol) under argon atmosphere. The reaction mixture
was cooled to 0 ꢀC, stirred for 30 min and octyl iodide (0.9 mL,
4.83 mmol) was then added. The temperature was raised to room
temperature and the mixture was stirred overnight. MeOH was
carefully added, followed by H2O and the mixture was diluted with
CH2Cl2. The organic layer was washed with H2O (4ꢂ), dried over
Na2SO4 and the solvent was removed under reduced pressure. The
crude product waspurified by flashchromatographyon silicagel with
hexanes to 2% EtOAc/hexanes as eluents to afford compound 15
(834 mg, 79% yield) asa colourlessoil.1H NMR (CDCl3, 400 MHz): 7.97
(d, J¼8.1 Hz, 1H), 7.91 (d, J¼8.1 Hz, 1H), 7.46 (s, 1H), 7.38 (t, J¼7.6 Hz,
1H), 7.33 (d, J¼7.6 Hz,1H), 7.26 (d, J¼7.6 Hz,1H), 7.16 (t, J¼7.4 Hz,1H),
4.11 (t, J¼7.2 Hz, 2H),1.74 (m, 2H),1.18 (m, 33H), 0.85(m, 4H);13C NMR
(CDCl3, 100 MHz): 141.1, 139.8, 126.0, 123.1, 122.9, 122.5, 120.5, 120.2,
120.0, 119.0, 112.1, 108.8, 108.7, 89.5, 42.9, 31.8, 31.6, 29.3, 29.2, 28.9,
27.2, 22.7, 18.8, 14.1, 11.5; HRMS (APPI-TOF) m/z calcd for C31H47NSi
[MþH]þ: 460.3394, found 460.3397. FT IR (ATR): 2926s, 2863s,
2148m, 1599m, 1456s, 1326s, 882m.
C14H21IO [M]
þ: 332.0632, found 332.0632. FT IR (ATR): 2923m,
*
2853m, 1586w, 1485s, 1281m, 1240s, 1173m, 998w, 817s.
4.2.12. 1-(Octyloxy)-4-((trimethylsilyl)ethynyl)benzene (18b). A 50 mL
round bottom flask equipped with a magnetic stir bar was charged
with 17b (2.5 g, 7.53 mmol), THF (38 mL), triethylamine (4.14 mL,
30.1 mmol), PdCl2(PPh3)2 (106 mg, 0.15 mmol), CuI (28 mg,
0.15 mmol) and trimethylsilylacetylene (2.13 mL, 15.1 mmol) under
argon atmosphere. The reaction mixture was stirred overnight at
room temperature, diluted in CH2Cl2, washed with NH4Cl (3ꢂ) and
dried over Na2SO4. The solvent was removed under reduced pres-
sure and the crude product was purified by flash chromatography on
silica gel with hexanes as eluent to afford the desired compound 18b
(1.91 g, 84% yield) as dark orange oil.1H NMR (CDCl3, 400 MHz): 7.38
(d, J¼8.8 Hz, 2H), 6.79 (d, J¼8.8 Hz, 2H), 3.93 (t, J¼6.6 Hz, 2H), 1.76
(m, 2H), 1.32 (m, 10H), 0.89 (m, 3H), 0.23 (s, 9H); 13C NMR (CDCl3,
4.2.10. 2-Ethynyl-9-octyl-9H-carbazole(16). A 10 mL round bottom
flask equipped with a magnetic stir bar was charged with 15

4238
S. Rondeau-Gagne´ et al. / Tetrahedron 66 (2010) 4230–4242
100 MHz): 159.3, 133.4 (2C), 115.0, 114.3 (2C), 105.3, 92.2, 68.0, 31.8,
29.3, 29.2, 29.1, 26.0, 22.7, 14.1, 0.1; HRMS (ESI-TOF) m/z calcd for
C19H30OSi [MþH]þ: 303.2140, found 303.2140. FT IR (ATR): 2955w,
2926w, 2870w, 2155w, 1604w, 1505m, 1245s, 862m, 820s, 758m.
desired compound 23 (326 mg, 92% yield) as dark orange oil. 1H
NMR (CDCl3, 400 MHz): 7.84 (d, J¼7.8 Hz, 1H), 7.47 (d, J¼7.12 Hz,
1H), 7.28 (t, J¼7.1 Hz, 1H), 6.97 (t, J¼7.4 Hz, 1H), 0.28 (s, 9H); 13C
NMR (CDCl3, 100 MHz): 138.9, 132.9, 129.8, 129.7, 128.4, 127.9, 106.7,
101.4, 0.18; HRMS (APPI-TOF) m/z calcd for C11H13ISi [MþH]þ:
300.9904, found 300.9902. FT IR (ATR): 2957w, 2160w, 1458m,
1247m, 1016m, 858s, 836s.
4.2.13. 1-Ethynyl-4-(octyloxy)benzene (19b). A 25 mL round bottom
flask equipped with a magnetic stir bar was charged with 18b (1.5 g,
4.96 mmol), KOH (1.13 g, 19.8 mmol), THF (6.0 mL), MeOH (6.0 mL)
and water (1.0 mL). The reaction mixture was stirred for 2 h, diluted
with CH2Cl2, washed with water (3ꢂ) and dried over Na2SO4. The
solvent was removed under reduced pressure and the crude
product was purified by flash chromatography on silica gel with
hexanes as eluent to afford compound 19b (1.09 g, 96% yield) as
yellow oil. 1H NMR (CDCl3, 400 MHz): 7.41 (d, J¼8.9 Hz, 2H), 6.82 (d,
J¼8.9 Hz, 2H), 3.93 (t, J¼6.6 Hz, 2H), 2.98 (s, 1H), 1.77 (m, 2H), 1.32
(m, 10H), 0.89 (m, 3H); 13C NMR (CDCl3, 100 MHz): 159.5, 133.5
(2C), 114.4 (2C), 113.8, 83.8, 75.6, 68.0, 31.8, 29.3, 29.2, 29.1, 26.0,
22.7, 14.1; HRMS (ESI-TOF) m/z calcd for C16H22O [MþH]þ: 231.1740,
found 231.1740. FT IR (ATR): 2920m, 2850m, 2346w, 1603m, 1505s,
1287m, 1240s, 1168s, 820s, 764m.
