A novel one-pot synthesis of biaryl derivatives by sequential strategies via Suzuki coupling/Knoevenagel condensation in aqueous medium at room temperature

Article abstract of DOI:10.1002/cjoc.201100700

A novel one-pot synthesis of biaryl derivatives has been developed starting from bromobenzaldehyde and phenylboronic acid in the presence of activated methylene compounds via sequential Suzuki coupling/Knoevenagel condensation in aqueous isopropanol medium at room temperature. Significantly, this strategy afforded a straightforward and efficient approach to construct original biaryls in which a new carbon double bond bound to activated moieties such as nitrile, ester and amide is formed from three simple substrates in a one-pot procedure. Moreover, a wide scope of substrates could effectively participate in the process affording the target products in moderate to excellent yields. Copyright

Full text of DOI:10.1002/cjoc.201100700

FULL PAPER
DOI: 10.1002/cjoc.201100700
A Novel One-pot Synthesis of Biaryl Derivatives by Sequential
Strategies via Suzuki Coupling/Knoevenagel Condensation in
Aqueous Medium at Room Temperature
Zhang, Zhanyi(张展翼)
Zheng, Jia(郑佳)
Du, Qingwei(杜庆伟)
Zhang, Wei(张伟)
Li, Yiqun*(李毅群)
Department of Chemistry, Jinan University, Guangzhou, Guangdong 510632, China
A novel one-pot synthesis of biaryl derivatives has been developed starting from bromobenzaldehyde and
phenylboronic acid in the presence of activated methylene compounds via sequential Suzuki coupling/Knoevenagel
condensation in aqueous isopropanol medium at room temperature. Significantly, this strategy afforded a straight-
forward and efficient approach to construct original biaryls in which a new carbon double bond bound to activated
moieties such as nitrile, ester and amide is formed from three simple substrates in a one-pot procedure. Moreover, a
wide scope of substrates could effectively participate in the process affording the target products in moderate to ex-
cellent yields.
Keywords one pot, Suzuki reaction, Knoevenagel reaction, sequential reaction, aqueous medium
Introduction
the Pd-catalyzed Suzuki catalytic mechanism. Based on
the Suzuki coupling mechanism and base-catalyzed
Knoevenagel condensation mechanism, we are encour-
aged to develop more novel and efficient synthetic
strategies combining Suzuki coupling and Knoevenagel
condensation using bases which will serve as both
dehalogenating agent in Suzuki coupling and catalyst in
Knoevenagel condensation in a one-pot reaction to syn-
thesize a series of multifunctionalized biaryls. To the
best of our knowledge, the strategy of one-pot sequen-
tial Suzuki coupling/Knoevenagel condensation has not
been explored. In our process of developing new syn-
thetic protocols, herein, we reported the use of Na2CO3
as a base in Suzuki coupling and Knoevenagel conden-
sation in order to synthesize a variety of polyfunctional
biaryls.
Multicomponent reactions (MCRs) have become an
efficient and powerful tool in modern synthetic organic
chemistry attribute to their valued features, such as atom
economy, easy purification of products (all the organic
reagents employed are consumed and are incorporated
into the target compound), straightforward reaction de-
sign and constructing target compounds by the introduc-
tion of several diversity elements in a single chemical
event.[1] The search and discovery of new MCRs, there-
fore, have gained tremendous importance. Biaryl de-
rivatives are well known to exhibit a wide range of ap-
plications such as dye,[2] biomedicine,[3] luminescent[4]
or liquid crystal materials.[5] The palladium-catalyzed
Suzuki coupling,[6] has proved to be one of the most
powerful and well-known chemical tools for forming
biaryls. The Knoevenagel reaction has also been termed
as a significant methodology in organic synthesis be-
cause of its remarkable applications in C＝C bond
forming reactions under Lewis bases or Lewis acids
catalysis, such as PVC-TEPA,[7] ZnCl2,[8] etc.
