Regioselective synthesis of tetra(aryl)-mono(silylmethyl)[60]fullerenes and derivatization to methanofullerene compound

Article abstract of DOI:10.1016/j.tet.2011.09.125

A method for the facile synthesis of tetraaryl-trimethylsilylmethyl- hydro[60]fullerenes, C₆₀Ar₄(CH₂SiMeR)H, has been developed in which readily prepared anionic mono(silylmethyl) fullerene is subjected to reaction conditi

Full text of DOI:10.1016/j.tet.2011.09.125

Tetrahedron 67 (2011) 9944e9949
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Regioselective synthesis of tetra(aryl)-mono(silylmethyl)[60]fullerenes and
derivatization to methanofullerene compound
*
*
Chang-Zhi Li, Yutaka Matsuo , Eiichi Nakamura
Department of Chemistry, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 3 August 2011
Received in revised form 27 September 2011
Accepted 28 September 2011
Available online 6 October 2011
A method for the facile synthesis of tetraaryl-trimethylsilylmethyl-hydro[60]fullerenes, C60Ar4(CH2
-
SiMeR)H, has been developed in which readily prepared anionic mono(silylmethyl) fullerene is subjected
to reaction conditions for organocopper-mediated multiple addition. Penta(organo)fullerene derivatives
bearing different substituents and diverse functionality were synthesized in moderate to good yield
under simple and mild reaction conditions. Further organic and organometallic transformations of these
fullerenes allowed us to synthesize transition-metal complexes and a new methanofullerene derivative,
1,9-methano-6,12,15,18-tetraphenyl[60]fullerene, C60Ph4(CH2).
Dedicated to Professor Gilbert Stork on the
occasion of his 90th birthday
Ó 2011 Elsevier Ltd. All rights reserved.
Keywords:
Fullerene
Organocopper reagent
Methanofullerene
Iron
Ferrocene
1. Introduction
Table 1
Synthesis of C60Ar4(CH2SiMeR)H (1) (Eq. 1)
Functionalization of fullerene has led to numerous derivatives1
that exhibit a surprising diversity of new properties that would
otherwise be unavailable, for example, unique biochemical activ-
ity,2 photoelectric function,3 self-assembly capability,4 and metal
complexation properties.5 To achieve selective multiple addition to
fullerene in high overall yield, one must control not only the
number of organic addends but also the regioselectivity of the
addition. As we have reported previously, the pentaaddition of an
arylcopper reagent to C60 is a good example of a reaction that ex-
clusively produces pentaarylated C60R5H in high yield.6 We have
been interested for some time in the multiple addition of different
organic groups, for instance, the addition of a phenylcopper reagent
to 1,4-dibenzylated C60 to synthesize C60Ph3(benzyl)2H7 and the
copper-mediated addition of alkylzinc reagents to synthesize
C60Ph4(C4H7O)H.8 In the present study, we demonstrate that het-
erogeneous pentaaddition is a promising approach to considerably
expanding the repertoire of available fullerene derivatives; herein,
we report efficient syntheses of tetra(aryl)-mono(silylmethyl)[60]
Entry
ArMgBr
RMe2SiCH2MgCl
Me3SiCH2MgCl
PhMe2SiCH2MgCl
iPrOMe2SiCH2MgCl
Me3SiCH2MgCl
Me3SiCH2MgCl
Conditions
45 ꢀC/6 h
45 ꢀC/5 h
45 ꢀC/5.5 h
1
Yield (%)
1
2
3
4
5
1a 71
1b 78
1c 72
45 ꢀC/13.5 h 1d 81
45 ꢀC/26 ha
1e 53
1f 73
6
n-OctylMe2SiCH2MgCl 50 ꢀC/6 h
Reaction performed in the presence of 15 equiv ArMgBr.
a
accomplished by reacting an anionic mono(silylmethyl) fullerene
with an organocopper reagent to synthesize the multiple addition
product regioselectively. The anionic intermediate can be readily
prepared in up to 93% yield through addition of RMe2SiCH2MgCl to
C60 in the presence of DMF.9 This has proved to be a practical
strategy not only for selectively introducing a diverse set of aryl and
silylmethyl groups to C60, but also for elaborating the products into
fullerene, C60Ar4(CH2SiMeR)H (Eq.
1 and Table 1), which
* Corresponding authors. Tel.: þ81 3 5841 4356; fax: þ81 3 5800 6889; e-mail
addresses: matsuo@chem.s.u-tokyo.ac.jp (Y. Matsuo), nakamura@chem.s.u-tokyo.ac.jp
(E. Nakamura).
0040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2011.09.125

C.-Z. Li et al. / Tetrahedron 67 (2011) 9944e9949
9945
a variety of new compounds through organic and organometallic
transformations of the silylmethyl moiety and the cyclopentadienyl
moiety.
