Novel one-pot synthesis of functionalized (Z)-2-arylvinyl bromides

Article abstract of DOI:10.1080/00397910902906511

A novel and versatile one-pot synthesis of functionalized (Z)-2-arylvinyl bromides was developed. The new procedure involved microwave-induced debrominative decarboxylation of cinnamic acid dibromide with Et3N and subsequent esterification in the presence

Full text of DOI:10.1080/00397910902906511

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Novel One-Pot Synthesis of
Functionalized (Z)-2-Arylvinyl
Bromides
Yubo Jiang a & Chunxiang Kuang a
a Department of Chemistry , Tongji University ,
Shanghai, China
Published online: 29 Oct 2009.
To cite this article: Yubo Jiang & Chunxiang Kuang (2009) Novel One-Pot Synthesis of
Functionalized (Z)-2-Arylvinyl Bromides, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 39:23, 4298-4308,
DOI: 10.1080/00397910902906511
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Synthetic Communications1, 39: 4298–4308, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910902906511
Novel One-Pot Synthesis of Functionalized
(Z)-2-Arylvinyl Bromides
Yubo Jiang and Chunxiang Kuang
Department of Chemistry, Tongji University, Shanghai, China
Abstract: A novel and versatile one-pot synthesis of functionalized (Z)-2-
arylvinyl bromides was developed. The new procedure involved microwave-
induced debrominative decarboxylation of cinnamic acid dibromide with Et3N
and subsequent esterification in the presence of dicyclohexyl carbodiimide
(DCC) and dimethyl-aminopyridine (DMAP).
Keywords: (Z)-2-Arylvinyl bromides, debrominative decarboxylation, esterification,
one-pot synthesis
INTRODUCTION
(Z)-2-Arylvinyl bromides are important building blocks in organic
synthesis, especially as intermediates for carbon–carbon and carbon–
heteroatom bond formation by transition-metal-catalyzed coupling
reactions.[1,2] The coupling products from functionalized (Z)-2-arylvinyl
bromides have found numerous applications in the preparation of phar-
maceuticals, functional polymeric material, and natural products.[3–6]
Although there is a need to incorporate functional groups into (Z)-
2-arylvinyl bromides to find novel functionalized compounds, available
synthetic methods are limited in scope. Traditional methods for prepara-
tion of (Z)-2-arylvinyl bromides can be classified into two major
categories. The first method is palladium-catalyzed hydrogenolysis of
Received November 1, 2008.
Address correspondence to Prof. Chunxiang Kuang, Department of Chemistry,
Tongji University, Siping Road 1239, Shanghai 200092, China. E-mail: kuangcx@
tongji.edu.cn
4298

Functionalized (Z)-2-Arylvinyl Bromides
4299
Scheme 1. One-pot synthesis of functionalized (Z)-2-arylvinyl bromides 4.
1,1-dibromo-1-alkenes by tributyltin hydride.[3] The second method is the
debrominative decarboxylation of cinnamic acid dibromides.[4–9] This
method might be one of the most useful method for synthesis of (Z)-1-
bromo-1-alkenes because the starting a,b-unsaturated acids are readily
available and the procedure is very simple. Generally, these methods
are not tolerant to reactive groups such as alkenyl, alkynyl, or aldehyde
groups. Hence, it is extremely difficult to apply these methods to the
preparation of (Z)-2-arylvinyl bromides bearing various functional
groups.
In this article, we report a novel synthetic route for preparing
functionalized (Z)-2-arylvinyl bromides (4) bearing various groups
from anti-2,3-dibromo-3-(4-carboxyphenyl)propanoic acid 1 in one pot
(Scheme 1). The reaction is operationally simple and can be easily carried
out. Moreover, most product molecules carry three functional groups,
such as vinyl bromide, ester, and other functional groups, as compared
to those already reported.
RESULTS AND DISCUSSION
The first step of this route was carried out under microwave-induced con-
ditions and gave (Z)-4-(2-bromovinyl)benzoic acid 2 in dimethylforma-
mide (DMF) with good yield and stereoselectivity. Compound 2,
carrying a carboxyl group, is a new synthon for preparation of various
derivatives that are useful intermediates in organic synthesis.[1–6]
The proposed reaction pathway for the present debrominative decar-
boxylation is shown in Scheme 2. The reaction probably proceeds via
trans-elimination involving simultaneous loss of carbon dioxide and
bromide ion to give (Z)-vinyl bromides (Scheme 2).
In the second step, we chose a mild reaction condition, which
involved dicyclohexyl carbodiimide (DCC)–dimethyl-aminopyridine
(DMAP) as coupling agent for the esterification of 2 with alcohols or
phenols 3. Otherwise, the reaction would afford poor yields as a result
of the activity of the vinyl bromide group in other reaction conditions
such as acid or high temperature. Benzene and a DMF–benzene mixture
were found to be the best two solvents for DCC=DMAP coupling

