Preparation of unsymmetrical terphenyls via the nickel-catalyzed cross-coupling of alkyl biphenylsulfonates with aryl Grignard reagents

Article abstract of DOI:10.1016/j.tet.2004.03.072

Unsymmetrical terphenyl derivatives were prepared by sequential transition metal-catalyzed cross-coupling reactions of neopentyl bromobenzenesulfonates with arylboronic acids and arylmagnesium bromides in good yields. Biphenylsulfonates undergo nickel-catalyzed coupling reactions more rapidly than the corresponding benzenesulfonates. The stepwise palladium- and nickel-catalyzed reaction of the bromobenzenesulfonates appears to be a promising and conceptually straightforward route for preparing unsymmetrical terphenyls.

Full text of DOI:10.1016/j.tet.2004.03.072

Tetrahedron 60 (2004) 4589–4599
Preparation of unsymmetrical terphenyls via the nickel-catalyzed
cross-coupling of alkyl biphenylsulfonates with aryl
Grignard reagents
*
Chul-Hee Cho, In-Sook Kim and Kwangyong Park
Department of Chemical Engineering, Chung-Ang University, Heukseok-Dong 221, Dongjak-Gu, Seoul 156-756, South Korea
Received 14 February 2004; revised 25 March 2004; accepted 25 March 2004
Abstract—Unsymmetrical terphenyl derivatives were prepared by sequential transition metal-catalyzed cross-coupling reactions of
neopentyl bromobenzenesulfonates with arylboronic acids and arylmagnesium bromides in good yields. Biphenylsulfonates undergo nickel-
catalyzed coupling reactions more rapidly than the corresponding benzenesulfonates. The stepwise palladium- and nickel-catalyzed reaction
of the bromobenzenesulfonates appears to be a promising and conceptually straightforward route for preparing unsymmetrical terphenyls.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
and low toxicity of the boronic acids as well as the mild
reaction conditions. Recently, the double coupling reactions
of the phenyl diboronic acids with aryl iodides18 and aryl
distannanes with phenyl bromides19 for the preparation of
symmetric terphenyls were also reported.
Transition metal-catalyzed cross-coupling reaction is an
extremely powerful tool for constructing carbon–carbon
bonds.1 The palladium- and nickel-catalyzed coupling
reactions of aryl halides and pseudohalides with arylboronic
acids,2 arylstannanes,3 arylzincs,4 and arylmagnesium
halides5 have been extensively examined to produce
unsymmetrical biaryls, which are of great interest due to
their biological6 and optical7 properties. However, the
preparation of unsymmetrical terphenyl derivatives has not
been well-known.
The traditional approach for unsymmetrical terphenyls
requires the halogenation or boration of the biphenyl
intermediates generated by the initial cross-coupling
reactions of the two aryl moieties. The brominations of
the biaryl compounds obtained by the initial coupling
reactions of the aryl halides with arylboronic acids produce
bromobiaryl intermediates, which undergo the following
Suzuki–Miyaura reactions with arylboronic acids to
generate the unsymmetrical terphenyls.20 An alternative
synthetic pathway by generating biphenyboronic acids as
intermediates was also reported.21
Terphenyl derivatives are known to exhibit a variety of
optical8 and electrical9 properties. They are particularly of
interest in the area of liquid crystals.10 Naturally isolated
p-terphenyl metabolites11 including terphenyllin,12
terferol,13 and terprenin14 have potent biological activities.
The efforts for substituting terphenyl-based architectures for
the alkenyl bridge of stilbene-based compounds15 and the
biphenyl nucleus of biologically active compounds16 have
also been reported.
More efficient method for introducing two different aryl
groups into a benzene ring is the stepwise chemoselective
cross-couplings of aryl compounds containing two dis-
similar reactive sites. The order of reactivity for the cross-
coupling reaction with organoboronic acids is I.Br.
OTfqCl. Therefore, the sequential cross-coupling reaction
of the bromoiodobenzene derivatives22 and bromophenyl
tosylates23 with two dissimilar arylboronic acids furnished
the unsymmetrical terphenyls. The stepwise cross-coupling
reactions of chlorophenylboronic acids with aryl triflates
and arylboronic acids24 as well as the sequential reactions of
the bromophenylboronic acids with the iodobenzenes and
arylboronic acids15 also produced the desired unsym-
metrical terphenyls. Similarly, the stepwise couplings of
aryl Grignard reagents with p- and m-bromochlorobenzenes
The most familiar synthetic pathway for symmetric
terphenyls is the double C–C cross-coupling reaction of
the dihalobenzene derivatives with two equivalents of aryl
nucleophiles.17 Among those processes, the Suzuki–
Miyaura reaction is the most preferred due to the stability
Keywords: Unsymmetrical terphenyls; Cross-coupling; Alkyl
biphenylsulfonates.
*
Corresponding author. Tel.: þ82-2-820-5330; fax: þ82-2-815-5476;
e-mail address: kypark@cau.ac.kr
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.03.072

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C.-H. Cho et al. / Tetrahedron 60 (2004) 4589–4599
catalyzed by non-ligated NiCl2 gave unsymmetrical
terphenyls.25
2. Results and discussion
The bromobenzenesulfonates 1 were prepared using a
previously reported procedure (Scheme 2).31 Two types of
neopentyl moieties, 2,2-dimethyl-3-phenyl-1-propyl and
neopentyl, were selected as alkyl groups in those sulfonates
to avoid the competitive substitution and elimination of the
arenesulfonate anions in the reactions with the Grignard
reagents 4. All the reactions proceeded well in 68–87%
isolated yields. The products 1a, 1b, and 1c were purified by
recrystallization from n-hexane to give white solids, while
1d was isolated by column chromatography (Et2O:n-
hexane¼1:4) as a colorless oil.
It is known that alkylthio and alkylsulfonyl groups, bonded
directly to arenes or alkenes, can be substituted for
nucleophilic aromatic substitution reactions with aryl and
alkyl Grignard reagents in the presence of a Ni(0) catalyst.26
Chlorobenzene is slightly more reactive than methylthio-
benzene in the reaction with BuMgBr in the presence of
dpppNiCl2.27 Therefore, the alkylthio groups were demon-
strated to serve as less reactive leaving groups compared to
halogens in the preparation of unsymmetrical terphenyls.
The chemoselective sequential couplings of chlorophenyl
alkyl sulfides with two different arylmagnesium halides
gave unsymmetrical terphenyls in moderate yields.28 The
sequential coupling reactions of bis(alkylthio)benzenes, in
which the selectivity originates from the difference in the
steric effects as a result of the two dissimilar alkylthio
groups, have also been reported to give terphenyls in low
yields.29 However, these approaches have not been
thoroughly explored presumably due to the inefficient
yield and the difficulty in obtaining the appropriate
substrates.
Bromobenzenesulfonates 1 underwent a palladium-
catalyzed cross-coupling reaction with arylboronic acids 2
smoothly in the presence of sodium carbonate. Since the
preparation of biaryls via the reactions of the arylboronic
acids with the aryl halides was first reported,32 the Suzuki–
Miyaura reaction has been used successfully to produce
biaryl derivatives from a variety of aryl halides and triflates.
