C60-catalyzed direct C-H arylation of benzene with aryl iodides in air

Article abstract of DOI:10.1016/j.tet.2015.04.044

C₆₀ at 1 mol % loading catalyzed the direct C-H arylation of benzene with aryl iodides in air to yield biaryls. The in situ generation of electron-rich C₆₀(OH)^2-, from C₆₀ and OH^-, reduced the aryl iodides to aryl radicals for arylation of benzene. The large surface area and spherical shape of C₆₀ facilitated this process.

Full text of DOI:10.1016/j.tet.2015.04.044

Accepted Manuscript
C
-Catalyzed direct C-H arylation of benzene with aryl iodides in air
60
Tsz Yiu Kwok, Christoph Sonnenschein, Ching Tat To, Jianwen Liu, Kin Shing Chan
PII:
S0040-4020(15)00543-8
10.1016/j.tet.2015.04.044
TET 26647
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 12 March 2015
Revised Date: 15 April 2015
Accepted Date: 16 April 2015
Please cite this article as: Kwok TY, Sonnenschein C, To CT, Liu J, Chan KS, C -Catalyzed direct C-H
60
arylation of benzene with aryl iodides in air, Tetrahedron (2015), doi: 10.1016/j.tet.2015.04.044.
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C60-Catalyzed direct C-H arylation of
benzene with aryl iodides in air
Leave this area blank for abstract info.
Tsz Yiu Kwok,a Christoph Sonnenschein,a Ching Tat To,a Jianwen Liub,* and Kin Shing Chana,*
aDepartment of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, The
People’s Republic of China
bNational Supercomputing Centre in Shenzhen, Shenzhen, 518055, The People’s Republic of China

1
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Tetrahedron
journal homepage: www.elsevier.com
C60-Catalyzed direct C-H arylation of benzene with aryl iodides in air
Tsz Yiu Kwoka , Christoph Sonnenscheina, Ching Tat Toa, Jianwen Liub, and Kin Shing Chana,
a Department of Chemistry and Centre for Scientific Modelling and Computation, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong,
The People’s Republic of China.
b National Supercomputing Centre in Shenzhen, Shenzhen, 518055, The People’s Republic of China.
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
C60 at 1 mol% loading catalyzed the direct C-H arylation of benzene with aryl iodides in air to
yield biaryls. The in situ generation of electron rich C60(OH)2•ꢀ, from C60 and OHꢀ, reduced the
aryl iodides to aryl radicals for arylation of benzene. The large surface area and spherical shape
of C60 facilitated this process.
Available online
2009 Elsevier Ltd. All rights reserved.
Keywords:
C60
Direct C-H arylation
Reduction
Biaryl
1. Introduction
Table 1. Selected surface area of organocatalysts for catalytic
direct C-H arylation (highlighted in blue)a
Cross-coupling reactions are widely used to construct biaryl
motifs, which are commonly found in functional materials such
as organic semiconductors and organic light emitting diodes1 as
well as in pharmaceuticals.2 The strategy of forming aryl-aryl
bond has evolved from using second row3 to first row4 transition
metal catalysts, and from activated arenes3,5 to parent arenes via
direct C-H arylation.6-8
The organocatalytic direct C-H arylation is first reported by
Itami in 2008,9 which has emerged as a new approach for the
biaryl synthesis. It is mechanistic interesting, that transition
metals are not required in the bond breaking and making
processes.10 The often expensive metal catalysts themselves and
the pharmaceutical requirement to remove metallic impurities
afterwards could be avoided. Thus the cross-coupling of
unreactive aromatic C-H bonds with aryl halides leads to a
cheaper and more environmentally friendly reaction.