4300
Y. Jiang and C. Kuang
Scheme 2. Proposed reaction pathway for the synthesis of (Z)-4-
(2-bromovinyl)benzoic acid 2.
esterification, whereas other solvents including DMF, CH2Cl2, and
tetrahydrofuran (THF) afforded only poor yields.
To our delight, we found that these two steps can be carried out
in one pot using a DMF–benzene mixture as solvent in the second
step. Various functionalized (Z)-2-arylvinyl bromides were prepared
smoothly by this one-pot method. The results are summarized in
Table 1.
These results indicated that the present reaction was very useful for
the synthesis of both 4-alkoxycarbonyl (4a–c) and 4-aryloxycarbonyl-
(4h–n) (Z)-b-arylvinyl bromides. (Z)-b-Arylvinyl bromides carrying
functional groups such as alkenyl (4d), alkynyl (4e), and vinyl bromide
(4l) were also easily prepared in excellent yields. Even if an
electron-withdrawing group like ꢀCHO or ꢀNO2 (4j–k) was contained
in the molecule, the reaction proceeded stereoselectively in good yields.
Further, acid 2 could be attached to the benzyl alcohol of Wang resin
using a DCC=DMAP coupling procedure at ambient temperature to
afford functionalized (Z)-2-arylvinyl bromide ester 5 in good yield
(Scheme 3). The Wang resin–bound ester 5 carrying an active bromovinyl
group can be applied to combinatorial and solid-phase organic synthesis,
which are efficient techniques for the production of combinatorial
libraries and are extensively used by the pharmaceutical and the agricul-
tural industries. Moreover, 5 is an excellent substrate for Stille, Suzuki,
and Heck reactions.[1]
In summary, we have developed a novel and efficient one-pot syn-
thetic route for preparation of 4-alkoxycarbonyl and 4-aryloxycarbonyl
(Z)-2-arylvinyl bromides bearing various functional groups in good
stereoselectivities and yields. A wide range of functional groups including
aldehyde, ester, nitro, olefin, alkenyl, and alkynyl groups were found to
tolerate the conditions of this method. These functionalized (Z)-2-
arylvinyl bromides are important synthetic targets and widely used
synthons for synthetic chemists.

Functionalized (Z)-2-Arylvinyl Bromides
4301
Table 1. One-pot synthesis of functionalized (Z)-2-arylvinyl bromides 4
Yield of
4 (%)a,b
Entry R-OH 3
Product 4
Alkyl
C2H5
n-C3H7
n-C8H17
3a
90
91
3b
3c
1
2
3
4
5
6
87
3d
3e
3f
85
88
90
92
94
3g
3h
R0
3i
3j
3k
3l
H
CHO
NO2
91
89
81
90
7
(E)-2-Bromovinyl
8
9
3m
3n
94
90
aIsolated yields.
1
bE=Z: > 99=1, determined by H NMR analysis.
Scheme 3. (Z)-4-(2-Bromovinyl)benzoic acid linked to Wang resin.