However, the reaction of the aryl electrophiles containing
sulfur-substituents has not been examined intensively.33
Although a detailed study to optimize the reaction
conditions has not been undertaken in this effort, most of
the reactions were complete within 6 h at the refluxing
temperature of toluene. The displacement of arene-
sulfonates34 was not observed under the standard reaction
conditions.
Recently, it was reported that the reaction of alkyloxy-
sulfonylarenes with arylmagnesium bromides produced
unsymmetrical biaryls in the presence of a nickel catalyst.30
The alkyloxysulfonyl group acts as an excellent leaving
group, while it is not reactive towards the typical palladium
catalysts. These results suggested that alkyl bromoarene-
sulfonates could be used as chemoselective precursors for
unsymmetrical terphenyls.
The result of the cross-coupling reactions between 1 and 2 is
summarized in Table 1. 2,2-Dimethyl-3-phenyl-1-propyl
4-bromobenzenesulfonate (1a) reacted rapidly with phenyl-
(2a), 4-tolyl- (2b), and 4-methoxyphenylboronic acid (2c) in
the presence of Pd(PPh3)4 to give the corresponding
biphenylsulfonates 3a–3c in good yields (entries 1–3).
Neopentyl 4-bromobenzenesulfonate (1b) showed a similar
reactivity with 1a toward 2b (entry 4), which shows that the
remote alkyl moiety does not influence the reaction.
This paper reports our efforts in preparing a variety of
unsymmetrical terphenyls via the sequential carbon–carbon
cross-coupling reactions of neopentyl bromobenzene-
sulfonates with arylboronic acids and arylmagnesium
bromides (Scheme 1). The results of this study are presented
and discussed.
Scheme 1.
Scheme 2.

C.-H. Cho et al. / Tetrahedron 60 (2004) 4589–4599
Table 1. Coupling reaction of bromobenzenesulfonates 1 with arylboronic acids 2
4591
Entry
Bromobenzenesulfonate
Arylboronic acid
Time (h)
Biphenylsulfonatea
Yield (%)b
1
6
71
1a
1a
2a
2b
3a
3b
2
6
73
3
4
1a
6
6
74
71
2c
3c
2b
1b
1c
3d
5
2b
15
67
3e
6
2b
6
72
1d
1d
3f
7
2c
6
69
3g
a
R1¼2,2-dimethyl-3-phenyl-1-propyl, R2¼neopentyl.
Isolated yields based on 1.
b
The reaction of 3-bromobenzenesulfonate (1c) with 2b also
produced the desired coupling product 3e in a competitive
yield, although it required more time (15 h) for a complete
reaction (entry 5). 2-Bromobenzenesulfonate (1d) under-
went the coupling process with 2b and 2c in a similar way as
with 1b (entries 6 and 7). There was no evidence showing
that the neighboring neopentyloxysulfonyl group provided a
noticeable steric hindrance in the coupling reaction.
Products 3a-3d were purified by recrystallization, while
3e-3g was isolated by column chromatography.
highest yields were generally obtained when 5 equiv. of 4
were added in two portions, 3 equiv. initially and 2 equiv.
after 8 h.
The biphenylsulfonates showed a higher reactivity than the
benzenesulfonates under the standard reaction conditions.
Most of 3 were completely consumed within 16 h, while the
benzenesulfonates typically required almost 30 h for the
completion. The faster reaction of more conjugated
arenesulfonates has been previously observed in the case
of naphthalenesulfonates. The p-electrons appear to play an
important role by precomplexing with the catalyst prior to
oxidative addition.
The cross-coupling reactions of 3 with 4 were performed in
the presence of dppfNiCl2 in refluxing THF, which were
previously demonstrated to be the most efficient reaction
conditions for the reactions of benzenesulfonates
(Scheme 3).30 Most of those processes proceeded in high
yields to give the corresponding unsymmetrical terphenyls 5
via the substitution of the neopentyloxysulfonyl groups. The
The results of the cross-coupling reactions between various 3
and 4 are summarized in Table 2. 2,2-Dimethyl-3-phenyl-1-
propyl-4-biphenylsulfonate (3a) reacted with phenyl- (4a),
4-tert-butylphenyl- (4b), and 3,5-dimethylphenylmagnesium

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C.-H. Cho et al. / Tetrahedron 60 (2004) 4589–4599
Scheme 3.
bromide (4c) to generate the unsymmetrical p-terphenyls
5a-5c respectively in good yields within 16 h (entries 1–3).
There was no significant difference in the reactivities of
those nucleophiles. However, the sterically hindered 4d
showed a reduced reactivity. Even though more time (50 h)
was allowed, the reaction of 3a with 4d generated the
coupling product 5d in only a moderate yield (entry 4).
the large amount of biphenyls derived by the dimerization of
4 made the purification of 5 by column chromatography
difficult in most cases. However, the products 5a-5j could be
easily purified by recrystallization from methanol to give
white solids.
3. Conclusion
The coupling reaction of 3b with 4a, 4b, and 4c also
efficiently produced the corresponding unsymmetrical
terphenyls 5e-5g within 16 h in refluxing THF (entries
5–7). The methyl group on the 40-position of biphenyl-
sulfonates did not have any significant effect on the
reactivity of those reactions. On the other hand, the
reactions of 3c possessing the 40-methoxy group with 4a
and 4b resulted in slightly lower yields, although the
products produced by the cleavage of the C–O bond were
not detected (entries 8 and 9).35 The reaction of 3c with 4d
proceeded slowly, as expected, and gave the reduced yield
(entry 10).
The Suzuki–Miyaura reaction followed by a nickel-
catalyzed cross-coupling reaction allows the introduction
of two different aryl groups into the benzene nucleus by the
sequential substitution of the bromo and neopentyloxy-
sulfonyl groups of the neopentyl bromobenzenesulfonates.
The coupling reaction of biphenylsulfonates with the
arylmagnesium bromides proceeds faster than the corre-
sponding benzenesulfonates. Neopentyl biphenylsulfonates
undergo nickel-catalyzed reactions much faster than
the 2,2-dimethyl-3-phenyl-1-propyl biphenylsulfonates.
2-Biphenylsulfonate showed a lower reactivity than the 3-
and 4-biphenylsulfonates.
The alkyl moiety of the biphenylsulfonates had a significant
influence in the progress of the reactions. Neopentyl
40-methyl-4-biphenylsulfonate (3d) required only 3 h for
the complete reaction with 3 equiv. of 4a (entry 11) while
3b required 16 h for the reaction with 5 equiv. of 4a (entry
5). This result was quite unexpected considering that both
alkyl groups were bulky neopentyl groups. The higher
reactivity of the neopentyl compounds compared to the 2,2-
dimethyl-3-phenyl-1-propyl substrates was constantly
observed in the reactions of 3e-3g.
