Visible-light-mediated addition of α-aminoalkyl radicals to [60]fullerene by using photoredox catalysts

Article abstract of DOI:10.1002/chem.201304731

The functionalization of fullerene has been extensively studied and various fullerene derivatives have been synthesized. We have succeeded in the functionalization of [60]fullerene by using α-aminoalkyl radicals generated by visible-light-mediated single-

Full text of DOI:10.1002/chem.201304731

DOI: 10.1002/chem.201304731
Full Paper
&
Photocatalysis
Visible-Light-Mediated Addition of a-Aminoalkyl Radicals to
[60]Fullerene by Using Photoredox Catalysts
Yoshihiro Miyake,*[a, b] Yuya Ashida,[a] Kazunari Nakajima,[a] and Yoshiaki Nishibayashi*[a]
Abstract: The functionalization of fullerene has been exten-
sively studied and various fullerene derivatives have been
synthesized. We have succeeded in the functionalization of
[60]fullerene by using a-aminoalkyl radicals generated by
visible-light-mediated single-electron oxidation of a-silyl-
amines as synthetic intermediates. In these reactions, the in-
troduction of diarylamino groups, which are useful electron
donors, has been easily achieved.
Introduction
Fullerenes bearing functional groups have attracted considera-
ble attention as structural and functional motifs for materials
and biological sciences.[1] For the construction of skeletons
with a fullerene moiety, a variety of methods for the function-
alization of fullerenes have been developed.[1] Photoinduced
reactions of [60]fullerene (C60) with tertiary amines have been
studied by several groups.[2–6] In these reactions, electron trans-
fer from amines to the photoexcited C60 triggers the formation
of a-aminoalkyl radicals, and a sequential radical reaction[7,8]
leads to the corresponding C60 adducts.[2–6] Applicable sub-
strates are quite limited to some trialkylamines and dialkylaryl-
amines. To the best of our knowledge, there is no reported use
of alkyldiarylamines for the photoreactions of C60.
Scheme 1. Visible-light-mediated addition of a-aminoalkyl radicals to
[60]fullerene with photoredox catalysts.
C60 moiety (Scheme 1). We believe that the method described
herein provides a new efficient route for the synthesis of
[60]fullerenes bearing an arylamino group as an electron-
donating group, which are expected to be useful candidates
for ambipolar charge-transporting materials[13] and donor–ac-
ceptor dyads.[14–16]
Recently, we reported a visible-light-mediated direct a-CÀH
alkylation[9a] and the amination[9b] of amines, in which a-amino-
alkyl radicals[10] mediated by photoredox catalysts[11] play a key
role as reactive intermediates. We also found that photoredox
catalysts are applicable for the generation of a-aminoalkyl radi-
cals from a-silylamines and for the addition reaction to a,b-un-
saturated carbonyl compounds.[9c,12] These facts prompted us
to investigate photoreactions of C60 with a-aminoalkyl radicals
with photoredox catalysts. In fact, we developed the visible-
light-mediated addition of a-aminoalkyl radicals generated
from a-silylamines to [60]fullerene, in which a variety of tertiary
amines including alkyldiarylamines can be introduced into the
Results and Discussion
First, we carried out the reaction of C60 with di(4-tert-butylphe-
nyl)(trimethylsilylmethyl)amine (1a; Table 1). When a solution
of C60 and 1.5 equivalents of 1a in the presence of 1 mol% of
[3a][ONf] (ONf: OSO2C4F9) in ortho-dichlorobenzene (ODCB)
and H2O was irradiated by visible light at room temperature
for 9 hours, 1-[N,N-di(4-tert-butylphenyl)aminomethyl]-1,9-
dihydro(C60-Ih)[5,6]fullerene (2a) was obtained in 41% yield
1
(Table 1, entry 1). The formation of 2a was confirmed by its H
and 13C NMR spectra. The details of the molecular structure of
2a were also determined by X-ray crystallographic studies. Re-
actions that used similar iridium complexes 3b and 3c and the
[Ru(bpy)3]2+ complex (bpy=2,2'-bipyridine) as catalysts also
proceeded to give 2a in moderate yields, but the selectivity of
2a was lower (Table 1, entries 2, 3, and 5). In the use of the
neutral iridium complex 4 and 9,10-dicyanoanthracene (DCA)
as photoredox catalysts, no formation of 2a was observed at
all (Table 1, entries 4 and 6). When chlorobenzene and toluene
were used as the solvents, moderate yields of 2a were ob-
tained (Table 1, entries 7 and 8). The addition of H2O was an
important factor to promote this addition reaction. The yield
of 2a decreased without the addition of H2O (Table 1, entry 9).
