Highly Selective Synthesis of Tetrahydronaphthaleno[60]fullerenes via Fullerene-Cation-Mediated Intramolecular Cyclization

Article abstract of DOI:10.1021/acs.joc.9b02618

A high-yielding protocol to construct six-membered carbon rings on fullerene is presented. This methodology with in situ fullerene-cation-mediated intramolecular cyclization provides high selectivity and efficient access to six-membered tetrahydronaphthal

Full text of DOI:10.1021/acs.joc.9b02618

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Note
Highly selective synthesis of tetrahydronaphthaleno[60]fullerenes
via fullerene-cation-mediated intramolecular cyclization
Xiao-Yu Yang, Hao-Sheng Lin, and Yutaka Matsuo
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.9b02618 • Publication Date (Web): 19 Nov 2019
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The Journal of Organic Chemistry
Highly Selective Synthesis of Tetrahydronaphthaleno[60]fullerenes via
Fullerene-Cation-Mediated Intramolecular Cyclization
Xiao-Yu Yang,a,┴ Hao-Sheng Linb,┴ and Yutaka Matsuoa,b,c,*
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a
Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, 96
Jinzhai Road, Hefei, Anhui 230026, China
b
Department of Mechanical Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo
113-8656, Japan
c
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.Institute of Materials Innovation, Institutes of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku,
Nagoya 468-8603, Japan
ABSTRACT: High-yielding protocol to construct six-membered carbon rings on fullerene is presented. This methodology with in-
situ fullerene-cation-mediated intramolecular cyclization provides high selectivity and efficient access to six-membered
tetrahydronaphthaleno[60]fullerenes with remarkable functional group tolerance and excellent yields. Furthermore, high solubilities
of tetrahydronaphthaleno[60]fullerenes are reported.
Cyclo[60]fullerenes are widely used [60]fullerene
derivatives with applications in several types of photovoltaic
devices, including organic thin-film solar cells,1 polymer solar
cells,2 and recently improved perovskite solar cells.3 In
particular, cyclo[60]fullerenes with six-membered carbon rings,
namely, tetrahydronaphthaleno[60]fullerenes, such as indene-
C60 bis-adduct4 and methano-indene fullerene,5 play a dominant
role in photovoltaics. Consequently, substantial effort has been
devoted to constructing cyclo[60]fullerenes and several
synthetic strategies have been established.6
Among the reported strategies, Diels–Alder cycloaddition is
the most commonly used method for constructing
tetrahydronaphthaleno[60]fullerenes.4a,5a,7
However,
this
approach suffers from several limitations, such as inevitable
multi-addition by-products, high reaction temperature, and low
yield. Furthermore, heteroaromatic substituents are
incompatible with this method, limiting the functional group
tolerance. Accordingly, more efficient synthetic strategies with
broader applicability would be of great value.
In our previous studies, fullerene-cation-mediated reactions
displayed impressive performance compared with fullerene-
radical-mediated and fullerene-anion-mediated approaches,8
suggesting the possibility of using fullerene-cation-mediated
reactions to construct tetrahydronaphthaleno[60]fullerenes.
Fullerene cations have a newly formed lowest unoccupied
molecular orbital (LUMO) with a lower energy level,8d,9
Figure. 1. Concept of the synthetic strategy adopted in this
work.
In this work, we report a versatile and scalable Cu(II)-
promoted fullerene-cation-mediated strategy to access
tetrahydronaphthaleno[60]fullerenes in high yields of up to
91%. Notably, thanks to the excellent functional group
tolerance,
dimethyl-substituted
tetrahydronaphthaleno[60]fullerene 2e was successfully
obtained and found to possess a remarkably high solubility of
34.8 mg/mL in chlorobenzene (CB) and 10.9 mg/mL in CHCl3,
which should enable this compound to be fabricated into
photovoltaics through the facile spin-coating method rather
than costly thermal deposition.10
permitting
a facile and highly efficient intramolecular
cyclization via a quasi-E2 pathway (Figure. 1).
Table 1. Optimization of Reaction Conditionsa
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O
1
2
3
Table 2. Fullerene-Cation-Mediated Intramolecular
Cyclization with Broad Functional Group Tolerancea
Oxidant
T
O
oC, t h
ODCB (4.0 mL)
4
5
6
O
2a
1a
7
Entry
Oxidant
Temp. (oC)
Time (h)
Yield (%)b
8
9
1
2
3
4
5
6
7
8
9
10
11
12
13d
14e
15f
–
100
100
100
100
100
100
100
100
80
120
100
100
100
100
100
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
2.0
4.0
3.0
3.0
3.0
–
N.D.c
<5
<5
10
24
32
89
61
75
63
81
74
58
89
K2S2O8
Ag2O
AgOAc
Cu(OAc)2
CuCl2
Cu(BF4)2
CuBr2
CuBr2
CuBr2
CuBr2
CuBr2
CuBr2
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60
CuBr2
CuBr2
a Unless otherwise specified, all reactions were performed using
0.02 mmol of 1a and oxidant (4.0 equiv.) in 4.0 mL of ortho-
dichlorobenzene (o-DCB) under ambient atmosphere. b Isolated
yield. c No desired product (N.D.). d 2.0 equiv. of CuBr2. e 6.0
equiv. of CuBr2. f Under argon atmosphere.
The investigation started with screening the reaction
conditions using the aryl[60]fullerenyl dimer 1a as a model
substrate, which was synthesized according to our previously
reported procedure and summarized in Table 1.8a–d First, 1a
(0.03 mmol) was directly heated to 100 °C under ambient
atmosphere for 3 h, but the desired product 2a was not obtained
(Table 1, entry 1). Therefore, the fullerene radical intermediate
did not promote the intramolecular cyclization. Subsequently,
to examine the feasibility of fullerene-cation-mediated
intramolecular cyclization, oxidants such as K2S2O8, Ag(I) and
Cu(II) salts were screened for the in situ generation of the
fullerene cation accessing the intramolecular cyclization (Table
1, entries 2–8). To our delight, 4.0 equiv. of CuBr2 efficiently
generated the fullerene cation intermediate, affording the
desired product in 89% yield (Table 1, entry 8). Decreasing the
temperature to 80 °C or increasing the temperature to 120 °C
did not improve the outcome (Table 1, entries 9 and 10).
Decreasing the reaction time to 2.0 h afforded 2a in 63% yield
with residual unreacted dimer 1a (Table 1, entry 11). However,
prolonging the reaction time to 4.0 h also led to a lower yield of
2a and the formation of by-products due to overoxidation
(Table 1, entry 12). Similarly, varying the amount of CuBr2 to
2.0 or 6.0 equiv. decreased the yield of 2a (Table 1, entries 13
and 14). Intriguingly, when the reaction was conducted under
argon atmosphere, the same yield of 2a was obtained as under
ambient atmosphere (Table 1, entry 15). This result
demonstrates the extremely high reactivity of fullerene cations
compared with fullerene anions and fullerene radicals, which
are conventionally prone to oxidation via a single-electron-
transfer (SET) pathway in the presence of oxygen.11 Thus, the
reaction proceeded best under the following conditions:
aryl[60]dimer 1a was heated at 100 °C in the presence of 4.0
equiv. of CuBr2 as oxidant for 3.0 h under ambient atmosphere,
affording tetrahydronaphthaleno[60]fullerene 2a in 89% yield.
a Unless otherwise specified, all reactions were performed
using 0.02 mmol of aryl[60]fullerenyl dimers 1a–g and 4.0
equiv. of CuBr2 in 4.0 mL o-DCB solution at 100 °C for
3.0 h under ambient atmosphere. Isolated yield. The
reaction was conducted at 120 °C.
b
c
With the optimized reaction conditions in hand, the substrate
scope and generality of this protocol were explored (Table 2).