The procedure described in this paper appears to be a
promising and conceptually straightforward route to the
unsymmetrical terphenyls. The application of this coupling
strategy in the solid-phase organic synthesis (SPOS) is also
in progress and will be reported in due course.
4. Experimental
All reactions were carried out under an inert atmosphere of
Ar. Solvents were distilled from an appropriate drying agent
prior to use: toluene from calcium hydride and THF from
sodium-benzophenone ketyl. Pyridine was dried over CaH2
and distilled. 1H NMR (300 or 500 MHz) and 13C NMR (75
or 125 MHz) were registered in CDCl3 as solvent and
tetramethylsilane (TMS) as internal standard. Chemical
shifts are reported in d units (ppm) by assigning TMS
resonance in the 1H spectrum as 0.00 ppm and CDCl3
resonance in the 13C spectrum as 77.2 ppm. All coupling
constants, J, are reported in hertz (Hz). Analytical and
preparative HPLC was performed with an instrument
equipped with a UV detector set at 254 nm. Octadecylsilane
coated columns, 4.6£250 mm or 20£250 mm, with 5 or
10 mm particle size were used for analytical or preparative
runs, respectively. A flow rate of 5 mL/min was used. GC
analysis was performed on a bonded 5% phenylpolysiloxane
BPX 5 capillary column (SGE, 30 m, 0.32 mm i.d.).
The bulkiness of the biphenyl moieties also had a great
effect on the reactivity of biphenylsulfonates 3. The reaction
of 3-biphenylsulfonate (3e) and 2-biphenylsulfonate (3f)
required 8 and 15 h, respectively for the complete reaction
with only 3 equiv. of 4a (entries 12 and 13). The ortho-
phenyl group to the alkyloxysulfonyl substituent appears to
significantly hinder the approach of the Ni catalyst to C–S
bonds. The 40-methoxy-2-biphenylsulfonate (3g), which
even contains a slightly deactivating methoxy group,
required 16 h for the complete reaction with 5 equiv. of
4b to produce 5m, and showed a reduced yield (entry 14).
The reaction of 3g with the sterically hindered 4d was
exceptionally slow in forming the o-terphenyl (5n) in a
lower yield.
Even though no significant levels of byproducts originating
from the biphenylsulfonates 3 were observed in this study,

C.-H. Cho et al. / Tetrahedron 60 (2004) 4589–4599
Table 2. Nickel-catalyzed coupling of biphenylsulfonates 3 with aryl Grignard reagents 4
4593
Entry
1
Biphenylsulfonate
Grignard reagent
Time (h)
16
Product
Yield (%)a
84
3a
5a
5b
4a
4b
2
3
3a
3a
16
16
82
80
5c
4c
4
3a
50
5d
54
4d
4a
5
6
3b
3b
16
16
5e
5f
81
76
4b
4c
7
3b
16
5g
75
8
9
3c
3c
4a
4b
16
16
5h
5i
73
75
10
11
3c
4d
50
3
5j
51
83
3d
4ab
5e
12
13
3e
3f
4ab
8
5k
5l
75
66
4ab
15
14
3g
3g
4b
4d
16
72
5m
69
38
15
5n
a
Isolated yields based on 3.
3 equiv. only.
b

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C.-H. Cho et al. / Tetrahedron 60 (2004) 4589–4599
Column chromatography was performed on silica gel 60,
70–230 mesh. Analytical thin-layer chromatography (TLC)
was performed using Merck Kieselgel 60 F254 precoated
plates (0.25 mm) with a fluorescent indicator and visualized
with UV light (254 and 365 nm) or by iodine vapor staining.
Electron impact (EI, 70 eV) was used as the ionization
method for the mass spectrometry. Mass data are reported in
mass units (m/z). Melting points were obtained using a
Barnstead/Thermolyne MEL-TEMP apparatus and are
uncorrected. 4-Tolyl- (2b), 4-methoxyphenylboronic acid
(2c) were prepared according to a literature procedure.36
3,5-Dimethylphenyl- (4c, 0.5 M, THF) and 2,4-dimethyl-
phenylmagnesium bromide (4d, 0.5 M, THF) were prepared
by reacting magnesium turnings with the appropriate
organic halides in THF. DppfNiCl2 was prepared
according to a literature procedure.37 [mp 282–283 8C
(lit. mp 283–284 8C)]. Phenylboronic acid 2a and phenyl-
(4a, 1.0 M, THF) and 4-tert-butylphenylmagnesium
bromide (4b, 2.0 M, Et2O) were purchased and used as
received.
305.9925. Found: 305.9936. Anal. Calcd for
C11H15BrO3S: C, 43.01; H, 4.92. Found: C, 42.95; H, 4.89.
4.1.3. Neopentyl 3-bromobenzenesulfonate (1c). The title
compound was prepared by the reaction of neopentyl
alcohol (0.36 g, 4.09 mmol) with m-bromobenzenesulfonyl
chloride (0.95 g, 3.72 mmol). The crude compound was
purified by recrystallization from n-hexane to give 1c
(0.93 g, 81%) as a white solid: TLC Rf 0.51 (Et2O:n-
hexane¼1:1); mp 44–45 8C; 1H NMR (300 MHz, CDCl3) d
0.92 (s, 9H), 3.72 (s, 2H), 7.45 (dd, J¼8.1, 7.9 Hz, 1H), 7.79
(ddd, J¼8.1, 2.0, 1.0 Hz, 1H), 7.85 (ddd, J¼7.9, 1.7, 1.0 Hz,
1H), 8.06 (dd, J¼2.0, 1.7 Hz, 1H); 13C NMR (125 MHz,
CDCl3) d 26.2 (£3), 31.9, 80.3, 123.3, 126.5, 130.9, 130.9,
136.9, 138.1; HRMS (EI, 70 eV) Calcd for C11H15BrO3S
(Mþ): 305.9925. Found: 305.9969.
4.1.4. Neopentyl 2-bromobenzenesulfonate (1d). The title
compound was prepared by the reaction of neopentyl
alcohol (0.57 g, 6.46 mmol) with o-bromobenzenesulfonyl
chloride (1.5 g, 5.87 mmol). The crude compound was
purified by column chromatography (Et2O:n-hexane¼1:4)
to afford 1d (1.23 g, 68%) as a viscous colorless oil: TLC Rf
4.1. General procedure for the preparation of neopentyl
bromobenzenesulfonates 1
1
0.56 (Et2O:n-hexane¼1:1); H NMR (300 MHz, CDCl3) d
To the alcohol (51.7 mmol) in chloroform (50 mL) at 0 8C,
was added pyridine (103 mmol) dropwise over a period of
20 min and bromobenzenesulfonyl chloride (47.0 mmol) in
small portions. This reaction mixture was stirred at room
temperature for 12 h and diluted with Et2O and then 0.1%
aqueous HCl. The separated organic layer was washed with
0.1% aq. HCl (2£30 mL), water (3£50 mL), and a brine;
dried over MgSO4; and concentrated in vacuo. The crude
bromobenzenesulfonates 1 were purified by either
recrystallization or column chromatography.