4302
Y. Jiang and C. Kuang
EXPERIMENTAL
Melting points were recorded using an A. Kruss Optronic GmbH KSPII
¨
melting-point meter and are uncorrected. A Xinyi MAS-II microwave
synthesizer was used for all microwave reactions. Infrared (IR) spectra
were performed on a Nexus Fourier transform (FT)–IR spectrophoto-
1
meter. H and 13C NMR spectra were recorded using a Bruker AM-
300 spectrometer. Elemental analyses were performed with a Perkin-
Elmer 2400 CHNS elemental analyzer. Mass spectra (MS) were recored
by electron impact (EI), MALDI, and electrospray ionization (ESI)
methods. Anti-2,3-dibromo-3-(4-carboxyphenyl)propanoic acid (1) was
prepared according to a literature procedure.[5]
Preparation of (Z)-4-(2-Bromovinyl)benzoic Acid (2)
A mixture of anti-2,3-dibromo-3-(4-carboxyphenyl)-propanoic acid (1,
1.0 mmol), Et3N (1.2 mmol), and DMF (5 mL) was was kept inside a
microwave oven and was irradiated for 40 s at 300 W. The reaction
mixture was acidified to pH 3 with 6% HCl when it was cooled to room
temperature. Then, 30 mL water and 20 mL EtOAc were added to the
mixture, and the organic layer was separated. The aqueous layer was
extracted two times with 15 mL EtOAc. The combined organic layers
were washed with water and brine and dried over anhydrous magnesium
sulfate. Evaporation of the solvent gave the product (Z)-4-(2-bromovinyl)
benzoic acid 2 in 97% yield. White solid; mp 159.7–159.8ꢁC; IR (KBr):
1
1709, 924, 782 cmꢀ1; H NMR (300MHz, DMSO-d6): d ¼ 6.86 (1H, d,
J ¼ 8.0 Hz), 7.34 (1H, d, J ¼ 8.0 Hz), 7.78 (2H, d, J ¼ 8.3 Hz), 7.95 (2H,
d, J ¼ 8.3 Hz). Anal. calcd. for C9H7BrO2: C, 47.61; H, 3.11; Br, 35.19.
Found: C, 47.56; H, 3.04; Br, 35.18.
General Procedure for the One-Pot Synthesis of Functionalized
(Z)-2-Arylvinyl Bromides 4a–n
A mixture of anti-2,3-dibromo-3-(4-carboxyphenyl)propanoic acid (1,
1.0 mmol), Et3N (1.2 mmol), and DMF (4 mL) was kept inside a micro-
wave oven, irradiated for 40 s at 300 W, and then cooled to room tem-
perature. Benzene (1 mL), ROH (3, 1.0 mmol), and DMAP (0.2 mmol)
were added to the reaction mixture and stirred for 10 min. DCC
(1.1 mmol) was added to the reaction mixture and stirred for 24 h at
ambient temperature. After evaporation of the solvent under reduced
pressure, the crude product was purified by column chromatography