[a] Dr. Y. Miyake, Y. Ashida, Dr. K. Nakajima, Prof. Dr. Y. Nishibayashi
Institute of Engineering Innovation
School of Engineering, The University of Tokyo
Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan)
Fax: (+81)3-5841-1175
E-mail: miyake@apchem.nagoya-u.ac.jp
ynishiba@sogo.t.u-tokyo.ac.jp
[b] Dr. Y. Miyake
Present address: Department of Applied Chemistry
Graduate School of Engineering, Nagoya University
Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan)
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201304731.
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Table 1. Photocatalytic reactions of C60 with 1a.[a]
Table 2. Photocatalytic reactions of C60 with a-silylalkyldiarylamines
1b–l.[a]
Entry
Photocatalyst
Solvent
Yield
[%][b]
Selectivity
[%][c]
Entry
a-silylamine (1)
Yield of 2
[%][b]
Selectivity
[%][c]
1
2
3
4
5
6
7
8
9[e]
10[f]
11
12[g]
[3a][ONf]
[3b][ONf]
[3c][ONf]
4
[Ru(bpy)3][ONf]2
DCA
[3a][ONf]
[3a][ONf]
[3a][ONf]
[3a][ONf]
none
ODCB
ODCB
ODCB
ODCB
ODCB
ODCB
PhCl
toluene
ODCB
ODCB
ODCB
ODCB
41 (32)[d]
23
28
0
20
0
20
21
27
0
87
72
74
–
56
–
69
55
61
–
1
2
R1 =R2 =Ph (1b)
2b: 47 (38) 64
2c: 38 (29) 75
2d: 44 (38) 56
2e: 42 (35) 55
R1 =R2 =4-MeC6H4 (1c)
3[d]
4
R1 =R2 =4-nBuC6H4 (1d)
R1 =4-tBuC6H4, R2 =Ph (1e)
R1 =4-tBuC6H4, R2 =4-PhC6H4 (1 f)
R1 =4-tBuC6H4, R2 =4-ClC6H4 (1g)
5[d]
6
2 f: 43 (39)
63
2g: 39 (26) 67
7
8
9
10[d]
11[e]
R1 =4-tBuC6H4, R2 =4-MeOC6H4 (1h) 2h: 40 (32) 87
R1 =4-tBuC6H4, R2 =4-(pinB)C6H4 (1i) 2i: 46 (24)
55
75
R1 =Ph, R2 =2-naphthyl (1j)
R1R2N=3,6-tBu2-carbazolyl (1k)
R1R2N=phenothiazinyl (1l)
2j: 41 (38)
2k: 43 (41) 80
2l: 36 (27) 82
0
0
–
–
[3a][ONf]
[a] All the reactions of C60 (0.14 mmol) with 1 (0.21 mmol) were carried
out in the presence of [3a][ONf] (0.0014 mmol) in ODCB (20 mL)/H2O
(0.1 mL) with visible-light irradiation (l=440 nm) at room temperature
for 9 h. [b] Determined by 1H NMR spectroscopic analysis; yields of the
isolated product 2 are given in the parentheses. [c] Determined by [yield
of 2 determined by NMR]/[conversion of C60]. [d] For 22 h. [e] For 120 h.
[a] All the reactions of C60 (0.14 mmol) with 1a (0.21 mmol) were carried
out in the presence of a photocatalyst (0.0014 mmol) in solvent (20 mL;
H2O=0.1 mL) with visible-light irradiation (l=440 nm) at room tempera-
ture for 9 h. [b] Determined by 1H NMR spectroscopic analysis. [c] Deter-
mined by [yield of 2a]/[conversion of C60]. [d] Yield of the isolated prod-
uct. [e] No addition of H2O. [f] Compound 5 was used in place of 1a.
[g] In the absence of light.
sponding C60 derivatives 2k and 2l in good yields (Table 2, en-
tries 10 and 11).
Previously, several groups have reported reactions of C60
with dialkylaryl- and trialkylamines under photoirradiation.[2–6]
In fact, reactions with dialkyl- and trialkylamines 1m and 1n
proceeded in the absence of a photocatalyst (Table 3, entries 2
When methyldi(4-tert-butylphenyl)amine (5) was used in place
of 1a, no reaction occurred at all (Table 1, entry 10). This result
indicates that only the CÀSi bond in the amine can be activat-
ed selectively in the present reaction system.[9c,12] Separately,
we confirmed that no formation of 2a was observed in the ab-
sence of a photocatalyst or visible light (Table 1, entries 11 and
12).