Experimental
General
Pd/C (10 wt% of the substrate) and all other reagents
were used as obtained from commercial sources without
further purification. Melting points were measured on
an ElectrothemalX6 microscopy digital melting point
apparatus (Beijing Tech Instrument Co. Ltd., Beijing,
China). IR spectra were recorded on a Nicolet 6700
FT-IR spectrometer in KBr pellets. Mass spectra were
An amine-free Knoevenagel condensation is of par-
ticular value as it reduces the surroundings damage and
avoiding cumbersome purification processes by using
inorganic bases as catalysts including NaCO3,[9]
K2O-Al2O3,[10] CaO,[11] etc.
1
It is well known that the base plays a key role in the
dehalogenation step and activation of arylbronic acid in
performed on an AB 4000 Q TRAP (USA). H NMR
and 13C NMR spectra were measured on a Bruker
*
E-mail: tlyq@jnu.edu.cn; Fax: ＋86-20-85223271
Received January 10, 2012; accepted February 12, 2012; published online XXXX, 2012.
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cjoc.201100700 or from the author.
Chin. J. Chem. 2012, XX, 1—5
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1

Zhang et al.
FULL PAPER
Avance 300 (300 MHz; Swiss Bruker Corporation,
Switzerland) by use of CDCl3 or DMSO-d6 containing
TMS as the internal standard.
(CAS No. 773083-13-9); 1H NMR (CDCl3, 300 MHz) δ:
8.29 (s, 1H, CH), 8.09 (d, J＝8.4 Hz, 2H, ArH), 7.74 (d,
J＝7.8 Hz, 2H, ArH), 7.57 (d, J＝8.1 Hz, 2H, ArH),
7.31 (d, J＝7.8 Hz, 2H, ArH), 4.45—4.38 (m, 2H,
OCH2), 2.44 (s, 3H, CH3), 1.43 (t, J＝6.9 Hz, 3H, CH3);
IR ν: 3025, 2995, 2903, 2216, 1715, 1596, 1499, 1469,
General procedure for the preparation of biphenyl-
4-methylene malononitrile 4
－
1
A mixture of benzaldehyde 1 (1.0 mmol), phenyl-
boronic acid 2 (1.1 mmol), Pd/C (2.0% mol of Pd) and
Na2CO3 (2.0 mmol) in H2O-isopropanol (V∶V＝1∶1,
6.0 mL) was magnetically stirred at room temperature
for a specific time (monitored by TLC). Then,
malononitrile 3 (1.0 mmol) was added to the reaction
mixture, which was stirred till the end of the reaction
(monitored by TLC). After completion, the Pd/C was
filtered and washed by 50% ethanol (8.0 mL×3). The
filtrate was dried and removed to obtain a crude product
4, which was further purifed by recrystalization from
ethanol. The product of 4m and 4n was purified by
column chromatography.
1364, 1275, 1195, 810 cm .
(E)-3-(4'-Chlorobiphenyl-4-yl)-2-cyanoacrylic
acid ethyl ester (4g) Green solid, m.p. 140—142 ℃
(CAS No. 773082-97-6); 1H NMR (CDCl3, 300 MHz) δ:
8.30 (s, 1H, CH), 8.10 (d, J＝8.1 Hz, 2H, ArH), 7.72 (d,
J＝8.1 Hz, 2H, ArH), 7.59 (d, J＝8.1 Hz, 2H, ArH),
7.47 (d, J＝8.4 Hz, 2H, ArH), 4.46—4.39 (m, 2H,
OCH2), 1.43 (t, J＝7.2 Hz, 3H, CH3); IR ν: 3061, 2981,
2937, 2222, 1715, 1590, 1484, 1442, 1366, 1267, 1191,
－
1
821 cm .
(E)-2-Cyano-3-(4'-fluorobiphenyl-4-yl)-acrylic
acid ethyl ester (4h) White solid, m.p. 129—131 ℃
(CAS No. 773082-98-7); 1H NMR (CDCl3, 300 MHz) δ:
8.29 (s, 1H, CH), 8.09 (d, J＝8.4 Hz, 2H, ArH), 7.70 (d,
J ＝ 8.4 Hz, 2H, ArH), 7.65—7.61 (m, 2H, ArH),
7.22—7.16 (m, 2H, ArH), 4.46—4.38 (m, 2H, OCH2),
1.43 (t, J＝7.2 Hz, 3H, CH3); IR ν: 3063, 2984, 2939,
2223, 1718, 1591, 1494, 1424, 1368, 1265, 1188, 823
2-(4'-Methoxybiphenyl-4-ylmethylene)-malono-
nitrile (4a) Yellow solid, m.p. 155—156 ℃ (Lit.[13]).