Functionalized (Z)-2-Arylvinyl Bromides
4303
on silica gel with EtOAc–hexane to give 4-alkoxycarbonyl and
4-aryloxycarbonyl-(Z)-2-arylvinyl bromides 4a–n.
Data
(Z)-Ethyl-4-(2-bromovinyl)benzoate (4a)
Colorless oil; IR (neat): 1719, 1276, 1103, 930, 777 cmꢀ1 1H NMR
.
(300 MHz, CDCl3): d ¼ 1.40 (3H, t, J ¼ 7.5 Hz), 4.37 (2H, q,
J ¼ 7.5 Hz), 6.62 (1H, d, J ¼ 8.1 Hz), 7.17 (1H, d, J ¼ 8.1 Hz), 7.31
(2H, d, J ¼ 8.3 Hz), 8.14 (2H, d, J ¼ 8.3 Hz). 13C NMR (125 MHz,
CDCl3): d ¼ 166.2, 139.3, 131.7, 130.0, 129.5, 128.8, 108.7, 61.0, 14.3.
EI-MS: m=z (%): 256 [(M þ 2)þ, 38], 254 (Mþ, 39), 228 (46), 226
(45), 211 (99), 209 (100), 181 (85), 102 (86). Anal. calcd. for
C11H11BrO2: C, 51.79; H, 4.35; Br, 31.32. Found: C, 51.72; H, 4.39;
Br, 31.30.
(Z)-Propyl-4-(2-bromovinyl)benzoate (4b)
White solid, mp 87.5–88.5ꢁC; IR (KBr): 1722, 1283, 1086, 934,
785 cmꢀ1
;
1H NMR (300 MHz, CDCl3): d ¼ 1.04 (3H, t, J ¼ 7.5 Hz),
1.82 (2H, m), 4.30 (2H, s, J ¼ 6.8 Hz), 6.62 (1H, d, J ¼ 8.1 Hz), 7.17
(1H, d, J ¼ 8.1 Hz), 7.31 (2H, d, J ¼ 8.3 Hz), 8.14 (2H, d, J ¼ 8.3 Hz).
13C NMR (125 MHz, CDCl3): d ¼ 165.9, 140.3, 131.2, 130.1, 129.1,
121.7, 109.4, 66.7, 22.1, 10.5. EI-MS: m=z (%): 270 [(M þ 2)þ, 46],
268 (Mþ, 47), 228 (42), 226 (41), 211 (99), 209 (100), 181 (80), 102
(90). Anal. calcd. for C12H13BrO2: C, 53.55; H, 4.87; Br, 29.69. Found:
C, 53.64; H, 4.90; Br, 29.74.
(Z)-Octyl-4-(2-bromovinyl)benzoate (4c)
Colorless oil; IR (neat): 1714, 1271, 1103, 944, 777 cmꢀ1 1H NMR
.
(300 MHz, CDCl3): d ¼ 0.98–1.52 (13H, m), 1.72–1.79 (2H, m), 4.32
(2H, t, J ¼ 6.6 Hz), 6.56 (1H, d, J ¼ 8.1 Hz), 7.12 (1H, d, J ¼ 8.1 Hz),
7.74 (2H, d, J ¼ 8.1 Hz), 8.05 (2H, d, J ¼ 8.1 Hz). 13C NMR (125 MHz,
CDCl3): d ¼ 166.3, 139.2, 131.7, 130.1, 129.4, 128.8, 108.6, 65.2, 31.8,
29.2, 29.1, 28.7, 26.0, 22.6, 14.1. EI-MS: m=z (%): 340 [(M þ 2)þ, 48],
338 (Mþ, 49), 228 (45), 226 (44), 211 (99), 209 (100), 181 (80), 102 (95).
Anal. calcd. for C17H23BrO2: C, 60.18; H, 6.83; Br, 23.55. Found: C,
60.24; H, 6.89; Br, 23.58.

4304
Y. Jiang and C. Kuang
(Z)-Allyl 4-(2-bromovinyl)benzoate (4d)
1
Colorless oil; IR (neat): 3076, 1719, 1421, 1273, 1113, 942, 775 cmꢀ1. H
NMR (300 MHz, CDCl3): d ¼ 4.82–4.84 (2H, m), 5.25–5.30 (1H, m),
5.40–5.43 (1H, m), 5.96–6.08 (1H, m) 6.53–6.56 (1H, m), 7.10 (1H, d,
J ¼ 8.2 Hz), 7.71–7.74 (2H, m), 8.04–8.07 (2H, m). 13C NMR
(125 MHz, CDCl3): d ¼ 65.8, 139.4, 132.1, 131.6, 129.5, 129.4, 128.8,
118.2, 108.7, 65.6. EI-MS: m=z (%): 268 [(M þ 2)þ, 37], 266 (Mþ, 38),
228 (41), 226 (40), 211 (99), 209 (100), 181 (85), 102 (94). Anal. calcd.
for C12H11BrO2: C, 53.96; H, 4.15; Br, 29.91. Found: C, 53.89; H, 4.29;
Br, 29.88.
(Z)-Prop-2-ynyl 4-(2-bromovinyl)benzoate (4e)
1
Colorless oil; IR (neat): 3308, 1714, 1271, 1103, 944, 777, 658 cmꢀ1. H
NMR (300 MHz, CDCl3): d ¼ 2.53 (1H, s), 4.93 (2H, s), 6.56 (1H, d,
J ¼ 8.2 Hz), 7.10 (1H, d, J ¼ 8.2 Hz), 7.73 (2H, d, J ¼ 8.4 Hz), 8.06 (2H,
d, J ¼ 8.4 Hz). 13C NMR (125 MHz, CDCl3): d ¼ 165.3, 139.7, 131.5,
129.7, 129.5, 128.9, 109.0, 77.6, 75.0, 52.5. EI-MS: m=z (%): 266
[(M þ 2)þ, 45], 264 (Mþ, 46), 228 (43), 226 (42), 211 (99), 209 (100),
181 (88), 102 (91). Anal. calcd. for C12H9BrO2: C, 54.37; H, 3.42; Br,
30.14. Found: C, 54.41; H, 3.43; Br, 30.10.
(Z)-Cyclohexyl-4-(2-bromovinyl)benzoate (4f)
Colorless oil; IR (neat): 1714, 1276, 1103, 940, 772 cmꢀ1 1H NMR
.
(300 MHz, CDCl3): d ¼ 0.96–1.96 (10H, m), 5.02 (1H, m), 6.56 (1H, d,
J ¼ 8.1 Hz), 7.12 (1H, d, J ¼ 8.1 Hz), 7.73 (2H, d, J ¼ 8.3 Hz), 8.05 (2H,
d, J ¼ 8.3 Hz). 13C NMR (125 MHz, CDCl3): d ¼ 164.5, 138.1, 130.7,
129.5, 128.4, 127.8, 107.6, 72.1, 30.6, 24.5, 22.6. EI-MS: m=z (%): 310
[(M þ 2)þ, 47], 308 (Mþ, 48), 228 (45), 226 (44), 211 (99), 209 (100),
181 (88), 102 (92). Anal. calcd. for C15H17BrO2: C, 58.27; H, 5.54; Br,
25.84. Found: C, 58.30; H, 5.62; Br, 25.80.
(Z)-Benzyl-4-(2-bromovinyl)benzoate (4g)
Colorless oil; IR (neat): 1713, 1271, 1097, 944, 777 cmꢀ1 1H NMR
.
(300 MHz, CDCl3): d ¼ 5.37 (2H, s), 6.56 (1H, d, J ¼ 8.3 Hz), 7.11 (1H,
d, J ¼ 8.3 Hz), 7.37–7.47 (5H, m), 7.73 (2H, d, J ¼ 8.1 Hz), 8.08 (2H, d,
J ¼ 8.1 Hz). 13C NMR (125 MHz, CDCl3): d ¼ 166.0, 139.4, 136.0,
131.6, 130.2, 129.6, 128.9, 128.6, 128.3, 128.2, 108.8, 66.8. EI-MS: m=z