To examine the influence of electronegativity on the proposed
method, fluoro- and methoxy-substituted aryl[60]fullerenyl
dimers 1b and 1c were selected as representative compounds
containing electron-withdrawing and electron-donating groups,
respectively (Table 2, entries 2 and 3). The former compound
2b was obtained in a lower yield (78%) than the latter
compound 2c (91%). Subsequently, the influence of steric
effects was examined by incorporating one or two methyl
groups at the benzylic position. The monomethyl- and
dimethyl-functionalized products 2d and 2e were obtained in
yields of 81% and 76%, respectively, indicating slight steric
effects (Table 2, entries 4 and 5). Furthermore, the substrate
scope also included heteroaromatic compounds, and thiophene-
functionalized cyclo[60]fullerene 2f was obtained in 75% yield
(Table 2, entry 6). It should be noted that 2f is the first six-
membered-ring-containing cyclo[60]fullerene including
a
thiophene structure, and this compound could represent a useful
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The Journal of Organic Chemistry
building block for thiophene functionalization at the 5-position
homolysis upon heating at 100 °C to generate the
for thin-film organic electronics.12 More intriguingly, the
fullerene-cation-mediated protocol provided access to a seven-
membered-ring-containing cyclo[60]fullerene, and the desired
product 2g was obtained in 48% yield (Table 2, entry 7). This
relatively low yield is presumably attributable to the instability
of seven-membered rings compared with six-membered rings
according to Baeyer ring-strain theory.13 In addition, the scale-
up synthesise was exemplified by applying 0.3 g of 1a under
the same conditions, producing 2a in a high yield of 82%, which
demonstrates a facile and scalable way for the production of
tetrahydronaphthaleno[60]fullerenes used in photovoltaics.
aryl[60]fullerenyl radical intermediate I (ArC60•). Subsequently,
the radical I is oxidized by Cu(II) through a SET process,
resulting in the in situ generation of the key species,
[60]fullerene cation II (ArC60+). Finally, cation II undergoes
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intramolecular
cyclization
to
afford
the
tetrahydronaphthaleno[60]fullerene derivative
2
with the
concomitant loss of one molecule of HBr, that is generated by
the deprotonation by a bromide anion.
9
Table 3. Solubility of Selected Products at 298.0 Ka
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60
Solubility in CB
(mg/mL)
6.4
Solubility in
CHCl3 (mg/mL)
0.3
Product
b
C60
Scheme 1. Preliminary Mechanistic Studies
2a
2d
29.1
24.7
34.8
40.0
18.9
15.5
21.8
27.6
2e
PC61BMc
a All solubilities were measured under the same conditions. b
The reported solubility of C60 is 6.5 mg/mL in CB and 0.3
mg/mL in CHCl3.14 c The reported solubility of PC61BM is 45.0
mg/mL in CB and 27.0 mg/mL in CHCl3.15
As the solubility of fullerenes is a crucial parameter for
photovoltaic applications,1c,12a,16 the solubility of selected
potential photovoltaic fullerene candidates was measured in the
conventionally used solvents CB and CHCl3 (Table 3). The
introduction of long aliphatic chain moieties, such as hexyl or
2-ethylhexyl groups, is a widely employed strategy for
improving
solubility.17
Intriguingly,
the
dimethyl-
To gain further insight into the reaction mechanism,
additional experiments were conducted using the conventional
functionalized compound 2e displayed a similar solubility to
PC61BM in both CB and CHCl3, demonstrating the possibility
of improving the solubility without introducing bulky long
aliphatic chains.
radical
scavenger
2,2,6,6-tetramethylpiperidine-1-oxyl
(TEMPO) (Scheme 1). The addition of 2.0 equiv. of TEMPO to
the reaction dramatically decreased the yield of 2a to 13%.
Further increasing the amount of TEMPO to 4.0 equiv.
terminated the reaction and produced large amounts of
insoluble materials that precipitated from the solution. These
results conclusively demonstrate that fullerene radicals are the
precursor of the fullerene cations during this reaction (Scheme
1b).
Table 4. Half-Wave Reduction Potentialsa
Fullerene
E1 (V)
–1.10
–1.17
–1.19
–1.17
–1.18
–1.20
–1.20
–1.17
–1.18
E2 (V)
–1.52
–1.56
–1.57
–1.56
–1.56
–1.60
–1.59
–1.57
–1.57
C60
PC61BM
2a
2b
2c
2d
2e
2f
2g
Scheme 2. Plausible Mechanism for The Formation of
Tetrahydronaphthaleno[60]fullerenes
a
The CVs of fullerenes (1.0 mM) were measured in o-DCB
containing 0.1 M of n-Bu4NClO4 versus ferrocene/ferrocenium
as internal reference.
Finally, cyclic voltammograms (CVs) of compounds 2a–g
were measured to evaluate their reduction potentials (Table 4).
As expected, tetrahydronaphthaleno[60]fullerenes displayed
similar LUMO levels to PC61BM, which can be reasonably
attributed to the same π-electron system (58 π electrons) smaller
than C60 (60 π electrons).1b,5a,18 The remarkably low LUMO
levels of these compounds could permit their application as
electron-transporting materials in perovskite solar cells.19
Based on the above experimental results and previous
studies,8b–d a plausible reaction mechanism involving a
fullerene cation intermediate was proposed (Scheme 2). First,
In summary, a highly selective and efficient synthesis of
tetrahydronaphthaleno[60]fullerenes based on fullerene-cation-
the aryl[60]fullerenyl dimer
1 (ArC60-C60Ar) undergoes
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mediated intramolecular cyclization has been successfully dichlorobenzene (o-DCB) (25.0 mL) containing 1,3-dimethyl-
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4
5
6
7
8
developed. This protocol features remarkably high yields,
excellent selectivity, and broad substrate scope, and not only
represents a novel alternative to conventional synthetic methods
but also generates fullerene materials with potential
photovoltaic applications.
2-imidazolidinone (476 mg, 4.17 mmol) was added a
tetrahydrofuran (THF) solution of different Grignard reagents
(ArMgBr, 0.556 mmol) under the argon atmosphere at 25 C.
o
After vigorously stirring for 20 min, CH3COOH solution (0.4
mL) was added to quench the reaction for 10 min at room
temperature. The resulting dark red solution was filtrated
through a pad of gel plug to remove the insoluble salts and then
volatile components were removed under reduced pressure. The
residue (ArC60H) was further purified by a silica gel column
with the CS2 as the eluent, producing hydroaryl[60]fullerenes
with isolated yields of 83–90%.
EXPERIMENTAL PROCEDURES AND
CHARACTERIZATIONS
General Information. Unless otherwise noted, all materials
including dry solvents were obtained from commercial
suppliers and used without further purification. Unless
otherwise noted, all reactions were performed with dry solvents
under an atmosphere of argon in flame-dried glassware with
standard vacuum-line techniques. All reactions that require
heating use an oil bath as the heat source. All NMR spectra were
taken at 400 MHz (Bruker AVANCE III 400 spectrometer).
Unless otherwise specified, all the NMR spectra were recorded
in parts per million (ppm, scale) with the proton of CDCl3 (7.26
ppm) or the proton of 1,1,2,2-tetrachloroethane-d2 (TCE-d2)
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Synthesis of aryl[60]fullerenyl dimers (ArC60-C60Ar). To
a solution of organo(hydro)[60]fullerenes precursors (ArC60H)
(0.100 mmol, 1.00 equiv.) in o-DCB (10.0 mL) was added a
THF solution of t-BuOK (0.120 mmol, 1.20 equiv., 1.00 mol/L)
under the argon atmosphere at room temperature. After
vigorously stirring for 20 min, NBS (0.40 mmol, 4.00 equiv.)
was added under the argon atmosphere at room temperature for
further 1 hour. Later, the resulting mixture was quenched by 0.2
mL water, and then evaporated in vacuo to remove the volatile
solvent. Finally, the residue was further separated on a silica gel
column with CS2 as the eluent to afford aryl[60]fullerenyl
dimers in 86–98%.
1
(6.00 ppm) for H NMR and carbon of CDCl3 (77.16 ppm) or
carbon of TCE-d2 (73.78 ppm) for 13C{1H} NMR as internal
reference, respectively. The data were presented as following
order: chemical shift, multiplicity (s = singlet, d = doublet, t =
triplet, hept = heptet, m = multiplet and/or multiplet
resonances), coupling constant in hertz (Hz), and signal area
integration in natural numbers, assignment (italic). High-
resolution mass spectra (HRMS) were obtained by MALDI or
ESI using a time-of-flight mass analyzer on a Bruker Ultra
exTOF/TOF spectrometer.