0.96 (s, 9H), 3.73 (s, 2H), 7.48–7.55 (m, 2H), 7.77–7.82
(m, 1H), 8.09–8.14 (m, 1H); 13C NMR (75 MHz, CDCl3) d
26.0 (£3), 31.5, 80.4, 120.6, 127.8, 132.0, 132.2, 134.8,
135.7; HRMS (EI, 70 eV) Calcd for C11H15BrO3S (Mþ):
305.9925. Found: 305.9948.
4.2. General procedure for the preparation of
biphenylsulfonates 3
To a solution of 1 (5.22 mmol) and Pd(PPh3)4 (0.157 mmol,
0.181 g) in toluene (12 mL) was added 2.0 M aqueous
Na2CO3 (6.0 mL) under an Ar atmosphere. To the resulting
mixture was added 2 (5.74 mmol), which was dissolved in
ethanol (3 mL). The reaction mixture was heated at reflux
for 6 h (15 h for 1c) with vigorous stirring. Upon cooling to
room temperature, 30% hydrogen peroxide (0.3 mL) was
added to oxidize the residual boronic acid. The mixture was
stirred at room temperature for ca. 1 h and diluted with
EtOAc. The organic layer was washed with water and brine;
dried over MgSO4; filtered through a small pad of silica gel
in a sintered glass filter; and concentrated in vacuo. The
biphenylsulfonates 3 were purified by recrystallization and/
or column chromatography.
4.1.1. 2,2-Dimethyl-3-phenyl-1-propyl 4-bromobenzene-
sulfonate (1a). The title compound was prepared by the
reaction of 2,2-dimethyl-3-phenyl-1-propanol (8.49 g,
51.7 mmol) with p-bromobenzenesulfonyl chloride
(12.0 g, 47.0 mmol). The crude compound was purified by
recrystallization from n-hexane to give 1a (15.7 g, 87%) as a
white solid: TLC Rf 0.38 (Et2O:n-hexane¼1:4); mp
1
82–83 8C; H NMR (300 MHz, CDCl3) d 0.88 (s, 6H),
2.55 (s, 2H), 3.68 (s, 2H), 6.99–7.03 (m, 2H), 7.19–7.22
(m, 3H), 7.71 (d, J¼8.7 Hz, 2H), 7.79 (d, J¼8.7 Hz, 2H);
13C NMR (75 MHz, CDCl3) d 24.1 (£2), 35.4, 44.3, 77.7,
126.6, 128.2 (£2), 129.2, 129.7 (£2), 130.6 (£2), 132.9
(£2), 135.3, 137.5; HRMS (EI, 70 eV) Calcd for
C17H19BrO3S (Mþ): 382.0238. Found: 382.0231. Anal.
Calcd for C17H19BrO3S: C, 53.27; H, 5.00. Found: C, 53.26;
H, 4.94.
4.2.1. 2,2-Dimethyl-3-phenyl-1-propyl 4-biphenyl-
sulfonate (3a). The title compound was prepared by the
reaction of 1a (2.0 g, 5.2 mmol) with 2a (0.7 g, 5.7 mmol) in
the presence of Pd(PPh3)4 (184.9 mg, 0.16 mmol) and 2 M
aq. Na2CO3 (6.0 mL) by using toluene (12.0 mL) as solvent.
The crude product was purified by recrystallization from
n-hexane to give 3a (1.41 g, 71%) as a white solid: TLC Rf
0.43 (Et2O:n-hexane¼1:4); mp 74–75 8C; 1H NMR
(300 MHz, CDCl3) d 0.89 (s, 6H), 2.57 (s, 2H), 3.72 (s,
2H), 7.00–7.05 (m, 2H), 7.15–7.21 (m, 3H), 7.42–7.53 (m,
3H), 7.63 (d, J¼6.7 Hz, 2H), 7.76 (d, J¼8.7 Hz, 2H), 7.99
(d, J¼8.7 Hz, 2H); 13C NMR (75 MHz, CDCl3) d 24.1 (£2),
35.4, 44.3, 77.4, 126.5, 127.6 (£2), 128.1 (£2), 128.2 (£2),
128.7 (£2), 129.0, 129.4 (£2), 130.7 (£2), 134.7, 137.6,
139.3, 147.0; HRMS (EI, 70 eV) Calcd for C23H24O3S
4.1.2. Neopentyl 4-bromobenzenesulfonate (1b). The title
compound was prepared by the reaction of neopentyl
alcohol (0.45 g, 5.11 mmol) with p-bromobenzenesulfonyl
chloride (1.19 g, 4.65 mmol). The crude compound was
purified by recrystallization from n-hexane to give 1b
(0.47 g, 78%) as a white needle solid: TLC Rf 0.48 (Et2O:n-
hexane¼1:1); mp 71 8C (lit.38 mp 70–71 8C); 1H NMR
(300 MHz, CDCl3) d 0.91 (s, 9H), 3.70 (s, 2H), 7.74 (dd,
J¼8.9, 8.9 Hz, 4H); 13C NMR (75 MHz, CDCl3) d 26.1
(£3), 31.8, 80.1, 129.1, 129.6 (£2), 132.8 (£2), 135.4;
HRMS (EI, 70 eV) Calcd for C11H15BrO3S (Mþ):

C.-H. Cho et al. / Tetrahedron 60 (2004) 4589–4599
4595
(Mþ): 380.1446. Found: 380.1403. Anal. Calcd for
C23H24O3S: C, 72.60; H, 6.36. Found: C, 72.67; H, 6.37.
hexane¼1:4) to give 3e (0.28 g, 67%) as a white solid: TLC
Rf 0.45 (Et2O:n-hexane¼1:4); mp 89–90 8C; 1H NMR
(300 MHz, CDCl3) d 0.92 (s, 9H), 2.42 (s, 3H), 3.72 (s, 2H),
7.30 (d, J¼8.2 Hz, 2H), 7.52 (d, J¼8.2 Hz, 2H), 7.61 (t,
J¼7.7 Hz, 1H), 7.85 (dd, J¼7.7, 1.9 Hz, 2H), 8.11 (t,
J¼1.9 Hz, 1H); 13C NMR (125 MHz, CDCl3) d 21.4, 26.2
(£3), 31.9, 80.0, 126.2, 126.3, 127.2 (£2), 129.8, 130.0 (£2),
132.1, 136.2, 136.8, 138.6, 142.6; HRMS (EI, 70 eV) Calcd
for C18H22O3S (Mþ): 318.1290. Found: 318.1259. Anal.
Calcd for C18H22O3S: C, 67.89; H, 6.96. Found: C, 67.75;
H, 6.91.