Compound 2. See the general procedure for addition of C60 to
terminal alkynes. The materials used were 19b (50 mg, 0.22 mmol),
C60 (313 mg, 0.43 mmol), THF (87 mL), LHMDS (0.5 mL, 0.43 mmol)
andTFA (0.3 mL, 4.16 mmol). Thecrudeproduct waspurified byflash
chromatography on silica gel with hexanes to 30% CS2/hexanes as
eluents to afford compound 2 (125 mg, 60% yield) as a brown
powder: mp>300 ꢀC; 1H NMR (CDCl3, 400 MHz): 7.74 (d, J¼8.5 Hz,
2H), 7.13 (s,1H), 6.99 (d, J¼8.8 Hz, 2H), 4.04 (t, J¼6.6 Hz, 2H),1.84 (m,
2H), 1.32 (m, 10H), 0.91 (m, 3H); 13C NMR (CDCl3, 100 MHz): 159.8,
151.8,147.7,146.8,146.5,146.3,145.9,145.8,145.7,145.5,145.4,144.8,
144.6, 143.3, 142.7 (2C), 142.2, 142.1, 142.0, 141.9, 141.7, 141.6, 140.4,
140.3,136.2,135.2,133.7 (27 signals from sp2-C in the C60 core),114.7
(–C], Ar), 114.1 (–C], Ar), 90.9 (–C], Ar), 83.7 (–C^), 68.2 (–C^),
61.9 (CH in the C60 core), 31.8 (CH2), 29.7 (CH2), 29.4 (CH2), 29.2
(CH2), 26.1 (CH2), 22.7 (CH2),14.1 (CH3); HRMS (APPI-TOF) m/z calcd
for C76H22O [MþH]þ: 951.1743, found 951.1742. FT IR (ATR): 2903w,
2843w, 2328w, 2200w, 1724w, 1597m, 1504s, 1238s, 1167s, 1030s,
823s, 763m.
4.2.16. 4-(Octyloxy)-1-((2-((trimethylsilyl)ethynyl)phenyl)ethynyl)-
benzene (24b). A 25 mL round bottom flask equipped with a mag-
netic stir bar was charged with 23 (300 mg, 0.99 mmol), THF
(5 mL), triethylamine (0.6 mL), PdCl2(PPh3)2 (14 mg, 0.02 mmol),
CuI (4 mg, 0.02 mmol) and 19b (460 mg, 2 mmol) under argon
atmosphere. The reaction mixture was stirred overnight, diluted in
CH2Cl2, washed with NH4Cl (3ꢂ) and dried over Na2SO4. The sol-
vent was removed under reduced pressure and the crude product
was purified by flash chromatography on silica gel with hexanes to
7% CH2Cl2/hexanes as eluents to afford compound 24b (341 mg,
85% yield) as a yellow solid. 1H NMR (CDCl3, 400 MHz): 7.5 (m, 4H),
7.31 (t, J¼7.6 Hz, 1H), 7.25 (t, J¼5.7 Hz, 1H), 6.87 (d, J¼8.8 Hz, 2H),
3.97 (t, J¼6.6 Hz, 2H), 1.79 (m, 2H), 1.45 (m, 2H), 1.29 (m, 8H), 0.89
(m, 3H), 0.29 (s, 9H); 13C NMR (CDCl3, 100 MHz): 133.4, 133.3, 131.8,
128.7,126.7,125.5,115.4,114.6,103.8, 98.6, 93.9, 87.1, 68.3, 32.1, 29.5,
29.4, 22.9, 14.4, 0.24; HRMS (APPI-TOF) m/z calcd for C27H34OSi
[MþH]þ: 403.2452, found 403.2456. FT IR (ATR): 2953w, 2921m,
2853w, 2161w, 1602m, 1505m, 1287m, 1246s, 1175m, 997m, 842s,
829s, 754s.
4.2.17. 1-Ethynyl-2-((4-(octyloxy)phenyl)ethynyl)benzene (25b). A
10 mL round bottom flask equipped with a magnetic stir bar was
charged with 24b (340 mg, 0.84 mmol), KOH (190 mg, 3.38 mmol),
THF (1.1 mL), MeOH (1.1 mL) and water (0.5 mL). The reaction
mixture was stirred for 15 min, diluted with CH2Cl2, acidified with
HCl 10%, washed with water (3ꢂ) and dried over Na2SO4. The sol-
vent was removed under reduced pressure and the crude product
was purified by flash chromatography on silica gel with hexanes to
7% CH2Cl2/hexanes as eluents to afford compound 25b (236 mg,
85% yield) as a yellow solid. 1H NMR (CDCl3, 400 MHz): 7.5 (m, 4H),
7.31 (t, J¼7.6 Hz, 1H), 7.25 (t, J¼5.7 Hz, 1H), 6.87 (d, J¼8.8 Hz, 2H),
3.97 (t, J¼6.6 Hz, 2H), 3.35 (s,1H),1.79 (m, 3H),1.45 (m, 2H),1.29 (m,
8H), 0.89 (m, 2H); 13C NMR (CDCl3, 100 MHz): 133.5, 132.8, 131.8,
128.7, 127.7, 126.9, 124.6, 114.8, 86.8, 85.1, 82.6, 81.2, 68.3, 32.1, 29.6,
4.2.14. 1-Bromo-2-ethynylbenzene (22). A 50 mL round bottom flask
equipped with a magnetic stir bar was charged with 1-bromo-2-
iodobenzene (2.0 g, 7.07 mmol), THF (35 mL), triethylamine (3.88 mL,
28.3 mmol), PdCl2(PPh3)2 (99 mg, 0.14 mmol), CuI (27 mg,
0.14 mmol) and trimethylsilylacetylene (1.05 mL, 7.42 mmol) under
argon atmosphere. The reaction mixture was stirred overnight at
room temperature, diluted in CH2Cl2, washed with NH4Cl (3ꢂ) and
dried over Na2SO4. The solvent was removed under reduced pressure
and the crude product was purified by flash chromatography on silica
gel with hexanes as eluent to afford the desired compound 22 (1.51 g,
84% yield) as dark orange oil. 1H NMR (CDCl3, 400 MHz): 7.58 (d,
J¼8.1 Hz, 1H), 7.49 (dd, J1¼7.76 Hz, J2¼1.42 Hz, 1H), 7.24 (t, J¼7.6 Hz,
1H), 7.16 (t, J¼7.6 Hz, 1H), 0.28 (s, 9H); 13C NMR (CDCl3, 100 MHz):
133.8,132.5,129.7,127.0,125.9,103.2, 99.8, 0.15;HRMS (APPI-TOF)m/z
29.5, 29.4, 26.3, 22.9, 14.3; HRMS (ESI-TOF) m/z calcd for C24H26
O
[MþH]þ: 331.2056, found 331.2058. FT IR (ATR): 3284w, 2936w,
2919w, 2850w, 1605m, 1509s, 1282m, 1247s, 998m, 836s, 763m.
