Palladium catalyzed Suzuki-Miyaura coupling with aryl chlorides using a bulky phenanthryl N-heterocyclic carbene ligand

Article abstract of DOI:10.1016/j.tet.2005.05.071

A novel bis-phenanthryl N-heterocyclic carbene (NHC) based palladium acetate catalyst was effective for the coupling of various aryl and vinyl chlorides with organoboron compounds. N,N-Bis-(2,9-dicyclohexyl-10-phenanthryl)- 4,5-dihydroimidazolium chloride 8 (H₂ICP·HCl) with Pd(OAc)₂ and KF·18-c-6 in THF at room temperature gave Suzuki-Miyaura coupling of aryl and vinyl chorides, including unactivated and di-ortho substituted substrates in high yields. Hindered tri- and tetra-ortho substituted products were also efficiently produced. Benzyl chloride was also found to be a useful coupling partner and trimethylboroxine was used to give methylated products. The effect of ligand, base, temperature, solvent, and reaction time are reported along with various substrates including halides and triflates.

Full text of DOI:10.1016/j.tet.2005.05.071

Tetrahedron 61 (2005) 7438–7446
Palladium catalyzed Suzuki–Miyaura coupling with aryl chlorides
using a bulky phenanthryl N-heterocyclic carbene ligand
c
b
b
a,
Chun Song,a Yudao Ma,b, Qiang Chai, Chanqin Ma, Wei Jiang and Merritt B. Andrus
*
*
aBrigham Young University, Department of Chemistry and Biochemistry, C100 BNSN, Provo, UT 84602, USA
bChemistry College of Shandong University, Shanda South Road #27, Jinan, Shandong 250100, People’s Republic of China
cShandong Academy of Medical Science, Jinan, Shandong 250062, People’s Republic of China
Received 4 February 2005; revised 18 May 2005; accepted 20 May 2005
Available online 15 June 2005
Abstract—A novel bis-phenanthryl N-heterocyclic carbene (NHC) based palladium acetate catalyst was effective for the coupling of various
aryl and vinyl chlorides with organoboron compounds. N,N-Bis-(2,9-dicyclohexyl-10-phenanthryl)-4,5-dihydroimidazolium chloride 8
(H2ICP$HCl) with Pd(OAc)2 and KF$18-c-6 in THF at room temperature gave Suzuki–Miyaura coupling of aryl and vinyl chorides,
including unactivated and di-ortho substituted substrates in high yields. Hindered tri- and tetra-ortho substituted products were also
efficiently produced. Benzyl chloride was also found to be a useful coupling partner and trimethylboroxine was used to give methylated
products. The effect of ligand, base, temperature, solvent, and reaction time are reported along with various substrates including halides and
triflates.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
perform well with aryl chloride substrates.8 Fu¨rstner and
Leitner have also investigated NHC ligands for aryl chloride
couplings with alkylboronates.9 Copper carboxylate
additives, reported by Liebeskind et al., can also be used
at lower temperatures and have the advantage of being used
without added base.10 Most recently, Glorius and
co-workers have developed a conformationally flexible
bis-cyclohexyl substituted NHC ligand for aryl chloride
coupling at room temperature.11 In this case di- and tri-ortho
substituted products were formed. We now report the use of
a novel bis-phenanthryl NHC ligand for the efficient
coupling of aryl chlorides at room temperature with
KF$18-c-6 in THF where all substrate types including
electron rich aryl chlorides and vinyl chlorides are shown to
be effective. Hindered products including tri-ortho and
tetrasubstituted products are readily formed from di-ortho
substituted substrates.
Coupling reactions with readily available aryl chlorides
continue to be actively investigated in an effort to develop
new catalysts and to provide economical routes to useful
products.1 Until recently, chloride coupling reactions were
limited to activated, electron poor, and aromatic hetero-
cyclic substrates. Typical conditions include the use of
palladium–phosphine catalysts at elevated temperatures in
polar solvents. The poor reactivity of aryl chlorides is
attributed to the strength of the aryl–Cl bond compared to
the more active bromides and iodides.2 While advances
have been made with aryl chlorides in a number of coupling
procedures, the Suzuki–Miyaura reaction holds great
promise due to the utility and versatility of the organoborane
coupling partner.3 Seminal studies by Buchwald4 and Fu
extended the process to unactivated, electron rich aryl
chlorides using biaryl aminophosphane ligands with
Pd(OAc)2 and with the bulky tri-t-butylphosphine ligand
at room temperature.5 Building on previous work with
N-heterocyclic carbene (NHC) ligands,6 Herrmann and
co-workers reported the use of a bis-adamantyl–NHC for
Suzuki couplings with aryl chlorides used at ambient
temperature.7 Nolan and others have reported the use of
imidazolium and diazabutadiene ligands with Pd2(dba)3 that
Catalyzed reactions using NHC–palladium complexes
continue to be the subject of intense interest due to their
enhanced reactivity and stability compared to the more
commonly employed phosphines.12 Successful transform-
ations now include Heck,13 Suzuki–Miyaura,14 Hiyama,15
and Kumada16 couplings together with asymmetric hydro-
genation reactions.17 We have previously reported base free
conditions with NHC catalysts for efficient Heck and Suzuki
couplings using reactive aryl diazonium ions,18 as part of an
effort to develop milder, low temperature conditions for
these transformations.19 Bulky bis-phenanthryl NHC
Keywords: Suzuki coupling; Imidazolium; Carbene; Palladium.