Synthesis
of
tetrahydronaphthaleno[60]fullerene
derivatives. To a solution of aryl[60]fullerenyl dimer (ArC60-
C60Ar) (0.0200 mmol, 1.00 equiv.) in o-DCB (4.0 mL) was
added anhydrous CuBr2 (0.0800 mmol, 4.00 equiv.) under an
air atmosphere. After stirring for 3 hours at 100 oC, the resulting
mixture was filtrated through a silica gel plug to remove
insoluble materials, and then evaporated in vacuo to remove the
solvent. Finally, the residue was further separated on a silica gel
Experimental procedures for synthesis of the starting
materials. The starting materials, aryl bromides used for the
synthesis of monoarylated fullerenes necessary in this work was
prepared from esters 3, which were converted to carboxylic
acids 4, alcohols 5, and then methyl ethers 6. When intermediate
compounds are commercially available, we can start synthesis
from those compounds. As for the conversion from 5 to 6, we
used a general procedure A.
General Procedure A: To a solution of 5 (10.0 mmol) in dry
N,N-dimethylformamide (20.0 mL) was cooled to 0 °C in an ice
water bath. And sodium hydride (60% in oil, 480 mg, 12.0
mmol) was slowly added and stirred for 10 min at 0 °C. Then
methyl iodide (2.13 g, 15.0 mmol) was added to the reaction
mixture. After stirring at room temperature for 3 h, it was
carefully quenched with water and the aqueous phase was
extracted with AcOEt (3 × 30.0 mL). The combined organic
layers were washed with brine (40.0 mL) and dried over sodium
sulfate and concentrated in vacuo. The crude product was
purified by column chromatography on silica gel (20:1 =
PE:EA) to afford the product 6.
Synthesis of Grignard reagents An anhydrous
tetrahydrofuran (THF) (5.0 mL) solution of aryl bromides 6a–
g (10 mmol) was slowly dropped into another anhydrous THF
(5.0 mL) solution with polished Mg powder (360.0 mg, 15
mmol) and a trace amount of BrCH2CH2Br under an argon
atmosphere at 0 oC. After vigorously stirred 1 hour, the prepared
Grignard solution was transferred by Schlenk operation and
stocked in a Schlenk bottle. The concentration was confirmed
before using through anhydrous titration by using menthol as
titrant with a trace amount of 1,10-phenanthroline as indicator
under an argon atmosphere.
column
with
CS2
as
the
eluent
to
afford
tetrahydronaphthaleno[60]fullerenes with isolated yields of 48–
91%.
Synthesis of 1-bromo-2-(2-methoxyethyl)benzene (6a). 6a
was synthesized from commercially sourced 5a (2-(2-
bromophenyl)ethan-1-ol) according to General Procedure A.
(2.01 g, 9.40 mmol, 94%). 1H NMR (400 MHz, CDCl3) δ 7.52
(dd, J1 = 8.0 Hz, J2 = 1.2 Hz, 1H), 7.27–7.20 (m, 2H), 7.07–7.03
(m, 1H), 3.60 (t, J = 7.2 Hz, 2H), 3.35 (s, 3H), 3.02 (t, J = 7.2
Hz, 2H). 13C{1H} NMR (101 MHz, CDCl3) δ 138.3, 132.9,
131.1, 128.1, 127.5, 124.7, 71.8, 58.7, 36.4. HRMS (ESI-TOF)
(m/z): [M+] calcd for C9H11BrO, 213.9993; found, 213.9996.
Synthesis of 2-(2-bromo-4-fluorophenyl)ethan-1-ol (5b).
To a solution of 2-(2-bromo-4-fluorophenyl)acetic acid (4.62 g,
20.0 mmol, 1.00 equiv.) in dry THF (80.0 mL) cooled in an ice
water bath were added NaBH4 pellets (1.52 g, 40.0 mmol, 2.00
equiv.) under a flow of nitrogen over 15 min. To the resulting
mixture was added BF3·Et2O (2.66 mL, 21.0 mmol, 1.05 equiv.)
dropwise by syringe over 15 min. The mixture was allowed to
stir at 60 °C for 1 h. Upon completion, the mixture was
quenched by addition of MeOH (30.0 mL) and was stirred at
room temperature overnight. The solvent was removed under
reduced pressure, and the residue was extracted with ethyl
acetate (150 mL), and the mixture was washed with brine (2 ×
50.0 mL). The organic layer was further dried over Na2SO4 and
concentrated under reduced pressure. The residue was purified
by flash chromatography on silica gel (petroleum ether/ethyl
acetate, 10:1) to afford the product 5b (4.26 g, 19.6 mmol,
98%).20 1H NMR (400 MHz, CDCl3) δ 7.26 (dd, J1 = 8.4 Hz, J2
= 2.8 Hz, 1H), 7.22–7.18 (m, 1H), 6.94 (ddd, J1 = 10.8 Hz, J2 =
8.4 Hz, J3 = 2.4 Hz, 1H), 3.77 (t, J = 6.8 Hz, 2H), 3.39 (br, 1H),
Synthesis of organo(hydro)[60]fullerenes precursors
(ArC60H). To a solution of C60 (100 mg, 0.139 mmol) in ortho-
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1
2.93 (t, J = 6.8 Hz, 2H). literature data: H NMR (400 MHz,
CDCl3) δ 7.28 (dd, J1 = 8.0 Hz, J2 = 1.5 Hz, 1H), 7.23–7.20 (m,
1H), 7.00 (ddd, J1 = 8.0 Hz, J2 = 7.5 Hz, J3 = 1.5 Hz, 1H), 3.73
(t, J = 7.1 Hz, 2H), 3.34 (s, 1H), 2.89 (t, J = 7.1 Hz, 2H).
reaction was quenched, the mixture was poured into 50.0 mL of
H2O. The aqueous phase was extracted with AcOEt (3 x 50.0
mL). The combined organic layers were washed with brine
(50.0 mL). The extracts were then dried over MgSO4 and
evaporated under reduced pressure. The residue was purified by
flash chromatography (heptanes/AcOEt: 8/1) to afford 5d as a
colorless oil (4.06 g, 19.0 mmol, 95%).22 1H NMR (400 MHz,
CDCl3) δ 7.55 (dd, J1 = 8.4 Hz, J2 = 1.6 Hz, 1H), 7.30–7.23 (m,
2H), 7.08–7.04 (m, 1H), 3.78–3.74 (m, 1H), 3.67–3.62 (m, 1H),
3.48 (dt, J1 = 13.2 Hz, J2 = 6.4 Hz, 1H), 1.93 (br, 1H), 1.27 (d,
1
2
3
4
5
6
7
8
Synthesis
of
2-bromo-4-fluoro-1-(2-
methoxyethyl)benzene (6b). 6b was synthesized from 5b (2.18
g, 10.0 mmol) according to General Procedure A. (2.16 g, 9.30
mmol, 93%). 1H NMR (400 MHz, CDCl3) δ 7.28–7.21 (m, 2H),
6.95 (ddd, J1 = 10.8 Hz, J2 = 8.0 Hz, J3 = 2.4 Hz, 1H), 3.57 (t, J
= 6.8 Hz, 2H), 3.35 (s, 3H), 2.98 (t, J = 7.2 Hz, 2H). 13C{1H}
NMR (101 MHz, CDCl3) δ 161.1 (d, J = 249.9 Hz), 134.2 (d, J
= 3.5 Hz), 131.8 (d, J = 8.3 Hz), 124.3 (d, J = 9.4 Hz), 119.9 (d,
J = 24.2 Hz), 114.5 (d, J = 20.8 Hz), 71.7, 58.7, 35.6. HRMS
(ESI-TOF) (m/z): [M+] calcd for C9H10BrFO, 231.9899; found,
231.9895.
Synthesis of 2-(2-bromo-4-methoxyphenyl)ethan-1-ol
(5c). 5c was synthesized from commercially sourced 4c (4.88
g, 20.0 mmol) according to the procedure from 4b to 5b. (4.32
g, 18.8 mmol, 94%). 1H NMR (400 MHz, CDCl3) δ 7.15 (d, J =
8.4 Hz, 1H), 7.10 (d, J = 2.8 Hz, 1H), 6.80 (dd, J1 = 8.4 Hz, J2
= 2.8 Hz, 1H), 3.81 (t, J = 6.8 Hz, 2H), 3.76 (s, 3H), 2.94 (t, J =
6.8 Hz, 2H), 2.03 (br, 1H). literature data: 1H NMR (400 MHz,
CDCl3) δ 7.20 (d, J = 8.4 Hz, 1H), 7.14 (d, J = 2.6 Hz, 1H), 6.84
(dd, J1 = 8.4 Hz, J2 = 2.6 Hz, 1H), 3.87 (t, J = 6.7 Hz, 2H), 3.81
(s, 3H), 2.99 (t, J = 6.7 Hz, 2H), 2.05 (s, 1H).