Functionalized (Z)-2-Arylvinyl Bromides
4305
(%): 318 [(M þ 2)þ, 48], 316 (Mþ, 49), 228 (44), 226 (43), 211 (99), 209
(100), 181 (89), 102 (90). Anal. calcd. for C16H13BrO2: C, 60.59; H,
4.13; Br, 25.19. Found: C, 60.62; H, 4.20; Br, 25.22.
(Z)-5-Isopropyl-2-methylphenyl-4-(2-bromovinyl)benzoate (4h)
Colorless oil; IR (neat): 1729, 1266, 1082, 930, 772 cmꢀ1 1H NMR
.
(300 MHz, CDCl3): d ¼ 1.21 (6H, d, J ¼ 6.9 Hz), 2.35 (3H, s), 3.06 (1H, m),
6.61 (1H, d, J ¼ 8.4 Hz), 6.95 (1H, s), 7.07 (1H, d, J ¼ 7.2 Hz), 7.17
(1H, d, J ¼ 8.4 Hz), 7.24 (1H, s), 7.82 (2H, d, J ¼ 8.3 Hz), 8.22 (2H,
J ¼ 8.3 Hz). 13C NMR (125 MHz, CDCl3): d ¼ 165.0, 148.1, 140.0,
137.2, 136.7, 131.6, 130.1, 129.2, 129.1, 127.2, 126.5, 122.8, 109.1, 27.3,
23.0, 20.8. EI-MS: m=z (%): 360 [(M þ 2)þ, 46], 358 (Mþ, 47), 228 (43),
226 (42), 211 (99), 209 (100), 181 (85), 102 (90). Anal. calcd. for
C19H19BrO2: C, 63.52; H, 5.33; Br, 22.24. Found: C, 63.48; H, 5.38;
Br, 22.38.
(Z)-Phenyl-4-(2-bromovinyl)benzoate (4i)
White solid, mp 84.1–84.2ꢁC; IR (KBr): 1734, 1276, 1072, 935,
772 cmꢀ1
.
1H NMR (300 MHz, CDCl3): d ¼ 6.61 (1H, d, J ¼ 8.3 Hz),
7.16 (1H, d, J ¼ 8.3 Hz), 7.21–7.31 (3H, m), 7.42–7.47 (2H, m), 7.81
(2H, d, J ¼ 8.6 Hz), 8.21 (2H, d, J ¼ 8.6 Hz). 13C NMR (125 MHz,
CDCl3): d ¼ 164.8, 150.9, 140.0, 131.6, 130.7, 130.1, 129.5, 129.0,
125.9, 121.7, 109.2. EI-MS: m=z (%): 304 [(M þ 2)þ, 38], 302 (Mþ,
39), 228 (40), 226 (39), 211 (99), 209 (100), 181 (84), 102 (88). Anal.
calcd. for C15H11BrO2: C, 59.43; H, 3.66; Br, 26.36. Found: C,
59.48; H, 3.69; Br, 26.40.
(Z)-4-(Formylphenyl)-4-(2-bromovinyl)benzoate (4j)
White solid, mp 93.2–93.4ꢁC; IR (KBr): 1741, 1734, 1271, 1072, 940,
741 cmꢀ1
.
1H NMR (300 MHz, CDCl3): d ¼ 6.64 (1H, d, J ¼ 8.3 Hz),
7.18 (1H, d, J ¼ 8.3 Hz), 7.43 (2H, d, J ¼ 8.6 Hz), 7.84 (2H, d, J ¼ 8.4 Hz),
8.00 (2H, d, J ¼ 8.6 Hz), 8.22 (2H, d, J ¼ 8.4 Hz), 10.04 (1H, s). 13C NMR
(125 MHz, CDCl3): d ¼ 190.9, 164.1, 140.5, 134.1, 131.5, 131.3, 130.9,
130.2, 129.2, 126.3, 122.5, 109.6. EI-MS: m=z (%): 332 [(M þ 2)þ, 49],
330 (Mþ, 50), 228 (41), 226 (40), 211 (99), 209 (100), 181 (88), 102 (91).
Anal. calcd. for C16H11BrO3: C, 58.03; H, 3.35; Br, 24.13. Found: C,
58.10; H, 3.30; Br, 24.19.