The reactivity of cyclopentadiene with these compounds is il-
lustrated by the smooth conversion of 1a to the corresponding iron
complex (2a), in 42% isolated yield through heating in the presence
of [CpFe(CO)2]2 in PhCN at 180 ꢀC for 29 h (Eq. 2).12
H
Ar
Ar
RMe2SiCH2MgCl
DMF (addtive)
1,2-Cl2C6H4
1) ArMgBr/CuBr·SMe2
THF/1,2-Cl2C6H4
45 °C, 2–26 h
Ar
SiMe2R
Ar
C60
(1)
2) aq. NH4Cl
10–30 min
R = Me, Ph, iPrO, nOctyl
Ar = Ph, C6H4-4-NMe2, C6H4-4-Adamantyl,
C6H4-4-OMe
X-ray crystallographic analysis of compound 2a revealed
a quasi-Cs symmetrical structure (Fig. 2). The average bond length
between the iron atom and the carbon atoms of the Cp ring was
2. Results and discussion
ꢀ
2.054 A and that between the iron atom and the carbon atoms of
We first examined the synthesis of tetraphenyl-
trimethylsilylmethyl-hydro[60]fullerenes, C60Ph4(CH2SiMe3)H.
ꢀ
the fullerene cyclopentadienide was 2.076 A. These values are
A
similar to those found in C1-symmetric Fe[C60Ph4(C4H7O)]Cp and
C5v-symmetric bucky ferrocene Fe(C60Ph5)Cp. The Cp ring rotates
about the CpeFeeC60 axis faster than the NMR time scale. The
cyclopentadienide in the fullerene core has Cs symmetry as shown
solution of anionic mono(silylmethyl) fullerene was prepared by
adding Me3SiCH2MgCl to C60 in the presence of DMF.9 This solution
was then added to a solution of organocopper reagent prepared
from PhMgBr and CuBr$SMe2 at room temperature. As monitored
by HPLC, the reaction proceeded smoothly to completion (C60
completely consumed) under stirring for 6 h at 45 ꢀC to produce
C60Ph4(CH2SiMe3)H as the major product in 71% isolated yield
(Table 1, entry 1).10 The reaction after 2 h at 45 ꢀC, however, was
incomplete and produced C60(CH2SiMe3)H in 32% HPLC yield, and
C60Ph4(CH2SiMe3)H in 13% HPLC yield, along with various in-
termediate products.
by three 13C singlets at
d
91.94, 93.02, and 97.01 due to the five sp3
¼3.38) and
carbons, while the Cp ring exhibits only one proton (
d
carbon (d¼72.16) singlet.
This straightforward method can selectively introduce aryl and
silylmethyl groups onto C60. The reaction produced C60Ar4(CH2
-
SiMeR)H (1) in moderate to good yield, and could be applied to
a wide array of aryl and silylmethyl Grignard reagents (Table 1,
entries 1e6). A molecular model of the tetra(4-adamantylphenyl)
derivative, C60(C6H4-4-admantyl)4[CH2SiMe3]H (1e), suggested an
intriguing molecular structure composed of a
and an entirely aliphatic top face.
p-rich bottom face
The product C60Ar4(CH2SiMeR)H (1) was characterized by 1H,
13C NMR, and APCIeHRMS. Three isomers differing in the position
of the Cp proton could not be separated and three proton signals
were detected by 1H NMR. X-ray analysis of a dark-red single crystal
of compound 1d revealed a quasi-Cs symmetrical molecular struc-
ture, C60(C6H4-4-NMe2)4(CH2SiMe3)H (Fig. 1).11 The cavity created
by the one silyl and four aryl addends can be clearly seen in Fig. 1b.
Fig. 2. Single-crystal structure of 2a. (a) Capped stick model. (b) Top view of space-
filling model. (c) Side view of space-filling model.
Cyclic voltammetry was carried out in THF containing tetrabu-
tylammonium perchlorate as a supporting electrolyte. Bucky fer-
rocene 2a exhibited a reversible one-electron oxidation wave at
0.39 V (Eo1x/2) and two-step, one-electron reduction waves at ꢁ1.43 V
(1Er1e/2d) and ꢁ2.04 V (2Er1e/2d) versus Fc/Fcþ (Fig. 3). The difference of
one addend between 2a and Fe(C60Ph5)Cp (Eo1x/2, 0.50 V)12e de-
creased the oxidation potential by 0.11 V, which can be ascribed to
the stronger electron-donating effect of the trimethylsilylmethyl
group compared with the phenyl group.
Selective chemical modification of the isopropoxy silylmethyl
group in C60Ph4[CH2SiMe2(OiPr)]H (1c) enabled access to several
interesting new fullerene derivatives (Eq. 2). For instance, silanol
derivative 3 was obtained in 91% yield through hydrolysis of the
corresponding chlorosilane intermediate.13 This hydrolysis reaction
was carried out by simply stirring the isopropoxy silyl compound in
THF with 10 equiv of 35% aq HCl at 50 ꢀC for 2 h and then treating
the reaction mixture with satd NaHCO3. Alternatively, nucleophilic
substitution of the silyl chloride with iPrNH2 gave the corre-
sponding silyl amide derivative (4).
Fig. 1. Single-crystal structure of 1d. (a) Capped stick model. (b) Top view of space-
filling model. (c) Side view of space-filling model.