Entry
Catalyst
C1
Surface area / Å2 loading / mol%
ref
6b
Later, various organocatalysts were found to catalyze the
direct C-H arylation in the presence of strong base, such as
1
2
3
4
5
6
30.6
20.6
20
20
5
C2
6c
DMEDA
(N,N’-dimethylethylenediamine),6a
1,10-
H2(ttp)
H2(obopc)
H(trip)
C60
81.8
11a
Phenanthroline,6b quinoline-amino-carboxylic acid,6c zwitterionic
radical6d and amino-linked N-heterocyclic carbine.6e However,
the catalyst loadings usually required 20 mol% and N2
atmosphere for satisfactory results. Alternatively, metal and base
120.6
90.0
3
11c
1
11b
149.6
1
this work
a estimated by Spartan ’10 at Semi-Empirical/AM1 level
———
a Corresponding author. Tel.: +852-39436376; fax: +852-26035057; e-mail: ksc@cuhk.edu.hk
b Corresponding author. Tel.: +86-775-86576112; fax: +86-755-86576000; e-mail: liujw@nsccsz.gov.cn

2
Tetrahedron
free, photocatalytic protocol using Eosin Y as photocatalyst has
Table 2. C loading effects on C -catalyzed direct C-H
ACCEPTED MANUSCRIPT
60
60
been discovered by König.7 Our group has reported the air-
compatible organocatalysts such as H2(ttp) (5 mol%),11a H(trip)
(1 mol%)11b and H2(obopc) (3 mol%).11c The larger surface area
of these catalysts tends to allow lower catalyst loading (Table 1,
entries 1-5).
arylation of benzene
A general accepted mechanism of these strong base-promoted
organocatalytic direct C-H arylation was initiated by one electron
reduction of aryl halide by an electron donor to generate an aryl
halide radical anion. This radical anion eliminates a halide anion
to give an aryl radical. The aryl radical then adds to an arene to
yield the biaryl product (Scheme 1).10,12 A recent report
suggested that in situ deprotonation of the organocatalyst gives
anionic electron-rich alkene species as the electron donor.13 The
one electron reduction of aryl halides by organic electron donors
has been well documented.14 Alternatively, reduction of aryl
halides via photo-induced electron transfer using PDI
(perylenediimide) photocatalyst has been reported.15
Entry
1b
C60 loading/ mol%
Time / h
Yield 1a / %a
5
5
2.5
3
59
68
65
71
58
32
2
3
2.5
1
6.5
9
4
5
0.1
0
36
72
6
a GC yield.
b Under N2
Table 3. Base effects on C60-catalyzed direct C-H arylation of
benzene
Entry
Bases
NaOH
KOH
CsOH
KOH
tBuOK
KOH
KOH
KOH
Equiv
10
Time / h
Yield 1a / %a
1
36
9
12
71
47
14
40
71
57
60
2
10
3
10
3
4b
10
30
3
Scheme 1. General mechanism of organocatalytic direct C-H
arylation
5b
10
6
20
3.5
3
7
8c
30
Donor-acceptor π-π interaction was found to be important in
the one-electron reduction via electron transfer from organic
superelectron donor.16 Hence, the electron-rich organocatalyst
with larger surface area may enhance the π-π interaction with the
aryl halides and facilitates the electron transfer process.
20
15
a GC yield.
b Without tBuOH.
c 180 °C
Inspired by the report from Fukuzumi and Kadish, C60 can be
readily reduced by MeOꢀ to generate a mixture of electron-rich
Control experiment without C60 yielded 32% of 1a in 72 h
(Table 2, entry 6). The formation of 1a is accounted by the direct
reduction of 4-iodotoluene by KOH via single electron transfer to
give the corresponding aryl iodide radical anion, which further
reacts according to the mechanism depicted in Scheme 1.14a
Alternatively, 4-iodotoluene reacts with KOH to generate an
aryne intermediate, which is then trapped by benzene.18
Therefore, the formation of 1a in the absence of C60 is minor due
to its longer reaction time and much lower product yield. The
•
C60(OMe)2 ꢀ and C60•ꢀ radical anion.17 Taking the advantage of
large surface area of C60 and its spherical shape to maximize π-π
interaction (Table 1, entry 6), the combination of C60 and a strong
base serves as the potential reducing agent for aryl halides in
catalytic direct C-H arylation. Herein we report the C60-catalyzed
direct C-H arylation of benzene with aryl iodides in air with only
1 mol% loading of C60.