4.2.2. 2,2-Dimethyl-3-phenyl-1-propyl 40-methyl-4-
biphenylsulfonate (3b). The title compound was prepared
by the reaction of 1a (2.0 g, 5.2 mmol) with 2b (0.78 g,
5.7 mmol) in the presence of Pd(PPh3)4 (184.9 mg,
0.16 mmol) and 2 M aq. Na2CO3 (6.0 mL) by using toluene
(12.0 mL) as solvent. The crude product was purified by
recrystallization from n-hexane to give 3b (1.50 g, 73%) as
a fluffy white solid: TLC Rf 0.45 (Et2O:n-hexane¼1:4); mp
89–91 8C; 1H NMR (300 MHz, CDCl3) d 0.89 (s, 6H), 2.42
(s, 3H), 2.56 (s, 2H), 3.71 (s, 2H), 7.00–7.03 (m, 2H), 7.15–
7.19 (m, 3H), 7.31 (d, J¼8.1 Hz, 2H), 7.53 (d, J¼8.1 Hz,
2H), 7.75 (d, J¼8.4 Hz, 2H), 7.97 (d, J¼8.4 Hz, 2H); 13C
NMR (75 MHz, CDCl3) d 21.3, 24.1 (£2), 35.4, 44.4, 77.4,
126.5, 127.5 (£2), 127.8 (£2), 128.2 (£2), 128.7 (£2), 130.1
(£2), 130.7(£2), 134.4, 136.4, 137.7, 139.1, 146.9; HRMS
(EI, 70 eV) Calcd for C24H26O3S (Mþ): 394.1603. Found:
394.1567. Anal. Calcd for C24H26O3S: C, 73.06; H, 6.64.
Found: C, 73.18; H, 6.65.
4.2.6. Neopentyl 40-methyl-2-biphenylsulfonate (3f). The
title compound was prepared by the reaction of 1d (0.49 g,
1.6 mmol) with 2b (0.25 g, 1.8 mmol) in the presence of
Pd(PPh3)4 (57.78 mg, 0.05 mmol) and 2 M aq. Na2CO3
(2.0 mL) by using toluene (10.0 mL) as solvent. The crude
product was purified by column chromatography (Et2O:n-
hexane¼1:4) to give 3f (0.37 g, 72%) as a colorless oil: TLC
Rf 0.47 (Et2O:n-hexane¼1:4); 1H NMR (300 MHz, CDCl3)
d 0.73 (s, 9H), 2.30 (s, 3H), 3.45 (s, 2H), 7.12 (d, J¼8.0 Hz,
2H), 7.24 (d, J¼8.0 Hz, 2H), 7.28 (dd, J¼7.7, 1.3 Hz, 1H),
7.40 (td, J¼7.7, 1.3 Hz, 1H), 7.52 (td, J¼7.6, 1.2 Hz, 1H),
8.01 (dd, J¼7.9, 1.3 Hz, 1H); 13C NMR (75 MHz, CDCl3) d
21.3, 26.1 (£3), 31.6, 79.4, 127.7, 128.6, 128.7, 129.5 (£2),
130.1, 133.2 (£2), 135.4, 136.4, 138.1, 142.4; HRMS (EI,
70 eV) Calcd for C18H22O3S (Mþ): 318.1290. Found:
318.1280.
4.2.3. 2,2-Dimethyl-3-phenyl-1-propyl 40-methoxy-4-
biphenylsulfonate (3c). The title compound was prepared
by the reaction of 1a (2.0 g, 5.2 mmol) with 2c (0.87 g,
5.7 mmol) in the presence of Pd(PPh3)4 (184.9 mg,
0.16 mmol) and 2 M aq. Na2CO3 (6.0 mL) by using toluene
(12.0 mL) as solvent. The crude product was purified by
recrystallization from n-hexane to give 3c (1.58 g, 74%) as a
white solid: TLC Rf 0.33 (Et2O:n-hexane¼1:4); mp 84–
85 8C; 1H NMR (300 MHz, CDCl3) d 0.89 (s, 6H), 2.57 (s,
2H), 3.71 (s, 2H), 3.88 (s, 3H), 7.00–7.05 (m, 2H), 7.03 (d,
J¼9.1 Hz, 2H), 7.16–7.21 (m, 3H), 7.59 (d, J¼9.1 Hz, 2H),
7.73 (d, J¼8.7 Hz, 2H), 7.96 (d, J¼8.7 Hz, 2H); 13C NMR
(75 MHz, CDCl3) d 24.1 (£2), 35.4, 44.3, 55.5, 77.3, 114.8
(£2), 126.5, 127.4 (£2), 128.2 (£2), 128.7 (£2), 128.8 (£2),
130.7(£2), 131.6, 134.0, 137.6, 146.5, 160.6; HRMS (EI,
70 eV) Calcd for C24H26O4S (Mþ): 410.1552. Found:
410.1597. Anal. Calcd for C24H26O4S: C, 70.22; H, 6.38.
Found: C, 70.25; H, 6.33.
4.2.7. Neopentyl 40-methoxy-2-biphenylsulfonate (3g).
The title compound was prepared by the reaction of 1d
(0.49 g, 1.6 mmol) with 2c (0.27 g, 1.8 mmol) in the
presence of Pd(PPh3)4 (57.58 mg, 0.05 mmol) and 2 M aq.
Na2CO3 (2.0 mL) by using toluene (10.0 mL) as solvent.
The crude product was purified by column chromatography
(Et2O:n-hexane¼1:4) to give 3g (0.37 g, 69%) as a pale
1
yellow oil: TLC Rf 0.28 (Et2O:n-hexane¼1:4); H NMR
(300 MHz, CDCl3) d 0.82 (s, 9H), 3.55 (s, 2H), 3.85 (s, 3H),
6.95 (d, J¼8.9 Hz, 2H), 7.38 (d, J¼8.9 Hz, 2H), 7.36–7.41
(m, 1H), 7.50 (ddd, J¼8.1, 7.6, 1.5 Hz, 1H), 7.63 (ddd,
J¼7.6, 7.6, 1.5 Hz, 1H), 8.11(dd, J¼8.1, 1.5 Hz, 1H); 13C
NMR (75 MHz, CDCl3) d 26.1 (£3), 31.7, 55.5, 79.5, 113.4,
127.6 (£2), 130.0, 130.9(£2), 131.6, 133.3, 133.4, 125.4,
142.2, 159.8; HRMS (EI, 70 eV) Calcd for C18H22O4S
(Mþ): 334.1239. Found: 334.1232.
4.2.4. Neopentyl 40-methyl-4-biphenylsulfonate (3d). The
title compound was prepared by the reaction of 1b (2.0 g,
6.5 mmol) with 2b (0.98 g, 7.2 mmol) in the presence of
Pd(PPh3)4 (231.1 mg, 0.2 mmol) and 2 M aq. Na2CO3
(7.0 mL) by using toluene (14.0 mL) as solvent. The crude
product was purified by recrystallization from n-hexane to
give 3d (1.47 g, 71%) as a white solid: TLC Rf 0.36 (Et2O:n-
hexane¼1:4); mp 116–118 8C; 1H NMR (300 MHz,
CDCl3) d 0.92 (s, 6H), 2.42 (s, 3H), 3.72 (s, 2H), 7.31 (d,
J¼7.7 Hz, 2H), 7.52 (d, J¼8.2 Hz, 2H), 7.74 (d, J¼8.9 Hz,
2H), 7.95 (d, J¼8.7 Hz, 2H); 13C NMR (75 MHz, CDCl3) d
21.2, 26.1 (£3), 31.8, 79.8, 127.4 (£2), 127.7 (£2), 128.7
(£2), 130.1 (£2), 134.5, 136.4, 139.1, 146.8; HRMS (EI,
70 eV) Calcd for C18H22O3S (Mþ): 318.1290. Found:
318.1280.