*
Corresponding authors. Tel.: C1 801 4228171; fax: C1 801 4220153
(M.B.A.); e-mail: mbandrus@chem.byu.edu
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.05.071

C. Song et al. / Tetrahedron 61 (2005) 7438–7446
Table 1. Effect of ligand and substrate
for use in copper-free Sonogashira coupling reactions.20
7439
ligands, now reported in this study, were initially developed
NHC imidazolium derived ligands provide enhanced
stability and reactivity compared to phosphine ligands due
to strong s-bond donation to the metal coupled with
attenuated back-bonding via N-lone pair donation.12 This
combined electronic effect renders the metal more electron
rich, allowing for more favorable oxidative insertion.
Typically, NHC complexes are formed by treatment of an
imidazolium salt precursor 1 with base to give a free
carbene 2 (Scheme 1). Free carbenes of this type, depending
on the size of the nitrogen substituent, have been shown to
be stable in solution and in crystalline form.21 Treatment
with a metal gives the carbene complex, many of which are
air stable and can be chromatographed. Alternatively, the
NHC–Pd complex can be formed in situ without added base
from the imidazolium precursor. NHC precursors investi-
gated in this study include the well-known non-aromatic
Ligand
R-
Time, h
Yield, %a
4
5
6
7
8
8
H
H
H
H
H
OMe
24
24
24
15
15
15
!1
10
30
67
89
68
a All yields are for isolated, chromatographed materials.
9-phenanthryl-4,5-dihydroimidazolium chloride 6 gave an
improved yield of 30%. The bis-9-cyclohexylphenanthryl
ligand 7 showed further improvement with a 67% yield
after 15 h. The optimal result was finally obtained using
N,N-bis-(2,9-dicyclohexyl-10-phenanthryl)-4,5-dihydro-
imidazolium chloride 8 (H2ICP$HCl) which gave an 89%
isolated yield. This bulky ligand 8 was also found to the
most effective complex for the copper-free Sonogashira
coupling.20 This finding is consistent with previous
observations that have demonstrated that increased steric
shielding of the NHC–palladium complex leads to increased
reactivity.12a,20 Use of the analogous 4,5-dehydro ligand
H2ICP$HCl, gave a somewhat lower yield of 86%. At a 2:1
ligand to palladium ratio, the loading of the catalyst was also
explored. When 1 mol% Pd(OAc)2 was used, together with
2 mol% 8, the yield dropped to 83%. Lowering the catalyst
further to 0.5 mol% gave a reduced yield of 61% after 15 h.
By raising the catalyst amount to 5 mol%, the yield obtained
was increased to 91%. When the ratio of palladium to ligand
was changed to 1:1 (both at 2 mol%), the yield was again
lowered to 77%. At 2:1 palladium to ligand 8 ratio, the yield
was only slightly lowered to 81%. When more ligand was
used, at a 1:3 palladium to ligand ratio, the yield was greatly
lowered to 47%. Initial investigations also included
o-methoxyphenylboronic acid and lower yields were
generally obtained, but the similar trends were observed
with the ligands and catalyst amounts.
N,N-bis-mesityl-4,5-dihydroimidazolium chloride
4
(H2IMes) and N,N-bis-2,6-diisopropylphenyl-4,5-dihydro
chloride 5 (H2IPr) and the bis-phenanthryl imidazolium
salts 6, 7, and 8 reported previously for the Sonogashira
investigation.20 These imidazolium ligands are made from
the corresponding anilines following the established route
of Arduen˜go.21
Numerous additives and bases were explored to optimize
the process using H2ICP$HCl 8 (Table 2) at room
temperature and at 50 8C in THF. Aryl chloride and boronic
acid substrates were used at 1:1.2 ratio. Stoichiometric
cesium fluoride, potassium t-butoxide, potassium fluoride,
Table 2. Effect of base and temperature
Scheme 1.
2. Results and discussion
Base
Time, h
Temperature, 8C
Yield, %
Use of either H2IMes 4 or H2IPr 5 as ligand precursors
produced low yields under all conditions explored for the
coupling of phenyl chloride and aryl boronic acid (Table 1).
Reaction with 2 mol% Pd(OAc)2 and 4 mol% of the ligand
in THF with various additives including KF$18-c-6, gave
only a 10% yield of biaryl product after a 24 h. Use of N,N-
CsF
KO-t-Bu
KF
KF/18-c-6
KF/18-c-6
Na2CO3/15-c-5
15
5
5
15
5
5
Room temperature
50
50
Room temperature
11
32
32
89
96
81
50
50

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C. Song et al. / Tetrahedron 61 (2005) 7438–7446
Table 3. Effect of solvent and time on coupling reactivity
new NHC 8–palladium catalyst combination (Table 3). The
time was held constant at 15 h for THF, dioxane, methanol,
and toluene at room temperature. The highest isolated yield
of product was obtained using THF at 89%. Dioxane, at
56%, was shown to be inferior. Methanol, and toluene
showed less reactivity. The yield was dependent on
temperature over the 15 h time period. At 30 8C, a 91%
yield was obtained and at 50 8C the yield further improved
to 96%. A linear response was obtained when time was
varied and the temperature was maintained. Runs termi-
nated at 6, 12, 18, and 24 h showed an exponential yield
profile with corresponding 30, 71, 88, and 90% isolated
product yields, respectively. Further extension of the
reaction time did not lead to an improvement in yield. A
similar response was noted with o-methoxyphenylboronic
acid at 24 h over a temperature range of 30–50 8C. An
excellent yield of 98% was obtained in this case at 50 8C.
R-
Solvent
Time, h
Temperature, 8C
Yield, %
H
H
H
H
H
OMe
THF
Diox.
MeOH
Tol.