9946
C.-Z. Li et al. / Tetrahedron 67 (2011) 9944e9949
In summary, we have developed a method for the facile syn-
thesis of mono(silylmethyl)-tetra(aryl)[60]fullerene, C60Ar4(CH2
-
SiMeR)H, in which a readily prepared anionic mono(silylmethyl)
fullerene is subjected to reaction conditions for organocopper-
mediated multiple addition. Subsequent organic and organome-
tallic transformations of these fullerenes enabled access to
transition-metal complexes and new fullerene derivatives.
3. Experimental
3.1. General
Fig. 3. Cyclic voltammogram of 2a in THF containing tetrabutylammonium perchlorate
All reactions dealing with air- or moisture-sensitive compounds
were carried out using standard Schlenk technique under an argon
or nitrogen atmosphere. HPLC analyses were performed on a Shi-
madzu LC-10A system equipped with SPD-M10A diode array de-
tector and a Buckyprep column (Nacalai Tesque Inc., 4.6 mm
IDꢂ250 mm). Preparative HPLC was performed on a Buckyprep
column (20 mm IDꢂ250 mm) using toluene/2-isopropanol (7/3 to
4/6) as eluent (flow rate 5e15 ml/min, detected at 350 nm with an
UV spectrophotometric detector, Shimadzu SPD-6A). Flash silica gel
column chromatography was performed on silica gel 60 N (Kanto,
spherical and neutral, 140e325 mesh) as described by Still.16 Gel
permeation column chromatography was performed on a Japan
Analytical Industry LC-9201 (eluent: toluene) with JAIGEL 2H and
3H polystyrene column. NMR spectra were measured with a JEOL
ECA-500 (500 MHz) spectrometer. Spectra are reported in parts per
as supporting electrolyte (vs Fc/Fcþ).
Cu(II)-promoted conversion of the silylmethyl fullerene into
methanofullerene14 converted 1c into a new type of meth-
anofullerene. Treatment of 1c with t-BuOK (1.5 equiv)15 in ortho-
dichlorobenzene followed by heating in the presence of CuCl2
(6 equiv) enabled 5 to be prepared in 58% isolated yield (Scheme 1).
The structure of 5 was confirmed by X-ray crystallographic
analysis (Fig. 4).
OH
H
Ph
Ph
SiMe2
Ph
1) Conc. aq. HCl/THF,
50 °C, 2 h
Ph
million from internal tetramethylsilane (
d
0.00 ppm) for 1H NMR,
from solvent carbon (e.g.,
d
77.00 ppm for chloroform) for 13C NMR.
2) Sat. aq. NaHCO3, rt, 1 h
91%
High-resolution mass spectra were measured by APCI using a time-
of-flight mass analyzer on a JEOL JMS-T100LC (AccuTOF) spec-
3
trometer. Me3SiCH2MgCl, PhMe2SiCH2MgCl, (iPrO)Me2SiCH2
-
OiPr
H
NHiPr
SiMe2
Ph
Ph
Ph
H
Ph
Ph
SiMgCl, and (C8H17)Me2SiCH2SiMgCl were prepared according to
the literatures,17 and titrated before use. Other materials were
purchased from Tokyo Chemical Industry Co., SigmaeAldrich Co.,
Kanto Chemical Co., Inc., Wako Pure Chemical Industries, or other
commercial suppliers and used after appropriate purification.
Ph
Ph
SiMe2
Ph
Ph
1) AlCl3, CH2Cl2, 1 h
2) NH2iPr, CH2Cl2, 1 h
Ph
88%
1c
4
3.2. General procedure for the synthesis of tetraaryl-
Ph
trimethylsilylmethyl-hydro[60]fullerenes (1aef)
CH2
Ph
tBuOK, CuCl2
To a solution of C60 (72 mg, 0.10 mmol) in 1,2-dichlorobenzene
(10 mL) containing N,N-dimethylformamide (0.23 mL, 3 mmol)
was added the THF solution of RMe2SiCH2MgCl (0.30 mmol) at
room temperature. After stirring for 10e30 min, the resulting dark-
green solution was transferred by a cannula to the slurry of orga-
nocopper reagent, which was prepared by mixing ArMgBr
(1.5 mmol) to CuBr$SMe2 (245 mg, 1.2 mmol) in THF (5 mL) for ca.
20 min. The combined mixture was stirred at 45 ꢀC until C60 dis-
appeared as monitored by HPLC (Also, the color of resulting mix-
ture changes from dark green to brown). The reaction was then
quenched with 0.10 mL satd aq NH4Cl solution, and dilute with
degassed toluene (ca. 10 mL). Then, the mixture was filtered
through a pad of silica gel and concentrated under reduced pres-
sure. The residue was purified with silica gel column or preparative
HPLC separation (Buckyprep 20 mm IDꢂ250 mm) to give desired
compound as a red solid. Three isomers (i.e., 6,9,13,15-tetraaryl-18-
trimethylsilylmethyl-1-hydro[60]fullerene, 6,13,15,18-tetraaryl-9-
1,2-Cl2C6H4, 140 °C
58%
5
Scheme 1. Conversion of the iPrO group of 1c to other functional fullerene derivatives.
trimethylsilylmethyl-1-hydro[60]fullerene,
and
9,13,15,18-
tetraaryl-6-trimethylsilylmethyl-1-hydro[60]fullerene)18 differing
in the position of the Cp proton could not be separated.