9
1
J = 7.2 Hz, 3H). literature data: H NMR (400 MHz, acetone-
10
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12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
d6) δ 1.25 (s, 3H), 3.50–3.64 (m, 1H), 3.67–3.81 (m, 2H), 7.01–
7.14 (m, 1H), 7.27–7.41 (m, 2H), 7.55 (d, J = 7.86 Hz, 1H).
Synthesis of 1-bromo-2-(1-methoxypropan-2-yl)benzene
(6d). 6d was synthesized from 5d (2.14 g, 10.0 mmol)
according to General Procedure A. (2.14 g, 9.40 mmol, 94%).
1H NMR (400 MHz, CDCl3) δ 7.44 (d, J = 7.6 Hz, 1H), 7.16 (d,
J = 4.4 Hz, 2H), 6.98–6.92 (m, 1H), 3.52–3.42 (m, 2H), 3.32–
3.27 (m, 1H), 3.25 (s, 3H), 1.18 (d, J = 6.4 Hz, 3H). 13C{1H}
NMR (101 MHz, CDCl3) δ 143.1, 133.0, 127.8, 127.7, 127.6,
124.9, 77.1, 58.8, 38.3, 17.7. HRMS (ESI-TOF) (m/z): [M+]
calcd for C10H13BrO, 228.0150; found, 228.0152.
Synthesis
of
methyl
2-(2-bromophenyl)-2-
methylpropanoate (3e’). To a stirred solution of HMDS (8.5
mL, 40.0 mmol, 2.00 equiv.) in THF (50.0 mL) was added n-
BuLi (22.0 mL, 1.60 M in hexane, 40.0 mmol, 2.00 equiv.) at 0
°C. After the mixture was stirred for 1.5 h, a solution of 3e (4.56
g, 20.0 mmol, 1.00 equiv.) in THF (50.0 mL) was added, and
the mixture was stirred for 2 h at room temperature. Then MeI
(2.5 mL, 40.0 mmol, 2.00 equiv.) was added at 0 °C, and the
mixture was stirred for 12 h at room temperature. The reaction
was quenched by addition of 1.00 M HCl at 0 °C. The crude
mixture was extracted with EtOAc (3 x 50.0 mL) and the
combined organic extracts were washed with brine, dried
(Na2SO4) and concentrated in vacuo. The residue was purified
by flash chromatography on silica gel (petroleum ether/ethyl
acetate, 10:1) to afford the product 3e’ (4.50 g, 17.6 mmol,
88%).23 1H NMR (400 MHz, CDCl3) δ 7.56 (dd, J1 = 8.0 Hz, J2
= 1.2 Hz, 1H), 7.42 (dd, J1 = 7.6 Hz, J2 = 1.6 Hz, 1H), 7.32 (ddd,
J1 = 8.8 Hz, J2 = 7.6 Hz, J3 = 1.2 Hz, 1H), 7.11 (ddd, J1 = 9.6
Hz, J2 = 8.0 Hz, J3 = 1.6 Hz, 1H), 3.68 (s, 3H), 1.64 (s, 6H).
literature data: 1H NMR (300 MHz, CDCl3) δ 7.58 (dd, J1 = 7.6
Hz, J2 = 1.2 Hz, 1H), 7.45 (dd, J1 = 7.6 Hz, J2 = 1.4 Hz, 1H),
7.33 (ddd, J1 = 8.6 Hz, J2 = 7.6 Hz, J3 = 1.2 Hz, 1H), 7.14 (ddd,
J1 = 8.6 Hz, J2 = 8.0 Hz, J3 = 1.6 Hz, 1H), 3.70 (s, 3H), 1.65 (s,
6H).
Synthesis of 2-(2-bromophenyl)-2-methylpropan-1-ol
(5e). 5e was synthesized from 3e’ (3.84 g, 15.0 mmol)
according to the procedure from 3d’ to 5d. (3.17 g, 13.9 mmol,
93%). 1H NMR (400 MHz, CDCl3) δ 7.38 (dd, J1 = 8.0 Hz, J2 =
2.0 Hz, 1H), 7.32–7.24 (m, 1H), 7.22–7.17 (m, 1H), 7.01–6.97
(m, 1H), 3.94 (s, 2H), 3.52 (s, 1H), 1.42 (s, 6H). literature data:
1H NMR (400 MHz, acetone-d6) δ 1.48 (s, 6H), 3.94 (d, J = 5.71
Hz, 2H), 7.04–7.15 (m, 1H), 7.26–7.35 (m, 1H), 7.50–7.65 (m,
2H).
Synthesis of 1-bromo-2-(1-methoxy-2-methylpropan-2-
yl)benzene (6e). 6e was synthesized from 5e (2.28 g, 10.0
mmol) according to General Procedure A. (2.30 g, 9.50 mmol,
95%). 1H NMR (400 MHz, CDCl3) δ 7.49 (dd, J1 = 7.6 Hz, J2 =
1.2 Hz, 1H), 7.33 (dd, J1 = 8.0 Hz, J2 = 1.6 Hz, 1H), 7.18–7.14
(m, 1H), 6.94 (ddd, J1 = 9.2 Hz, J2 = 8.0 Hz, J3 = 1.2 Hz, 1H),
3.68 (s, 2H), 3.24 (s, 3H), 1.42 (s, 6H). 13C{1H} NMR (101
MHz, CDCl3) δ 144.7, 135.8, 129.6, 127.8, 127.4, 122.5, 80.0,
Synthesis
of
2-bromo-4-methoxy-1-(2-
methoxyethyl)benzene (6c). 6c was synthesized from 5c (2.30
g, 10 mmol) according to General Procedure A. (2.27 g, 9.30
mmol, 93%). 1H NMR (400 MHz, CDCl3) δ 7.16 (d, J = 8.4 Hz,
1H), 7.09 (d, J = 2.8 Hz, 1H), 6.79 (dd, J1 = 8.4 Hz, J2 = 2.4 Hz,
1H), 3.76 (s, 3H), 3.56 (t, J = 7.2 Hz, 2H), 3.36 (s, 3H), 2.96 (t,
J = 6.8 Hz, 2H). 13C{1H} NMR (101 MHz, CDCl3) δ 158.7,
131.4, 130.1, 124.7, 118.0, 113.7, 72.1, 58.7, 55.6, 35.5. HRMS
(ESI-TOF) (m/z): [M−OCH3]+ calcd for C9H10BrO, 212.9915;
found, 212.9900.
Synthesis of methyl 2-(2-bromophenyl)propanoate (3d’).
NaHMDS (17.5 mL of a 2.00 M solution in THF, 35.0 mmol,
1.00 equiv.) was added dropwise at 0 °C to a stirred solution of
the ester 3d (7.98 g, 35.0 mmol, 1.00 equiv.) in freshly distilled
THF (110.0 mL). The mixture was stirred at 20°C for 45 min
and iodomethane (2.2 mL, 35.0 mmol, 1.00 equiv.) was added
dropwise. After stirring at 20°C for 3 h, the reaction mixture
was quenched with a saturated aq. solution of NH4Cl and the
aqueous phase was extracted with AcOEt (3 x 20.0 mL). The
combined organic layers were washed with brine (40.0 mL).
The extracts were then dried over MgSO4 and evaporated under
reduced pressure. The residue was purified by flash
chromatography (heptanes/AcOEt: 9/1) to afford 3d’ as
colorless oil (7.04 g, 29.1 mmol, 83%).21 1H NMR (400 MHz,
CDCl3) δ 7.56 (d, J = 8.4 Hz, 1H), 7.32–7.26 (m, 2H), 7.13–
7.09 (m, 1H), 4.23 (q, J = 6.8 Hz, 1H), 3.68 (s, 3H), 1.49 (d, J
1
= 7.2 Hz, 3H). literature data: H NMR (300 MHz, CDCl3) δ
7.56 (d, J = 7.9 Hz, 1H), 7.30 (m, 2H), 7.11 (m, 1H), 4.22 (q, J
= 7.0 Hz, 1H), 3.69 (s, 3H), 1.49 (d, J = 7.0 Hz, 3H).