Table 3. Photocatalytic reactions of C60 with a-silylamines 1m and 1n.[a]
Other reactions with a variety of a-silylalkyldiarylamines
1 were investigated with [3a][ONf] as a photocatalyst (typical
results are shown in Table 2). Reactions with a-silylamines 1b–
e proceeded smoothly to give the corresponding products in
moderate yields (Table 2, entries 1–4). The introduction of
a substituent, such as phenyl, chloro, or methoxy groups, at
the para position in the one of the benzene ring of 1a did not
affect the yield of 2 much (Table 2, entries 5–7). When the reac-
tion with the amine bearing a boronic acid ester 1i was carried
out, 2i was obtained in 46% yield (Table 2, entry 8). The reac-
tion with naphthylamine (1j) also took place smoothly to give
2j in 41% yield (Table 2, entry 9). Interestingly, the a-silyl-
amines bearing a carbazolyl 1k and phenothiazinyl moiety 1l
were applicable to this reaction system, thus giving the corre-
Entry
a-silylamine (1)
Yield of 2
Selectivity
[%][c]
[%][b]
1
2[d]
2m: 36 (32)
2m: 15 (13)
47
75
3
4[d]
2n: 31 (27)
2n: 15 (15)
94
88
[a] All the reactions of C60 (0.14 mmol) with 1 (0.21 mmol) were carried
out in the presence of [3a][ONf] (0.0014 mmol) in ODCB (20 mL)/H2O
(0.1 mL) with visible-light irradiation (l=440 nm) at room temperature
for 9 h. [b] Determined by 1H NMR spectroscopic analysis; yields of the
isolated product 2 are given in the parentheses. [c] Determined by [yield
of 2 determined by NMR]/[conversion of C60]. [d] In the absence of
[3a][ONf].
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and 4), but the presence of [3a][ONf] in the reaction system in-
creased the yields of 2m and 2n substantially (Table 3, en-
tries 1 and 3). Photoredox catalysts such as 3a also promoted
the introduction of a variety of tertiary amines into C60 effi-
ciently through photoinduced electron transfer (Table 3).
The transformation of adduct 2a was investigated as a syn-
thetic application (Scheme 2). The hydrogen atom in hydroful-
lerenes is quite acidic,[17] and deprotonation with conventional
bases has been known to occur readily.[18] The deprotonation
of 2a with KOtBu and the sequential treatment of methyl
iodide afforded the corresponding 1,4-dialkylfullerene (6a) in
49% yield. The reaction with methyl 2-(bromomethy)acrylate
also proceeded smoothly to give the 1,4-adduct 6b in 84%
yield.
cate that the hydrogen atom on the fullerenyl moiety of 2 is
derived from H2O and that the possibility of radical hydrogen-
atom abstraction from other species is excluded. Furthermore,
when the reaction was carried out in a 1:1 mixture of H2O/D2O,
the formation of 2a was superior to that of [D1]-2a (2a/[D1]-
2a=71:29; Scheme 3b). A similar kinetic isotope effect was
À
·
previously observed in the protonation of C60 generated
from a one-electron reduction of C60.[19,20] In sharp contrast,
when the fullerenyl anion A generated from the deprotonation
of 2a was quenched by a 1:1 mixture of H2O/D2O, the product
distribution of 2a and [D1]-2a was almost equal (Scheme 3c).
These results suggest that the reaction of C60 with 1 in the
presence of 3a proceeds not via a fullerenyl anion A but via
À
·
the radical anion, C60
.
By considering the experimental results, a plausible reaction
pathway is proposed in Scheme 4. The initial step is the forma-
tion of the radical anion, C60 À, from a single-electron reduction
·
of C60 by the excited photocatalyst (*cat) and subsequent pro-
À
·
tonation of C60 occurs to give B with the formation of the
ÀOH ion. The oxidation of a-silylamine 1 by the one-electron
oxidized form of photocatalyst (cat+) and sequential desilyla-
tion assisted by the ÀOH ion occurs to give an a-aminoalkyl
radical C with the formation of Me3SiOH.[12] In fact, we con-
firmed the formation of Me3SiOH by GC-MS analysis of the
crude reaction mixture. Finally, the radical–radical coupling be-
tween B and C leads the corresponding product 2. The other
reaction pathway might be assumed as follows: the direct ad-
dition of C to C60 and subsequent reduction occurs to give
a fullerenyl anion, such as A, followed by the protonation of A
Scheme 2. Transformation of 2a.