4.3. General procedure for the preparation of
unsymmetrical terphenyls 5
To a stirred solution of 3 (0.3 mmol) and dppfNiCl2
(0.015 mmol) in dry THF (6 mL) was slowly added aryl
Grignard reagents 4 (0.9 mmol) via syringe at room
temperature. This resulted in a color change from dark
green to dark brown. The reaction mixture was heated at
reflux for ca. 8 h, cooled to room temperature, and an
additional 0.6 mmol of 4 was added to the solution. After
the resulting mixture was heated at reflux for 8–64 h, cooled
to room temperature, and diluted with Et2O. The organic
layer was washed with a 1% aqueous HCl (2£10 mL),
water, and brine; dried over MgSO4; and concentrated in
vacuo. The product 5a-j were purified by recrystallization
from MeOH to give white solids, and the product 5k-n were
purified by preparative HPLC (CH3CN:MeOH¼2:3).
4.2.5. Neopentyl 40-methyl-3-biphenylsulfonate (3e). The
title compound was prepared by the reaction of 1c (0.4 g,
1.3 mmol) with 2b (0.19 g, 1.4 mmol) in the presence of
Pd(PPh3)4, (46.22 mg, 0.04 mmol) and 2 M aq. Na2CO3
(1.5 mL) by using toluene (10.0 mL) as solvent. The crude
product was purified by column chromatography (Et2O:n-

4596
C.-H. Cho et al. / Tetrahedron 60 (2004) 4589–4599
4.3.1. p-Terphenyl (5a). The title compound was prepared
by the reaction of 3a (114.15 mg, 0.30 mmol) with 4a
(1.0 M in THF, 0.9 mL, 0.9 mmolþ0.6 mL, 0.6 mmol) in
the presence of dppfNiCl2. The crude compound was
purified by recrystallization from MeOH to afford 5a
(58.05 mg, 84%) as a white solid: TLC Rf 0.72 (Et2O:n-
hexane¼1:4); mp 211–213 8C [an authentic sample39 (mp
212–213 8C)]; 1H NMR (500 MHz, CDCl3) d 7.36 (t,
J¼7.4 Hz, 2H), 7.46 (t, J¼7.7 Hz, 4H), 7.64 (d, J¼7.2 Hz,
4H), 7.68 (s, 4H); 13C NMR (75 MHz, CDCl3) d 127.3 (£4),
127.6 (£2), 127.8 (£4), 129.1 (£4), 140.4 (£2), 141.0 (£2).
the presence of dppfNiCl2. The crude compound was
purified by recrystallization from MeOH to afford 5e
(59.37 mg, 81%) as a white solid: TLC Rf 0.66 (Et2O:n-
hexane¼1:4); mp 209–210 8C; 1H NMR (500 MHz,
CDCl3) d 2.41 (s, 3H), 7.27 (d, J¼8.0 Hz, 2H), 7.35 (t,
J¼7.4 Hz, 1H), 7.46 (t, J¼7.6 Hz, 2H), 7.55 (d, J¼8.0 Hz,
2H), 7.64 (d, J¼7.6 Hz, 2H), 7.66 (s, 4H); 13C NMR
(75 MHz, CDCl3) d 21.2, 127.2 (£2), 127.3 (£2), 127.6
(£2), 127.6, 127.7 (£2), 129.1 (£2), 129.8 (£2), 137.4,
138.1, 140.1, 140.4, 141.1; HRMS (EI, 70 eV) Calcd for
C19H16 (Mþ): 244.1252. Found: 244.1249.
4.3.2. 4-tert-Butyl-p-terphenyl (5b). The title compound
was prepared by the reaction of 3a (114.15 mg, 0.30 mmol)
with 4b (2.0 M in THF, 0.45 mL, 0.9 mmolþ0.3 mL,
0.6 mmol) in the presence of dppfNiCl2. The crude
compound was purified by recrystallization from MeOH
to afford 5b (70.47 mg, 82%) as a white solid: TLC Rf 0.70
(Et2O:n-hexane¼1:4); mp 180–181 8C; 1H NMR
(500 MHz, CDCl3) d 1.38 (s, 9H), 7.35 (t, J¼7.4 Hz, 1H),
7.46 (t, J¼7.7 Hz, 2H), 7.49 (d, J¼8.3 Hz, 2H), 7.59 (d,
J¼8.3 Hz, 2H), 7.64 (d, J¼7.5 Hz, 2H), 7.67 (s, 4H); 13C
NMR (75 MHz, CDCl3) d 31.5 (£3), 34.7, 126.0 (£2), 127.0
(£2), 127.3 (£2), 127.5, 127.6 (£2), 127.7 (£2), 129.1 (£2),
138.0, 140.1, 140.3, 141.1, 150.7; HRMS (EI, 70 eV) Calcd
for C22H22 (Mþ): 286.1721. Found: 286.1724. Anal. Calcd
for C22H22: C, 92.26; H, 7.74. Found: C, 92.16; H, 7.69.
4.3.6. 4-tert-Butyl-400-methyl-p-terphenyl (5f). The title
compound was prepared by the reaction of 3b (118.35 mg,
0.30 mmol) with 4b (2.0 M in THF, 0.45 mL,
0.9 mmolþ0.3 mL, 0.6 mmol) in the presence of dppfNiCl2.
The crude compound was purified by recrystallization from
MeOH to afford 5f (68.50 mg, 76%) as a pale yellowish
solid: TLC Rf 0.68 (Et2O:n-hexane¼1:4); mp 203–205 8C;
1H NMR (300 MHz, CDCl3) d 1.37 (s, 9H), 2.41 (s, 3H),
7.27 (d, J¼8.7 Hz, 2H), 7.49 (d, J¼8.7 Hz, 2H), 7.55 (d,
J¼8.1 Hz, 2H), 7.59 (d, J¼8.6 Hz, 2H), 7.65 (s, 4H); 13C
NMR (75 MHz, CDCl3) d 21.2, 31.5 (£3), 34.7, 126.0 (£2),
126.9 (£2), 127.1 (£2), 127.5 (£2), 127.6 (£2), 129.8 (£2),
137.3, 138.1, 138.2, 139.9, 140.0, 150.6; HRMS (EI, 70 eV)
Calcd for C23H24 (Mþ): 300.1878. Found: 300.1898.