Compound 10. See the general procedure for addition of C60 to
terminal alkynes. The materials used were compound 25b (70 mg,
0.21 mmol), C60 (305 mg, 0.42 mmol), THF (85 mL), LHMDS (1.0 mL,
0.85 mmol) and TFA (0.3 mL, 4.2 mmol). The crude product was
purified by flash chromatography on silica gel with hexanes to 30%
CS2/hexanes as eluents to afford compound 10 (73 mg, 33% yield) as
a brown powder. 1H NMR (CDCl3, 400 MHz): 7.81 (m, 1H), 7.65 (m,
1H), 7.52 (d, J¼8.7 Hz, 2H), 7.43 (t, J¼3.6 Hz, 2H), 7.18 (s, 1H), 6.73 (d,
J¼8.7 Hz, 2H), 3.86 (t, J¼6.5 Hz, 2H), 1.71 (m, 2H), 1.39 (m, 2H), 1.26
(m, 8H), 0.87 (m, 3H); 13C NMR (CDCl3, 100 MHz): 159.4, 151.6,
151.4, 147.6, 147.4, 146.7, 146.5, 146.4 (2C), 146.2 (2C), 145.8, 145.7,
145.6, 145.4, 145.3, 144.7, 144.5, 143.2, 142.6, 142.5, 142.1, 142.0 (2C),
141.9, 141.7, 141.6, 140.4, 136.1, 135.3 (30 signals from sp2-C in the
C60 core), 133.3 (–C], Ar), 133.2 (–C], Ar), 132.0 (–C], Ar), 131.6
(–C], Ar), 128.7 (–C], Ar), 127.8 (–C], Ar), 127.3 (–C], Ar), 124.9
(–C], Ar), 114.9 (–C], Ar), 114.6 (–C], Ar), 96.2 (–C], Ar), 94.5
(–C^), 87.2 (–C^), 82.7 (–C^), 68.0 (–C^), 62.0 (CH in the C60
core), 31.9 (CH2), 29.8 (CH2), 29.7 (CH2), 29.5 (CH2), 26.4 (CH2), 23.1
(CH2), 14.5 (CH3); HRMS (APPI-TOF) m/z calcd for C84H26O [MþH]þ:
1051.2056, found 1051.2060. FT IR (ATR): 2916w, 2849w, 2050w,
1601w, 1506m, 1246s, 1014m, 946w, 827s, 756s.
calcd for C11H13BrSi [M]
þ: 251.9954, found 251.9970. FT IR (ATR):
*
2959w, 2162w, 1465m, 1248m, 1045w, 860s, 836s.
4.2.15. 1-Iodo-2-ethynylbenzene (23). A 50 mL round bottom flask
equipped with a magnetic stir bar was charged with 22 (300 mg,
1.19 mmol), THF (11.9 mL) and Et2O (11.9 mL). The temperature was
cooled to ꢁ78 ꢀC and t-BuLi (1.4 mL, 2.37 mmol) was added slowly.
The reaction mixture was stirred for one hour and 1,2-diiodoethane
was added (500 mg, 1.78 mmol). The reaction mixture was stirred
overnight at room temperature, diluted in CH2Cl2, washed with
H2O (3ꢂ) and dried over Na2SO4. The solvent was removed under
reduced pressure and the crude product was purified by flash
chromatography on silica gel with hexanes as eluent to afford the

S. Rondeau-Gagne´ et al. / Tetrahedron 66 (2010) 4230–4242
4239
4.2.18. 4-(Octyloxy)-1-((4-((trimethylsilyl)ethynl)phenyl)ethynyl)-
benzene(20b). A 10 mL roundbottomflaskequipped witha magnetic
stir bar was charged with 1-iodo-4-[2-(trimethylsilyl)ethynyl]-
benzene (300 mg, 1.00 mmol), THF (5.0 mL), triethylamine (0.6 mL),
PdCl2(PPh3)2 (14 mg, 0.02 mmol), CuI (4 mg, 0.02 mmol) and 19b
(460 mg, 2.00 mmol) under argon atmosphere. The reaction mixture
was stirred overnight, diluted in CH2Cl2, washed with NH4Cl (3ꢂ) and
dried over Na2SO4. The solvent was removed under reduced pressure
and the crude product was purified by flash chromatography on silica
gelwithhexanes to 8%CH2Cl2/hexanes aseluents to afford compound
20b (393 mg, 97% yield) as a yellow solid. 1H NMR (CDCl3, 400 MHz):
7.43 (m, 6H), 6.86 (d, J¼8.8 Hz, 2H), 3.97 (t, J¼6.5 Hz, 2H),1.79 (m, 2H),
1.46 (m, 2H),1.29 (m, 8H), 0.89 (m, 3H), 0.25 (s, 9H); 13C NMR (CDCl3,
100 MHz): 133.4, 133.2, 132.1, 131.4, 127.4, 121.8, 115.6, 114.8, 114.7,
113.8, 105.9, 104.9, 96.2, 32.0, 31.9, 29.6, 29.5, 29.4, 29.3, 26.3, 22.9,
11.2, 0.24; HRMS (ESI-TOF) m/z calcd for C27H34OSi [MþH]þ:
403.2452, found 403.2454. FT IR (ATR): 2954w, 2920w, 2851w,
2153w, 1596w, 1515m, 1248m, 864m, 830s, 757m.
crude product was purified by flash chromatography on silica gel
with hexanes to 8% CH2Cl2/hexanes as eluents to afford the desired
compound 24d (198 mg, 51% yield) as a yellow oil. 1H NMR (CDCl3,
400 MHz): 8.05 (t, J¼7.0 Hz, 2H), 7.59 (s, 1H), 7.56 (d, J¼6.9 Hz, 1H),
7.52 (d, J¼7.0 Hz, 1H), 7.44 (t, J¼7.5 Hz, 2H), 7.35 (d, J¼8.1 Hz, 1H),
7.23 (m, 3H), 4.22 (t, J¼7.3 Hz, 2H), 1.82 (m, 2H), 1.22 (m, 10H), 0.85
(t, J¼6.9 Hz, 3H), 0.32 (s, 9H); 13C NMR (CDCl3, 100 MHz): 141.1,
132.3, 128.2, 127.7, 126.1, 125.4, 123.0, 122.8, 122.5, 120.6, 120.2,
119.1, 111.9, 108.8, 95.0, 43.2, 31.8, 29.4, 29.2, 29.0, 27.3, 22.6, 14.1,
0.12; HRMS (APPI-TOF) m/z calcd for C33H37NSi [MþH]þ: 476.2768,
found 476.2770. FT IR (ATR): 3060w, 2926s, 2854m, 2208w, 2159w,
1598m, 1471m, 1326s, 1248m, 864s, 842s, 759s.