THF
THF
15
15
15
15
15
24
Room temperature
Room temperature
Room temperature
Room temperature
50
89
56
33
21
96
98
50
and others when used alone gave product with low yields
even at elevated temperature. Only when 18-c-6 crown ether
was added in combination with base were high yields finally
obtained. Potassium fluoride, a potent Lewis basic boronic
acid activator in the presence of 18-c-6, gave an excellent
yield of product at both 50 8C, 96% and at room temperature
and in 89% yield after 15 h. The hindered NHC ligand
conditions of Glorius include potassium t-butoxide or
potassium hydride as base together with added cesium
fluoride.11 The bulky diadamantyl-NHC of Herrmann was
used with excess cesium fluoride in dioxane.7
Various electron rich and deficient aryl chloride substrates
were coupled to organoboron compounds using the
palladium–NHC 8 catalyst conditions. Comparisons are
made for each example for reactions performed at both
room temperature and at 50 8C. Electron rich aryl chlorides
have proven to be particularly unreactive and normally
elevated temperatures are needed especially with ortho-
substituted substrates.1 Phenyl chloride coupled to o-tolyl
boronic acid with excellent yields at both temperatures
Solvents were screened along with reaction times using the
Table 4. Electron rich aryl chloride coupling
Ar0Z
ArZ
Temperature, 8C
(Time, h), yield, %
Room temperature
50
(15) 89
(6) 96
(15) 89
(6) 97
(15) 89
(6) 88
(15) 89
(6) 98
Room temperature
50
(24) 89
(6) 99
(24) 87
(8) 98
(36) 57
(8) 87
(24) 84
(8) 96
Room temperature
50
(18) 51
(12) 90
(24) 43
(16) 84
(36) 37
(12) 88
(24) 51
(12) 81
Room temperature
50
(24) 68
(6) 98
(12) 57
(6) 91
(24) 17
(6) 86
(24) 41
(6) 94
Room temperature
50
(24) 51
(12) 89
(16) 37
(12) 88
(24) 11
(24) 81
(18) 37
(12) 88
Room temperature
50
(36) 51
(24) 90
(36) 50
(24) 89
(48) 31
(24) 87
(48) 33
(24) 92

C. Song et al. / Tetrahedron 61 (2005) 7438–7446
7441
Table 5. Electron deficient aryl chloride coupling
Ar0Z
ArZ
Temperature, 8C
(Time, h), yield, %
Room temperature
50
(24) 93
(12) 99
(24) 91
(12) 99
(48) 57
(12) 95
(36) 83
(12) 98
Room temperature
50
(16) 81
(10) 96
(24) 81
(12) 96
(24) 56
(18) 91
(12) 66
(16) 95
Room temperature
50
(6) 92
(12) 99
(12) 91
(8) 97
(18) 90
(12) 97
(8) 90
(8) 97
Room temperature
50
(9) 91
(3) 97
(8) 92
(3) 96
(16) 93
(3) 97
(8) 82
(3) 99
Room temperature
(24) 95
(34) 97
(36) 88
(24) 93
investigated (Table 4). 2,6-Dimethoxyphenyl and
1-naphthyl boronic acids also gave excellent yields.
O-Tolyl chloride required extended reaction times. In
particular, after 36 h with 2,6-dimethoxyphenylboronic
acid, a low yield of 57% was obtained at room temperature.
At 50 8C after 8 h, an 87% yield of tri-ortho-substituted
product was obtained. Similar trends were observed with
1-chloro-2,6-dimethylbenzene. Low yields were seen with
all substrates used at room temperature. However, at 50 8C
with this hindered chloride, excellent yields were found
including the tetra-ortho-substituted product from 2,6-
dimethoxyphenylboronic acid. Previous to this result, only
two other tetra-ortho-substituted Suzuki products have been
reported, one generated from 9-chloroanthracene using a
Table 6. Vinyl boronic acid, pinnacolborane, and boroxazine
ArZ
Temperature, 8C
Organo-borane
(Time, h), yield, %
Room temperature
(24) 68
(6) 96
(24) 81
(5) 96
(12) 31
(6) 88
(12) 51
(10) 91
(12) 57
(6) 98
(12) 78
(10) 91
50
Room temperature
50
Room temperature
(18) 94
(24) 93
(16) 91
Room temperature
(8) 93
(24) 87
(5) 93
(16) 91
(24) 81
(5) 90
(8) 93
(20) 87
(5) 88
50
50
aPinnacolatoborane and boraxazine couplings were performed in THF/H2O (4:1) as solvent.

7442
C. Song et al. / Tetrahedron 61 (2005) 7438–7446
hindered phosphine–palladium catalyst at 110 8C,22 and the
other using a bulky, flexible carbene ligand with
t-butoxide.11b The methoxy substituted chlorobenzenes
also showed poor reactivity at room temperature with low
yields. Again, the yields with these substrates were greatly
improved at higher temperature. p-Chloroaniline, used
previously as a substrate by Fu and Littke,5b also coupled
with success under the bulky NHC 8 conditions. 50 8C
proved to be the optimal temperature for high reactivity in
this case.
Vinyl chlorides were also shown to perform well as
substrates for the coupling conditions with the bulky NHC
ligand 8 (Table 7). Reflux temperature at 50 8C was needed
due the lower reactivity of these halides. NHC ligands have
not been used previously with vinyl chlorides. Tri-t-
butylphosphine ligands have been successful for this class
of substrates when used at elevated temperature. At room
temperature with NHC 8, coupling products were obtained
in very low yields. At 50 8C however, good to excellent
yields of products were obtained will all coupling partners
shown. The only exception was with 2,6-dimethoxy-
phenylboronic acid, where the yields were only moderate.
Benzyl chloride in contrast showed good reactivity even at
room temperature after a 24 h period.