4.3.7. 3,5-Dimethyl-400-methyl-p-terphenyl (5g). The title
compound was prepared by the reaction of 3b (118.35 mg,
0.30 mmol) with 4c (0.5 M in THF, 1.8 mL, 0.9 mmolþ1.2
mL, 0.6 mmol) in the presence of dppfNiCl2. The crude
compound was purified by recrystallization from MeOH to
afford 5g (61.29 mg, 75%) as a white solid: TLC Rf 0.72
(Et2O:n-hexane¼1:4); mp 151–152 8C; 1H NMR
(500 MHz, CDCl3) d 2.39 (s, 6H), 2.40 (s, 3H), 7.00 (s,
1H), 7.25 (s, 2H), 7.26 (d, J¼8.1 Hz, 2H), 7.54 (d,
J¼8.1 Hz, 2H), 7.64 (s, 4H); 13C NMR (75 MHz, CDCl3)
d 21.2, 21.5 (£3), 125.3 (£2), 127.1 (£2), 127.4 (£2), 127.8
(£2),129.1, 129.8 (£2), 137.4, 138.2, 138.6 (£2), 140.2,
140.4, 141.1; HRMS (EI, 70 eV) Calcd for C21H20 (Mþ):
272.1565. Found: 272.1557. Anal. Calcd for C21H20: C,
92.60; H, 7.40. Found: C, 92.43; H, 7.51.
4.3.3. 3,5-Dimethyl-p-terphenyl (5c). The title compound
was prepared by the reaction of 3a (114.15 mg, 0.30 mmol)
with 4c (0.5 M in THF, 1.8 mL, 0.9 mmolþ1.2 mL,
0.6 mmol) in the presence of dppfNiCl2. The crude
compound was purified by recrystallization from MeOH
to afford 5c (62.00 mg, 80%) as a white solid: TLC Rf 0.70
1
(Et2O:n-hexane¼1:4); mp 88–90 8C; H NMR (500 MHz,
CDCl3) d 2.39 (s, 6H), 7.00 (s, 1H), 7.26 (s, 2H), 7.35 (t,
J¼7.4 Hz, 1H), 7.45 (t, J¼7.7 Hz, 2H), 7.64 (d, J¼7.7 Hz,
2H), 7.65 (s, 4H); 13C NMR (75 MHz, CDCl3) d 21.5 (£2),
125.3 (£2), 127.3 (£2), 127.5, 127.7 (£2), 127.8 (£2), 129.1
(£2), 129.3, 138.6 (£2), 140.2, 140.7, 141.0, 141.1; HRMS
(EI, 70 eV) Calcd for C20H18 (Mþ): 258.1409. Found:
258.1403. Anal. Calcd for C20H18: C, 92.98; H, 7.02. Found:
C, 92.70; H, 7.12.
4.3.8. 4-Methoxy-p-terphenyl (5h). The title compound
was prepared by the reaction of 3c (123.15 mg, 0.30 mmol)
with 4a (1.0 M in THF, 0.9 mL, 0.9 mmolþ0.6 mL,
0.6 mmol) in the presence of dppfNiCl2. The crude
compound was purified by recrystallization from MeOH
to afford 5h (57.01 mg, 73%) as a white solid: TLC Rf 0.54
(Et2O:n-hexane¼1:4); mp 224–225 8C; 1H NMR
(500 MHz, CDCl3) d 3.86 (s, 3H), 7.13 (d, J¼8.7 Hz, 2H),
7.35 (t, J¼7.4 Hz, 1H), 7.45 (t, J¼7.6 Hz, 2H), 7.58 (d,
J¼8.7 Hz, 2H), 7.61–7.65 (m, 6H); 13C NMR (75 MHz,
CDCl3) d 55.5, 114.5 (£2), 127.3 (£2), 127.4 (£2), 127.5,
127.7 (£2), 128.3 (£2), 129.1 (£2), 133.5, 139.8, 140.0,
141.1; HRMS (EI, 70 eV) Calcd for C19H16O (Mþ):
260.1201. Found: 260.1210.
4.3.4. 2,4-Dimethyl-p-terphenyl (5d). The title compound
was prepared by the reaction of 3a (114.15 mg, 0.30 mmol)
with 4d (0.5 M in THF, 1.8 mL, 0.9 mmolþ1.2 mL,
0.6 mmol) in the presence of dppfNiCl2. The crude
compound was purified by recrystallization from MeOH
to afford 5d (41.85 mg, 54%) as a white solid: TLC Rf 0.68
1
(Et2O:n-hexane¼1:4); mp 97–98 8C; H NMR (300 MHz,
CDCl3) d 2.30 (s, 3H), 2.37 (s, 3H), 7.08 (d, J¼7.7 Hz, 1H),
7.12 (s, 1H), 7.19 (d, J¼7.7 Hz, 1H), 7.32–7.48 (m, 5H),
7.63 (d, J¼8.4 Hz, 2H), 7.65 (d, J¼8.4 Hz, 2H); 13C NMR
(75 MHz, CDCl3) d 20.6, 21.2, 126.8, 127.0 (£2), 127.3
(£2), 127.5, 129.1 (£2), 130.0 (£2), 130.0, 131.5, 135.5,
137.3, 138.9, 139.7, 141.2, 141.2; HRMS (EI, 70 eV) Calcd
for C20H18 (Mþ): 258.1409. Found: 258.1406. Anal. Calcd
for C20H18: C, 92.98; H, 7.02. Found: C, 92.84; H, 7.00.
4.3.9. 4-tert-Butyl-400-methoxy-p-terphenyl (5i). The title
compound was prepared by the reaction of 3c (123.15 mg,
0.30 mmol) with 4b (2.0 M in THF, 0.45 mL,
0.9 mmolþ0.3 mL, 0.6 mmol) in the presence of dppfNiCl2.
The crude compound was purified by recrystallization from
4.3.5. 4-Methyl-p-terphenyl (5e). The title compound was
prepared by the reaction of 3b (118.35 mg, 0.30 mmol) with
4a (1.0 M in THF, 0.9 mL, 0.9 mmolþ0.6 mL, 0.6 mmol) in

C.-H. Cho et al. / Tetrahedron 60 (2004) 4589–4599
4597
MeOH to afford 5i (71.19 mg, 75%) as a white solid: TLC
1
13C NMR (75 MHz, CDCl3) d 21.2, 126.6, 127.5 (£2),
127.7 (£2), 128.1 (£2), 128.9 (£2), 130.0, 130.1 (£2), 130.9
(£2), 136.3, 138.8, 140.8, 142.0; HRMS (EI, 70 eV) Calcd
for C19H16 (Mþ): 244.1252. Found: 244.1247. Anal. Calcd
for C19H16: C, 93.40; H, 6.60. Found: C, 93.22; H, 6.57.