4.2.21. 2-((2-Ethynylphenyl)ethynyl)-9-octyl-9H-carbazole (25d). A
10 mL round bottom flask equipped with a magnetic stir bar was
charged with compound 24d (190 mg, 0.40 mmol), KOH (90 mg,
1.60 mmol), THF (1.0 mL), MeOH (1.0 mL) and water (0.5 mL). The
reaction mixture was stirred for 15 min, diluted with CH2Cl2,
acidified with HCl 10%, washed with water (3ꢂ) and dried over
Na2SO4. The solvent was removed under reduced pressure and the
crude product was purified by flash chromatography on silica gel
with hexanes to 8% CH2Cl2/hexanes as eluents to afford compound
25d (183 mg, quantitative yield) as a yellow oil. 1H NMR (CDCl3,
400 MHz): 8.06 (d, J¼7.8 Hz, 1H), 8.03 (d, J¼8.1 Hz, 1H), 7.64–7.52
(br m, 3H) 7.46 (m, 2H), 7.37 (d, J¼8.2 Hz, 1H), 7.32 (t, J¼7.6 Hz, 1H),
7.29–7.19 (br m, 2H), 4.24 (t, J¼7.0 Hz, 2H), 3.40 (s, 1H), 1.84 (m, 2H),
1.40–1.16 (br m, 10H), 0.85 (t, J¼6.9 Hz, 3H); 13C NMR (CDCl3,
100 MHz): 141.1, 139.9, 132.6, 131.7, 128.6, 127.7, 126.6, 126.2, 124.5,
123.1, 122.7, 122.5, 120.6, 120.2, 119.7, 119.1, 112.0, 108.8, 95.2, 87.4,
82.4, 81.1, 43.1, 31.8, 29.3, 29.2, 28.9, 27.3, 22.6,14.1; HRMS (ESI-TOF)
m/z calcd for C30H29N [MþH]þ: 404.2373, found 404.2376. FT IR
(ATR): 3286w, 3058w, 2924s, 2852m, 2206w, 1598m, 1454s, 1325s,
1225m, 850m, 814m, 756s.
Compound 12. See the general procedure for addition of C60 to
terminal alkynes. The materials used were compound 25d (100 mg,
0.25 mmol), C60 (357 mg, 0.49 mmol), THF (99 mL), LHMDS (4.5 mL,
4.5 mmol) and TFA (0.4 mL, 4.9 mmol). The crude product was
purified by flash chromatography on silica gel with hexanes to 40%
CS2/hexanes as eluent to afford compound 12 (33 mg, 12% yield) as
a brown powder. 1H NMR (CDCl3, 400 MHz): 7.98 (d, J¼7.9 Hz, 1H),
7.92 (d, J¼7.6 Hz, 1H), 7.86 (m, 1H), 7.75 (m, 1H), 7.67 (s, 1H), 7.53 (d,
J¼7.9 Hz, 1H), 7.48 (m, 2H), 7.42 (m, 1H), 7.32 (d, J¼8.3 Hz, 1H), 7.18
(m, 2H), 4.18 (t, J¼7.3 Hz, 2H), 1.82 (m, 2H), 1.25 (m, 10H), 0.84 (m,
3H); 13C NMR (CDCl3, 100 MHz): 151.5, 151.3, 146.5, 146.3, 146.2,
146.1, 145.7, 145.6, 145.3 (2C), 144.6, 144.4, 143.1, 143.0, 142.5, 142.0,
141.9, 141.8, 141.6, 141.0, 140.2, 139.9, 135.9, 135.2 (24 signals from
sp2-C in the C60 core), 131.9 (–C], Ar), 131.7 (–C], Ar), 128.8 (2C,
–C], Ar), 128.1 (–C], Ar), 127.2 (–C], Ar), 126.6 (–C], Ar), 126.2
(–C], Ar), 125.3 (–C], Ar), 122.3 (–C], Ar), 120.6 (–C], Ar), 120.4
(–C], Ar), 119.2 (–C], Ar), 111.9 (–C], Ar), 108.7 (–C^), 96.5
(–C^), 95.8 (–C^), 88.1 (–C^), 62.0 (CH in the C60), 43.2 (CH2), 31.9
(CH2), 29.8 (CH2), 29.5 (CH2), 29.1 (CH2), 27.4 (CH2), 22.7 (CH2), 14.2
(CH3); HRMS (APPI-TOF) m/z calcd for C90H29N [MþH]þ: 1124.2373,
found 1124.2375. FT IR (ATR): 2917s, 2847s, 2203w, 1596m, 1458s,
1324s, 1181m, 810s, 754s.
4.2.19. 1-Ethynyl-4-((4-(octyloxy)phenyl)ethynyl)benzene(21b). A
10 mL round bottom flask equipped with a magnetic stir bar was
charged with compound 20b (350 mg, 0.87 mmol), KOH (195 mg,
3.48 mmol), THF (1.1 mL), MeOH (1.1 mL) and water (0.5 mL). The
reaction mixture was stirred for 15 min, diluted with CH2Cl2,
acidified with HCl 10%, washed with water (3ꢂ) and dried over
Na2SO4. The solvent was removed under reduced pressure and the
crude product was purified by flash chromatography on silica gel
with hexanes to 7% CH2Cl2/hexanes as eluents to afford compound
21b (269 mg, 94% yield) as a yellow solid. 1H NMR (CDCl3,
400 MHz): 7.44 (m, 6H), 6.86 (d, J¼8.6 Hz, 2H), 3.95 (t, J¼6.7 Hz,
2H), 3.15 (m, 1H), 1.77 (m, 2H), 1.44 (m, 2H), 1.29 (m, 8H), 0.89 (m,
3H); 13C NMR (CDCl3, 100 MHz): 159.4, 133.1, 132.0, 131.3, 124.2,
121.4, 114.7, 114.5, 91.7, 87.5, 83.4, 78.7, 68.0, 31.9, 29.4, 29.2, 28.1,
26.0, 22.7, 14.1; HRMS (ESI-TOF) m/z calcd for C24H26O [MþH]þ:
331.2056, found 331.2055. FT IR (ATR): 3269w, 2921m, 2852w,
1607w, 1514m, 1250m, 1109w, 1024w, 824s.