Synthesis of 2-(2-bromophenyl)propan-1-ol (5d). In a 250
mL round bottom flask, 4.84 g (20.0 mmol, 1.00 equiv.) of the
ester (3d’) was taken up in 100.0 mL of dry THF under an
atmosphere of N2. The reaction solution was cooled to 0°C in a
wet ice bath. To this was slowly added 11.0 mL (22.0 mmol,
1.10 equiv.) of the LAH solution (2.00 M in THF). The reaction
was allowed to stir for 1 h. The wet ice bath was recharged with
more ice and the reaction was then slowly and carefully
quenched with 20.0 mL of 2.00 M HCl solution. Once the
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59.3, 41.2, 25.5 (2C). HRMS (ESI-TOF) (m/z): [M+] calcd for
C11H15BrO, 242.0306; found, 242.0303.
procedure, the chromatography with the CS2 as eluent provided
1
2
3
4
5
6
7
8
an air-stable dark brown solid 7b in a yield of 83% (100.8 mg).
1H NMR (400 MHz, TCE-d2/CS2) δ 8.16 (dd, J1 = 10.8 Hz, J2 =
2.4 Hz, 1H), 7.77 (dd, J1 = 7.4 Hz, J2 = 6.0 Hz, 1H), 7.32 (ddd,
J1 = 10.0 Hz, J2 = 8.4 Hz, J3 = 2.8 Hz, 1H), 6.92 (s, 1H), 4.24
(t, J = 6.4 Hz, 2H), 4.03 (t, J = 6.4 Hz, 2H), 3.52 (s, 3H);
13C{1H} NMR (101 MHz, CS2/CDCl3, all 2C unless indicated)
δ 161.2 (d, J = 247.8 Hz, 1C), 152.7 (1C), 147.3 (1C), 147.2
(3C), 146.9, 146.4 (3C), 146.1 (3C), 146.0, 145.89 (3C), 145.87
(3C), 145.4, 145.3, 145.1 (6C), 144.4, 144.2, 143.0 (3C), 142.7
(1C), 142.4 (3C), 142.3 (3C), 141.83 (3C), 141.80 (3C), 141.4
(3C), 141.0, 140.1, 139.6 (1C), 134.1 (d, J = 3.4 Hz, 1C), 133.6
(d, J = 7.7 Hz, 1C), 117.0 (d, J = 23.7 Hz, 1C), 115.0 (d, J =
20.5 Hz, 1C), 73.3 (1C, sp3-C of C60), 67.7 (1C, sp3-C of C60),
62.3 (1C), 58.6 (1C), 32.6 (1C); HRMS (MALDI-TOF) (m/z):
[M+] calcd for C69H11OF, 874.0794; found, 874.0790.
Synthesis of methyl 2-(2-bromothiophen-3-yl)ethan-1-ol
(5f’). In the absence of light, a solution of NBS (3.56 g, 20.0
mmol, 1.00 equiv.) in DMF (20.0 mL) was added dropwise to a
solution of 5f (2.56 g, 20.0 mmol, 1.00 equiv.) in DMF (20.0
mL). After stirring for 3 h, the reaction mixture was quenched
with ice-water and extracted with dichloromethane. Combined
organic phases were washed with water, dried over magnesium
sulfate, and concentrated under vacuum. Distillation of the
crude product gave 3.75 g (18.2 mmol, 91%) of desired
product.24 1H NMR (400 MHz, CDCl3) δ 7.22 (d, J = 5.6 Hz,
1H), 6.87 (d, J = 5.6 Hz, 1H), 3.83 (t, J = 6.8 Hz, 2H), 2.86 (t,
9
10
11
12
13
14
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16
17
18
19
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24
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34
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36
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47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
J = 6.8 Hz, 2H), 1.69 (s, 1H). literature data: H NMR (400
MHz, CDCl3) δ 7.23 (d, J = 5.6 Hz, 1H), 6.87 (d, J = 5.6 Hz,
1H), 3.84 (t, J = 6.6 Hz, 2H), 2.87 (t, J = 6.6 Hz, 2H), 1.53 (s,
1H).
Synthesis of monoadduct 7c ((2-CH3OCH2CH2-5-CH3O-
Synthesis of 2-bromo-3-(2-methoxyethyl)thiophene (6f).
6f was synthesized from 5f’ (2.06 g, 10 mmol) according to
General Procedure A. (2.11 g, 9.60 mmol, 96%). 1H NMR (400
MHz, CDCl3) δ 7.20 (d, J = 5.6 Hz, 1H), 6.86 (d, J = 5.6 Hz,
1H), 3.57 (t, J = 6.8 Hz, 2H), 3.36 (s, 3H), 2.86 (t, J = 6.8 Hz,
2H). 13C{1H} NMR (101 MHz, CDCl3) δ 138.4, 128.7, 125.5,
110.0, 71.7, 58.7, 30.0. HRMS (ESI-TOF) (m/z): [M+] calcd for
C7H9BrSO, 219.9557; found, 219.9556.
Synthesis of 3-(2-bromophenyl)propan-1-ol (5g). 5g was
synthesized from commercially sourced 4g (4.56 g, 20.0 mmol)
according to the procedure from 4b to 5b. (3.94 g, 18.4 mmol,
92%). 1H NMR (400 MHz, CDCl3) δ 7.52 (d, J = 7.6 Hz, 1H),
7.24–7.20 (m, 2H), 7.07–7.02 (m, 1H), 3.68 (t, J = 6.4 Hz, 2H),
2.84–2.80 (m, 2H), 2.57 (br, 1H), 1.92–1.85 (m, 2H). literature
data: 1H NMR (400 MHz, CDCl3) δ 7.53 (d, J = 7.8 Hz, 1H),
7.25–7.22 (m, 2H), 7.07–7.03 (m, 1H), 3.65 (t, J = 6.4 Hz, 2H),
2.86–2.81 (m, 2H), 2.59 (s, 1H), 1.94–1.88 (m, 2H).
Synthesis of 1-bromo-2-(3-methoxypropyl)benzene (6g).
6g was synthesized from 5g (2.14 g, 10.0 mmol) according to
General Procedure A. (2.10 g, 9.20 mmol, 92%). 1H NMR (400
MHz, CDCl3) δ 7.51 (d, J = 8.0 Hz, 1H), 7.22–7.18 (m, 2H),
7.06–7.00 (m, 1H), 3.40 (t, J = 6.4 Hz, 2H), 3.34 (s, 3H), 2.82–
2.78 (m, 2H), 1.92–1.85 (m, 2H). 13C{1H} NMR (101 MHz,
CDCl3) δ 141.3, 132.9, 130.5, 127.6, 127.4, 124.5, 71.8, 58.6,
32.8, 29.7. HRMS (ESI-TOF) (m/z): [M+] calcd for C10H13BrO,
228.0150; found, 228.0145.
C6H3)C60H).
2-hydro-1-(2-methoxyethyl-5-
methoxy)phenyl[60]fullerene By following the general
procedure, the chromatography with the CS2 as eluent provided
an air-stable dark brown solid 7c in a yield of 88% (108.3 mg).
1H NMR (400 MHz, CS2/CDCl3) δ 7.90 (d, J = 2.4 Hz, 1H),
7.62 (d, J = 8.4 Hz, 1H), 7.07 (dd, J1 = 8.4 Hz, J2 = 2.4 Hz, 1H),
6.87 (s, 1H), 4.13 (t, J = 6.8 Hz, 2H), 3.97–3.94 (m, 5H), 3.46
(s, 3H); 13C{1H} NMR (101 MHz, CS2/CDCl3, all 2C unless
indicated) δ 158.4 (1C), 153.2 (1C), 147.4 (1C), 147.1 (1C),
146.7 (4C), 146.3 (3C), 146.2, 146.08 (3C), 146.07 (3C), 145.7
(3C), 145.4, 145.35 (3C), 145.34 (3C), 145.30 (3C), 144.7,
144.4, 143.3 (3C), 142.6 (3C), 142.5, 142.1 (3C), 142.0 (3C),
141.6 (3C), 141.3, 140.3, 139.8, 133.4 (1C), 130.2 (1C), 117.4
(1C), 112.6 (1C), 74.0 (1C, sp3-C of C60), 68.3 (1C, sp3-C of
C60), 62.7 (1C), 58.8 (1C), 55.1 (1C), 32.8 (1C); HRMS
(MALDI-TOF) (m/z): [M+] calcd for C70H14O2, 886.0994;
found, 886.0990.