Electron deficient arylchlorides reacted with excellent
yields at room temperature and at 50 8C with the same
range of arylboronic acids under NHC 8–palladium
catalysis (Table 5). The cyano and trifluoromethyl chloro-
benzene substrates required longer reaction times. In
contrast, o-chloronitrobenzene and 4-chloroacetophenone
both gave excellent yields in much reduced time, 6–8 h.
Near quantitative yields were obtained with these chlorides
when the couplings were performed at 50 8C.
2-Chloropyridine gave excellent yields of Suzuki products
with all the boronic acids tested. This result bodes well for
the efficiency of the process with other aromatic hetero-
cycles chlorides.
To round out the study, aryl and vinyl bromides, iodides,
and triflates were also subjected to the new Suzuki
conditions (Table 8). As expected all three showed higher
reaction rates and isolated yields compared to the
corresponding chlorides. When 3-methoxychlorobenzene
was used at room temperature for 24 h with 2,6-
dimethoxyphenylboronic acid, a low 17% yield was
obtained. In contrast all the other halides, including the
triflates were found to be superior.
The coupling reaction conditions were extended to
vinylboronic acid, phenyl pinnacolatoborane, and trimethyl-
boroxine23 for the generation of methylated products
(Table 6). With chlorobenzene, the reaction at 50 8C gave
higher yields, however, methoxy, cyano, and nitro chloro-
benzene all gave excellent yields of stilbene products when
reacted at room temperature with 2-styrylboronic acid. The
pinnacol and boroxine couplings were performed in THF/
H20, 4:1, due to solubility problems when THF alone was
used. In general, phenyl pinnacolatoborane did not perform
as well as the corresponding phenylboronic acid giving
lower yields with extended reaction times. Methylated, tolyl
products were obtained in high yields with all the
arylchlorides shown using trimethylboroxine. In general,
the electron rich substrates again showed somewhat lower
reactivity, and lower yields.
3. Summary
In summary, new conditions for efficient Suzuki–Miyaura
coupling of organo boron compounds with aryl and vinyl
chlorides have been developed. Key to the success of these
reactions, at both room temperature and at 50 8C, is the use
of the bulky NHC ligand N,N-bis-(2,9-dicyclohexyl-10-
phenanthryl)-4,5-dihydroimidazolium chloride 8 (H2-
ICP$HCl) with Pd(OAc)2 and KF$18-c-6 in THF. Electron
rich substrates, including vinyl chlorides couple with aryl,
vinyl, and methyl boron reagents in high yield. Tri and tetra-
ortho substituted products are efficiently produced under
mild conditions. Applications to other palladium catalyzed
coupling reactions are currently under investigation using
these reactive NHC ligands.
Table 7. Vinyl and benzyl chloride–arylborane coupling
ArZ
Temperature, 8C
Aryl-borane
(HO)2B–Ph
(Time, h), yield, %
(24) 68
50
50
(16) 87
(12) 92
(24) 81
(16) 91
(24) 58
(24) 52
50
(16) 77
(24) 83
Room temperature
50
(24) 71
(8) 89
(24) 51
(12) 80
aPinnacolatoborane and boraxazine couplings were performed in THF/H2O (4:1) as solvent.

C. Song et al. / Tetrahedron 61 (2005) 7438–7446
7443
Table 8. Aryl and vinyl halide–arylborane coupling
Ar0Z
RX
(Time, h), yield, %
(3) 97
(1.5) 98
(3) 94
(5) 89
(6) 92
(6) 87
(3) 98
(8) 92
(6) 90
(2) 98
(8) 89
(8) 62
(3) 89
(12) 61
4. Experimental
13C NMR (CDCl3) 56.1, 110.5, 118.2, 128.1, 128.5, 132.2,
139.1, 162.8; MS (m/z) 214.
4.1. General method
1
4.1.6. 4-Trifluoromethylbiphenyl. H NMR (CDCl3) 7.40
(d, 1H, JZ6.9 Hz), 7.47 (m, 2H), 7.60–7.68 (m, 6H); 13C
NMR (CDCl3) 125.8, 127.5, 127.7, 128.7, 129.6, 139.6,
145.1; MS (m/z) 222.
To a flame dried flask under nitrogen were added the organo
halide (0.100 mmol) and the organoboron (0.120 mmol),
followed by Pd(OAc)2 (1.40 mg, 0.002 mmol, 2 mol%),
dihydroimidazolium chloride salt (3.4 mg, 0.004 mmol,
4 mol%), 18-crown-6 (39.6 mg, 0.150 mmol) and KF
(16.8 mg, 0.150 mmol) in anhydrous THF (5 mL). The
resulting suspension was stirred at room temperature or at
reflux temperature (as indicated) for the time shown in the
tables. Progress of the reaction was monitored by TLC.
Upon completion, to the reaction mixture was added water
(15 mL) and the mixture was extracted with ethyl acetate
(2!3 mL). The combined ethyl acetate fraction was
washed 3 times with aqueous brine (5 mL) and dried over
anhydrous magnesium sulphate. The solvent was removed
by rotary evaporation and the crude material was purified by
silica gel chromatography using ethyl acetate/hexanes
(0–20%). The known compounds, with the isolated yields
indicated in the table, were characterized by the individual
data shown below.
1
4.1.7. 2-Cyanobiphenyl. H NMR (CDCl3) 7.41–7.50 (m,
3H), 7.59–7.71 (m, 6H); 13C NMR (CDCl3) 110.8, 118.6,
127.5, 127.9, 128.7, 128.9, 133.1, 137.7, 139.2, 146.0; MS
(m/z) 179.