1H NMR (CDCl3, 300 MHz) δ: 7.99 (d, J＝8.4 Hz, 2H,
ArH), 7.77 (d, J＝6.9 Hz, 2H, ArH), 7.73 (s, 1H, CH),
7.63 (d, J＝8.7 Hz, 2H, ArH), 7.04 (d, J＝8.7 Hz, 2H,
ArH), 3.90 (s, 3H, OCH3); IR ν: 3031, 2969, 2839, 2221,
－
1
cm .
－
1
(E)-2-Cyano-3-(4'-methoxybiphenyl-4-yl)-acrylic
acid methyl ester (4i) Green solid, m.p. 136—138 ℃
(Lit.[13]); 1H NMR (CDCl3, 300 MHz) δ: 8.30 (s, 1H,
CH), 8.08 (d, J＝8.4 Hz, 2H, ArH), 7.72 (d, J＝8,4 Hz,
2H, ArH), 7.62 (d, J＝8.7 Hz, 2H, ArH), 7.03 (d, J＝8.7
Hz, 2H, ArH), 3.99 (s, 3H, OCH3), 3.91 (s, 3H, OCH3);
IR ν: 3030, 2947, 2840, 2222, 1721, 1590, 1499, 1436,
1602, 1572, 1546, 1497, 1368, 1200, 820 cm .
2-(4'-Methylbiphenyl-4-ylmethylene)-malono-
nitrile (4b) Yellow solid, m.p. 171—172 ℃ (CAS
NO. 771569-90-5); 1H NMR (CDCl3, 300 MHz) δ: 8.00
(d, J＝8.7Hz, 2H, ArH), 7.80 (s, 1H, CH), 7.77 (d, J＝
9.3 Hz, 2H, ArH), 7.57 (d, J＝5.7 Hz, 2H, ArH), 7.33 (d,
J＝8.1 Hz, 2H, ArH), 2.45 (s, 3H, CH3); IR ν: 3027,
－
－
1
1
1327, 1273, 1180, 819 cm .
2914, 2226, 1604, 1582, 1403, 1368, 808 cm .
2-(4'-Chlorobiphenyl-4-ylmethylene)-malononi-
trile (4c) Yellow solid, m.p. 204—205 ℃ (CAS No.
(E)-2-Cyano-3-(4'-methylbiphenyl-4-yl)-acrylic
acid methyl ester (4j) White solid, m.p. 183—184
℃; 1H NMR (CDCl3, 300 MHz) δ: 8.30 (s, 1H, CH),
8.09 (d, J＝8.1 Hz, 2H, ArH), 7.74 (d, J＝8.7 Hz, 2H,
ArH), 7.57 (d, J＝8.4 Hz, 2H, ArH), 7.31 (d, J＝7.8 Hz,
2H, ArH), 3.97 (s, 3H, OCH3), 2.44 (s, 3H, CH3);13C
NMR (DMSO-d6, 75 MHz) δ: 20.73, 53.31, 101.33,
115.84, 126.82, 127.01, 129.73, 129.99, 131.63, 135.52,
138.34, 144.69, 154.57, 162.48; IR ν: 3027, 2949, 2223,
1
771569-42-7); H NMR (CDCl3, 300 MHz) δ: 8.02 (d,
J＝8.7 Hz, 2H, ArH), 7.81 (s, 1H, CH), 7.75 (d, J＝9.3
Hz, 2H, ArH), 7.60 (d, J＝8.4 Hz, 2H, ArH), 7.50 (d,
J＝8.4 Hz, ArH); IR ν: 3023, 2223, 1581, 1544, 1484,
－
1
809 cm .
2-(4'-Fluorobiphenyl-4-ylmethylene)-malononi-
trile (4d) Yellow solid, m.p. 178—179 ℃ (CAS No.
－
1
1
1721, 1594, 1498, 1433, 1271, 1194, 810 cm ; Mass
(ESI) m/z: 278 (M＋1). Anal. calcd for C18H15NO2: C
77.96, H 5.45, N 5.05; found C 78.01, H 5.77, N 5.01.