2. Results and discussion
conditions shown in Table 1, entry
4 was chosen for
investigations on base effects at reasonably low C60 loading (1
mol%) and short reaction time.
Initially, treatment of 4-iodotoluene (1 equiv) with KOH (10
t
equiv), BuOH (10 equiv) and C60 (5 mol%) in benzene (100
o
equiv) at 200 C under N2 for 2.5 h gave direct C-H arylation
The cations of group 1 metal hydroxides affect the coupling
product 4-methylbiphenyl 1a in 59% yield (Table 2, entry 1). To
our delight, the reaction was compatible with air and yielded
68% of 1a in 3 h (Table 2, entry 2).
reaction significantly. Among the three Group
1 metal
hydroxides examined, KOH was the best base (Table 3, entries 1-
3). Although CsOH took a shorter reaction time, lower yield of
1a was resulted due to the co-formation of significant amounts of
4-t-butoxytoluene and 3-t-butoxytoluene (Table 3, entry 3). The
nucleophilic aromatic substitution of 4-iodotoluene with t-
butoxide, formed in situ from KOH and tBuOH, through benzyne
With 2.5 mol% C60 loading, the reaction took 6.5 h for
completion to yield 65% of 1a (Table 2, entry 3). Further
lowering the catalyst loading to 1 mol% produced 1a in 71%
yield in 9 h (Table 2, entry 4). Surprisingly, the reaction also
proceeded smoothly with only 0.1 mol% of C60 to yield 58% of
1a in 36 h (Table 2, entry 5). The high catalytic activity of C60 is
consistent with its large surface area (Table 1).
t
mechanism became significant.19 Without any BuOH, the yield
of 1a decreased significantly even after 30 h (Table 3, entry 4).
t
We reasoned that BuOH help to solubilize KOH better in
benzene.

3
equimolar mixture of benzene and benzene-d6 (eq 1). The KIE
Table 4. C -catalyzed direct C-H arylation of benzene with
aryl iodides
ACCEPTED MANUSCRIPT
60
was measured to be 1.11±0.01 from GCMS analysis. Therefore
the C-H bond cleavage is not rate-determining.
Entry
1
Aryl Halides
Time / h
3.5
Product
Yield / %a
71
1a
2
3
5
1b
1c
79
43
Table 5. Reaction enthalpies and Gibbs free energies at 298K
and 473K using B3LYP/SVP. All energies are given in
kcal/mol.
13
4
5
6
3
1d
1e
78
71
3.5
3.5
1f
1gb
Trace
74
1h
38
47
7
4.5
72
1gb
8
1a
11
a GC yield.
b 1g = p-terphenyl
The direct use of BuOK instead of KOH/tBuOH combination
was not satisfactory (Table 3, entry 5). 1a was yielded in 40%
after 3 h with the co-formation of 4-t-butoxytoluene and 3-t-
butoxytoluene in about 1:1 ratio from GCMS analysis.20
Increasing the KOH loading to 20 equiv shortened the reaction
time to 3.5 h (Table 3, entry 6). 30 Equiv of KOH led to
significant substitution products and hence decreased 1a yield
(Table 3, entry 7).
t
Reaction
ꢁE
-115.6
10.2
-19.3
10.2
-21.5
-90.6
-14.8
ꢁG (298 K)
-103.7
6.8
ꢁG (473 K)
-84.4
-7.7
2
3
4
5
6
7
8
-21.0
4.0
-7.2
-91.9
-14.8
-8.9
0.4
0.3
-92.8
-15.7
Finally, we attempted to carry out the coupling reaction at
o
milder temperature. The reaction at 180 C was slowed down to
15 h with only 60% yield of 1a (Table 3, entry 8). Therefore we
selected the conditions in Table 2, entry 6 as the optimal
conditions to examine the substrate scopes.