1
4.1.8. 4-Nitrobiphenyl. H NMR (CDCl3) 7.23–7.61 (m,
7H), 8.21–8.33 (m, 2H); 13C NMR (CDCl3) 124.3, 127.5,
128.5, 134.1, 136.3, 138.2, 145.0; MS (m/z) 199.
1
4.1.9. 2-Phenylpyridine. H NMR (CDCl3) 7.20–7.29 (m,
5H), 7.37–7.40 (m, 2H), 7.75 (m, 1H), 8.68 (m, 1H); MS
(m/z) 155.
1
4.1.10. 4-Aminobiphenyl. H NMR (CDCl3) 5.51 (broad,
2H), 6.81–6.87 (m, 2H), 7.23–7.51 (m, 7H); 13C NMR
(CDCl3) 117.2, 126.7, 126.9, 128.7, 128.9, 131.2, 137.7,
141.0, 146.1; MS (m/z) 169.
4.1.1. Biphenyl. 1H NMR (CDCl3) 7.32–7.68 (m, 10H); MS
(m/z) 154.
4.1.11. 4-Acetylbiphenyl. 1H NMR (CDCl3) 7.18–7.30 (m,
5H), 7.45 (d, 2H, JZ8.6 Hz), 8.00 (d, 2H, JZ8.6 Hz); 13C
NMR (CDCl3) 27.1, 125.8, 129.1, 129.8, 135.9, 136.2,
141.0, 146.8, 196.7; MS (m/z) 196.
1
4.1.2. 2-Methylbiphenyl. H NMR (CDCl3) 2.30 (s, 3H)
7.32–7.68 (m, 9H); MS (m/z) 168.
1
4.1.3. 2,6-Dimethylbiphenyl. H NMR (CDCl3) 1.92 (s,
6H), 7.00–7.03 (m, 1H), 7.07–7.37 (m, 6H); MS (m/z) 182.
1
4.1.12. 2,20-Dimethylbiphenyl. H NMR (CDCl3) 2.31 (d,
6H) 7.17–7.57 (m, 8H); 13C NMR (CDCl3) 21.3, 125.6,
127.1, 129.2, 135.9, 141.1; MS (m/z) 196. MS (m/z) 182.
4.1.4. 2-Methoxylbiphenyl. 1H NMR (CDCl3) 3.86 (s, 3H),
7.02 (d, 1H), 7.09 (t, 1H), 7.37–7.45 (m, 7H); 13C NMR
(CDCl3) 56.5, 111.8, 119.6, 126.8, 127.9, 128.5, 129.9,
131.1, 139.0, 156.1; MS (m/z) 184.
1
4.1.13. 2,20,6-Trimethylbiphenyl. H NMR (CDCl3) 1.93
(s, 6H), 1.97 (s, 3H), 7.00–7.03 (m, 1H), 7.07–7.31 (m, 6H);
13C NMR (CDCl3) 19.6, 21.2, 126.3, 127.5, 128.1, 129.1,
129.8, 135.7, 135.9, 136.2, 141.3, 142.8; MS (m/z) 196.
4.1.5. 3,5-Dimethoxylbiphenyl. 1H NMR (CDCl3) 3.68 (s,
6H), 6.41 (m, 1H), 6.63–6.72 (m, 2H), 7.27–7.57 (m, 5H);
1
4.1.14. 2-Methyl-20-methoxylbiphenyl. H NMR (CDCl3)

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C. Song et al. / Tetrahedron 61 (2005) 7438–7446
2.30 (s, 3H), 368 (s, 6H), 6.41–6.57 (m, 3H), 7.13–7.74 (m,
4H); 13C NMR (CDCl3) 20.3, 56.2110.2, 112.8, 127.6,
130.2, 131.1, 141.9, 159.3; MS (m/z) 228.
4.1.26. 2,6,30,50-Tetramethoxylbiphenyl. 1H NMR
(CDCl3) 3.68 (s, 6H), 3.80 (s, 6H), 6.27–6.42 (m, 2H),
6.73–6.84 (m, 3H), 7.17–7.21 (m, 2H); 13C NMR (CDCl3)
55.3, 55.8, 96.7, 105.2, 124.5, 127.6, 163.7, 165.2; MS (m/z)
274.
4.1.15. 3,5-Dimethoxyl-20-methylbiphenyl. 1H NMR
(CDCl3) 2.31 (s, 3H), 3.66 (s, 6H), 6.39 (m, 1H), 6.65–
6.75 (m, 2H), 7.28–7.59 (m, 4H); 13C NMR (CDCl3) 20.5,
55.8, 111.2, 120.1, 127.3, 128.1, 128.7, 131.8, 138.7, 160.5;
MS (m/z) 228.
4.1.27. 2,6-Dimethoxyl-40-trifluoromethylbiphenyl. 1H
NMR (CDCl3) 3.68 (s, 6H), 6.76 (m, 2H), 7.03–7.11 (m,
2H), 7.26–7.62 (m, 3H); 13C NMR (CDCl3) 55.9, 96.2,
105.2, 122.9, 127.3, 130.8, 130.9, 135.2, 167.2; MS (m/z)
282.
4.1.16. 4-Trifluoromethyl-20-methybiphenyl. 1H NMR
(CDCl3) 2.30 (s, 3H), 7.37 (d, 1H, JZ6.8 Hz), 7.43 (m,
2H), 7.58–7.63 (m, 5H); 13C NMR (CDCl3) 20.1, 125.3,
127.1, 127.3, 128.2, 129.0, 139.2, 144.8; MS (m/z) 236.