(E)-3-(4'-Chlorobiphenyl-4-yl)-2-cyano-acrylic
acid methyl ester (4k) White solid, m.p. 165—167
℃; 1H NMR (CDCl3, 300 MHz) δ: 8.31 (s, 1H, CH),
8.10 (d, J＝8.1 Hz, 2H, ArH), 7.72 (d, J＝8.4 Hz, 2H,
Ar H), 7.59 (d, J＝8.7 Hz, 2H, ArH), 7.48 (d, J＝8.4 Hz,
2H, ArH), 3.97 (s, 3H, OCH3); 13C NMR (75 MHz,
DMSO-d6) δ: 53.34, 101.87, 115.73, 127.30, 128.48,
128.75, 128.94, 129.07, 130.59, 131.59, 133.60, 137.22,
143.23, 154.39, 162.37; IR ν: 3032, 2951, 2221, 1722,
771569-43-8); H NMR (CDCl3, 300 MHz) δ: 7.91 (d,
J＝4.2 Hz, 2H, ArH), 7.71 (s, 1H, CH), 7.64 (d, J＝4.2
Hz, 2H, ArH), 7.56—7.51 (m, 2H, ArH), 7.11 (t, J＝8.7
Hz, 2H, ArH); IR ν: 3021, 2225, 1581, 1549, 1497,
－
1
1239, 1197, 814 cm .
(E)-2-Cyano-3-(4'-methoxybiphenyl-4-yl)-acrylic
acid ethyl ester (4e) Green solid, m.p. 98—100 ℃
(CAS No. 773082-85-2); 1H NMR (CDCl3, 300 MHz) δ:
8.28 (s, 1H, CH), 8.08 (d, J＝8.4 Hz, 2H, ArH), 7.72 (d,
J＝8.4 Hz, 2H, ArH), 7.62 (d, J＝9.0 Hz, 2H, ArH),
7.03 (d, J＝8.7 Hz, 2H, ArH), 4.45—4.38 (m, 2H, CH2),
1.43 (t, J＝6.9 Hz, 3H, CH3); IR ν: 3025, 2941, 2840,
2220, 1719, 1590, 1497, 1363, 1440, 1252, 1190, 823
－
1
1594, 1483, 1428, 1396, 1267, 1091, 813 cm ; Mass
(ESI) m/z: 298 (M＋1). Anal. calcd for C17H12ClNO2: C
68.58, H 4.06, N 4.70; found C 68.97, H 2.83, N 4.45.
(E)-2-Cyano-3-(4'-fluorobiphenyl-4-yl)-acrylic
－
1
cm .
(E)-2-Cyano-3-(4-methylbiphenyl-4-yl)-acrylic
acid ethyl ester (4f) White solid, m.p. 139—140 ℃
2
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Chin. J. Chem. 2012, XX, 1—5

Synthesis of Biaryl Derivatives by Sequential Strategies via Suzuki Coupling/Knoevenagel Condensation
acid methyl ester (4l) Green solid, m.p. 138—140 ℃;
1H NMR (CDCl3, 300 MHz) δ: 8.31 (s, 1H, CH), 8.10
(d, J＝8.4 Hz, 2H, ArH), 7.71 (d, J＝8.4 Hz, 2H, ArH),
7.65—7.61 (m, 2H, ArH), 7.22—7.17 (m, 2H, ArH),
3.97 (s, 3H, OCH3); 13C NMR (DMSO-d6, 75 MHz) δ:
53.27, 101.56, 115.72, 115.78, 116.07, 127.20, 129.03,
129.14, 130.19, 131.56, 134.83, 134.87, 143.54, 154.39,
160.89, 162.38, 164.15; IR ν: 3061, 2960, 2223, 1721,
Table 1 Optimization of model domino reaction conditionsa
CHO
+
Pd/C
(1)
B(OH)2
i-PrOH/H2O (V/V=1/1), base, r.t.
Br
CN
(2)
1
MeO
2a
CN
3a
－
1
1596, 1498, 1435, 1270, 1196, 819 cm ; Mass (ESI)
m/z: 282 (M＋1). Anal. calcd for C17H12FNO2: C 72.59,
H 4.30, N 4.98; found C 72.62, H 3.99, N 4.91.