To gain mechanistic understandings on the C60-catalyzed
direct C-H arylation and the nature of electron donor, we carried
out DFT calculations and evaluated the thermodynamics of each
reaction steps at both 298 K and 473 K using 4-iodotoluene as
substrate (Table 5). The calculations were performed using
hybrid functional B3LYP22 with split-valence-ζ plus polarization
basis sets (SVP)23 implemented in Gaussian 03.24
As C60 is an ideal electron receptor, it easily reacts with OH–
to form C60(OH)ꢀ anion (eq 2).25 The reaction is highly favorable
with ∆G of -84.4 kcal/mol at 473 K. This agrees with the
spontaneous addition of MeOꢀ to C60 giving C60(OMe)ꢀ with
equilibrium constant estimated to be 4.3 x 105 M-1.17 Further
reaction of C60(OH)ꢀ with OHꢀ produces hydroxyl radical and
C60(OH)2•ꢀ (eq 3). Although it is endergonic at 298 K, it becomes
exergonic at 473 K, indicating that temperature plays an essential
role for this step. C60(OH)2•ꢀ then transfers an electron to 4-
iodotoluene to generate an aryl iodide radical anion with the
recovery of C60(OH)ꢀ (eq 4). It is shown that C60(OH)2•ꢀ is the
reducing agent for 4-iodotoluene. Direct electron transfer from
C60(OH)ꢀ to 4-iodotoluene is endergonic by more than 50
kcal/mol and therefore C60(OH)ꢀ is not the electron donor.
The optimized conditions proved to be general to various aryl
iodides (Table 4). 3-Iodotoluene as well as iodobenzene
underwent smooth direct C-H arylation with benzene to give 1b
and 1d in good yields (Table 4, entries 2 and 4). Electron rich 4-
iodoanisole reacted well to produce 1e in 71% yield (Table 4,
entry 5). The sterically demanding 2-iodotoluene gave the
coupling product 1c in 43% yield (Table 4, entry 3). Cross-
coupling involving aryl bromide was unsatisfactory (Table 4,
entry 8).
4-Chloroiodobenzene underwent double-arylation with
benzene to yield 74% of p-terphenyl 1g as the major product in
3.5 h, with only trace amount of mono-arylated product 4-
chlorobiphenyl 1f formed (Table 4, entry 6). The double-
arylation was less extensive for 4-fluoroiodobenzene, yielding
38% of mono-arylated product 4-fluorobiphenyl 1h and 47% of
di-arylated product 1g after 4.5 h (Table 4, entry 7). The mono-
arylation occurs selectively at the more easily reduced Ar-I
bond.21
To gain more insight on the C-H cleavage step, a competition
experiment was performed by reacting 4-iodotoluene with an
The cleavage of C-I bond in aryl iodide radical anion to form
aryl radical and iodide is more favorable at 473 K (eq 5). The

4
Tetrahedron
ACCEPTED MANUSCRIPT
addition of aryl radical to benzene generate cyclohexadienyl
Unless otherwise specified, all reagents were purchased from
radical (eq 6), which can easily be deprotonated by excess OHꢀ to
generate biaryl radical anion with ∆G of -92.8 kcal/mol (eq 7).10
Biaryl radical anion then transfer electron to 4-iodotoluene to
yield another aryl iodide radical anion and furnish the biaryl
product (eq 8).
commercial suppliers and used without further purification.
Hexane for chromatography was distilled from anhydrous
calcium chloride. Thin layer chromatography was performed on
precoated silica gel 60 F254 plates. Silica gel (Merck, 70-230 and
1
230-400 mesh) was used for column chromatography in air. H
NMR spectra were recorded on a Bruker AvanceIII 400 (400
MHz) spectrometer. Spectra were referenced internally to the
solvent residual proton resonance in CDCl3 (δ 7.26 ppm) or with
tetramethylsilane (TMS, δ 0.00 ppm) as the internal standard.
Chemical shifts (δ) are reported in parts per million (ppm).