To obtain information on the reaction pathway, we investi-
gated the reaction of C60 with 1a in ODCB/D2O (Scheme 3a).
The exclusive formation of [D1]-2a (>99% D-enriched at the
hydrogen atom on the fullerenyl moiety) was confirmed,
whereas no deuterium incorporation into 2a was observed in
the reaction of C60 with 1a in [D4]ODCB/H2O. These results indi-
to give 2.[9a,c] However, the results shown in Scheme 3 support
À
·
that the reaction pathway through the protonation of C60 is
predominant.[19,20]
Scheme 4. Plausible pathway for the formation of 2.
The electronic absorption (Figure 1) and emission spectra
(see Figures S1–S3 in the Supporting Information) of 2a, 2k,
and 2l in toluene were observed. The absorption features are
similar to those of the previously reported a-aminoalkyl radi-
cal/C60 1,2-adducts (Figure 1).[2b,c,6] The adducts, such as 2a,
2k, and 2l, exhibited relatively weak and broad fluorescence,
and the emission spectra have a mirror-image relationship
with the absorption spectra at around 710 nm (see Figures S1–
S3 in the Supporting Information).[21]
The cyclic voltammetric analysis of 2a, 2k, and 2l with
phenyl C61 butyric acid methyl ester (PCBM) and C60 as referen-
ces was also performed in ODCB with 0.1m nBu4NBF4 as the
Scheme 3. Deuterium isotope-labeling experiments.
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Experimental Section
General method
1H NMR (270 MHz) and 13C NMR (67.8 MHz) spectra were recorded
on a JEOL Excalibur 270 spectrometer in a suitable solvent.
19F NMR (471 MHz) spectra were recorded on a JEOL JNM-ECP 500
spectrometer. Elemental analyses were performed at the Microana-
lytical Center at The University of Tokyo. Mass spectra were mea-
sured on a JEOL JMS-700 mass spectrometer. GC-MS analyses were
carried out on a Shimadzu GC-MS QP-2010 spectrometer. Absorp-
tion and emission spectra were recorded on Shimadzu MultiSpec-
1500 and Shimadzu RF-5300PC spectrometers, respectively. All the
reactions were carried out in a dry nitrogen atmosphere. Solvents
were dried by using general methods and degassed before use.
Photoirradiation was carried out with an Ushio high-pressure mer-
cury lamp USH-250SC (250 W) with a band-pass filter of l=440 nm
(Kenko B-440 filter). Cyclic voltamograms were recorded on an
ALS/Chi model 610C electrochemical analyzer with a platinum
working electrode in 1,2-dichlorobenzene containing 0.1m
nBu4NBF4 as a supporting electrolyte. All the potentials were mea-
sured against an Ag/Ag+ reference electrode and converted versus
the ferrocene/ferrocenium+ couple.
Figure 1. Electronic absorption spectra of 2a, 2k, and 2l.
Table 4. Redox potentials of 2a, 2k, and 2l.[a]
ox
1=2
red1
1=2
red2
1=2
red3
1=2
Compound
E
E
E
E
HOMO–LUMO
gap [eV]
[V]
[V]
[V]
[V]
2a
2k
2l
PCBM
C60
+0.53
+0.76
+0.41
–
À1.21
À1.18
À1.20
À1.17
À1.08
À1.59
À1.56
À1.59
À1.56
À1.48
À2.12
–
–
1.74
1.94
1.61
–
À2.07
General procedure for photocatalytic reactions of fullerene
–
À1.94
–
with a-silylamines 1
[a] Potential in volts versus the ferrocene/ferrocenium+ couple by means
of cyclic voltammetry in ODCB containing nBu4NBF4 (0.1m) as a support-
ing electrolyte; stick Pt, Pt wire, and Ag/Ag+ were used as the working-,
counter-, and reference electrodes, respectively.
A typical experimental procedure for the reaction of [60]fullerene
(C60) with di(4-tert-butylphenyl)(trimethylsilylmethyl)amine (1a) is
described. Water (100 mL) and 1a (77.3 mg, 0.210 mmol) were
added to C60 (101 mg, 0.140 mmol), [3a][ONf] (1.5 mg,
0.0014 mmol), and 1,2-dichlorobenzene (20 mL) in a Schlenk flask
(50 mL, diameter=4.0 cm) under N2. The reaction flask was placed
in a water bath and illuminated with an Ushio high-pressure mer-
cury lamp USH-250SC (250 W) with a band-pass filter of l=440 nm
at room temperature for 9 h. The solution was concentrated in
vacuo. The residue was purified by column chromatography (SiO2)
with cyclohexane as the eluent to give 1-[N,N-di(4-tert-butylphen-
yl)aminomethyl]-1,9-dihydro(C60-Ih)[5,6]fullerene (2a) as a brown
solid (46.0 mg, 0.0453 mmol, 32%). Crystals suitable for elemental
analysis and X-ray analysis were obtained by slow evaporation
from toluene.