NC
CN
MeO
(E)-2-Cyano-3-(4'-methylbiphenyl-4-yl)-acryl-
amide (4m) White solid, m.p. 202—204 ℃; 1H NMR
(CDCl3, 300 MHz) δ: 8.22 (s, 1H, CH), 8.03 (d, J＝8.4
Hz, 2H, ArH), 7.94 (s, 1H, NH), 7.87 (d, J＝8.4 Hz, 2H,
ArH), 7.80 (s, 1H, NH), 7.67 (d, J＝8.1 Hz, 2H, ArH),
7.31 (d, J＝8.1 Hz, 2H, ArH), 2.36 (s, 3H, CH3); 13C
NMR (75 MHz, DMSO-d6) δ: 20.70, 105.77, 116.66,
126.68, 126.92, 129.68, 130.56, 130.77, 135.69, 138.01,
143.61, 150.04, 162.77; IR ν: 3408, 3308, 3196, 3030,
2923, 2216, 1692, 1589, 1495, 1420, 1372, 1193, 812
4a
Entry Catalyst (mol% of Pd)
Base
Yieldb/%
1
2
3
4
5
6
7
8
Pd/C (1.0%)
Pd/C (2.0%)
Pd/C (3.0%)
Pd/C (2.0%)
Pd/C (2.0%)
Pd/C (2.0%)
Pd/C (2.0%)
Pd/C (2.0%)
Na2CO3
Na2CO3
Na2CO3
67
75
76
Na3PO4•12H2O 70
K2CO3
NaOH
Cs2CO3
NEt3
50
32
52
12
－
1
cm ; Mass (ESI) m/z: 263 (M＋1).
(E)-3-(4'-Chlorobiphenyl-4-yl)-2-cyano-acryl-
amide (4n) Green solid, m.p. 242—244 ℃; 1H NMR
(CDCl3, 300 MHz) δ: 8.23 (s, 1H, CH), 8.05 (d, J＝8.4
Hz, 2H, ArH), 7.95 (s, 1H, NH), 7.90 (d, J＝8.4 Hz, 2H,
ArH), 7.81 (s, 1H, NH), 7.82 (d, J＝8.4 Hz, 2H, ArH),
7.57 (d, J＝8.7 Hz, 2H, ArH); 13C NMR (75 MHz,
DMSO-d6) δ: 106.29, 116.55, 127.21, 128.61, 129.01,
130.75, 131.18, 133.36, 137.40, 142.19, 149.88, 162.69;
IR ν: 3451, 3366, 3305, 3160, 2787, 2209, 1689, 1587,
a Reaction conditions: 4-bromobenzaldehyde (1.0 mmol), 4-meth-
oxyphenylboronic acid (1.1 mmol), malononitrile (1.0 mmol),
base (2.0 mmol), i-PrOH/H2O (V∶V＝1∶1, 6.0 mL), r.t.. b Iso-
lated yields.
1, Entries 6, 7), and weaker organic base, NEt3 (Table 1,
Entry 8), the product yields are much lower than that
with Na2CO3. Thus, Na2CO3 was chosen as base in this
protocol. Increasing the amount of catalyst from 1.0 to
3.0 mol% as using 2.0 equiv. of Na2CO3, the product
yields obtained in 67%, 75% and 76% respectively.
Therefore, 2.0 mol% of the palladium and 2.0 equiv. of
Na2CO3 were enough to complete the reaction.
Encouraged by this result, we further demonstrated
the scope and generality of the present method by the
reaction of 4-bromobenzaldehyde 1 with various aryl-
boronic acids 2 and activated methylene compounds 3
under the above-mentioned conditions. In all cases,
moderate to good yields with good selectivity were ob-
tained. All of results are listed in Table 2. It is worth to
note that the more active malononitrile (Table 2, Entries
1—4) afforded higher yields than those of ethyl cyano-
acetate, methyl cyanoacetate, and cyanoacetamide (Ta-
ble 2, Entries 1—14).
－
1
1480, 1422, 1371, 1198, 813 cm ; Mass (ESI) m/z: 283
(M＋1).