4306
Y. Jiang and C. Kuang
(Z)-4-(Nitrophenyl)-4-(2-bromovinyl)benzoate (4k)
Yellow solid, mp 112.5–113.5ꢁC; IR (KBr): 1734, 1266, 1067, 930,
772 cmꢀ1
.
1H NMR (300 MHz, CDCl3): d ¼ 6.57 (1H, d, J ¼ 8.4 Hz),
7.10 (1H, d, J ¼ 8.4 Hz), 7.36 (2H, d, J ¼ 9.0 Hz), 7.76 (2H, d, J ¼ 8.0 Hz),
8.14 (2H, d, J ¼ 8.0 Hz), 8.27 (2H, d, J ¼ 9.0 Hz). 13C NMR (125 MHz,
CDCl3): d ¼ 163.8, 155.7, 145.5, 140.7, 131.4, 130.3, 129.2, 127.9, 125.3,
122.6, 109.7. EI-MS: m=z (%): 349 [(M þ 2)þ, 47], 347 (Mþ, 48), 228
(40), 226 (39), 211 (99), 209 (100), 181 (85), 102 (93). Anal. calcd. for
C15H10BrNO4: C, 51.75; H, 2.90; Br, 22.95. Found: C, 51.78; H, 2.96;
Br, 22.86.
4-((E)-2-Bromovinyl)phenyl 4-((Z)-2-bromovinyl)benzoate (4l)
White solid, mp 118.5–119.5ꢁC; IR (KBr): 1729, 1271, 1072, 935, 772 cmꢀ1
.
1H NMR (300MHz, CDCl3): d ¼ 6.62 (1H, d, J ¼ 8.1 Hz), 6.77 (1H, d,
J ¼ 8.1 Hz), 7.10–7.18 (4H, m), 7.37 (2H, d, J ¼ 8.4 Hz), 7.82 (2H, d,
J ¼ 8.4 Hz), 8.20 (2H, d, J ¼ 8.4 Hz). 13C NMR (125MHz, CDCl3):
d ¼ 164.6, 150.7, 140.1, 136.2, 133.8, 131.5, 130.1, 129.1, 127.2, 126.1, 122.1,
109.3, 106.7. EI-MS: m=z (%): 410 [(M þ 4)þ, 10], 408 [(M þ 2)þ, 80],
406 (Mþ, 40), 228 (41), 226 (40), 211 (99), 209 (100), 181 (83), 102
(91). Anal. calcd. for C17H12Br2O2: C, 50.03; H, 2.96; Br, 39.16. Found:
C, 50.08; H, 3.01; Br, 39.12.
(Z)-Naphthalen-2-yl-4-(2-bromovinyl)benzoate (4m)
White solid, mp 126.4–126.9ꢁC; IR (KBr): 1734, 1266, 1067, 925 cmꢀ1
.
1H NMR (300 MHz, CDCl3): d ¼ 6.62 (1H, d, J ¼ 8.3 Hz), 7.17 (1H, d,
J ¼ 8.3 Hz), 7.35–7.38 (1H, m), 7.47–7.54 (2H, m), 7.70 (1H, d,
J ¼ 2.4 Hz), 7.82–7.93 (5H, m), 8.26 (2H, d, J ¼ 8.7 Hz). 13C NMR
(125 MHz, CDCl3): d ¼ 164.9, 148.6, 140.1, 133.8, 131.6, 131.5, 130.1,
129.5, 129.1, 127.8, 127.7, 126.6, 125.8, 121.2, 118.7, 110.7, 109.2. EI-MS:
m=z (%): 354 [(M þ 2)þ, 51], 352 (Mþ, 52), 228 (40), 226 (39), 211 (99),
209 (100), 181 (83), 102 (90). Anal. calcd. for C19H13BrO2: C, 64.61; H,
3.71; Br, 22.62. Found: C, 64.70; H, 3.75; Br, 22.58.
(Z)-Naphthalen-1-yl-4-(2-bromovinyl)benzoate (4n)
White solid, mp 82.0–83.0ꢁC; IR (KBr): 1719, 1261, 925, 767 cmꢀ1
.
1H NMR (300 MHz, CDCl3): d ¼ 6.64 (1H, d, J ¼ 8.1 Hz), 7.19 (1H, d,
J ¼ 8.1 Hz), 7.38 (1H, d, J ¼ 7.2 Hz), 7.50–7.55 (3H, m), 7.79–7.95
(5H, m), 8.34 (2H, d, J ¼ 8.1 Hz). 13C NMR (125 MHz, CDCl3):