Synthesis of monoadduct 7d ((2-CH3OCH2CH(CH3)-
C6H4)C60H).
2-hydro-1-(2’-methyl-2-methoxyethyl-5-
methoxy)phenyl[60]fullerene By following the general
procedure, the chromatography with the CS2 as eluent provided
an air-stable dark brown solid 7d in a yield of 89% (107.6 mg).
1H NMR (400 MHz, CS2/CDCl3) δ 8.28 (d, J = 8.4 Hz, 1H),
7.70 (dd, J1 = 7.6 Hz, J2 = 1.6 Hz, 1H), 7.56–7.51 (m, 1H), 7.44–
7.40 (m, 1H), 7.20 (s, 1H), 5.37–7.34 (m, 1H), 4.00–3.90 (m,
1H), 3.70–3.57 (m, 1H),3.44 (s, 3H), 1.39 (d, J = 9.6 Hz, 3H);
13C{1H} NMR (101 MHz, CS2/CDCl3, all 2C unless indicated)
δ 154.9 (1C), 147.5 (3C), 147.2 (3C), 146.93 (1C), 146.86 (1C),
146.40 (3C), 146.37, 146.2 (6C), 145.8 (1C), 145.7 (1C), 145.6
(4C), 145.5 (3C), 145.42 (3C), 145.39 (3C), 144.8, 143.4 (1C),
143.3 (1C), 142.68 (3C), 142.66 (3C), 142.6 (1C), 142.15 (4C),
142.14 (3C), 142.11, 141.8 (1C), 141.7 (1C), 141.4 (1C), 140.4
(1C), 140.3 (1C), 130.0 (1C), 129.0 (1C), 128.4 (1C), 127.1
(1C), 68.5 (1C, sp3-C of C60), 62.7 (1C, sp3-C of C60), 59.4 (1C),
50.8 (1C), 35.3 (1C), 20.1 (1C); HRMS (MALDI-TOF) (m/z):
[M+] calcd for C70H14O, 870.1045; found, 870.1043.
Synthesis
of
monoadduct
7a
((2-
CH3OCH2CH2C6H4)C60H).
2-hydro-1-(2-
methoxyethyl)phenyl[60]fullerene By following the general
procedure, the chromatography with the CS2 as eluent provided
an air-stable dark brown solid 7a in a yield of 90% (107.1 mg).
1H NMR (400 MHz, CS2/CDCl3) δ 8.41 (dd, J1 = 7.6 Hz, J2 =
1.6 Hz, 1H), 7.74 (dd, J1 = 7.6 Hz, J2 = 1.6 Hz, 1H), 7.60–7.52
(m, 2H), 6.88 (s, 1H), 4.25 (t, J = 6.8 Hz, 2H), 4.02 (t, J = 6.8
Hz, 2H), 3.48 (s, 3H); 13C{1H} NMR (101 MHz, CS2/CDCl3,
all 2C unless indicated) δ 153.5 (1C), 147.7 (1C), 147.4 (1C),
146.9 (3C), 146.5 (3C), 146.4, 146.30 (3C), 146.29 (3C), 146.1,
145.9, 145.63, 145.55, 145.53, 145.51, 144.9, 144.7, 143.5,
142.8 (3C), 142.7, 142.25 (3C), 142.21 (3C), 141.8 (4C), 141.5
(3C), 140.5, 140.0, 138.6 (3C), 132.6 (1C), 130.3 (1C), 128.8
(1C), 127.5 (1C), 73.9 (1C, sp3-C of C60), 68.6 (1C, sp3-C of
C60), 63.0 (1C), 59.1 (1C), 33.7 (1C); HRMS (MALDI-TOF)
(m/z): [M+] calcd for C69H12O, 856.0888; found, 856.0899.
Synthesis of monoadduct 7b ((2-CH3OCH2CH2-5-F-
Synthesis of monoadduct 7e ((2-CH3OCH2C(CH3)2-
C6H4)C60H).
2-hydro-1-(2’-dimethyl-2-methoxyethyl-5-
methoxy)phenyl[60]fullerene By following the general
procedure, the chromatography with the CS2 as eluent provided
an air-stable dark brown solid 7e in a yield of 86% (105.6 mg).
1H NMR (400 MHz, TCE-d2/CS2) δ 9.23 (dd, J1 = 8.0 Hz, J2 =
1.2 Hz, 1H), 7.89 (dd, J1 = 8.0 Hz, J2 = 1.2 Hz, 1H), 7.73–7.69
(m, 1H), 7.54–7.50 (m, 1H), 6.88 (s, 1H), 4.05 (s, 2H), 3.45 (s,
3H), 1.97 (s, 6H); 13C{1H} NMR (101 MHz, TCE-d2/CS2, all
2C unless indicated) δ 153.5 (1C), 147.2 (1C), 146.8 (1C),
C6H3)C60H).
2-hydro-1-(2-methoxyethyl-5-
fluoro)phenyl[60]fullerene By following the general
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146.5 (3C), 146.1 (3C), 146.0, 145.88, 145.87, 145.5, 145.4,
C of C60), 70.1 (sp3-C of C60), 58.7, 56.5 (dr), 34.2, 31.9 (dr);
HRMS (MALDI-TOF) (m/z): [M+] calcd for C69H10O,
1
2
3
4
5
6
7
8
145.2 (3C), 145.15, 145.08, 145.0, 144.9 (3C), 144.4 (3C),
144.2 (3C), 143.1, 142.41, 142.40, 142.0, 141.8, 141.6, 141.5,
141.3, 140.7, 140.1, 138.9, 136.7 (1C), 135.2 (1C), 130.0 (1C),
127.3 (1C), 127.2 (1C), 81.5 (1C, sp3-C of C60), 69.6 (1C, sp3-
C of C60), 65.4 (1C), 58.7 (1C), 40.7 (1C), 29.5 (2C); HRMS
(MALDI-TOF) (m/z): [M+] calcd for C71H16O, 884.1201; found,
884.1187.
854.0732; found, 854.0721. (*dr = diastereomer)
Synthesis of compound 2b. C60-fused 3-methoxy-7-fluoro-
3,4-dihydrotetrahydronaphthaleno[60]fullerene
By
following the general procedure, the chromatography with the
CS2 as eluent provided a brownish shinning powder 2b in a
yield of 78% (27.2 mg). 1H NMR (400 MHz, TCE-d2/CS2) δ for
R isomer: 8.22–8.18 (m, 1H), 7.70–7.60 (m, 1H), 7.29–7.24 (m,
1H), 5.45–5.41 (m, 1H), 4.43 (d, J = 14.8 Hz, 1H), 3.93 (d, J =
1.2 Hz, 1H), 3.88 (s, 3H); δ for S isomer: 8.22–8.18 (m, 1H),
7.70–7.60 (m, 1H), 7.29–7.24 (m, 1H), 4.95 (d, J = 11.6 Hz,
1H), 4.14 (t, J = 12.8 Hz, 1H), 3.82 (d, J = 14.8 Hz, 1H), 3.64
(s, 3H); 13C{1H} NMR (101 MHz, TCE-d2/CS2, all 1C unless
indicated) δ 153.5 (d, J = 94.1 Hz, 1C), 147.2, 146.9, 146.4
(2C), 146.03 (2C), 145.96 (2C), 145.82 (2C), 145.81 (2C),
145.5 (2C), 145.4 (2C), 145.2 (2C), 145.09 (2C), 145.07 (2C),
145.0 (2C), 144.4 (2C), 144.2 (2C), 143.0 (2C), 142.30 (3C),
142.26 (2C), 141.79 (3C), 141.75 (3C), 141.4 (4C), 141.1 (2C),
140.0 (2C), 139.6, 138.4 (3C), 134.4 (3C), 132.3, 129.9, 128.4,
127.1, 116.4 (3C), 72.8, 71.1 (sp3-C of C60), 68.1 (sp3-C of C60),
62.6, 33.4; HRMS (MALDI-TOF) (m/z): [M+] calcd for
C69H9FO, 872.0637; found, 872.0635.