3.2.1. C60(H)(C6H5)4[CH2SiMe3] (1a). Synthesis of 1a was per-
formed according to the general procedure at 45 ꢀC for 6 h. The
concentrated residue was purified with silica gel column chroma-
tography (eluent: first CS2/hexane¼5/1, then CS2) to give
Fig. 4. Single-crystal structure of 5. (a) Capped stick model. (b) Top view of space-
filling model. (c) Side view of space-filling model.

C.-Z. Li et al. / Tetrahedron 67 (2011) 9944e9949
9947
compound 1a (79.3 mg, 71% yield, 94% purity) as a red solid. 1H
NMR (500 MHz, CDCl3):
156.98, 157.08, 158.90; APCIeHRMS (ꢁ): m/z calcd for C90H36OSi
(MꢁHþ), 1159.2463; found, 1159.2475.
d
ꢁ0.04 (s, 5H, SiCH3), 0.17 (s, 4H, SiCH3),
1.75e2.04 (m, 2H, CH2), 4.94, 5.16, 5.17 (s, 1H, C60H, three signals
due to isomers), 7.10e7.27 (m, 5H, AreH), 7.32e7.62 (m, 10H,
3.2.4. C60(H)(C6H4-4-NMe2)4[CH2SiMe3] (1d). Synthesis of 1d was
performed according to the general procedure at 45 ꢀC for 13.5 h. The
concentrated residue was purified with preparative HPLC separation
(toluene/2-isopropanol¼70/30, flow rate 10 ml/min) to give com-
pound 1d (120 mg, 81% yield, 96% purity) as red solid. 1H NMR
AreH), 7.76e8.00 (m, 5H, AreH); 13C NMR (125 MHz, CDCl3):
d 0.69,
1.18, 1.25, 29.79, 29.86, 53.70, 54.29, 55.74, 59.34, 59.49, 59.61,
59.66, 61.30, 61.66, 61.77, 62.72, 63.32, 128.02, 128.19, 128.22,
128.29, 128.32, 128.42, 128.44, 128.47, 128.51, 128.57, 128.72, 128.82,
128.89, 129.22, 129.30, 129.46, 129.53, 129.59, 129.63, 129.67,
129.83, 140.17, 140.45, 140.49, 140.56, 140.64, 140.82, 143.55, 143.71,
143.74, 143.83, 144.17, 144.31, 144.44, 144.48, 144.58, 144.68, 144.71,
144.74, 144.76, 144.80, 144.89, 144.93, 144.99, 145.05,145.31,145.34,
145.74, 145.84, 145.87, 146.02, 146.22, 146.32, 146.36, 146.40, 146.43,
146.45, 146.58, 146.62, 146.65, 146.76, 146.82, 147.08, 147.21, 147.56,
147.62, 147.70, 147.76, 147.80, 147.86, 147.89, 148.30, 148.34, 148.44,
148.65, 148.68, 148.72, 148.75, 148.79, 148.81, 148.89, 148.92,
149.02, 149.10, 149.15, 149.32, 149.37, 149.39, 149.42, 149.46, 149.80,
149.84, 151.05, 151.98, 152.33, 152.53, 152.72, 153.16, 154.12, 154.32,
154.41, 157.04, 157.27, 157.70, 157.85, 159.88; APCIeHRMS (ꢁ): m/z
calcd for C88H32Si (MꢁHþ), 1115.2195; found, 1115.2200.
(500 MHz, CDCl3):
d
ꢁ0.11e0.22 (m, 9H, SiCH3), 1.54e2.03 (m, 2H,
CH2), 2.83e3.03 (m, 24H, N(CH3)2), 4.84, 5.08, 5.10 (s, 1H, C60H, three
signals due to isomers), 6.52e6.65 (m, 4H, AreH), 6.71e6.90 (m, 4H,
AreH), 7.40e7.50 (m, 3H, AreH), 7.62e7.90 (m, 5H, AreH); 13C NMR
(125 MHz, CDCl3):
d
ꢁ0.01, 0.39, 40.79 (br), 52.90, 53.53, 54.56, 54.94,
57.55,57.96,58.12,58.18,58.25,58.30,60.30,62.02,113.04(br),125.28,
128.21, 128.45, 128.55, 128.61, 128.79, 128.91, 129.02, 129.16, 141.81,
142.65, 142.83, 143.24, 143.53, 143.84, 143.87, 143.94, 143.96, 144.01,
144.05, 144.10, 144.19, 144.26, 144.45, 144.59, 144.64, 144.92, 145.26,
145.31, 145.47, 145.61, 145.70, 145.78, 145.85, 146.00, 146.19, 146.27,
146.39, 146.71, 146.82, 146.92, 146.97, 147.04, 147.10, 147.12, 147.49,
147.61, 147.67, 147.88, 147.91, 147.93, 147.97, 148.08, 148.13, 148.20,
148.24, 148.26, 148.30, 148.32, 148.35, 148.40, 148.45, 148.51, 148.58,
148.60, 148.64, 148.69, 149.19, 149.39, 149.75, 156.64; APCIeHRMS
(ꢁ): m/z calcd for C96H52SiN4 (MꢁHþ), 1287.3883; found, 1287.3886.