electrolyte (Table 4). Compound 2a has three reversible reduc-
tion potentials assigned to the formation of the anion, dianion,
and trianion of the C60 moiety, whereas compounds 2k and 2l
have two reversible reduction potentials. All the compounds
show the first reduction waves at approximately À1.2 V, which
are more negative than those of PCBM and C60. Furthermore,
2a, 2k, and 2l also have one reversible oxidation wave as-
signed to the oxidation of the amino groups, with a very
narrow HOMO–LUMO gap for all the compounds. These results
demonstrate the significant potential of these adducts 2 for
ambipolar charge-transporting materials.[13b]
1
2a: H NMR (C6D6/CS2): d=7.34–7.24 (m, 8H), 6.53 (s, 1H), 5.59 (s,
2H), 1.28 ppm (s, 18H); 13C NMR (C6D6/CS2): d=154.8, 154.0, 147.6,
147.5, 147.4, 146.9, 146.7, 146.6, 146.5, 146.41, 146.36, 146.0,
145.71, 145.67, 145.6, 144.9, 144.8, 143.6, 142.91, 142.89, 142.4,
142.3, 142.01, 141.99, 141.96, 140.6, 140.3, 136.8, 135.9, 126.7,
122.3, 68.0, 66.1, 58.0, 34.2, 31.7 ppm; HRMS (FAB, ortho-nitrophen-
yl octyl ether (NPOE) and meta-nitrobenzyl alcohol (NBA)) m/z
calcd for C81H30N [M+H]: 1016.2378; found: 1016.2365; elemental
analysis calcd (%) for C88H37N (2a·C6H5CH3): C 95.37, H 3.37, N 1.26;
found: C 95.27, H 3.51, N 1.05.
Conclusion
We have developed the efficient functionalization of [60]fuller-
ene, in which the visible-light-mediated generation of a-ami-
noalkyl radicals is the key step. Our reaction system is applica-
ble to the addition of a wide range of tertiary amines to C60.[22]
We believe that the results described herein provide an effi-
cient methodology for the introduction of the arylamino
group as an electron-donating moiety into C60. Further work is
currently in progress to research the electronic properties of
adduct 2 and to synthesize novel materials by using this
methodology.
1
2b: A brown solid (38%). H NMR (C6D6/CS2): d=7.34–7.30 (m, 4H),
7.23–7.19 (m, 4H), 6.94–6.88 (m, 2H), 6.40 (s, 1H), 5.55 ppm (s, 2H);
13C NMR (C6D6/CS2): d=154.4, 153.7, 148.6, 147.6, 147.5, 147.3,
146.9, 146.63, 146.58, 146.45, 146.39, 146.0, 145.69, 145.67, 145.63,
145.60, 144.9, 144.8, 143.5, 143.3, 142.9, 142.4, 142.3, 142.0, 141.9,
140.6, 140.3, 136.6, 135.9, 129.9, 123.3, 122.6, 67.9, 66.2, 58.2 ppm;
HRMS (FAB, NPOE) calcd for C73H13N [M]: 903.1048; found:
903.1066.
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2c: A brown solid (29%). 1H NMR (C6D6/CS2): d=7.24 (d, 4H, J=
8.1 Hz), 7.02 (d, 4H, J=8.1 Hz), 6.45 (s, 1H), 5.54 (s, 2H), 2.21 ppm
(s, 6H); 13C NMR (C6D6/CS2): d=154.8, 154.0, 147.6, 147.5, 147.4,
147.1, 146.8, 146.7, 146.6, 146.5, 146.4, 146.1, 145.73, 145.71,
145.68, 145.6, 144.9, 144.8, 143.5, 143.3, 142.9, 142.44, 142.37,
142.35, 142.03, 142.01, 142.00, 140.6, 140.3, 136.7, 136.0, 132.2,
130.5, 122.6, 68.1, 66.6, 58.3, 21.0 ppm; HRMS (FAB, NPOE) calcd for
C75H17N [M]: 931.1361; found: 931.1357.