4.1.28. 2,6-Dimethoxyl-20-cyanobiphenyl. 1H NMR
(CDCl3) 3.80 (s, 6H), 6.93 (m, 1H), 7.02–7.15 (m, 3H),
7.43 (m, 1H), 7.72 (m, 1H), 7.92 (m, 1H); 13C NMR
(CDCl3) 55.9, 88.1, 104.2, 107.0, 125.9, 127.9, 135.2,
137.1, 166.9; MS (m/z) 239.
4.1.17. 2-Cyano-20-methybiphenyl. 1H NMR (CDCl3) 2.28
(s, 3H), 7.39–7.48 (m, 3H), 7.58–7.70 (m, 5H); 13C NMR
(CDCl3) 19.8, 111.0, 117.8, 127.1, 127.6, 128.0, 128.2,
133.3, 137.7, 139.0, 147.2; MS (m/z) 193.
4.1.29. 2,6-Dimethoxyl-40-nitrobiphenyl. 1H NMR
(CDCl3) 3.80 (s, 6H), 6.82 (m, 2H), 7.13–7.17 (m, 1H),
7.52–7.63 (m, 2H), 8.03–8.12 (m, 2H); 13C NMR (CDCl3)
56.3, 125.8, 126.3, 128.2, 135.7, 135.9, 169.7; MS (m/z)
261.
1
4.1.18. 4-Nitro-20-methybiphenyl. H NMR (CDCl3) 2.29
(s, 3H), 7.19–7.57 (m, 6H), 8.20–8.29 (m, 2H); 13C NMR
(CDCl3) 19.8, 123.8, 126.7, 128.2, 133.7, 135.9, 138.2,
144.8; MS (m/z) 213.
1
4.1.30. 2-(20, 60-Dimethoxyl) pyridine. H NMR (CDCl3)
1
4.1.19. 2-o-Tolylpyridine. H NMR (CDCl3) 2.36 (s, 3H),
7.22–7.31 (m, 4H), 7.35–7.40 (m, 2H), 7.75 (m, 1H), 8.70
(m, 1H); 13C NMR (CDCl3) 19.8, 126.8, 128.7, 129.2,
130.7, 135.9, 136.2, 140.3, 148.8, 160.1; MS (m/z) 169.
3.81 (d, 6H), 6.74 (m, 2H), 7.12–7.15 (m, 1H), 7.42 (m, 2H),
7.37–7.41 (m, 2H), 7.67 (m, 1H), 8.63 (m, 1H); 13C NMR
(CDCl3) 55.9, 104.5, 117.0, 119.2, 122.9, 128.0, 138.6,
139.2, 143.5, 149.8, 162.7; MS (m/z) 215.
4.1.20. 4-Amino-20-methylbiphenyl. 1H NMR (CDCl3)
2.28 (s, 3H), 4.47 (broad, 2H), 6.72 (d, 2H, JZ8.6 Hz),
7.12–7.30 (m, 6H); 13C NMR (CDCl3) 21.2, 114.2, 125.7,
126.2, 128.3, 128.7, 130.2, 137.1, 142.0, 145.3; MS (m/z)
183.
4.1.31. 2,6-Dimethoxyl-40-aminobiphenyl. 1H NMR
(CDCl3) 3.78 (s, 6H), 6.81–6.95 (m, 2H), 7.13–7.27 (m,
2H), 7.42–7.51 (m, 3H); 13C NMR (CDCl3) 55.8, 105.4,
120.7, 125.8, 127.3, 145.8, 161.2; MS (m/z) 229.
4.1.32. 2,6-Dimethoxyl-40-acetylbiphenyl. 1H NMR
(CDCl3) 2.46 (s, 3H), 3.66 (s, 6H), 6.67–6.81 (m, 2H),
7.08–7.15 (m, 3H), 7.73–7.95 (m, 2H); 13C NMR (CDCl3)
25.9, 56.0, 95.7, 105.1, 120.3, 132.2, 133.2, 162.6, 193.7;
MS (m/z) 256.
4.1.21. 4-Acetyl-20-methylbiphenyl. 1H NMR (CDCl3)
2.26 (s, 3H), 7.19–7.26 (m, 4H), 7.42 (d, 2H, JZ8.6 Hz),
7.96 (d, 2H, JZ8.6 Hz); 13C NMR (CDCl3) 20.3, 26.8,
125.2, 128.5, 129.3, 129.7, 135.3, 136.2, 146.2, 197.7; MS
(m/z) 196.
4.1.33. 1-Phenylnaphthalene. 1H NMR (CDCl3) 7.43–8.07
(m, 12H); 13C NMR (CDCl3) 124.5, 126.0, 127.8, 128.2,
128.5, 131.2, 135.6, 143.7; MS (m/z) 204.
4.1.22. 2,6-Dimethoxylbiphenyl. 1H NMR (CDCl3) 3.68 (s,
6H), 6.82 (m, 2H), 6.92–7.05 (m, 2H), 7.28 (m, 1H), 7.38
(m, 1H), 7.57 (m, 2H); 13C NMR (CDCl3) 21.1, 55.8, 91.3,
104.1, 121.3, 128.1, 133.2, 163.7; MS (m/z) 214.
1
4.1.34. 1-o-Tolylnaphthalene. H NMR (CDCl3), 2.23 (s,
3H), 7.29–8.02 (m, 11H); 13C NMR (CDCl3) 21.0, 124.2,
126.3, 127.5, 128.1, 129.1, 129.8, 135.0, 142.1; MS (m/z)
218.