Results and Discussion
Though Kitamura et al.[12] have reported Na3PO4•
12H2 O as the most efficient base in Pd/C-
catalyzed Suzuki coupling in aqueous isopropanol (V∶
V＝1∶1), we found that it is not the best suitable cata-
lyst for Knoevenagel condensation in aqueous media.
Initially, we speculated the effectiveness of various ba-
sic catalysts and the optimum reaction conditions using
4-bromobenzaldehyde (1), 4-methoxyphenylboronic
acid (2a) and malononitrile (3a) as model substrates.
The results of these experiments are shown in Table 1.
As can be seen from Table 1, it was found that
Pd/C-Na2CO3 system showed excellent catalytic activi-
ties. The reaction proceeded smoothly and afforded the
expected product 4a in all cases in satisfactory yields
(Table 1, Entries 1—3). Notably, when 2.0 mol% of the
palladium in couple with Na2CO3 (2.0 mmol) were used,
the yield of the product reached 75% at r.t. in aqueous
isopropanol (V∶V＝1∶1) media (Table 1, Entry 2).
Among the bases screened, Na2CO3 worked best
(Table 1, Entries 1—3). Na3PO4•12H2O afforded the
product with comparable yields (Table 1, Entry 4). Us-
ing stronger bases, such as NaOH and Cs2CO3 (Table
Conclusions
In conclusion, a novel and efficient parallel proce-
dure for the synthesis of multifunctionalized biaryl de-
rivatives were prepared via the one-pot Suzuki cou-
pling/Knoevenagel condensation in aqueous isopropanol
medium at room temperature. This procedure offers
several advantages including mild reaction condition,
convenient procedure and environmental friendliness.
Chin. J. Chem. 2012, XX, 1—5
© 2012 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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3

Zhang et al.
FULL PAPER
Table 2 The synthesis of biaryl derivativesa
NC
R1
Na2CO3, Pd/C (2.0 mol% of Pd )
CN
R
R
B(OH)2
Br
CHO
+
+
R1
i-PrOH/H2O (V:V = 1:1), r.t.
3
2
4
1
R = MeO, Me, Cl, F
R1 = CN, COOEt, COOMe, CONH2
Entry
1
R
R1
Product
Time/h
Yieldb/%
75
NC
CN
MeO
CN
2.5
4.5
5.5
5.5
3
MeO
4a
NC
CN
2
Me
Cl
CN
CN
CN
81
84
74
45
57
57
39
40
50
60
Me
Cl
4b
4c
NC
CN
3
NC
CN
4
F
F
4d
NC
COOEt
5
MeO
Me
Cl
COOEt
COOEt
COOEt
COOEt
COOMe
COOMe
COOMe
COOMe
MeO
Me
Cl
4e
NC
NC
COOEt
COOEt
6
5
4f
7
6
4g
NC
COOEt
8
F
6
F
4h
NC
COOMe
9
MeO
Me
Cl
4
MeO
Me
4i
NC
NC
COOMe
COOMe
COOMe
10
11
6
4j
7
Cl
F
4k
NC
12
4
F
7
37
4l
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Chin. J. Chem. 2012, XX, 1—5

Synthesis of Biaryl Derivatives by Sequential Strategies via Suzuki Coupling/Knoevenagel Condensation
Continued
Yieldb/%
Entry
13
R
R1
Product
Time/h
6
NC
NC
COONH2
COONH2
Me
COONH2
40c
58c
Me
4m
4n
14
Cl
COONH2
7
Cl
a Reaction conditions: 4-bromobenzaldehyde (1.0 mmol), phenylboronic acid (1.1 mmol), 3 (1.0 mmol), Na2CO3 (2.0 mmol), Pd/C (2.0
mol% of Pd), i-PrOH/H2O (V∶V＝1∶1, 6.0 mL), r.t.. b Isolated yields. c Purified by column chromatography.
Giuseppone, N.; Giannakakou, P.; O’Brate, A. J. Am. Chem. Soc.
2004, 126, 12897.
Acknowledgement
This work was supported by the National Natural
Science Foundation of China (Nos. 21072077, 20672046),
and the Guangdong Natural Science Foundation (Nos.
10151063201000051, 8151063201000016).
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