Coupling constants (J) are reported in hertz (Hz). GC-MS
analysis was conducted on a GCMS-QP2010 Plus system using a
Rtx-5MS column (30 m x 0.25 mm). The details of GC program
are as follow: The column oven temperature and injection
temperature were 100.0 and 290.0 oC. Helium was used as carrier
gas. Flow control mode was chosen as linear velocity (36.3 cm s-
1) with pressure 68.8 kPa. The total flow, column flow and purge
flow were 13.5, 0.95 and 3.0 mL min-1, respectively. Split mode
injection with split ratio 10.0 was applied. Samples were injected
Based on the experimental findings, DFT calculations and
previous accepted mechanism, a catalytic cycle for the C60-
catalyzed direct C-H arylation is proposed in Scheme 2. Instead
of deprotonation of electron donor precursor by base,13 the
reaction is initiated by addition of OH- to C60 to form C60(OH)ꢀ,
which is faster in the presence of O2.25 Then, a single electron
transfer from another OH- to C60(OH)ꢀ generates the C60(OH)2•ꢀ.
C60(OH)2•ꢀ with a large surface area interacts with Ar-I via π-π
interaction and reduces it to form an aryl iodide radical anion,
which undergoes Ar-I cleavage to eliminate Iꢀ and produces an
aryl radical . The aryl radical adds to benzene to generate a
cyclohexadienyl radical intermediate, which is deprotonated by
OH- to give biaryl radical anion.10 This radical anion undergoes
one electron transfer to Ar-I to yield the coupling product 1 and
the new aryl iodide radical anion to complete the catalytic cycle.
Alternatively, direct aromatization of the cyclohexadienyl radical
with O2 also leads to 1.26 The reaction is thus compatible with air.
o
as solutions in hexane. The GC oven was held at 100.0 C for 2
o
o
o
min, ramped to 250.0 C at 30.0 C min-1, and held at 250.0 C
for 1 min. The detector was a quadrupole MS with 70 eV
electron impact ionization. Naphthalene was used as internal
standard. Unless specified, all the reactions were carried out in a
closed system under air and dark in a thick-wall glass tube
equipped with a Teflon-stoppered Rotaflo stopcock. The reaction
vessel was covered with aluminum foil to protect from light and
was heated on an aluminum block. Cardboard was used as
protective shield around the heater. The reactions were
duplicated and the yields are the average yields. The coupling
products are known compounds and with identical properties to
those reported in the literature.
4.2 Procedures for the C60 loading effects on catalytic direct
C-H arylation of benzene.
4.2.1. With 5 mol% C60 under N2. C60 (8.1 mg, 0.0112 mmol), 4-
iodotoluene (48.8 mg, 0.224 mmol), KOH (125 mg, 2.24 mmol)
t
and BuOH (215 ꢂL, 2.24 mmol) were dissolved in benzene (2.0
mL, 22.4 mmol). The mixture was degassed for three freeze-
pump-thaw cycles and heated at 200 °C. After confirming the
complete consumption of the aryl halide by GCMS analysis the
solvent was removed by rotary evaporator. The crude residue was
purified by column chromatography (silica gel, 230-400 mesh)
eluting with hexane to afford the 4-methylbiphenyl 1a.
Scheme 2. Proposed catalytic cycle of C60-catalyzed direct C-H
arylation
The formation of p-terphenyl 1g from 4-haloiodobenzene is
due to a competitive intramolecular reduction process (Scheme
3). Instead of electron transfer to another aryl iodide substrate,
the 4-halobiaryl radical anion eliminates the halide anion to give
biaryl radical, which couples with benzene to yield 1g.
4.2.2. With 5 mol% C60 under air. C60 (8.1 mg, 0.0112 mmol), 4-
iodotoluene (48.8 mg, 0.224 mmol), KOH (125 mg, 2.24 mmol),
tBuOH (215 ꢂL, 2.24 mmol) were dissolved in benzene (2.0 mL,
22.4 mmol). The mixture was heated at 200 °C. After confirming
the complete consumption of the aryl halide by GCMS analysis
the solvent was removed by rotary evaporator. The crude residue
was purified by column chromatography (silica gel, 230-400
mesh) eluting with hexane to afford the 4-methylbiphenyl 1a.