Compound 7. See the general procedure for addition of C60 to
terminal alkynes. The materials used were compound 21b (70 mg,
0.21 mmol), C60 (305 mg, 0.42 mmol), THF (85 mL), LHMDS
(0.48 mL, 0.42 mmol) and TFA (0.3 mL, 3.9 mmol). The crude
product was purified by flash chromatography on silica gel with
hexanes to 30% CS2/hexanes as eluents to afford compound 7
(97 mg, 44% yield) as a brown powder. 1H NMR (CDCl3, 400 MHz):
7.79 (d, J¼8.1 Hz, 1H), 7.62 (d, J¼8.1 Hz, 1H), 7.50 (d, J¼8.5 Hz, 1H),
7.45 (m, 3H), 7.14 (s, 1H), 6.90 (d, J¼8.5 Hz, 1H), 6.87 (d, J¼8.9 Hz,
1H), 3.98 (m, 2H), 1.79 (m, 2H), 1.46 (m, 2H), 1.30 (m, 8H), 0.89 (m,
3H); 13C NMR (CDCl3, 100 MHz): 151.8, 151.7, 151.3, 147.7, 147.3,
146.7, 146.5 (2C), 146.3, 145.9, 145.8, 145.7, 145.5 (2C), 145.4, 144.8,
144.6, 143.3, 143.1, 142.7, 142.6, 142.2, 142.1, 142.0, 141.9, 141.8, 141.7,
140.5, 140.4, 140.3, 136.1, 135.3 (32 signals from sp2-C in the C60
core), 133.2 (–C], Ar), 133.1 (–C], Ar), 132.1 (–C], Ar), 132.0 (–C],
Ar), 131.6 (–C], Ar), 131.3 (–C], Ar), 93.8 (–C], Ar), 91.6 (–C], Ar),
87.7 (–C^), 83.4 (–C^), 78.7 (–C^), 68.1 (–C^), 61.8 (CH in the C60
core), 33.6 (CH2), 31.8 (CH2), 29.4 (CH2), 29.2 (CH2), 29.1 (CH2), 26.0
(CH2), 22.7 (CH2), 14.1 (CH3); HRMS (APPI-TOF) m/z calcd for
C84H26O [MþH]þ: 1051.2056, found 1051.2069. FT IR (ATR): 3269w,
2920m, 2849, 1595w, 1511m, 1242m, 1106w, 826s.
4.2.22. 9-Octyl-2-((4-((trimethylsilyl)ethynyl)phenyl)ethynyl)-9H-
carbazole(20d). A 10 mL round bottom flask equipped with a mag-
netic stir bar was charged with 1-iodo-4-[2-(trimethylsilyl)ethy-
nyl]benzene (312 mg, 1.04 mmol), THF (3.5 mL), triethylamine
(0.4 mL), PdCl2(PPh3)2 (10 mg, 0.01 mmol), CuI (3 mg, 0.01 mmol)
and compound 16 (210 mg, 0.69 mmol) under argon atmosphere.
The reaction mixture was stirred overnight, diluted in CH2Cl2,
washed with NH4Cl (3ꢂ) and dried over Na2SO4. The solvent was
removed under reduced pressure and the crude product was
purified by flash chromatography on silica gel with hexanes to 8%
4.2.20. 9-Octyl-2-((2-((trimethylsilyl)ethynyl)phenyl)ethynyl)-9H-
carbazole (24d). A 10 mL round bottom flask equipped with
a magnetic stir bar was charged with 23 (371 mg, 1.24 mmol), THF
(4.1 mL), triethylamine (0.5 mL), PdCl2(PPh3)2 (12 mg, 0.02 mmol),
CuI (3 mg, 0.02 mmol) and compound 16 (250 mg, 0.83 mmol)
under argon atmosphere. The reaction mixture was stirred over-
night, diluted in CH2Cl2, washed with NH4Cl (3ꢂ) and dried over
Na2SO4. The solvent was removed under reduced pressure and the

4240
S. Rondeau-Gagne´ et al. / Tetrahedron 66 (2010) 4230–4242
CH2Cl2/hexanes as eluents to afford compound 20d (215 mg, 66%
yield) as a white solid. 1H NMR (CDCl3, 400 MHz): 8.06 (d, J¼7.8 Hz,
1H), 8.03 (d, J¼8.2 Hz, 1H), 7.57 (s, 1H), 7.51 (d, J¼8.2 Hz, 2H), 7.47
(m, 3H), 7.38 (d, J¼7.8 Hz, 2H), 7.22 (t, J¼7.5 Hz, 1H), 4.25
(t, J¼7.2 Hz, 2H), 1.85 (m, 2H), 1.27 (m, 10H), 0.85 (t, J¼6.9 Hz, 3H),
0.26 (s, 9H); 13C NMR (CDCl3, 100 MHz): 141.4, 140.2, 132.2, 131.6,
126.5, 123.9, 123.4, 122.9, 122.7, 122.6, 120.9, 120.6, 119.8, 119.4, 112.2,
112.1,109.1,105.0, 96.5, 93.2, 88.9, 43.4, 32.1, 29.6, 29.4, 29.2, 27.6, 22.9,
14.4, 0.22; HRMS (APPI-TOF) m/z calcd for C33H37NSi [MþH]þ:
476.2768, found 476.2770. FT IR (ATR): 3050w, 2917m, 2851w,
2149 m, 1599w, 1471m, 1326m, 1219m, 856s, 831s, 814s, 760s.
132.9,130.3,123.8,102.9,100.9, 0.30; HRMS (APPI-TOF) m/z calcd for
C
2952w, 2160w, 1591w, 1516m, 1345m, 1247m, 1106w, 837s, 763m.
11H13NO2Si [MþNH4]þ: 237.1054, found 237.1060. FT IR (ATR):
4.2.25. 1-Ethynyl-4-nitrobenzene (19c). A 25 mL round bottom
flask equipped with a magnetic stir bar was charged with 18c
(500 mg, 2.28 mmol), KOH (512 mg, 9.12 mmol), THF (6.5 mL),
MeOH (6.5 mL) and water (0.5 mL). The reaction mixture was stir-
red for 15 min, diluted with CH2Cl2, acidified with HCl 10%, washed
with water (3ꢂ) and dried over Na2SO4. The solvent was removed
under reduced pressure and the crude product was purified by flash
chromatography on silica gel with hexanes to 2% acetone/hexanes
as eluents to afford product 19c (243 mg, 73% yield) as a yellow
solid. 1H NMR (CDCl3, 400 MHz): 8.20 (d, J¼8.2 Hz, 2H), 7.64 (d,
J¼8.8 Hz, 2H), 3.36 (s, 1H); 13C NMR (CDCl3, 100 MHz): 132.9, 128.9,
123.6, 82.3, 81.6. Compound 19c was not observed by mass spec-
trometry analysis. FT IR (ATR): 3247m, 3105w, 2105w, 1591m,
1506m, 1339m, 1287m, 1105w, 964w, 850s.