3.2.2. C60(H)(C6H5)4[CH2SiMe2Ph] (1b). Synthesis of 1b was per-
formed according to the general procedure at 45 ꢀC for 5 h. The
concentrated residue was purified with preparative HPLC separa-
tion (toluene/2-isopropanol¼7/3, flow rate 10 ml/min) to give
compound 1b (92 mg, 78% yield, 94% purity) as a red solid. 1H NMR
3.2.5. C60(H)(C6H4-4-Admantyl)4[CH2SiMe3] (1e). Synthesis of 1e
was performed according to the general procedure by using
15 equiv 4-Admantyl phenyl magnesium bromide at 45 ꢀC for 26 h
as monitored by HPLC. The concentrated residue was purified with
preparative HPLC separation (toluene/2-isopropanol¼70/30, flow
rate 10 ml/min) to give compound 1e (88 mg, 53% yield, 99% purity)
(500 MHz, CDCl3):
d 0.07e0.22 (m, 6H, SiCH3), 1.80e2.12 (m, 2H,
CH2), 4.70, 4.89, 4.90 (s, 1H, C60H, three singlet due to isomers),
6.84e7.02 (m, 8H, AreH), 7.03e7.24 (m, 12H, AreH), 7.29e7.69 (m,
5H, AreH). 13C NMR (125 MHz, CDCl3):
d
ꢁ1.37, ꢁ1.22, ꢁ1.18, ꢁ0.96,
28.03, 28.28, 52.76, 53.34, 54.80, 58.46, 58.54, 58.71, 58.74, 58.86,
58.93, 60.55, 60.87, 60.93, 61.04, 62.02, 62.61, 65.31, 127.50, 127.54,
127.59, 127.68, 127.73, 127.75, 127.88, 128.00, 128.10, 128.16, 128.55,
128.60, 128.76, 128.87, 128.89, 128.94, 128.96, 129.01, 129.15, 129.21,
133.68, 133.82, 137.96, 138.00, 138.07, 139.42, 139.72, 139.74, 139.81,
139.91, 140.09, 140.10, 140.16, 142.51, 143.00, 143.07, 143.20, 143.42,
143.61,143.62, 143.82, 143.84, 143.93, 143.97, 144.00, 144.02, 144.06,
144.14, 144.18, 144.24, 144.27, 144.29, 144.42, 144.53, 144.86, 145.05,
145.23, 145.48, 145.50, 145.57, 145.63, 145.68, 145.71, 145.87, 145.96,
145.98, 146.13, 146.78, 146.93, 146.99, 147.02, 147.04, 147.09, 147.12,
147.54, 147.57, 147.61, 147.69, 147.94, 147.96, 147.99, 148.01, 148.03,
148.16,148.22, 148.52, 148.55, 148.57, 148.59, 148.64,148.66,148.68,
148.70, 148.95, 150.52, 151.04, 151.27, 151.63, 151.77, 151.97, 152.31,
152.34, 152.93, 153.42, 153.55, 153.60, 155.85, 156.13, 156.33, 156.93,
158.89; APCIeHRMS (ꢁ): m/z calcd for C93H34Si (MꢁHþ),
1177.2357; found, 1177.2347.
as a red solid. 1H NMR (500 MHz, CDCl3):
d 0.11e0.22 (m, 9H, SiCH3),
1.62e2.15 (m, 62H, CH and CH2), 4.94, 5.10, 5.22 (s, 1H, C60H, three
signals due to isomers), 7.06e7.24 (m, 8H, AreH), 7.28e7.36 (m, 4H,
AreH), 7.37e7.48 (m, 2H, AreH), 7.50e7.90 (m, 2H, AreH); 13C NMR
(125 MHz, CDCl3):
d 0.34, 0.64, 21.44, 28.89, 35.87, 35.93, 35.99,
36.03e36.82, 43.05, 43.11e43.24, 53.53, 54.56, 55.14, 58.37, 58.58,
60.72, 125.04, 125.28, 125.29, 125.36, 125.54, 127.37, 127.42, 127.59,
127.62, 127.76, 127.99, 128.06, 128.09, 128.20, 129.01, 138.72, 140.64,
142.93,143.98,144.08,144.21,144.30, 144.52,145.59,145.63,145.73,
145.94, 146.34, 146.81, 147.05, 147.08, 147.54, 147.69, 147.91, 147.96,
148.15, 148.21, 148.24, 148.33, 148.44, 148.52, 148.62, 148.63, 148.66,
148.69, 150.19, 150.33, 150.64, 150.67, 151.96, 152.50, 157.11;
APCIeMS (ꢁ): m/z 1287.4; APCIeMS, APCIeHRMS calcd for
C128H88Si (MꢁHþ), 1651.6582; found, 1651.6578.
3.2.6. C60(H)(C6H4-4-OMe)4[CH2SiMe2(n-C8H17)] (1f). Synthesis of
1f was performed according to the general procedure at 45 ꢀC for 6 h.