Functionalized (Z)-2-Arylvinyl Bromides
4307
d ¼ 164.8, 146.8, 140.2, 134.7, 131.6, 130.2, 129.2, 128.8, 128.1, 126.9,
126.5, 126.1, 125.5, 121.2, 118.2, 109.3. EI-MS: m=z (%): 354
[(M þ 2)þ, 49], 352 (Mþ, 50), 228 (38), 226 (37), 211 (99), 209 (100),
181 (81), 102 (95). Anal. calcd. for C19H13BrO2: C, 64.61; H, 3.71; Br,
22.62. Found: C, 64.71; H, 3.74; Br, 22.66.
Preparation of (Z)-4-(2-Bromovinyl)benzoic Acid
Linked to Wang Resin (5)
The Wang resin (5 mmol, 1.0 mmol=g) was swollen in a minimal amount
of benzene, and (Z)-4-(2-bromovinyl)benzoic acid (2, 15 mmol), DCC
(15 mmol), and DMAP (1 mmol) in benzene (30 mL) were added sequen-
tially to the resin. The resulting mixture was reacted for 24 h. The resin
was filtered and washed consecutively with benzene, CH2Cl2, and metha-
nol (MeOH). The resin was then dried under reduced pressure for 24 h.
The loading of the resin was estimated by IR analysis (vC O: 1736 cmꢀ1).
=
The coupling yield was determined by cleaving 100 mg of the resin with a
solution of 20% trifluoroacetic acid (TFA) in CH2Cl2 for 20 min at ambi-
ent temperature. The solvent mixture was evaporated to provide 2 in 90%
yield. Compound 2 was identical with authentic samples.
ACKNOWLEDGMENTS
The work was supported by the Natural Science Foundation of
Shanghai, China (No. 06ZR14085), the Key Projects of Shanghai in Bio-
medical (No. 08431902700), and by the Scientific Research Foundation
for the Returned Overseas Chinese Scholars, State Education Ministry.
We thank the Instrumental Analysis Center, Tongji University, China,
for assistance.
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