4.1.23. 2,6-Dimethoxyl-20-methylbiphenyl. 1H NMR
(CDCl3) 2.32 (s, 3H), 3.68 (s, 6H), 6.83 (m, 2H), 6.92–
7.07 (m, 1H), 7.31 (m, 1H), 7.38 (m, 1H), 7.58 (m, 2H); 13C
NMR (CDCl3) 56.0, 91.6, 104.3, 120.8, 128.0, 133.2, 163.8;
MS (m/z) 228.
4.1.35. 1-(20,60-Dimethylphenyl) naphthalene. Yield: as in
the table; H NMR (CDCl3) 1.97 (d, 6H), 7.12–8.07 (m,
1
11H); 13C NMR (CDCl3) 19.7, 20.3, 124.1, 126.7, 127.3,
128.1, 129.5, 129.8, 131.2, 137.1, 142.0; MS (m/z) 232.
1
4.1.24. 2,6-Dimethoxyl-20,60-dimethylbiphenyl. H NMR
(CDCl3) 2.31 (d, 6H), 3.66 (d, 6H), 6.83 (m, 2H), 7.28 (m,
1H), 7.31 (m, 1H), 7.62 (m, 2H); 13C NMR (CDCl3) 20.6,
56.0, 91.6, 104.2, 120.5, 128.1, 133.2, 163.1; MS (m/z) 242.
4.1.36. 1-(20-Methoxylphenyl) naphthalene. 1H NMR
(CDCl3) 3.66 (s, 3H), 6.46–6.71 (m, 3H), 7.40–8.17 (m,
8H); 13C NMR (CDCl3) 56.0, 110.9, 118.3, 126.3, 127.5,
128.1, 131.1, 131.7, 131.9, 133.2, 134.0, 160.3; MS (m/z)
234.
4.1.25. 2,6,20-Trimethoxylbiphenyl. 1H NMR (CDCl3)
3.81 (s, 3H), 3.88 (s, 6H), 6.82 (m, 2H), 7.01–7.12 (m,
3H), 7.20–7.25 (m, 2H); 13C NMR (CDCl3) 55.9, 100.1,
106.2, 113.2, 123.7, 123.9, 125.6, 127.1, 128.3, 155.7,
159.7; MS (m/z) 244.
4.1.37. 1-(30,50-Dimethoxylphenyl) naphthalene. 1H NMR
(CDCl3) 3.65 (s, 6H), 6.31 (t, 1H), 6.73 (m, 2H), 7.46–8.29

C. Song et al. / Tetrahedron 61 (2005) 7438–7446
7445
(m, 7H); 13C NMR (CDCl3) 55.6, 111.0, 118.3, 126.2,
127.8, 131.4, 133.5, 134.0, 161.2; MS (m/z) 264.
5H); 13C NMR (CDCl3) 21.2, 23.6, 33.5, 33.6, 125.1, 125.6,
128.9, 134.1, 136.7, 142.6; MS (m/z) 144.
4.1.38. 1-(40-Trifluoromethylphenyl) naphthalene. 1H
NMR (CDCl3) 7.42–7.69 (m, 5H), 7.87–8.21 (m, 6H); 13C
NMR (CDCl3) 120.2, 125.3, 125.9, 126.2, 127.5, 127.8,
133.1, 133.2, 135.6, 147.3; MS (m/z) 272.
4.1.50. 1-Phenyl-4-t-butylcyclohexene. Yield as indicated
in the table; H NMR (CDCl3) 0.93 (s, 9H), 1.22–1.45 (m,
2H), 1.87–2.01 (m, 2H), 2.13–2.32 (m, 3H), 5.53–5.61 (m,
1H), 7.01–7.21 (m, 5H); 13C NMR (CDCl3) 20.1, 24.5, 27.3,
27.6, 32.1, 32.7, 45.2, 125.5, 125.8, 126.3, 128.3, 129.9,
135.7, 138.6, 142.8; MS (m/z) 214.
1
4.1.39. 1-(20-Cyanophenyl) naphthalene. 1H NMR
(CDCl3) 7.47–8.27 (m, 11H); 13C NMR (CDCl3) 118.5,
126.2, 126.9, 128.2, 130.5, 130.9, 131.0, 133.6, 134.1,
137.1; MS (m/z) 229.
4.1.51. 2-Methyl-1-phenylpropene. Yield as indicated in
the table; 1H NMR (CDCl3) 1.70 (d, 3H), 1.90 (d, 3H), 6.22
(m, 1H), 7.09–7.12 (m, 5H); 13C NMR (CDCl3) 19.7, 21.1,
26.5, 124.8, 125.3, 126.5, 129.1, 129.6, 135.1, 136.7, 138.2;
MS (m/z) 132.
4.1.40. 1-(40-Nitrophenyl) naphthalene. 1H NMR (CDCl3)
7.43–7.7.70 (m, 7H), 8.03–8.41 (m, 4H); 13C NMR (CDCl3)
124.1, 125.7, 126.3, 127.2, 127.7, 130.5, 136.8, 137.1,
140.6, 146.1; MS (m/z) 249.
4.1.52. Diphenylmethane. Yield as indicated in the table;
1H NMR (CDCl3) 3.32 (m, 2H), 7.03–7.15 (m, 10H); MS
(m/z) 168.
4.1.41. 2-(10-Naphthalyl) pyridine. 1H NMR (CDCl3)
7.27–8.05 (m, 10H), 8.63 (m, 1H); 13C NMR (CDCl3)
122.2, 124.5, 126.3, 127.1, 127.5, 128.1, 129.3, 139.5,
145.7, 151.2; MS (m/z) 205.