Compound 3. See the general procedure for addition of C60 to
terminal alkynes. The materials used were compound 19c (30 mg,
0.20 mmol), C60 (294 mg, 0.41 mmol), THF (82 mL), LHMDS (0.51 mL,
0.41 mmol) and TFA (0.3 mL, 3.9 mmol). The crude product was
purified by flash chromatography on silica gel with hexanes to 40%
CS2/hexanes as eluents to afford 3 (42 mg, 24% yield) as a brown
powder. 1H NMR (CDCl3, 400 MHz): 8.37 (d, J¼8.3 Hz, 2H), 7.99 (d,
J¼8.9 Hz, 2H), 7.14 (s, 1H); 13C NMR (CDCl3/CS2 1:1, 100 MHz): 151.0,
150.4, 147.7, 147.6, 147.4, 146.6, 146.5, 146.4, 146.3, 145.8, 145.6 (2C),
145.5, 145.4, 144.7, 144.5, 143.3, 143.0, 142.7, 142.6, 141.1, 141.0, 141.7
(3C), 140.5, 140.4, 135.9, 135.4 (29 signals from sp2-C in the C60 core),
133.0 (–C], Ar), 132.9 (–C], Ar), 129.3 (–C], Ar), 123.8 (–C], Ar),
97.3 (–C^), 81.6, (–C^), 61.5 (CH in the C60 core), 55.1 (quaternary
sp3-C in the C60 core); HRMS (APPI-TOF) m/z calcd for C68H5NO2
[MþH]þ: 868.0393, found 867.0307. FT IR (ATR): 2918w, 2849w,
2323w, 1592m, 1515m, 1340s, 1184w, 1106w, 852m.
4.2.23. 2-((4-Ethynylphenyl)ethynyl)-9-octyl-9H-carbazole(21d). A
10 mL round bottom flask equipped with a magnetic stir bar was
charged with compound 20d (200 mg, 0.42 mmol), KOH (94 mg,
1.68 mmol), THF (1.3 mL), MeOH (1.3 mL) and water (0.5 mL). The
reaction mixture was stirred for 15 min, diluted with CH2Cl2,
acidified with HCl 10%, washed with water (3ꢂ) and dried over
Na2SO4. The solvent was removed under reduced pressure and the
crude product was purified by flash chromatography on silica gel
with hexanes to 8% CH2Cl2/hexanes as eluents to afford compound
21d (170 mg, quantitative yield) as a white solid. 1H NMR (CDCl3,
400 MHz): 8.05 (t, J¼9.0 Hz, 2H), 7.57 (s, 1H), 7.53 (d, J¼8.3 Hz, 2H),
7.48 (t, J¼8.0 Hz, 3H), 7.38 (m, 2H), 7.22 (d, J¼7.4 Hz, 1H), 4.26 (t,
J¼7.3 Hz, 2H), 3.17 (s, 1H), 1.85 (m, 2H), 1.24 (br m, 10H), 0.86 (m,
3H); 13C NMR (CDCl3, 100 MHz): 141.1, 139.9, 132.1, 131.4, 126.2,
124.1, 123.1, 122.5, 122.5, 121.6, 120.6, 120.3, 119.4, 119.1, 111.9, 108.8,
93.0, 88.4, 83.3, 78.8, 43.1, 31.8, 29.4, 29.2, 28.9, 27.3, 22.6, 14.1;
HRMS (ESI-TOF) m/z calcd for C30H29N [MþH]þ: 404.2373, found
404.2376. FT IR (ATR): 3301w, 3048w, 2917m, 2853m, 1491w,
1470m, 1325m, 844s, 831s, 813s, 766m.
Compound 9. See the general procedure for addition of C60 to
terminal alkynes. The materials used were 21d (80 mg, 0.20 mmol),
C60 (284 mg, 0.39 mmol), THF (79 mL), LHMDS (0.45 mL, 0.4 mmol)
and TFA (0.3 mL, 3.9 mmol). The crude product was purified by flash
chromatography on silica gel with hexanes to 30% CS2/hexanes as
eluents to afford compound 9 (130 mg, 59% yield) as a brown
powder. 1H NMR (CDCl3, 400 MHz): 8.10 (m, 2H), 7.83 (d, J¼7.9 Hz,
2H), 7.71 (d, J¼7.9 Hz, 2H), 7.64 (s, 1H), 7.44 (br m, 4H), 7.15 (s, 1H),
4.33 (t, J¼7.2 Hz, 2H), 1.91 (m, 2H), 1.27 (br m, 10H), 0.86 (m, 3H); 13C
NMR (CDCl3, 100 MHz): 151.4, 151.1, 147.6, 146.6, 146.4, 146.3, 146.2
(2C), 145.8, 145.7, 145.6, 145.5, 145.4, 145.3, 144.7, 144.5, 143.2, 143.0,
142.6 (2C), 142.2, 142.1, 142.0, 141.8, 141.7, 141.6, 141.0, 140.4 (2C),
139.9, 136.1, 135.2 (32 signals from sp2-C in the C60 core),132.1 (–C],
Ar), 131.7 (–C], Ar), 126.3 (–C], Ar), 123.2 (–C], Ar), 122.6 (–C],
Ar),121.9 (–C], Ar),120.6 (2C, –C], Ar),120.3 (–C], Ar),119.5 (–C],
Ar), 119.3 (–C], Ar), 111.9 (–C], Ar), 108.8 (–C], Ar), 93.9 (–C^),
88.8 (–C^), 61.8 (CH in the C60 core), 43.2 (CH2), 31.9 (CH2), 29.6
(CH2), 29.4 (CH2), 29.1 (CH2), 27.5 (CH2), 22.8 (CH2),14.2 (CH3); HRMS
4.2.26. 4-Nitro-1-((2-((trimethylsilyl)ethynyl)phenyl)ethynyl)-
benzene(24c). A 25 mL round bottom flask equipped with a mag-
netic stir bar was charged with compound 23 (765 mg, 2.55 mmol),
THF (8.5 mL), triethylamine (0.9 mL), PdCl2(PPh3)2 (24 mg,
0.03 mmol), CuI (6 mg, 0.03 mmol) and compound 19c (250 mg,
1.70 mmol) under argon atmosphere. The reaction mixture was
stirred overnight, diluted in CH2Cl2, washed with NH4Cl (3ꢂ) and
dried over Na2SO4. The solvent was removed under reduced pres-
sure and the crude product was purified by flash chromatography
on silica gel with hexanes to 8% CH2Cl2/hexanes as eluents to afford
compound 24c (268 mg, 49% yield) as a yellow solid. 1H NMR
(CDCl3, 400 MHz): 8.22 (d, J¼8.9 Hz, 2H), 7.68 (d, J¼8.9 Hz, 2H), 7.53
(m, 2H), 7.33 (m, 2H), 0.28 (s, 9H); 13C NMR (CDCl3, 100 MHz):
132.4,132.2,131.9,130.2,128.8,128.3,125.9,124.7,123.6,102.9, 99.2,
93.4, 91.2; HRMS (APPI-TOF) m/z calcd for C19H17NO2Si [MþH]þ:
320.1121, found 320.1101. FT IR (ATR): 2958w, 2219w, 2157w,
1594w, 1516m, 1338s, 1248w, 837s, 755s.