3. Conclusions
In summary, C60 reacts with KOH to give electron rich
C60(OH)2•ꢀ for the reduction of aryl iodides, which initiates the
catalytic direct C-H arylation of benzene in air. The large surface
4.2.3. With 2.5 mol% C60 under air. The procedures follow the
same as 5 mol% C60 under air except C60 (4.0 mg, 0.0056 mmol)
was used.
Scheme 3. Proposed mechanism for p-terphenyl formation
4.2.4. With 1 mol% C60 under air. The procedures follow the
same as 5 mol% C60 under air except C60 (1.6 mg, 0.00224 mmol)
was used.
area of C60 greatly enhances the catalytic activity and allows
loading down to 0.1 mol%.
4.2.5. With 0.1 mol% C60 under air. The procedures follow the
same as 5 mol% C60 under air except C60 (0.16 mg, 0.224 µmol)
was used.
4. Experimental section
4.1 General.

5
4.2.6. Without C60 under air. The procedures follow the same as
5 mol% C60 under air except no C60 was added.
4.4.7. p-Terphenyl (1g).4b 1H NMR (400 MHz, CDCl3) δ 7.36 (t,
ACCEPTED MANUSCRIPT
J = 7.3 Hz, 2 H), 7.46 (t, J = 7.6 Hz, 4 H), δ 7.65 (d, J = 7.6 Hz, 4
H), δ 7.68 (s, 4 H).
4.4.8. 4-Fluorobiphenyl (1h).4b 38% yield. H NMR (400 MHz,
4.3 Procedures for the base effects on catalytic direct C-H
arylation of benzene.
1
CDCl3) δ 7.13 (t, J = 8.6 Hz, 2 H), 7.35 (t, J = 7.2 Hz, 1 H), 7.44
(t, J = 7.6 Hz, 2 H), 7.53-7.56 (m, 4 H).
4.3.1. With 10 equiv NaOH. C60 (1.6 mg, 0.00224 mmol), 4-
iodotoluene (48.8 mg, 0.224 mmol), NaOH (89.6 mg, 2.24
t
mmol), BuOH (215 ꢂL, 2.24 mmol) were dissolved in benzene
Acknowledgments
(2.0 mL, 22.4 mmol). The mixture was heated at 200 °C. After
confirming the complete consumption of the aryl halide by
GCMS analysis the solvent was removed by rotary evaporator.
The crude residue was purified by column chromatography
(silica gel, 230-400 mesh) eluting with hexane to afford the 4-
methylbiphenyl 1a.
We thank the Innovation and Technology Support Programme
(ITSP/001/12) of the HKSAR, and the People’s Republic of
China for financial support.
References and notes
4.3.2. With 10 equiv CsOH. The procedures follow the same as
10 equiv NaOH except CsOH (336 mg, 2.24 mmol) was used.
1. (a) Cicoira, F.; Santato, C. Adv. Funct. Mater. 2007, 17, 3421-
3434. (b) Allard, S.; Forster, M.; Souharce, B.; Thiem, H.; Scherf,
U. Angew. Chem., Int. Ed. 2008, 47, 4070-4098. (c) Facchetti, A.;
Vaccaro, L.; Marrocchi, A. Angew. Chem., Int. Ed. 2012, 51,
3520-3523.
2. (a) MedAdNews 200 - World's Best-Selling Medicines,
MedAdNews, 2007. (b) Roughley, S. D.; Jordan, A. M. J. Med.
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3. (a) Tamao, K.; Sumitani, K.; Kisa, Y.; Zambayashi, M.; Fujioka,
A.; Kodama, A.; Nakajima, I.; Minato, A.; Kumada, M. Bull.
Chem. Soc. Jpn. 1976, 49, 1958-1969. (b) Negishi, E.; King, A.
O.; Okukado, N. J. Org. Chem. 1977, 42, 1821-1823. (c) Milstein,
D.; Stille, J. K. J. Am. Chem. Soc. 1978, 100, 3636-3638. (d)
Stille, J. K. Angew. Chem., Int. Ed. Engl. 1986, 25, 508-524. (e)
Miyaura, N.; Suzuki, A. Chem. Commun. 1979, 866-867. (f)
Hatanaka, Y.; Hiyama, T. J. Org. Chem. 1988, 53, 918-920. (g)
Hiyama, T. J. Organomet. Chem. 2002, 653, 58-61.