The concentrated residue was purified with preparative HPLC sepa-
ration (toluene/2-isopropanol¼70/30, flow rate 10 ml/min) to give
compound 1f (98 mg, 73% yield, 99% purity) as a red solid. 1H NMR
3.2.3. C60(H)(C6H5)4[CH2SiMe2(OiPr)] (1c). Synthesis of 1c was
performed according to the general procedure at 45 ꢀC for 5.5 h.
The concentrated residue was purified with preparative HPLC
separation (toluene/2-isopropanol¼65/35, flow rate 10 ml/min) to
give compound 1c (106 mg, 72% yield, 99% purity) as a red solid. 1H
(500 MHz, CDCl3):
d
ꢁ0.04 (m, 3H, SiCH3), 0.09 (m, 3H, SiCH3),
0.84e0.88 (m, 5H, SiCH2 and CH3), 1.09e1.18 (m,13H, CH2), 1.73e2.06
(m, 2H, CH2Si), 3.75e3.88 (m, 12H, OCH3), 4.92, 5.10, 5.16 (s, 1H, C60H,
three signals due to isomers), 6.68e7.00 (m, 8H, AreH), 7.26 (m, H,
AreH), 7.28e7.88 (m, 7H, AreH); 13C NMR (125 MHz, CDCl3):
NMR (500 MHz, CDCl3):
d 0.07e0.22 (m, 6H, SiCH3), 0.89e1.05 (m,
6H, CH3), 1.80e2.12 (m, 2H, CH2), 3.76e4.94 (m, 1H, CH), 4.96, 5.15
(s, 1H, C60H, two signals due to isomers), 7.10e7.53 (m, 12H, AreH),
7.62e7.63 (m, 2H, AreH), 7.78e8.00 (m, 6H, AreH); 13C NMR
d
ꢁ1.36, ꢁ1.29, ꢁ1.14, ꢁ1.05, 14.12, 16.28, 16.54, 22.64, 23.53, 23.78,
(125 MHz, CDCl3):
d
0.67, 0.78, 0.85, 1.03, 1.31, 25.44, 25.51, 25.54,
29.15, 29.21, 29.24, 29.29, 31.91, 33.47, 33.56, 54.98, 55.30, 55.39, 55.41,
55.43, 57.90, 58.20, 59.95, 62.16, 62.66, 113.95, 113.99, 114.05, 114.13,
114.17, 114.26, 114.35, 114.43, 114.47, 116.00, 128.68, 128.77, 128.87,
128.90, 129.02, 129.08, 129.15, 129.20, 129.29, 129.35, 131.63, 131.91,
131.98, 132.14, 132.25, 132.30, 138.17, 138.44, 140.32, 142.73, 142.93,
142.97, 143.05, 143.38, 143.54, 143.62, 143.68, 143.79, 143.86, 143.91,
143.95, 144.05, 144.15, 144.23, 144.28, 144.43, 144.49, 144.63, 145.00,
145.03, 145.28, 145.44, 145.53, 145.61, 145.67, 145.80, 145.87, 145.97,
146.08, 146.36, 146.48, 146.80, 146.85, 146.92, 146.99, 147.04, 147.06,
147.11, 147.12, 147.56, 147.66, 147.68, 147.71, 147.91, 147.98, 148.00,
25.69, 28.81, 52.02, 52.68, 54.04, 58.46, 58.68, 58.81, 58.90, 58.96,
60.58, 60.97, 61.07, 62.05, 62.61, 65.11, 65.24, 65.31, 127.53, 127.60,
127.69, 127.72, 127.79, 127.83, 128.04, 128.10, 128.53, 128.59, 128.76,
128.82, 128.89, 128.94, 128.96, 129.,14, 139.48, 139.78, 139.88,
140.00, 143.12, 143.39, 143.67, 143.80, 143.87, 143.95, 143.99, 144.02,
144.05, 144.11, 144.20, 144.24, 144.35, 144.51, 145.15, 145.25, 145.32,
145.52, 145.62, 145.66, 145.73, 145.99, 146.07, 146.88, 147.12, 147.17,
147.63, 147.72, 147.74, 147.96, 148.02, 148.05, 148.08, 148.19, 148.27,
148.33, 148.40, 148.60, 148.65, 148.69, 148.76, 153.67, 156.57, 156.66,

9948
C.-Z. Li et al. / Tetrahedron 67 (2011) 9944e9949
148.04, 148.09, 148.11, 148.14, 148.20, 148.23, 148.26, 148.26, 148.32,
148.34, 148.50, 148.53, 148.55, 148.62, 148.65, 148.68, 148.71, 148.95,
149.08, 150.64, 151.50, 151.88, 152.07, 152.22, 152.55, 153.82, 154.08,
156.09, 156.50, 157.00, 157.32, 158.50, 158.65, 158.76, 158.89, 158.91,
158.98, 159.10, 159.11; APCIeMS (ꢁ): m/z (MꢁHþ) 1334.4;
APCIeHRMS calcd for C99H54O4Si (MꢁHþ), 1333.3719; found,
1333.3730.