Rf 0.55 (Et2O:n-hexane¼1:4); mp 236–237 8C; H NMR
(500 MHz, CDCl3) d 1.37 (s, 9H), 3.86 (s, 3H), 6.99 (d,
J¼8.7 Hz, 2H), 7.48 (d, J¼8.3 Hz, 2H), 7.58 (d, J¼8.7 Hz,
2H), 7.58 (d, J¼8.2 Hz, 1H), 7.62 (d, J¼8.2 Hz, 2H), 7.65
(d, J¼8.3 Hz, 2H); 13C NMR (75 MHz, CDCl3) d 31.5 (£3),
34.7, 55.5, 114.5 (£2), 126.0 (£2), 126.9 (£2), 127.3 (£2),
127.6 (£2), 128.3 (£2), 133.6, 138.2, 139.6, 139.7, 150.6,
159.5; HRMS (EI, 70 eV) Calcd for C23H24O (Mþ):
316.1827. Found: 316.1836. Anal. Calcd for C23H24O: C,
87.30; H, 7.64. Found: C, 87.19; H, 7.59.
4.3.14. 4-tert-Butyl-40-methoxy-(1,10,20,100)-terphenyl
(5m). The title compound was prepared by the reaction of
3g (33.44 mg, 0.10 mmol) with 4b (2.0 M in THF, 0.15 mL,
0.3 mmolþ0.1 mL, 0.2 mmol) in the presence of dppfNiCl2.
The crude compound was purified by preparative HPLC
(CH3CN:MeOH¼2:3) to afford 5m (21.83 mg, 69%) as a
pale yellow oil that solidified upon standing to a yellow
solid: TLC Rf 0.53 (EtOAc:n-hexane¼1:4); 1H NMR
(300 MHz, CDCl3) d 1.30 (s, 9H), 3.79 (s, 3H), 6.73–6.78
(m, 2H), 7.04–7.10 (m, 4H), 7.22–7.26 (m, 2H), 7.35–7.43
(m, 4H); 13C NMR (75 MHz, CDCl3) d 31.4 (£3), 34.5,
55.3, 113.5, 125.1, 127.3 (£2), 127.5 (£2), 129.7, 130.8
(£2), 131.0 (£2), 131.2, 134.4, 138.9, 140.4, 140.7, 149.5,
158.5; HRMS (EI, 70 eV) Calcd for C23H24O (Mþ):
316.1827. Found: 316.1844.
4.3.10. 2,4-Dimethyl-400-methoxyterphenyl (5j). The title
compound was prepared by the reaction of 3c (123.15 mg,
0.30 mmol) with 4d (0.5 M in THF, 1.8 mL, 0.9 mmolþ1.2
mL, 0.6 mmol) in the presence of dppfNiCl2. The crude
compound was purified by recrystallization from MeOH to
afford 5j (44.12 mg, 51%) as a white solid: TLC Rf 0.56
(Et2O:n-hexane¼1:4); mp 136–137 8C; 1H NMR
(300 MHz, CDCl3) d 2.30 (s, 3H), 2.38 (s, 3H), 3.86 (s,
3H), 7.00 (d, J¼8.7 Hz, 2H), 7.08 (d, J¼7.7 Hz, 1H), 7.12
(s, 1H), 7.19 (d, J¼7.7 Hz, 1H), 7.37 (d, J¼8.7 Hz, 2H),
7.59 (d, J¼8.7 Hz, 2H), 7.60 (d, J¼8.7 Hz, 2H); 13C NMR
(75 MHz, CDCl3) d 20.6, 21.2, 55.5, 114.5 (£2), 126.6 (£2),
126.8, 128.3 (£2), 129.9 (£2), 130.0, 131.4, 133.7, 135.5,
137.2, 139.0, 139.3, 140.6, 159.4; HRMS (EI, 70 eV) Calcd
for C21H20O (Mþ): 288.1514. Found: 288.1522. Anal.
Calcd for C21H20O: C, 87.46; H, 6.99. Found: C, 87.53; H,
7.06.
4.3.15. 2,4-Dimethyl-40-methoxy-(1,10,20,100)-terphenyl
(5n). The title compound was prepared by the reaction of
3g (33.44 mg, 0.10 mmol) with 4d (0.5 M in THF, 0.6 mL,
0.3 mmolþ0.4 mL, 0.2 mmol) in the presence of dppfNiCl2.
The crude compound was purified by preparative HPLC
(CH3CN:MeOH¼2:3) to afford 5n (10.96 mg, 38%) as a
pale yellow oil that solidified upon standing to a yellow
solid: TLC Rf 0.52 (EtOAc:n-hexane¼1:4); 1H NMR
(300 MHz, CDCl3) d 1.85 (s, H), 2.30 (s, H), 3.75 (s, 3H),
6.68–6.73 (m, 2H), 6.89 (s, 1H), 6.92 (s, 1H), 6.95 (s, 1H),
7.01–7.06 (m, 3H), 7.31–7.43 (m, 3H); 13C NMR (75 MHz,
CDCl3) d 20.0, 21.2, 55.3, 113.4, 126.4, 126.9 (£2), 127.6
(£2), 130.1, 130.7 (£2), 131.2 (£2), 134.3, 135.8, 136.7,
138.9, 140.5, 141.0, 158.5; HRMS (EI, 70 eV) Calcd for
C19H16 (Mþ): 288.1514. Found: 288.1556.
4.3.11. 4-Methyl-p-terphenyl (5e). The title compound was
prepared by the reaction of 3d (31.84 mg, 0.10 mmol) with
4a (1.0 M in THF, 0.3 mL, 0.3 mmol) in the presence of
dppfNiCl2. The crude compound was purified by recrys-
tallization from MeOH to afford 5e (20.28 mg, 83%) as a
white solid.
4.3.12. 4-Methyl-(1,10,30,100)-terphenyl (5k). The title
compound was prepared by the reaction of 3e (31.84 mg,
0.1 mmol) with 4a (1.0 M in THF, 0.3 mL, 0.3 mmol) in the
presence of dppfNiCl2. The crude compound was purified
by preparative HPLC (CH3CN:MeOH¼2:3) to afford 5k
(18.32 mg, 75%) as a colorless oil that solidified upon
standing to a yellow solid: TLC Rf 0.62 (EtOAc:n-
Acknowledgements
This research was supported by the Chung-Ang University
research grants in 2003.
1
hexane¼1:4); H NMR (500 MHz, CDCl3) d 2.41 (s, 3H),
7.27 (d, J¼8.0 Hz, 2H), 7.37 (t, J¼7.4 Hz, 1H), 7.46 (t,
J¼7.7 Hz, 2H), 7.50 (d, J¼7.5 Hz, 1H), 7.38–7.58 (m, 4H),
7.65 (d, J¼8.0 Hz, 2H), 7.79 (s, 1H); 13C NMR (125 MHz,
CDCl3) d 21.3, 126.1, 126.2, 126.2, 127.3 (£2), 127.5 (£2),
127.6, 129.0 (£2), 129.4, 129.7 (£2), 137.4, 138.5, 141.5,
141.9, 142.0; HRMS (EI, 70 eV) Calcd for C19H16 (Mþ):
244.1252. Found: 244.1240. Anal. Calcd for C19H16: C,
93.40; H, 6.60. Found: C, 93.28; H, 6.57.
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