(APPI-TOF) m/z calcd for C90H29
1124.2354. FT IR (ATR): 3683w, 3313w, 3051w, 2312m, 2854m,
2327m, 2202m, 1596m, 1426s, 1323s, 1180s, 832s, 808s, 763m.
N
[MþH]þ: 1124.2373, found
4.2.24. 1-Nitro-4-((trimethylsilyl)ethynyl)benzene (18c). A 25 mL
round bottom flask equipped with a magnetic stir bar was charged
with 4-iodonitrobenzene (1.0 g, 4.02 mmol), THF (13 mL), triethyl-
amine (2.2 mL, 16.1 mmol), PdCl2(PPh3)2 (31 mg, 0.08 mmol), CuI
(15 mg, 0.08 mmol) and trimethylsilylacetylene (1.1 mL, 8.03 mmol)
under argon atmosphere. The reaction mixture was stirred over-
night at room temperature, diluted in CH2Cl2, washed with NH4Cl
(3ꢂ) and dried over Na2SO4. The solvent was removed under
reduced pressure and the crude product was purified by flash
chromatography on silica gel with hexanes to 2% acetone/hexanes as
eluents to afford the desired compound 18c (695 mg, 79% yield) as
a yellow solid.1H NMR (CDCl3, 400 MHz): 8.17 (d, J¼8.7 Hz, 2H), 7.59
(d, J¼8.5 Hz, 2H), 0.28 (s, 9H); 13C NMR (CDCl3, 100 MHz): 147.4,
4.2.27. 1-Ethynyl-2-((4-nitrophenyl)ethynyl)benzene(25c). A 10 mL
round bottom flask equipped with a magnetic stir bar was charged
with compound 24c (250 mg, 0.78 mmol), KOH (176 mg,
3.13 mmol), THF (1.9 mL), MeOH (1.9 mL) and water (0.5 mL). The
reaction mixture was stirred for 15 min, diluted with CH2Cl2,
acidified with HCl 10%, washed with water (3ꢂ) and dried over
Na2SO4. The solvent was removed under reduced pressure and the
crude product was purified by flash chromatography on silica gel
with hexanes to 8% CH2Cl2/hexanes as eluents to afford compound
25c (175 mg, 90% yield) as a yellow solid. 1H NMR (CDCl3,
400 MHz): 8.23 (d, J¼6.8 Hz, 2H), 7.70 (d, J¼6.8 Hz, 2H), 7.57 (m,
2H), 7.37 (m, 2H), 3.39 (s, 1H); 13C NMR (CDCl3, 100 MHz): 147.1,
132.7, 132.4, 131.9, 130.0, 128.9, 128.7, 125.0 (2C), 123.6, 92.9, 91.4,

S. Rondeau-Gagne´ et al. / Tetrahedron 66 (2010) 4230–4242
4241
þ
81.8, 81.7; HRMS (APPI-TOF) m/z calcd for C16H9NO2 [M]
*
:
core), 133.3 (–C], Ar),133.2 (–C], Ar), 131.9 (–C], Ar), 129.8 (–C],
Ar), 123.7 (–C], Ar), 123.4 (–C], Ar), 122.7 (–C], Ar), 94.7 (–C^),
94.2 (–C^), 89.8 (–C^), 83.0 (–C^), 61.7 (CH in the C60 core), 55.2
(quaternary sp3-C in the C60 core); HRMS (APPI-TOF) m/z calcd for
247.0628, found 247.0635. FT IR (ATR): 3369m, 2218w, 1592m,
1507s, 1333s, 1305m, 1101m, 850m, 759m.
Compound 11. See the general procedure for addition of C60 to
terminal alkynes. The materials used were compound 25c (50 mg,
0.20 mmol), C60 (292 mg, 0.41 mmol), THF (81 mL), LHMDS
(0.46 mL, 0.46 mmol) and TFA (0.3 mL, 3.9 mmol). The crude
product was purified by flash chromatography on silica gel with
hexanes to 40% CS2/hexanes as eluents to afford compound 11
(110 mg, 57% yield) as a brown powder. 1H NMR (CDCl3, 400 MHz):
8.23 (d, J¼8.4 Hz, 2H), 7.70 (m, 2H), 7.57 (m, 3H), 7.35 (m, 2H); 13C
NMR (CDCl3/CS2 1:1, 100 MHz): 151.2, 146.5 (2C), 146.4, 145.7, 145.6,
145.5 (3C), 145.4, 144.7, 144.5, 144.2, 143.0, 142.6 (2C), 142.2, 142.1,
141.8,141.7,141.4,135.2 (22 signals from sp2-C in the C60 core), 134.6
(–C], Ar), 132.4 (–C], Ar), 132.3 (–C], Ar), 132.2 (–C], Ar), 129.2
(–C], Ar), 129.0 (–C], Ar), 128.8 (–C], Ar), 127.6 (–C], Ar), 127.0
(–C], Ar), 124.7 (–C], Ar), 124.3 (–C], Ar), 123.6 (–C], Ar), 120.3
(–C], Ar), 120.0 (–C^), 65.2 (–C^), 61.8 (CH in the C60 core), 55.3
(quaternary sp3-C in the C60 core); HRMS (APPI-TOF) m/z calcd for
C76H9NO2 [MþH]þ: 968.0706, found 968.0670. FT IR (ATR): 3300w,
2323w, 1712w, 1592m, 1513s, 1446m, 1337s, 1098w, 849m, 759m.
C76H9NO2 [M]
þ: 967.0628, found 967.0636. FT IR (ATR): 3098w,
*
2920w, 2324w, 2212w, 1918w, 1589m, 1510s, 1335s, 1102m, 832s.