was added, and the mixture was stirred for 1 h. The concentrated
residue was precipitated with MeCN. Purification with a silica gel
column by eluting with CS2/toluene gave 4 (44 mg, 88% yield). 1H
NMR (500 MHz, CDCl3):
d 0.06e0.08 (m, 4H, SiCH3), 0.18 (s, 1H,
SiCH3), 0.21 (s,1H, SiCH3), 0.88e1.04 (m, 6H, CH3),1.79e2.10 (m, 2H,
CH2), 3.78e3.91 (m,1H, CH), 4.95, 5.12, 5.14 (s,1H, C60H, three signals
due to isomers), 7.10e7.51 (m, 12H, AreH), 7.61e7.64 (m, 1H, AreH),
7.77e7.88 (m, 4H, AreH), 7.98e8.00 (m, 1H, AreH); 13C NMR
3.3. Synthesis of (6,9,12,15-tetraphenyl-18-
trimethylsilylmethyl[60]fullerenyl)iron cyclopentadienide, Fe
[C60(C6H5)4(CH2SiMe3)](C5H5) (2a)
(125 MHz, CDCl3): d 0.92, 1.00, 1.04, 1.10, 1.26, 2.72, 25.70, 25.77,
25.80, 25.94, 29.04, 52.27, 52.92, 54.29, 58.70, 58.92, 59.06, 59.15,
59.21, 60.83, 61.21, 61.32, 62.31, 62.85, 65.36, 65.49, 65.55, 127.30,
1127.39, 127.55, 127.72, 127.78, 127.85, 127.93, 127.97, 128.04, 128.08,
128.29, 128.34, 128.42, 128.77, 128.85, 129.01, 129.08, 129.15, 129.19,
129.22, 129.38, 139.73, 140.05, 140.12, 140.16, 140.43, 142.95, 143.63,
144.05,144.12,144.14,144.20,144.24,144.26,144.28,144.36,144.43,
144.44,144.49,144.59,144.66,144.76,144.86,145.39,145.49,145.57,
145.60, 145.77, 145.87, 145.90, 145.98, 146.13, 146.17, 146.24, 146.32,
146.63, 146.77, 147.12, 147.25, 147.36, 147.42, 147.74, 147.88, 147.96,
147.99, 148.21, 148.30, 148.33, 148.36, 148.43, 148.52, 148.55, 148.58,
148.65, 148.85, 148.90, 148.94, 149.00, 149.10, 149.37, 150.64, 151.16,
151.50, 151.86, 152.07, 152.21, 152.28, 152.62, 152.67, 153.58, 153.92,
154.29, 156.19, 156.71, 156.82, 157.26, 157.33, 159.18; APCIeHRMS
(ꢁ): m/z calcd for C90H37SiN (Mꢁ), 1159.2695; found, 1159.2742.
To a 25-mL round bottomed flask equipped with a condenser was
chargedwith1a(50 mg, 0.045 mmol)and[Fe(C5H5)(CO)2]2 (63.4 mg,
0.18 mmol). The reaction vessel was flushed with nitrogen, and then
benzonitrile (5 mL) was added. After stirring at 180 ꢀC for 29 h,
benzonitrile was removed by distillation at 70 ꢀC under vacuum. The
residue was purified with a silica gel column using CS2 as an eluent,
and preparative HPLC separation (toluene/2-isopropanol¼55/45,
flow rate 10 ml/min) to give compound 2a (23 mg, 42% yield) as a red
solid. 1H NMR (500 MHz, CDCl3):
d 0.24 (s, 9H, SiCH3), 2.54 (s, 2H,
CH2Si), 3.38 (s, 5H, C5H5), 7.47 (t, J¼7.5 Hz, 4H, AreH), 7.95 (d,
J¼7.5 Hz, 4H, AreH), 8.07 (d, J¼7.5 Hz, 4H, AreH); 13C NMR (125 MHz,
CDCl3): d 0.64 (SiCH3), 34.39 (CH2Si), 52.47, 58.42, 72.16 (C5H5), 91.74,
93.02, 97.01, 152.28, 127.50, 127.68, 127.83, 128.20, 128.85, 129.02,
129.09, 137.86, 142.74, 143.04, 143.07, 143.10, 143.12, 143.22, 143.72,
144.04, 144.11, 144.17, 144.53, 147.34, 147.42, 147.44, 148.13, 148.15,
148.18, 148.21, 148.39, 148.42, 148.47, 152.23, 152.65, 152.86, 153.39,
154.44; APCIeMS (ꢁ): m/z (MꢁHþ); APCIeHRMS calcd for
C93FeH36Si (MꢁHþ), 1235.1857; found, 1235.1797.
3.6. Synthesis of 1,9-methano-6,12,15,18-tetraphenyl[60]
fullerene, C60(C6H5)4(CH2) (5)
To the suspension of 1c (20 mg, 0.017 mmol) and CuCl2
(13.9 mg, 0.103 mmol) in ortho-dichlorobenzene (3 mL) was added
a THF solution of t-BuOK (26 mL, 0.026 mmol, 1 M). After stirring at
140 ꢀC for 19 h, the mixture was stirred further at 160 ꢀC for 69 h.