Synthesis of compound 2c. C60-fused 3-methoxy-7-
methoxy-3,4-dihydrotetrahydronaphthaleno[60]fullerene
By following the general procedure, the chromatography with
the CS2 as eluent provided a brownish shinning powder 2c in a
yield of 91% (32.2 mg). 1H NMR (400 MHz, TCE-d2/CS2) δ for
R isomer: 8.00 (s, 1H), 7.60–7.54 (m, 1H), 7.08 (d, J = 8.0 Hz
1H), 5.40 (d, J = 3.2 Hz, 1H), 4.41 (d, J = 15.6 Hz, 1H), 3.94 (s,
3H), 3.88 (s, 3H), 3.85 (d, J = 4.0 Hz, 1H); δ for S isomer: 8.00
(s, 1H), 7.60–7.54 (m, 1H), 7.08 (d, J = 8.0 Hz 1H), 4.94 (d, J
= 10.8 Hz, 1H), 4.10 (t, J = 13.6 Hz, 1H), 3.94 (s, 3H), 3.78 (d,
J = 14.4 Hz, 1H), 3.64 (s, 3H); 13C{1H} NMR (101 MHz, TCE-
d2/CS2, all 1C unless indicated) δ 159.2, 158.8, 154.0, 153.5,
147.4, 146.14 (2C), 146.12 (2C), 145.84 (2C), 145.81 (2C),
145.75, 145.73, 145.15, 145.13, 145.10 (2C), 144.99, 144.9
(4C), 144.83 (2C), 144.81 (2C), 144.7 (2C), 144.3 (3C), 142.8
(3C), 142.4 (3C), 142.3 (3C), 142.1 (2C), 142.0 (2C), 141.9
(2C), 141.83 (2C), 141.79 (2C), 141.75, 141.3 (2C), 141.11
(2C), 141.07, 131.0, 130.5, 115.4, 114.7, 112.6, 112.1, 84.5,
84.1 (dr)*, 69.7 (sp3-C of C60), 68.7 (sp3-C of C60), 58.4, 56.1
(dr), 54.9, 33.1, 30.7 (dr); HRMS (MALDI-TOF) (m/z): [M+]
calcd for C70H12O2, 884.0837; found, 884.0835. (*dr =
diastereomer)
Synthesis of monoadduct 7f ((3-CH3OCH2CH2-
C4SH2)C60H).
2-hydro-1-(3-
9
methoxyethyl)thiophenyl[60]fullerene By following the
general procedure, the chromatography with the CS2 as eluent
provided an air-stable dark brown solid 7f in a yield of 89%
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(106.6 mg). H NMR (400 MHz, CS2/CDCl3) δ 7.42–7.37 (m,
2H), 7.03 (s, 1H), 4.02 (t, J = 6.4 Hz, 2H), 3.92 (t, J = 6.4 Hz,
2H), 3.52 (s, 3H); 13C{1H} NMR (101 MHz, CS2/CDCl3, all 2C
unless indicated) δ 153.0 (1C), 152.7, 147.6 (1C), 147.3 (1C),
146.7, 146.41, 146.39, 146.23, 146.18, 145.84, 145.81, 145.7,
145.5, 145.45, 145.40, 145.1 (1C), 144.7, 144.5, 143.3, 142.65,
142.61, 142.13 (4C), 142.10, 141.8, 141.7, 141.5, 140.4, 140.2,
137.2, 136.1, 135.6, 131.0 (1C), 123.4 (1C), 72.8 (1C, sp3-C of
C60), 63.5 (1C, sp3-C of C60), 63.0 (1C), 58.9 (1C), 29.9 (1C);
HRMS (MALDI-TOF) (m/z): [M+] calcd for C67H10SO,
862.0452; found, 862.0450.
Synthesis of monoadduct 7g ((2-CH3OCH2CH2CH2-
C6H4)C60H).
2-hydro-1-(2-
methoxypropyl)phenyl[60]fullerene By following the general
procedure, the chromatography with the CS2 as eluent provided
an air-stable dark brown solid 7g in a yield of 88% (106.3 mg).
1H NMR (400 MHz, CS2/CDCl3) δ 8.37 (dd, J1 = 8.0 Hz, J2 =
1.2 Hz, 1H), 7.68 (dd, J1 = 7.6 Hz, J2 = 1.6 Hz, 1H), 7.58–7.48
(m, 2H), 6.77 (s, 1H), 4.03 (br, 2H), 3.67 (t, J = 6.0 Hz, 2H),
3.40 (s, 3H), 2.34–2.27 (m, 2H); 13C{1H} NMR (101 MHz,
CS2/CDCl3, all 2C unless indicated) δ 153.2 (1C), 147.5 (1C),
147.2 (1C), 146.7 (3C), 146.4 (3C), 146.3, 146.1 (4C), 145.7
(3C), 145.54, 145.49, 145.44, 145.40, 145.3, 144.7, 144.5 (1C),
143.3 (3C), 142.62 (3C), 142.59 (3C), 142.13 (3C), 142.07
(3C), 141.7 (3C), 141.6 (3C), 141.4 (3C), 140.3 (3C), 139.9,
132.25 (1C), 130.16 (1C), 128.8 (1C), 127.0 (1C), 72.2 (1C,
sp3-C of C60), 68.4 (1C, sp3-C of C60), 63.0 (1C), 58.6 (1C), 32.6
(1C), 30.0 (1C); HRMS (MALDI-TOF) (m/z): [M+] calcd for
C70H14O, 870.1045; found, 870.1043.
Synthesis of compound 2a. C60-fused 3-methoxy-3,4-
dihydrotetrahydronaphthaleno[60]fullerene By following
the general procedure, the chromatography with the CS2 as
eluent provided a brownish shinning powder 2a in a yield of
Synthesis of compound 2d. C60-fused 3-methoxy-4-
methyl-3,4-dihydrotetrahydronaphthaleno[60]fullerene By
following the general procedure, the chromatography with the
CS2 as eluent provided a brownish shinning powder 2d in a
1
89% (30.4 mg). H NMR (400 MHz, CDCl3) δ for R isomer:
8.51–8.49 (m, 1H), 7.71–7.60 (m, 1H), 7.58–7.48 (m, 2H), 5.40
(d, J = 3.6 Hz, 1H), 4.47 (d, J = 15.6 Hz, 1H), 3.89 (dd, J1 =
16.0 Hz, J2 = 3.6 Hz, 1H), 3.84 (s, 3H); δ for S isomer: 8.51–
8.49 (m, 1H), 7.71–7.60 (m, 1H), 7.58–7.48 (m, 2H), 4.96 (d, J
= 10.8 Hz, 1H), 4.18 (t, J = 12.4 Hz, 1H), 3.79 (d, J = 14.4 Hz,
1H), 3.62 (s, 3H); 1H NMR (400 MHz, TCE-d2, 373 K) δ 8.54
(br, 1H), 7.68 (br, 1H), 7.57 (br, 2H), 5.23 (br, 1H), 4.11 (br,
2H), 3.78 (br, 3H); 13C{1H} NMR (101 MHz, CS2/CDCl3, all
1C unless indicated) δ 155.4, 154.3, 152.3, 147.6, 147.1, 146.4
(2C), 146.42 (2C), 146.40, 146.2, 146.15 (2C), 146.12, 146.10,
146.0, 145.44 (2C), 145.40, 145.3, 145.2 (2C), 145.1, 144.7,
144.6, 144.4, 143.1 (2C), 142.71, 142.69, 142.64, 142.62,
142.3, 142.2, 142.18, 142.16, 142.1, 141.9, 141.8, 141.64 (2C),
141.62 (2C), 141.44, 141.39 (2C), 141.37, 140.6, 140.4, 138.4,
137.7, 136.9, 136.8, 136.5, 130.5, 129.9, 128.8, 128.3, 128.0,
127.74 (2C), 127.71, 127.65, 127.63, 84.6, 84.4 (dr)*, 74.4 (sp3-
1
yield of 81% (28.1 mg). H NMR (400 MHz, TCE-d2/CS2) δ
8.54 (d, J = 7.6 Hz, 1H), 7.81 (d, J = 7.6 Hz, 1H), 7.64–7.54 (m,
2H), 4.60 (d, J = 10.4 Hz, 1H), 4.46–4.38 (m, 1H), 3.86 (s, 3H),
2.01 (d, J = 6.4 Hz, 1H); 13C{1H} NMR (101 MHz, TCE-d2/CS2,
all 1C unless indicated) δ 155.0, 153.8, 152.2, 148.7, 147.4,
147.2 (2C), 147.1, 146.2 (4C), 146.0, 145.9 (2C), 145.82 (3C),
145.77, 145.6, 145.11 (2C), 145.08, 145.0, 144.93 (3C), 144.87,
144.5 (2C), 144.3 (2C), 144.2, 144.0, 142.8 (3C), 142.5, 142.4
(2C), 142.3 (2C), 142.1 (2C), 142.0 (2C), 141.9 (2C), 141.53,
141.50, 141.41, 141.36, 141.18, 141.14, 141.08, 140.1, 139.5,
138.5, 138.4, 135.8, 128.3, 127.8, 127.7, 125.8, 89.5, 69.1 (sp3-
C of C60), 62.4 (sp3-C of C60), 38.8, 29.7, 13.9; HRMS
(MALDI-TOF) (m/z): [M+] calcd for C70H12O, 868.0888; found,
868.0888.