4.1.53. 1-(20,60-Dimethoxylphenyl) cyclopentene. Yield as
indicated in the table; 1H NMR (CDCl3) 2.03–2.35 (m, 2H),
2.38–2.51 (m, 2H), 2.62–2.68 (m, 2H), 3.86 (s, 6H), 6.17
(m, 1H), 6.72 (m, 2H), 7.32 (m, 1H); 13C NMR (CDCl3)
20.3, 23.3, 33.3, 33.5, 55.6, 125.2, 125.7, 129.1, 134.2,
136.7, 142.6, 162.1; MS (m/z) 204.
4.1.42. 1-(40-Aminophenyl) naphthalene. 1H NMR
(CDCl3) 5.45 (broad, 2H), 6.65–6.71 (m, 2H), 7.43–7.68
(m, 7H), 8.12–8.21 (m, 2H); 13C NMR (CDCl3) 115.2,
124.1, 124.5, 125.7, 125.9, 126.2, 127.6, 127.8, 133.1,
134.8, 135.6, 140.4, 148.3; MS (m/z) 219.
4.1.54. 1-(20,60-Dimethoxylphenyl)-4-t-butylcyclohexene.
Yield as indicated in the table; H NMR (CDCl3) 0.91 (s,
1
4.1.43. 1-(40-Acetylphenyl) naphthalene. 1H NMR
(CDCl3) 2.67 (s, 3H), 7.43–7.87 (m, 9H), 8.09–8.21 (m,
2H); 13C NMR (CDCl3) 26.3, 124.1, 124.5, 126.2, 126.7,
128.4, 128.9, 129.8, 142.7, 192.7; MS (m/z) 246.
9H), 1.21–1.43 (m, 2H), 1.85–1.99 (m, 2H), 2.13–2.31 (m,
3H), 5.58–5.62 (m, 1H), 6.72–6.77 (m, 2H), 7.31 (m, 1H);
13C NMR (CDCl3) 20.3, 24.2, 27.4, 27.7, 32.3, 32.7, 45.5,
55.7, 125.5, 125.8, 126.3, 128.3, 130.2, 135.7, 138.5, 142.8,
161.7; MS (m/z) 274.
1
4.1.44. trans-Stillbene. Yield as indicated in the table; H
NMR (CDCl3) 5.87 (d, 1H), 6.45 (d, 1H), 7.18–7.54 (m,
10H); MS (m/z) 180.
4.1.55. 2-Methyl-1-(20,60-dimethoxylphenyl) propene.
Yield as indicated in the table; H NMR (CDCl3) 1.72 (d,
3H), 1.91 (d, 3H), 3.86 (s, 6H), 6.53 (m, 1H), 6.73 (m, 2H),
7.34 (m, 1H); 13C NMR (CDCl3) 19.2, 20.3, 26.1, 55.6,
114.2, 125.8, 125.9, 128.5, 129.1, 134.8, 138.2, 140.1,
160.0; MS (m/z) 192.
1
4.1.45. 2-Methoxyl-trans-stillbene. 1H NMR (CDCl3) 3.80
(s, 3H) 5.85 (d, 1H), 6.46 (d, 1H), 7.13–7.54 (m, 8H); 13C
NMR (CDCl3) 26.3, 56.2, 118.5 124.0, 124.8, 125.1, 126.2,
126.7, 128.4, 128.9, 129.8, 160.0; MS (m/z) 210.
1
4.1.56. 20,60-Dimethoxylphenylmethane. Yield as indi-
4.1.46. trans-2-Cyanostillbene. H NMR (CDCl3) 5.89 (d,
1H), 6.68 (d, 1H), 7.21–7.57 (m, 9H); 13C NMR (CDCl3)
110.2, 117.3, 126.5, 126.7, 127.7, 127.9, 128.4, 128.9,
129.8, 133.0, 136.4, 139.1; MS (m/z) 205.
1
cated in the table; H NMR (CDCl3) 3.32 (m, 2H), 3.82 (s,
6H), 6.64–6.73 (m, 4H) 7.12–7.27 (m, 6H); 13C NMR
(CDCl3) 27.5, 55.8, 108.1, 124.2, 125.2, 125.9, 128.5,
129.1, 134.8, 160.3; MS (m/z) 228.
4.1.47. trans-4-Aminostillbene. Yield as indicated in the
table; 1H NMR (CDCl3) 5.47 (broad, 2H), 6.02 (d, 2H), 6.87
(m, 2H), 6.91 (d, 2H), 7.21–7.53 (m, 7H); 13C NMR
(CDCl3) 110.2, 127.4, 127.7, 128.6, 130.9, 132.3, 148.7; MS
(m/z) 246; MS (m/z) 195.
Acknowledgements
We are grateful for the support provided by Brigham Young
University, the National Institutes of Health (GM57275),
and the Chemical College of Shandong U.
4.1.48. trans-4-Acetylstillbene. Yield as indicated in the
table; 1H NMR (CDCl3) 2.32 (s, 3H), 5.45 (d, 1H), 6.41 (d,
1H), 7.11–7.34 (m, 7H), 7.87 (d, 2H); 13C NMR (CDCl3)
26.1, 128.4, 128.9, 129.8, 132.0, 132.6, 144.7, 195.7; MS
(m/z) 246; MS (m/z) 222.
Supplementary data
4.1.49. 1-Phenylcyclopentene. Yield as indicated in the
table; H NMR (CDCl3) 2.01 (quintet, 2H), 2.47–2.58 (m,
2H), 2.66–2.73 (m, 2H), 6.11 (quintet, 1H), 7.10–7.31 (m,
1
Supplementary data associated with this article can be found
at 10.1016/j.tet.2005.05.071

7446
C. Song et al. / Tetrahedron 61 (2005) 7438–7446
1
Characterization data, including H and 13C NMR spectra,
are provided online with the paper at ScienceDirect.
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