The concentrated residue was purified with a silica gel column by
eluting with CS2 to give compound 5 (10 mg, 58% yield, 99% purity
3.4. Synthesis of tetraphenyl-[hydroxy(dimethyl)silylmethyl]-
hydro[60]fullerene, C60(C6H5)4[CH2SiMe2OH] (3)
by HPLC). 1H NMR (500 MHz, CDCl3):
d
3.44 (s, 2H, CH2), 7.27e7.36
(m, 12H, AreH), 7.62 (d, J¼6 Hz, 4H, AreH), 7.78 (d, J¼6 Hz, 4H,
AreH); 13C NMR (125 MHz, CDCl3):
33.33, 51.72, 57.21, 59.29,
A mixture of compound 1c (150 mg, 0.129 mmol), aq HCl
(1.29 mmol), andTHF(10 mL)wasstirredat50 ꢀCfor2 h.Theresulting
solution was then extracted with toluene/water. The organic phase
wasseparatedandconcentratedtoca. 5 mLofvolume. Totheresulting
solution satd aq NaHCO3 (5 mL)/THF (5 mL) was added and subjected
to Ar babbling for 5 min. After stirring for 1 h, the suspension was
extracted with toluene/water. The organic layer was collected, dried
by anhydrous Na2SO4, and concentrated to a small volume. Pre-
cipitation by addition of n-hexane afforded compound 3 (131 mg, 91%
d
127.48, 127.68, 127.84, 128.31, 128.58, 128.92, 128.97, 139.31, 139.86,
143.26,143.91,144.05,144.08,144.48,144.96,145.26,145.33,145.56,
146.72, 146.85, 146.87, 147.15, 147.24, 147.34, 147.59, 147.79, 148.16,
148.89, 149.12, 151.06, 151.09, 155.06; APCIeHRMS (ꢁ): m/z calcd
for C85H22 (Mꢁ), 1042.1722; found, 1042.1715.
3.7. Electrochemical properties of compound 2a
yield, 92%purity)asaredsolid.1HNMR(500 MHz,CDCl3):
d0.03e0.21
(m, 6H, SiCH3),1.85e2.12(m, 2H, CH2), 5.12,5.18,5.19(s,1H, C60H, three
signals due to isomers), 7.12e7.57 (m, 12H, AreH), 7.62e7.64 (m, 2H,
Cyclic voltammetry (CV) was performed using HOKUTO DENKO
HZ-5000 voltammetric analyzer. Measurements were carried out in
a one-compartment cell under Ar gas, equipped with a glassy-
carbon working electrode, a platinum wire counter electrode, and
an Ag/Agþ reference electrode. Measurements were performed in
THF solution containing tetrabutylammonium perchlorate (0.1 M)
as a supporting electrolyte at 25 ꢀC with a scan rate of 0.1 V/s. All
potentials were corrected against Fc/Fcþ.
AreH), 7.81e8.00 (m, 6H, AreH); 13C NMR (125 MHz, CDCl3):
d 0.95,
1.26, 1.69, 1.84, 1.87, 29.88, 52.00, 52.82, 54.09, 58.62, 58.80, 58.82,
58.97, 60.63, 60.85, 60.97, 61.08, 61.93, 62.11, 62.72, 125.28, 127.10,
127.27, 127.36, 127.50, 127.54, 127.56, 127.62, 127.73, 127.81, 127.86,
127.92, 128.00, 128.13, 128.21, 128.28, 128.54, 128.61, 128.79, 128.91,
128.94, 129.02, 129.07, 137.86, 139.39, 139.62, 139.64, 139.70, 139.77,
140.05, 140.39, 142.92, 143.05, 143.84, 144.02, 144.04, 144.07, 144.10,
144.20, 144.22, 144.28, 144.38, 145.58, 145.65, 145.68, 146.39, 147.03,
147.07, 147.13, 147.18, 147.77, 148.00, 148.02, 148.09, 148.20, 148.24,
148.34, 148.65, 148.69, 148.73, 148.75, 150.59, 151.04, 151.26, 151.63,
151.78, 151.95, 152.05, 152.43, 152.49, 153.11, 153.33, 153.68, 154.83,
156.28, 156.39, 156.45, 156.97, 157.24, 158.37; APCIeHRMS (ꢁ): m/z
calcd for C87H30OSi (MꢁHþ),1117.1993; found, 1117.1988.
Acknowledgements
This study was partially supported by the Funding Program for
Next-Generation World-Leading Researchers (to Y.M.) and the
Strategic Promotion of Innovative Research and Development from
Japan Science and Technology Agency and KAKENHI (No.
22000008) (to E.N.).
3.5. Synthesis of tetraphenyl-{(2-propylamino)(dimethyl)
silylmethyl}-1-hydro[60]fullerene C60(C6H5)4[CH2SiMe2NHiPr] (4)
Supplementary data
To the CH2CI2 solution of 1c (50 mg, 0.043 mmol) was added
Supplementary data includes CIF files for 1d, 2a, and 5. Sup-
plementary data associated with this article can be found, in the
online version, at doi:10.1016/j.tet.2011.09.125.
a suspension of AlCl3 (37.0 mg, 0.276 mmol) in 5 mL CH2CI2. After
i
stirring at room temperature for 1 h, PrNH2 (1.08 mmol, 64.0 mg)

C.-Z. Li et al. / Tetrahedron 67 (2011) 9944e9949
9949
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