4. (a) Vallee, F.; Mousseau, J. J.; Charette, A. B. J. Am. Chem. Soc.
2010, 132, 1514-1516. (b) Liu, W.; Cao, H.; Lei, A. Angew.
Chem., Int. Ed. 2010, 49, 2004-2008. (c) Hatakeyama, T.;
Hashimoto, S.; Ishizuka, K.; Nakamura, M. J. Am. Chem. Soc.
2009, 131, 11949-11963. (d) Ohmiya, H.; Yorimitsu, H.; Oshima,
K. Chem. Lett. 2004, 33, 1240-1241. (e) Korn, T. J.; Knochel, P.
Angew. Chem., Int. Ed. 2005, 44, 2947-2951. (f) Kobayashi, O.;
Uraguchi, D.; Yamakawa, T. Org. Lett. 2009, 11, 2679-2682. (g)
Tobisu, M.; Hyodo, I.; Chatani, N. J. Am. Chem. Soc. 2009, 131,
12070-12071.
t
4.3.3. With 10 equiv KOH and without BuOH. The procedures
follow the same as 10 equiv NaOH except KOH (125 mg, 2.24
mmol) and no tBuOH were used.
t
t
4.3.4. With 10 equiv BuOK and without BuOH. The procedures
t
follow the same as 10 equiv NaOH except BuOK (251 mg, 2.24
mmol) and no tBuOH were used.
4.3.5. With 20 equiv KOH. The procedures follow the same as 10
equiv NaOH except KOH (251 mg, 4.48 mmol) was used.
4.3.6. With 30 equiv KOH. The procedures follow the same as 10
equiv NaOH except KOH (377 mg, 6.72 mmol) was used.
o
4.3.7. With 20 equiv KOH at 180 C. The procedures follow the
same as 10 equiv NaOH except KOH (251 mg, 4.48 mmol) was
used and the reaction was heated at 180 °C.
4.4 General Procedures for the C60-catalytic direct C-H
arylation of benzene with aryl halides.
C60 (0.00224 mmol), aryl halides (0.224 mmol), KOH (4.48
t
mmol) and BuOH (2.24 mmol) were dissolved in benzene (2.0
mL, 22.4 mmol). The mixture was heated at 200 °C. After
confirming the complete consumption of the aryl halide by
GCMS analysis the solvent was removed by rotary evaporator.
The crude residue was purified by column chromatography
(silica gel, 230-400 mesh) eluting with hexane to afford the
corresponding biaryls 1.
5. Do, H. Q.; Khan, R. M. K.; Daugulis, O. J. Am. Chem. Soc. 2008,
130, 15185-15192.
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1
4.4.1. 4-Methylbiphenyl (1a).4b 71% yield. H NMR (400 MHz,
CDCl3) δ 2.40 (s, 3 H), 7.24 (d, J = 7.9 Hz, 2 H), 7.32 (t, J = 7.3
Hz, 1 H), 7.42 (t, J = 7.6 Hz, 2 H), 7.49 (d, J = 8.0 Hz, 2 H), 7.58
(d, J = 7.4 Hz, 2 H).
1
4.4.2. 3-Methylbiphenl (1b).4b 79% yield. H NMR (400 MHz,
CDCl3) δ 2.43 (s, 3 H), 7.17 (d, J = 7.3 Hz, 1 H), 7.33 (t, J = 7.4
Hz, 2 H), 7.39-7.45 (m, 4 H), 7.59 (d, J = 7.3 Hz, 2 H).
4.4.3. 2-Methylbiphenyl (1c).4b 43% yield. Inseparable with
biphenyl by column chromatography. 1H NMR(400 MHz, CDCl3)
δ 2.27 (s, 3 H), 7.24-7.26 (m, 4 H), 7.31-7.35 (m, 3 H), 7.40 (d, J
=7.3 Hz, 2 H).