145.4, 145.03, 144.99, 144.97, 144.4, 144.2, 144.1, 142.8, 142.18,
142.17, 141.75, 141.68, 141.6, 141.4, 141.33, 141.29, 139.8, 139.6,
136.5, 136.1, 135.5, 130.1, 126.5, 116.7, 83.2, 67.4, 65.6, 57.8, 34.2,
31.2, 24.7 ppm; HRMS (FAB, NPOE) calcd for C83H32O2NB [M]:
1085.2526; found: 1085.2512.
2j: A brown solid (38%). 1H NMR (C6D6/CS2): d=7.77 (d, 1H, J=
2.2 Hz), 7.61–7.57 (m, 3H), 7.44 (dd, 1H, J=8.9 Hz and 2.4 Hz),
7.40–7.35 (m, 2H), 7.30–7.18 (m, 4H), 6.97–6.91 (m, 1H), 6.41 (s,
1H), 5.64 ppm (s, 2H); 13C NMR (C6D6/CS2): d=154.5, 153.8, 148.8,
147.6, 147.5, 147.3, 147.0, 146.7, 146.6, 146.5, 146.4, 146.0, 145.73,
145.71, 145.67, 145.6, 144.9, 144.8, 143.5, 142.93, 142.91, 142.4,
142.3, 142.03, 141.97, 141.96, 140.6, 140.3, 136.7, 135.8, 134.8,
130.3, 130.0, 129.7, 127.4, 127.0, 125.1, 123.5, 123.3, 122.8, 118.8,
67.9, 66.4, 58.4 ppm; HRMS (FAB, NPOE) calcd for C77H16N [M+H]:
954.1283; found: 954.1277.
1
2d: A brown solid (38%). H NMR (C6D6/CS2): d=7.31–7.26 (m, 4H),
7.07–7.02 (m, 4H), 6.51 (s, 1H), 5.58 (s, 2H), 2.52 (t, 4H, J=7.6 Hz),
1.60–1.49 (m, 4H), 1.37–1.24 (m, 4H), 0.89 ppm (t, 6H, J=7.2 Hz);
13C NMR (C6D6/CS2): d=154.8, 154.0, 147.6, 147.5, 147.4, 147.0,
146.8, 146.7, 146.6, 146.5, 146.4, 146.1, 145.71, 145.68, 145.6, 144.9,
144.8, 143.5, 143.3, 142.92, 142.90, 142.41, 142.35, 142.02, 142.00,
141.98, 140.6, 140.3, 137.4, 136.7, 135.9, 129.8, 122.6, 68.0, 66.4,
58.2, 35.5, 34.3, 23.0, 14.5 ppm; HRMS (FAB, NPOE) calcd for
C81H29N [M]: 1015.2300; found: 1015.2272.
2k: A brown solid (41%). 1H NMR (C6D6/CS2): d=8.17 (d, 2H, J=
1.8 Hz), 7.68 (d, 2H, J=8.6 Hz), 7.52 (dd, 2H, J=8.6 Hz and 1.8 Hz),
6.26 (s, 1H), 5.74 (s, 2H), 1.42 ppm (s, 18H); 13C NMR (C6D6/CS2):
d=153.8, 153.4, 147.62, 147.60, 147.2, 146.8, 146.7, 146.6, 146.5,
146.4, 146.0, 145.9, 145.8, 145.7, 145.6, 144.9, 144.7, 143.5, 143.0,
142.9, 142.8, 142.5, 142.3, 142.2, 142.1, 141.9, 141.8, 140.6, 140.5,
140.4, 136.5, 135.8, 124.2, 124.1, 117.2, 109.9, 67.9, 58.5, 57.3, 34.8,
32.2 ppm; HRMS (FAB, NPOE) calcd for C81H27N [M]: 1013.2144;
found: 1013.2164.
1
2e: A brown solid (35%). H NMR (C6D6/CS2): d=7.36–7.19 (m, 8H),
6.91–6.85 (m, 1H), 6.47 (s, 1H), 5.56 (s, 2H), 1.27 ppm (s, 9H);
13C NMR (C6D6/CS2): d=154.6, 153.9, 149.0, 147.55, 147.47, 147.3,
146.9, 146.63, 146.58, 146.5, 146.44, 146.38, 146.0, 145.8, 145.67,
145.66, 145.62, 145.58, 144.9, 144.8, 143.5, 143.3, 142.87, 142.85,
142.34, 142.30, 142.0, 141.9, 140.6, 140.3, 136.7, 135.9, 129.8, 126.8,
123.7, 122.4, 121.1, 67.9, 66.1, 58.1, 34.3, 31.7 ppm; HRMS (FAB,
NPOE and NBA) calcd for C77H22N [M+H]: 960.1752; found:
960.1754.