Compound 13. A 50 mL round bottom flask equipped with a mag-
netic stir bar was charged with compound 6 (75 mg, 0.07 mmol) and
THF (29 mL) under argon atmosphere. The reaction mixture was
sonicated for 10 min and LHMDS (0.2 mL, 0.15 mmol) was then added
at room temperature to the brownish solution formed after sonica-
tion. After the addition of LHMDS, the reaction was stirred for 5 min,
quenched with benzoyl chloride (0.85 mL, 7.32 mmol) and the sol-
vent was removed under reduced pressure. The crude product was
purifiedbyflashchromatographyonsilicagelwithhexanestoCH2Cl2/
CS2/hexanes 3:1:1 aseluentto afford compound 13 (19 mg, 22% yield)
as a brown powder: mp>300 ꢀC; 1H NMR (CDCl3, 400 MHz): 8.50 (d,
J¼7.9, 2H), 7.99 (d, J¼7.9 Hz, 1H), 7.78 (d, J¼7.9 Hz, 1H), 7.73 (d,
J¼7.9 Hz,1H), 7.62 (m, 3H), 7.48 (m, 3H), 7.33 (t, J¼7.9 Hz,1H), 7.22 (m,
1H), 4.09(t, J¼7.4 Hz, 2H),1.72 (m, 2H),1.25 (m,10H), 0.84 (m, 3H); 13C
NMR (CDCl3, 100 MHz): 151.9, 150.4, 149.6, 147.6, 147.4, 147.2 (2C),
145.9, 145.8, 145.7, 145.6 (2C), 145.2, 145.1, 144.6, 144.5 (2C), 144.4 (2C),
144.2, 144.0, 143.9, 143.6, 143.5, 143.1, 136.7 (26 signals from sp2-C in
the C60 core),133.8 (–C], Ar),133.7 (–C], Ar),129.6 (–C], Ar),126.7
(–C], Ar), 123.6 (–C], Ar), 122.5 (–C], Ar), 121.0 (–C], Ar), 120.9
(–C], Ar), 120.3 (–C], Ar), 110.8 (–C], Ar), 110.0 (–C], Ar), 109.1
(–C], Ar), 71.5 (C/Bz in the C60 core), 43.3 (CH2), 32.2 (CH2), 32.0
(CH2), 29.9 (CH2), 29.4 (CH2), 27.5 (CH2), 24.0 (CH2),14.4 (CH3); HRMS
(ESI-TOF) m/z calcd for C89H29NO [MþH]þ: 1128.2322, found
1128.2302. FT IR (ATR): 2917s, 2848s, 1666m, 1594m, 1430s, 1324s,
1221s, 998m, 900m.
4.2.28. 4-Nitro-1-((4-((trimethylsilyl)ethynyl)phenyl)ethynyl)-
benzene(20c). A 10 mL round bottom flask equipped with a magnetic
stir bar was charged with 1-iodo-4-[2-(trimethylsilyl)ethynyl]-
benzene (224 mg, 0.75 mmol), THF (3.4 mL), triethylamine (0.3 mL),
PdCl2(PPh3)2 (10 mg, 0.01 mmol), CuI (3 mg, 0.01 mmol) and
compound 19c (100 mg, 0.68 mmol) under argon atmosphere. The
reaction mixture was stirred overnight, diluted in CH2Cl2, washed
with NH4Cl (3ꢂ) and dried over Na2SO4. The solvent was removed
under reduced pressure and the crude product was purified by flash
chromatography on silica gel with hexanes to 1.5% CH2Cl2/hexanes as
eluents to afford the desired compound 20c (182 mg, 84% yield) as
a yellow solid. 1H NMR (CDCl3, 400 MHz): 8.22 (d, J¼9.0 Hz, 2H), 7.65
(d, J¼8.5 Hz, 2H), 7.48 (s, 4H), 0.26 (s, 9H); 13C NMR (CDCl3,100 MHz):
147.2, 132.4, 132.1, 131.8, 130.1, 124.2, 123.8, 122.1, 104.4, 97.2, 94.3,
89.4, 0.11; HRMS (APPI-TOF) m/z calcd for C19H17NO2Si [MþH]þ:
320.1101, found 320.1038. FT IR (ATR): 3255m, 2210w, 1589m, 1498s,
1334s, 1103m, 830s.
Acknowledgements
We thank the National Science and Engineering Council of
Canada (NSERC) through the NRC-BDC-NSERC Initiative program
´
´
´
for funding, and the Centre Quebecois sur les Materiaux Fonc-
tionnels (CQMF). We also thank Prof. M. Leclerc for helpful dis-
cussions and Dr. Dominic Thibeault for HRMS measurements.
4.2.29. 1-Ethynyl-4-((4-nitrophenyl)ethynyl)benzene(21c). A 25 mL
round bottom flask equipped with a magnetic stir bar was charged
with compound 20c (450 mg,1.41 mmol), KOH (316 mg, 5.60 mmol),
THF (6.5 mL), MeOH (3 mL) and water (0.5 mL). The reaction mixture
was stirred for 15 min, diluted with CH2Cl2, acidified with HCl 10%,
washed with water (3ꢂ) and dried over Na2SO4. The solvent was re-
moved underreducedpressureandthecrudeproductwaspurified by
flash chromatography on silica gel with CH2Cl2 as eluent to afford
compound 21c (330 mg, 95% yield) as a yellow solid. 1H NMR (CDCl3,
400 MHz): 8.23 (d, J¼8.6 Hz, 2H), 7.67 (d, J¼8.6 Hz, 2H), 7.51 (s, 4H),
3.21 (s,1H); 13CNMR (CDCl3,100 MHz):147.1,132.3,132.2,131.7,129.9,
123.7, 123.0, 122.5, 93.9, 82.9, 79.6; HRMS (APPI-TOF) m/z calcd for
C16H9NO2 [MþH]þ: 248.0706, found 248.0674. FT IR (ATR): 3255m,
2210w, 1589s, 1498s, 1355s, 1104s, 838s.
Compound 8. See the general procedure for addition of C60 to
terminal alkynes. The materials used were compound 21c (50 mg,
0.20 mmol), C60 (292 mg, 0.41 mmol), THF (81 mL), LHMDS
(1.51 mL,1.50 mmol) and TFA (0.3 mL, 3.9 mmol). The crude product
was purified by flash chromatography on silica gel with hexanes to
50% CS2/hexanes as eluents to afford compound 8 (108 mg, 55%
yield) as a brownpowder.1H NMR (CDCl3/CS2 1:1, 400 MHz): 8.25 (d,
J¼8.7 Hz, 2H), 7.83 (d, J¼8.2 Hz, 2H), 7.71 (d, J¼8.2 Hz, 2H), 7.66 (d,
J¼7.7 Hz, 2H), 7.14 (s, 1H); 13C NMR (CDCl3/CS2 1:1, 100 MHz): 151.3,
150.9, 147.6, 147.4, 147.1, 146.6, 146.5, 146.4, 146.2, 145.8, 145.7, 145.6,
145.5 (2C), 145.3, 144.7, 144.5, 143.2, 142.7 (2C), 142.1, 142.0 (2C),
141.8,141.7,141.6,140.4,136.0,135.2 (29 signals from sp2-C in the C60
Supplementary data
Detailed description of the experimental method, 1H and 13C
NMR spectra for all new compounds, and a table reporting the
theoretical HOMO, LUMO, HOMO/LUMO gaps and dipole moments
obtained from DFT calculations for all compounds. Supplementary
data associated with this article can be found in online version at
doi:10.1016/j.tet.2010.03.092.
References and notes
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nikov, V.; Gisselbrecht, J.-P.; Groos, M.; Hadziioannou, G.; Nierengarten, J.-F.
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