1
4.4.4. Biphenyl (1d).4b 78% yield. H NMR (400 MHz, CDCl3) δ
7.35 (t, J = 7.3 Hz, 2 H), 7.45 (t, J = 7.6 Hz, 4 H), 7.60 (d, J = 7.4
Hz, 4 H).
1
4.4.5. 4-Methoxybiphenyl (1e).4b 71% yield. H NMR (400 MHz,
CDCl3) δ 3.85 (s, 3 H), 6.98 (d, J = 8.6 Hz, 2H), 7.30 (t, J = 7.5
Hz, 1 H), 7.42 (t, J = 7.5 Hz, 2 H), 7.54 (t, J = 8.3 Hz, 4 H).
4.4.6. 4-Chlorobiphenyl (1f). Attempted purification by column
chromatography was failed due to trace amount formation.

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Tetrahedron
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16. Doni, E.; Mondal, B.; O’Sullivan, S.; Tuttle, T.; Murphy, J. A. J.
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6673-6680.
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20. Co-formation of 1:1 mixture of 3-t-butoxytoluene and 4-t-
butoxytoluene was observed in the organocatalytic direct C-H
arylation using tBuOK as base at 155 oC. See: Shirakawa, E.; Itoh,
K.; Higashino, T.; Hayashi, T. J. Am. Chem. Soc. 2010, 132,
15537-15539.
21. The reduction potentials of iodobenzene, chlorobenzene and
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respectively. See: (a) Enemærke, R. J.; Christensen, T. B.; Jensen,
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(b) Andrieux, C. P.; Blocman, C.; Savéant, J. M. J. Electroanal.
Chem. 1979, 105, 413-417.
Supplementary Material
1
Details of competition experiment, H NMR spectra of the
isolated products and a typical GCMS spectrum. Supplementary
data associated with this article can be found in the online
version, at
22. (a) Becke, A. D. J. Chem. Phys. 1993, 98, 5648-5652. (b) Lee, C.
T.; Yang, W. T.; Parr, R. G. Phys. Rev. B 1988, 37, 785-789.
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Supplementary Materials
C60-Catalyzed direct C-H arylation of benzene with aryl iodides in air
Tsz Yiu Kwok,a Christoph Sonnenschein,a Ching Tat To,a Jianwen Liub,* and Kin
Shing Chana,*
a
Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong
Kong, The People’s Republic of China.
Tel: +852-39436376; Fax: +852-26035057; E-mail: ksc@cuhk.edu.hk
b National Supercomputing Centre in Shenzhen, Shenzhen, 518055, The People’s Republic of China.
Tel:+86-755-86576112; Fax:+86-755-86576000; E-mail: liujw@nsccsz.gov.cn
List of Contents
Pages
1. Competition Experiment and GCMS Analysis
2. 1H NMR Spectra of Products
3. GCMS Spectrum
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3
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Competition Experiment. C60 (1.6 mg, 0.00224 mmol), 4-iodotoluene (48.8 mg,
0.224 mmol), KOH (251 mg, 4.48 mmol), tBuOH (215 μL, 2.24 mmol) were added in
benzene (1.0 mL, 11.2 mmol) and benzene-d6 (0.991 mL, 11.2 mmol). The mixture
was heated at 200 °C. The isotopic ratio was determined from the relative ratio of the
total absolute intensities of m/z at 168 (1a) and at 173 (1a-d5) from retention time
6.292 min to 6.483 min in GCMS analysis. The intensity ratio of 1a/1a-d5 gave the
KIE value, e.g. 7388282/6660115 = 1.11.
Product m/z Total absolute intensities
168
173
7388282
6660115
1a
1a-d5
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1H NMR Spectra of Products
4-Methylbiphenyl 1a
3-Methylbiphenyl 1b
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2-Methylbiphenyl 1c
Biphenyl 1d
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4-Methoxybiphenyl 1e
p-Terphenyl 1g
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4-Fluorobiphenyl 1h
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GCMS Spectrum
Typical spectrum showing the product analysis of C60-catalyzed direct C-H arylation
of benzene with 4-iodotoluene
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