1
2l: A brown solid (27%). H NMR (C6D6/CS2): d=7.27–7.23 (m, 2H),
7.13–7.05 (m, 4H), 6.88–6.82 (m, 2H), 6.63 (s, 1H), 5.77 ppm (s, 2H);
13C NMR (C6D6/CS2): d=154.0, 153.7, 147.6, 147.3, 146.61, 146.58,
146.5, 146.41, 146.37, 146.0, 145.74, 145.71, 145.62, 145.60, 144.9,
144.7, 143.5, 142.8, 142.4, 142.31, 142.25, 141.9, 141.7, 140.4, 140.2,
136.4, 136.2, 135.6, 129.0, 128.5, 124.3, 67.9, 60.9, 58.0 ppm; HRMS
(FAB, NPOE) calcd for C73H11NS [M]: 933.0612; found: 933.0648.
1
2 f: A brown solid (39%). H NMR (C6D6/CS2): d=7.47–7.41 (m, 5H),
7.39–7.36 (m, 3H), 7.35–7.32 (m, 2H), 7.30–7.27 (m, 1H), 7.26–7.21
(m, 2H), 6.49 (s, 1H), 5.62 (s, 2H), 1.28 ppm (s, 9H); 13C NMR (C6D6/
CS2): d=154.6, 153.9, 148.6, 147.6, 147.5, 147.4, 147.2, 147.0, 146.7,
146.6, 146.5, 146.4, 146.1, 145.73, 145.68, 145.65, 145.56, 144.9,
144.8, 143.6, 142.94, 142.92, 142.38, 142.35, 142.04, 141.99, 140.8,
140.6, 140.3, 136.7, 136.0, 134.7, 129.1, 127.1, 126.91, 126.89, 124.5,
120.7, 67.9, 66.1, 58.2, 34.4, 31.7 ppm; HRMS (FAB, NPOE) calcd for
C83H26N [M+H]: 1036.2065; found: 1036.2101.
Reaction of 2a with methyl iodide
A solution of KOtBu (30 mL, 1.0m, 0.030 mmol) in THF was added
to 2a (24.8 mg, 0.0244 mmol) and benzonitrile (7 mL) in a Schlenk
flask (50 mL) under N2 at room temperature. After stirring for
10 min, MeI (30 mL, 0.5 mmol) was added to the reaction mixture,
which was stirred for 12 h at room temperature. After the solution
was concentrated in vacuo, the residue was purified by column
chromatography (SiO2) with cyclohexane as the eluent to give 6a
1
2g: A brown solid (26%). H NMR (C6D6/CS2): d=7.30 (br, 4H), 7.13
(br, 4H), 6.40 (s, 1H), 5.51 (s, 2H), 1.27 ppm (s, 9H); 13C NMR (C6D6/
CS2): d=154.3, 153.7, 147.9, 147.6, 147.5, 147.3, 146.8, 146.7, 146.6,
146.5, 146.4, 146.0, 145.73, 145.68, 145.6, 145.3, 144.9, 144.8, 143.6,
142.94, 142.92, 142.34, 142.33, 142.03, 141.97, 141.9, 140.6, 140.3,
136.6, 135.9, 129.7, 127.0, 126.9, 124.7, 121.2, 67.7, 66.2, 58.2, 34.4,
31.6 ppm; HRMS (FAB, NPOE) calcd for C77H20NCl [M]: 993.1284;
found: 993.1249.
1
as a brown solid (12.4 mg, 0.0120 mmol, 49%). H NMR (C6D6/CS2):
d=7.31–7.20 (m, 8H), 5.34 (d, 1H, J=14.9 Hz), 5.25 (d, 1H, J=
14.9 Hz), 2.63 (s, 3H), 1.25 ppm (s, 18H); 13C NMR (C6D6/CS2): d=
159.0, 156.7, 153.0, 150.4, 149.3, 148.94, 148.91, 148.4, 148.1,
147.52, 147.48, 147.4, 147.30, 147.25, 147.19, 147.17, 146.6, 145.82,
145.79, 145.5, 145.4, 145.3, 145.2, 145.09, 145.07, 145.0, 144.74,
144.71, 144.67, 144.6, 144.54, 144.47, 144.46, 144.3, 144.2, 144.1,
144.0, 143.53, 143.49, 143.3, 143.04, 142.99, 142.98, 142.8, 142.7,
142.6, 142.4, 142.3, 141.2, 139.3, 139.0, 138.9, 138.0, 126.5, 122.2,
63.7, 62.2, 54.8, 34.2, 31.6, 29.1 ppm; HRMS (FAB, NPOE) calcd for
C82H31N [M]: 1029.2457; found: 1029.2473.