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Synthesis of compound 2e. C60-fused 3-methoxy-4-
Page 8 of 10
140.7, 140.6, 140.0, 139.3, 136.7, 135.2, 134.9, 134.5, 129.1,
128.7, 126.6, 126.0, 77.4, 74.6 (sp3-C of C60), 70.8 (sp3-C of
C60), 58.7, 54.0, 37.5; HRMS (MALDI-TOF) (m/z): [M+] calcd
for C70H12O, 868.0888; found, 868.0888.
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2
3
4
5
6
7
8
dimethyl-3,4-dihydrotetrahydronaphthaleno[60]fullerene
By following the general procedure, the chromatography with
the CS2 as eluent provided a brownish shinning powder 2e in a
yield of 76% (26.8 mg). 1H NMR (400 MHz, CS2/CDCl3) δ for
R isomer: 8.73 (dd, J1 = 8.0 Hz, J2 = 1.2 Hz, 1H), 7.86 (dd, J1 =
8.0 Hz, J2 = 1.2 Hz, 1H), 7.57–7.50 (m, 2H), 4.84 (s, 1H), 3.84
(s, 3H), 2.09 (s, 3H), 1.98 (s, 3H); δ for S isomer: 8.70 (dd, J1 =
8.0 Hz, J2 = 1.2 Hz, 1H), 7.78 (dd, J1 = 8.0 Hz, J2 = 1.2 Hz, 1H),
7.49–7.41 (m, 2H), 4.89 (s, 1H), 3.77 (s, 3H), 2.22 (s, 3H), 2.06
(s, 3H); 13C{1H} NMR (101 MHz, CS2/CDCl3, all 1C unless
indicated, diastereomer, 142C) δ 160.1, 159.8, 157.9, 157.3,
156.0, 155.6, 155.3, 153.8, 149.0, 148.0, 147.74, 147.67,
147.55, 147.53, 147.4, 146.7, 146.5, 146.45 (2C), 146.44 (2C),
146.39, 146.36, 146.3, 146.22, 146.16, 146.1, 146.05 (4C),
146.02 (2C), 145.9, 145.8 (2C), 145.7, 145.6, 145.5, 145.40,
145.37, 145.34, 145.31 (2C), 145.27 (2C), 145.23, 145.21,
145.17, 145.15 (2C), 145.06, 145.04, 145.00 (2C), 144.8 (2C),
144.72, 144.66 (2C), 144.6, 144.5, 144.4, 144.3, 143.6, 143.3,
143.2, 143.1 (2C), 142.75, 142.72 (2C), 142.67, 142.61, 142.57
(2C), 142.5, 142.4, 142.35, 142.32, 142.27 (2C), 142.20,
142.16, 142.1, 141.8, 141.71, 141.65 (4C), 141.6, 141.5,
141.39, 141.38, 141.34, 141.31 (2C), 141.2, 141.14, 141.09,
140.3, 140.1, 140.0, 139.9, 139.5, 138.7, 138.3, 138.2, 137.7,
137.2, 135.6, 135.3, 134.6, 134.1, 134.0, 133.7, 133.6, 133.4,
130.6, 130.4, 129.8, 128.1, 127.9, 127.55, 127.50, 126.9, 126.6,
95.6, 90.3, 69.6 (sp3-C of C60), 68.4 (sp3-C of C60), 67.1 (sp3-C
of C60), 64.5 (sp3-C of C60), 63.8, 62.6, 42.2, 42.1, 31.6, 28.5,
27.2, 25.7; HRMS (MALDI-TOF) (m/z): [M+] calcd for
C71H14O, 882.1045; found, 882.1041.
ASSOCIATED CONTENT
Supporting Information
Experimental section including 1H and 13C NMR spectra, and CV.
This material is available free of charge via the Internet at
http://pubs.acs.org.
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AUTHOR INFORMATION
Corresponding Author
* E-mail: matsuo@ustc.edu.cn; matsuo@photon.t.u-tokyo.ac.jp
Notes
The authors declare no competing financial interest.
┴These authors contributed equally.
ACKNOWLEDGMENT
This work was supported by high-level human resource funding
from the University of Science and Technology of China. Part of
this work was financially supported by Grants-in-Aid for Scientific
Research (JSPS KAKENHI Grant Nos. JP15H05760 and
JP19K22181) and the Ministry of Education, Culture, Sports,
Science and Technology (MEXT), Japan.
Synthesis of compound 2f. C60-fused 3-methoxy-3,4-
REFERENCES
dihydrotetrahydrobenzo[b]thiopheno[60]fullerene
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1
of 75% (25.8 mg). H NMR (400 MHz, CS2/CDCl3) δ for R
isomer: 7.49 (d, J = 5.2 Hz, 1H), 7.24 (d, J = 4.8 Hz, 1H), 5.16–
5.11 (m, 1H), 3.99–3.94 (m, 2H), 3.79 (s, 3H); δ for S isomer:
7.61 (d, J = 5.2 Hz, 1H), 7.33 (d, J = 5.2 Hz, 1H), 6.20 (d, J =
3.2 Hz, 1H), 3.90 (s, 3H), 3.48 (s, 2H); 13C{1H} NMR (101
MHz, TCE-d2/CS2, all 1C unless indicated) δ 147.2, 146.9,
146.4 (3C), 146.04 (3C), 145.96 (2C), 145.83 (3C), 145.81
(3C), 145.78 (2C), 145.4 (3C), 145.2 (2C), 145.1 (2C), 145.0
(3C), 144.4 (2C), 144.20 (2C), 144.16, 143.0 (3C), 142.31 (3C),
142.27 (3C), 141.8 (3C), 141.7 (3C), 141.4 (3C), 141.1 (2C),
140.0, 139.6, 135.7 (3C), 133.1, 129.9, 128.2, 127.3, 104.8,
68.0 (sp3-C of C60), 65.0 (sp3-C of C60), 62.3, 37.5; HRMS
(MALDI-TOF) (m/z): [M+] calcd for C67H8SO, 860.0296;
found, 860.0293.
Synthesis of compound 2g. C60-fused 3-methoxy 4,5-
tetrahydrobenzo[7]annuleno[60]fullerene By following the
general procedure, the chromatography with the CS2 as eluent
provided a brownish shinning powder 2g in a yield of 48% (16.7
1
mg). H NMR (400 MHz, CS2/CDCl3) δ 8.13–8.11 (m, 1H),
7.81–7.79 (m, 1H), 7.61–7.58 (m, 2H), 5.44 (t, J = 6.4 Hz, 1H),
4.03–3.97 (m, 2H), 3.06 (dt, J1 = 14.4 Hz, J2 = 7.2 Hz, 1H), 2.75
(dt, J1 = 14.4 Hz, J2 = 7.6 Hz, 1H); 13C{1H} NMR (101 MHz,
CS2/CDCl3, all 1C unless indicated) δ 158.3, 154.9, 154.7,
153.7, 147.5, 147.3, 146.5, 146.3, 146.25, 146.22, 146.12,
146.09, 146.08, 146.05, 146.03 (2C), 145.94, 145.88, 145.8,
145.5, 145.4, 145.35, 145.30, 145.27, 145.25 (2C), 145.16,
145.1, 144.9, 144.6, 144.5 (2C), 144.1, 143.25, 143.21, 142.73,
142.69, 142.66, 142.6, 142.4, 142.33, 142.32, 142.28, 142.2,
142.10 (2C), 142.08, 142.0, 141.9, 141.85, 141.78, 141.76,
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