1
2h: A brown solid (32%). H NMR (C6D6/CS2): d=7.41–7.35 (m, 2H),
7.20–7.16 (m, 2H), 7.10–7.04 (m, 2H), 6.88–6.82 (m, 2H), 6.63 (s,
1H), 5.66 (s, 2H), 3.73 (s, 3H), 1.28 ppm (s, 9H); 13C NMR (C6D6/CS2):
d=157.0, 154.6, 153.9, 147.7, 147.5, 147.4, 147.3, 146.8, 146.6,
146.5, 146.4, 146.3, 146.0, 145.62, 145.57, 145.5, 144.8, 144.7, 143.4,
143.1, 142.8, 142.3, 142.2, 141.92, 141.89, 140.8, 140.5, 140.3, 136.7,
135.9, 127.6, 126.4, 118.2, 115.3, 68.0, 66.9, 58.2, 55.3, 33.9,
31.8 ppm; HRMS (FAB, NPOE) calcd for C78H23ON [M]: 989.1780;
found: 989.1760.
Reaction of 2a with methyl 2-(bromomethyl)acrylate
A solution of KOtBu (30 mL, 1.0m, 0.030 mmol) in THF was added
to 2a (25.0 mg, 0.0246 mmol) and benzonitrile (7 mL) in a Schlenk
flask (50 mL) under N2 at room temperature. After stirring for
10 min, methyl 2-(bromomethyl)acrylate (60 mL, 0.5 mmol) was
added to the reaction mixture, which was stirred for 1 h at room
1
2i: A brown solid (24%). H NMR (C6D6/CS2): d=7.75–7.70 (m, 2H),
7.41–7.30 (m, 4H), 7.23–7.19 (m, 2H), 6.49 (s, 1H), 5.63 (s, 2H), 1.29
(s, 9H), 1.21 ppm (s, 12H); 13C NMR ([D4]ODCB): d=154.0, 153.3,
152.0, 148.5, 147.0, 146.9, 146.7, 146.4, 146.0, 145.9, 145.8, 145.7,
Chem. Eur. J. 2014, 20, 6120 – 6125
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Full Paper
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temperature. After the solution was concentrated in vacuo, the res-
idue was purified by column chromatography (SiO2) with cyclohex-
ane/toluene (2:1) as the eluent to give 6b as a brown solid
1
(23.0 mg, 0.0206 mmol, 84% ). H NMR (C6D6/CS2): d=7.30–7.20 (m,
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8H), 6.44 (d, 1H, J=1.1 Hz), 5.51 (br, 1H), 5.41 (d, 1H, J=14.9 Hz),
5.34 (d, 1H, J=14.9 Hz), 4.10 (d, 1H, J=13.0 Hz), 4.00 (d, 1H, J=
13.0 Hz), 3.53 (s, 3H), 1.25 ppm (s, 18H); 13C NMR (C6D6/CS2): d=
166.9, 156.8, 156.7, 151.4, 150.7, 149.1, 148.9, 148.8, 148.0, 147.50,
147.47, 147.3, 147.24, 147.16, 147.1, 146.7, 145.81, 145.78, 145.6,
145.43, 145.37, 145.23, 145.16, 145.14, 145.06, 144.99, 144.96,
144.74, 144.71, 144.63, 144.60, 144.56, 144.5, 144.4, 144.3, 144.1,
144.0, 143.9, 143.51, 143.49, 143.4, 143.3, 143.2, 143.01, 142.97,
142.9, 142.70, 142.66, 142.4, 142.31, 142.25, 141.1, 139.3, 139.2,
138.9, 138.5, 135.6, 130.2, 126.5, 122.3, 63.7, 62.3, 59.1, 51.8, 44.2,
34.2, 31.7 ppm; HRMS (FAB, NPOE) calcd for C86H36O2N [M+H]:
1114.2746; found: 1114.2764.
Acknowledgements
This work was supported by the Funding Program for Next
Generation World-Leading Researchers (GR025) and a Grant-in-
Aid for Scientific Research on Innovative Areas “Advanced Mo-
lecular Transformations by Organocatalyst” from MEXT, Japan.
We also thank the Research Hub for Advanced Nano Character-
ization at The University of Tokyo for X-ray analysis.
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Keywords: aminoalkylation · fullerenes · photooxidation ·
radicals · redox chemistry
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Received: December 3, 2013
Published online on April 2, 2014
Chem. Eur. J. 2014, 20, 6120 – 6125
www.chemeurj.org
6125
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim