CuI/L-proline-catalyzed coupling reactions of vinyl bromides with activated methylene compounds

Article abstract of DOI:10.1055/s-2006-944227

The Ullmann-type coupling reaction of vinyl bromides and activated methylene compounds under CuI/L-proline in DMSO, at 90 °C in the presence of Cs₂CO₃ gives the corresponding vinyl compounds in moderate to good yields. This is a good method for preparing compounds with multiple functional groups including double bonds, carbonyls, and/or esters. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2006-944227

LETTER
1719
CuI/L-Proline-Catalyzed Coupling Reactions of Vinyl Bromides with
Activated Methylene Compounds
Coupling
Reacti
n
V
inyl Bromides
w
P
ithActivatedM
e
ethylene
C
ompo
,
unds Weixing Qian*
Department of Chemistry, Zhejiang University, Campus Yuquan, Hangzhou, Zhejiang 310028, P. R. of China
E-mail: weixingqian@zju.edu.cn
Received 6 March 2006
vinyl bromides with imidazoles in ionic liquids.9 There
are also some papers regarding the reactions of vinyl
bromides with phenols and aliphatic alcohols.7a,10 To the
best of our knowledge, efficient procedures for the direct
Abstract: The Ullmann-type coupling reaction of vinyl bromides
and activated methylene compounds under CuI/L-proline in DMSO,
at 90 °C in the presence of Cs2CO3 gives the corresponding vinyl
compounds in moderate to good yields. This is a good method for
preparing compounds with multiple functional groups including formation of carbon–carbon bonds via condensation of
double bonds, carbonyls, and/or esters.
vinyl halides with carbanions in the presence of a catalytic
amount of copper or copper salts are relatively scarce.
Here, we wish to report the coupling reaction of vinyl
bromides with activated methylene compounds.
Key words: carbon–carbon coupling reaction, Ullmann-type reac-
tion, activated methylene compounds, copper iodide, vinyl bromide
In order to optimize the coupling reaction conditions, in-
cluding ligands, bases, solvents, and temperature, the re-
action of pentane-2,4-dione was conducted under various
conditions, and the results are listed in Table 1.
Carbon–carbon bond-forming reactions are among the
most important types of bond constructions in organic
chemistry.1 Among many methods available for carbon–
carbon bond-forming reactions, a great deal of effort has
been focused on the development of palladium-catalyzed Table 1 Coupling Reaction of (E)-1-(2-bromovinyl)benzene with
Pentane-2,4-dione under CuI Catalysisa
methods.1i,2 Although some exciting achievements have
already appeared, high costs and toxicity of Pd reagents
limit their application in industry. The Ullmann-type cou-
pling reaction is the most common method for forming a
carbon–carbon bond with copper as the catalyst instead of
Pd.3
O
Br
O
CuI/ligand
+
base/solvent
O
O
Entry Base
Solvent
Ligand
Temp Time Yield
(°C) (h)
90 26
90 20
90 20
90 20
90 20
(%)b
The Hurtley reaction is a carbon–carbon coupling reaction
of activated methylene compounds in the presence of
copper or copper salts. The scope of this type of reaction
is very limited, with only o-bromobenzoic acid and its
closely related bromides being reactive.4 The major draw-
back of this reaction is that in nearly all cases stoichiomet-
ric or even excess amounts of copper salts must be used to
ensure good results.5 Great progress was made in 1993,
when Miura and co-workers reported a coupling reaction
using a catalytic amount of copper salts at 120 °C.6 Today,
there are still several laboratories doing research on mild
Ullmann-type reactions based on employing specific
ligands. Ma’s group found that L-proline and other amino
acids were effective ligands for copper-catalyzed cou-
pling reactions of aryl halides with amines, N-hetero-
cycles, sodium azide, sulfinic acid salts, phenols and 1-
alkynes.3e,7 Buchwald and co-workers also reported vari-
ous copper-catalyzed coupling reactions.3d,8
1
2
3
4
5
Cs2CO3 DMSO
Cs2CO3 DMSO
Cs2CO3 DMSO
L-Proline
None
74
33
Glycine
L-Proline
L-Proline
30
K2CO3
DMSO
18
Na3PO4· DMSO
10H2O
10
6
7
8
9
Cs2CO3 DMF
L-Proline
L-Proline
90 24
90 20
90 24
90 24
90 24
35 60
120 10
20
trace
0
Cs2CO3 p-xylene
Cs2CO3 [Emim]+[BF4]– L-Proline
Cs2CO3 [Bmim]+[BF4]– L-Proline
0
10 Cs2CO3 [Bmim]+[PF6]– L-Proline
0
11 Cs2CO3 DMSO
12 Cs2CO3 DMSO
L-Proline
L-Proline
trace
60
More recently, Ma and co-workers described the coupling
reaction of aryl bromides with activated methylene com-
pounds under CuI/L-proline catalysis.7j Bao’s group re-
ported the L-proline-promoted Ullmann-type reaction of
a Reaction conditions: CuI (0.05 mmol), amino acid (0.1 mmol), (E)-
1-(2-bromovinyl)benzene (0.5 mmol), base (1 mmol), solvent (2.0 g),
N2 atmosphere.
b Isolated yield.
SYNLETT 2006, No. 11, pp 1719–1723
1
2
.0
7
.2
0
0
6
Advanced online publication: 04.07.2006
DOI: 10.1055/s-2006-944227; Art ID: W05006ST
© Georg Thieme Verlag Stuttgart · New York

1720
L. Pei, W. Qian
LETTER
It was found that 10 mol% CuI and 20 mol% L-proline Under the optimized reaction conditions, a brief study of
gave (E)-3-styrylpentane-2,4-dione in 74% isolated yield the generality of the reaction was undertaken with various
(Table 1, entry 1). In the absence of L-proline, the reaction vinyl bromides and activated methylene compounds;11 the
gave only a 33% yield at the same temperature (Table 1, results are summarized in Table 2. It seems that the vinyl-
entry 2), whereas glycine proved to be even worse bromide with an electron-withdrawing group (chloro) on
(Table 1, entry 3). L-Proline, therefore, was crucial to this the phenyl ring gave the best results when coupled with
type of coupling reaction. Other bases such as K2CO3 or pentane-2,4-dione, ethyl acetoacetate, and diethyl mal-
Na3PO4 gave the desired product at 90 °C, in poor 18% onate (Table 2, entries 5–7). However, the electron-donat-
and 10% yields, respectively (Table 1, entries 4 and 5). ing groups such as methyl or methoxy group on the phenyl
Among the solvents examined, the reaction in DMF gave rings retarded the reaction and afforded lower yields
a 20% yield (Table 1, entry 6), while p-xylene provided (Table 2, entries 8–11). This trend is in agreement with
only a trace amount of product (Table 1, entry 7). To our the classical Ullmann-type coupling reaction. Notably,
surprise, when this reaction was performed in ionic some functional vinyl bromides (e.g., chloro, methyl, and
liquids 1-ethyl-3-methylimidazolium tetrafluoroborate methoxy) tolerated the reaction conditions. No desired
[emim]+[BF4]–, 1-butyl-3-methylimidazolium tetrafluoro- coupling product was formed from the reaction with
borate [bmim]+[BF4]– and 1-butyl-3-methylimidazolium (E)-1-(2-bromovinyl)-4-methoxybenzene with diethyl
hexafluorophosphate [bmim]+[PF6] –, no product was de- malonate (Table 2, entry 12). (E)-1-(2-Bromoprop-1-
tected (Table 1, entries 8–10); we repeated the reaction enyl)benzene with some steric hindrance could couple
several times to verify this. By prolonging the reaction with pentane-2,4-dione and gave the corresponding
time to 60 hours at 35 °C, a trace amount of product was product in 60% yield (Table 2, entry 13). We found that
formed (Table 1, entry 11), which indicated that a higher Z-vinyl bromide did not react with 2,4-dione, probably be-
temperature is necessary for the reaction to succeed. The cause of the increased steric hindrance (Table 2, entry
reaction rate increased greatly at elevated temperature 14).9 Of the four activated methylene compounds tested,
(120 °C), but the yield was moderate (Table 1, entry 12), diethyl malonate presented the best reactivity, maybe due
because the product easily decomposed under these con- to its lowest acidity.7j We obtained none of the desired
ditions. Interestingly, a little of water does not influence coupling product when (E)-1-(2-bromovinyl)benzene
the results of the reaction greatly.
reacted with ethyl cyanoacetate (Table 2, entry 4). The
reason for this drawback is not clear yet.
Table 2 Coupling Reaction of Vinyl Bromide with Activated Methylene Compounds under CuI/L-Proline Catalysisa
R1
O
R1
R2
Br
CuI/L-proline
O
+
O
O
Cs2CO3, DMSO, 90 °C
R2
R
R
Entry
Vinyl bromide
R1
R2
Product
Time (h)
26
Yield (%)b
74
O
Br
1
2
Me
Me
EtO
Me
O
O
O
O
EtO
22
76
O
O
O
3
4
5
EtO
19
20
26
80
0
O
O
No reaction
NC
O
O
Br
Me
Me
79
O
O
Cl
Cl
Cl
O
O
6
Me
EtO
23
81
Synlett 2006, No. 11, 1719–1723 © Thieme Stuttgart · New York

LETTER
Coupling Reactions of Vinyl Bromides with Activated Methylene Compounds
1721
Table 2 Coupling Reaction of Vinyl Bromide with Activated Methylene Compounds under CuI/L-Proline Catalysisa (continued)
R1
O
R1
R2
Br
CuI/L-proline
O
O
+
O
O
Cs2CO3, DMSO, 90 °C
R2
R
R
Entry
Vinyl bromide
R1
R2
Product
Time (h)
19
Yield (%)b
84
O
O
7
8
EtO
Me
EtO
O
Cl
O
Br
Me
23
23
20
70
73
77
O
Me
Me
O
9
Me
EtO
EtO
O
O
O
O
Me
O
10
EtO
O
Me
O
Br
11
12
13
Me
EtO
Me
Me
EtO
Me
23
21
28
50
0
O
MeO
MeO
No reaction
O
Br
60
O
O
14
Me
Me
19
trace
Br
O
a Reaction conditions: CuI (0.05 mmol), L-proline (0.1 mmol), vinyl bromides (0.5 mmol), Cs2CO3 (1 mmol), DMSO (2.0 g), N2 atmosphere.
b Isolated yield.
103, 733. (d) Casiraghi, G.; Zanardi, F.; Appendino, G.;
Rassu, G. Chem. Rev. 2000, 100, 1929. (e) Luh, T.-Y.;
Leung, M.-K.; Wong, K.-T. Chem. Rev. 2000, 100, 3187.
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Lautens, M. Chem. Rev. 2003, 103, 169. (h) Svedendahl,
M.; Hult, K.; Berglund, P. J. Am. Chem. Soc. 2005, 127,
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M.; Remorova, A. A. J. Am. Chem. Soc. 2004, 126, 15354.
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Hartwig, J. F. J. Am. Chem. Soc. 2002, 124, 12557.
In conclusion, we have developed a new CuI/L-proline-
catalyzed coupling reaction of vinyl bromides with acti-
vated methylene compounds. The yields of these reactions
are moderate to good. The products obtained by this
method bear a variety of functional groups and are very
useful synthetic intermediates, which can be applied to
further reactions. Other CuI/L-proline-catalyzed coupling
reactions of vinyl bromides is underway in our laboratory.
(b) You, J.; Verkade, J. G. Angew. Chem. Int. Ed. 2003, 42,
5051. (c) You, J.; Verkade, J. G. J. Org. Chem. 2003, 68,
8003. (d) Beare, N. A.; Hartwig, J. F. J. Org. Chem. 2002,
67, 541. (e) Stauffer, S. R.; Beare, N. A.; Stambuli, J. P.;
Hartwig, J. F. J. Am. Chem. Soc. 2001, 123, 4641. (f) Fox,
J. M.; Huang, X.; Chieffi, A.; Buchwald, S. L. J. Am. Chem.
Soc. 2000, 122, 1360. (g) Moradi, W. A.; Buchwald, S. L. J.
Am. Chem. Soc. 2001, 123, 7996. (h) Terao, Y.; Fukuoka,
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2002, 41, 953. (j) Kashin, A. N.; Mitin, A. V.; Beletskaya, I.
Acknowledgment
We are grateful to the Natural Science Foundation of China for
financial support (No. 20572095).
References and Notes
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Synlett 2006, No. 11, 1719–1723 © Thieme Stuttgart · New York

1722
L. Pei, W. Qian
LETTER
P.; Wife, R. Tetrahedron Lett. 2002, 43, 2539. (k) Hamada,
T.; Chieffi, A.; Åhman, J.; Buchwald, S. L. J. Am. Chem.
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Nolan, S. P. Org. Lett. 2002, 4, 4053.
16.4 Hz, CH), 7.34–7.43 (5 H, m, ArH) 16.75 (1 H, s, OH).
13C NMR (100 MHz, CDCl3): d = 24.23, 111.30, 122.73,
126.05, 127.65, 128.66, 134.16, 137.02, 191.16. MS (70
eV): m/z (%) = 209.0992 (43), 176.0828 (100). HRMS (70
eV): m/z calcd for C13H14O2, 202.0988; found: 202.0992.
(E)-Ethyl-2-acetyl-4-phenylbut-3-enoate (Table 2, entry
2): IR (film): 3459.6, 3061.9, 3029.3, 2982.8, 2936.7,
1732.5, 1599.7, 1449.9, 1368.5, 1247.5, 1079.8, 1018.0,
757.9, 699.6 cm–1. 1H NMR (400 MHz, CDCl3): d = 1.29
(1.2 H, t, J = 7.2 Hz, CH3), 1.35 (1.8 H, t, J = 7.2 Hz, CH3),
2.22 (1.8 H, s, CH3), 2.28 (1.2 H, s, CH3), 4.23 (0.8 H, q, J =
7.2 Hz, CH2), 4.24 (0.4 H, s, CH), 4.30 (1.2 H, q, J = 7.2 Hz,
CH2), 6.42 (0.4 H, dd, J = 16.0, 9.2 Hz, CH), 6.58 (0.4 H, d,
J = 16.0 Hz, CH), 6.60 (0.6 H, d, J = 16.0 Hz, CH), 6.74 (0.6
H, d, J = 16.0 Hz, CH), 7.31–7.42 (5 H, m, ArH), 13.37 (0.6
H, s, OH). 13C NMR (100 MHz, CDCl3): d = 14.03, 14.19,
20.28, 28.45, 60.92, 61.68, 63.87, 101.28, 120.99, 121.57,
125.91, 126.56, 127.04, 128.18, 128.54, 128.60, 130.62,
135.36, 135.99, 138.03, 168.41, 172.63, 174.64, 201.38. MS
(70 eV): m/z (%) = 232.1099 (84) [M+], 205.0856 (100),
190.0986 (97), 171.0440 (62). HRMS (70 eV): m/z calcd for
C14H16O3: 232.1094; found: 232.1099.
(3) (a) Hassan, J.; Sévignon, M.; Gozzi, C.; Schulz, E.; Lemaire,
M. Chem. Rev. 2002, 102, 1359. (b) Ley, S. V.; Thomas, A.
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Scholz, U.; Ganzer, D. Synlett 2003, 2428. (d) Hennessy, E.
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(E)-Diethyl-2-styrylmalonate (Table 2, entry 3): IR (film):
2983.3, 2938.7, 2909.6, 1732.6, 1465.2, 1449.4, 1369.3,
1258.4, 1151.3, 1033.8, 967.1, 857.8, 757.9, 692.7 cm–1. 1H
NMR (400 MHz, CDCl3): d = 1.28 (6 H, t, J = 7.2 Hz, CH3),
4.17–4.26 (5 H, m, CH2, CH), 6.42 (1 H, dd, J = 16.0, 8.8
Hz, CH), 6.59 (1 H, d, J = 16.0 Hz, CH), 7.27–7.42 (5 H, m,
ArH). 13C NMR (100 MHz, CDCl3): d = 13.96, 55.86,
61.40, 120.84, 126.56, 128.01, 128.49, 134.96, 136.04,
167.96. MS (70 eV): m/z (%) = 262.1204 (100) [M+],
190.0989 (53), 189.0911 (28). HRMS (70 eV): m/z calcd for
C15H18O4: 262.1200; found: 262.1204.
(E)-3-(4-Chlorostyryl)pentane-2,4-dione (Table 2, entry
5): IR (film): 3055.4, 2913.6, 1443.6, 1071.7, 748.8, 692.1
cm–1. 1H NMR (400 MHz, CDCl3): d = 2.22 (6 H, s, CH3),
6.36 (1 H, d, J = 16.4 Hz, CH), 6.72 (1 H, d, J = 16.4 Hz,
CH), 7.30–7.36 (4 H, m, ArH) 16.78 (1 H, s, OH). 13C NMR
(100 MHz, CDCl3): d = 24.27, 111.12, 123.38, 127.23,
128.78, 132.74, 133.22, 135.51, 191.20. MS: m/z (%) =
236.0601 (100) [M+], 238.0575 (35) [M+ + 2], 221.0365
(30). HRMS (70 eV): m/z calcd for C13H13ClO2: 236.0599;
found: 236.0601.
(E)-Ethyl-2-acetyl-4-(4-chlorophenyl)but-3-enoate
(Table 2, entry 6): IR (film): 3471.5, 2982.2, 2929.3, 1722.1,
1592.1, 1491.8, 1368.8, 1247.0, 1092.0, 1013.7, 974.4,
828.9 cm–1. 1H NMR (400 MHz, CDCl3): d = 1.30 (1.2 H, t,
J = 7.2 Hz, CH3), 1.36 (1.8 H, t, J = 7.2 Hz, CH3), 2.22 (1.8
H, s, CH3), 2.29 (1.2 H, s, CH3), 4.24 (0.8 H, q, J = 7.2 Hz,
CH2), 4.25 (0.4 H, s, CH), 4.30 (1.2 H, q, J = 7.2 Hz, CH2),
6.40 (0.4 H, dd, J = 16.0, 8.8 Hz, CH), 6.52 (0.4 H, d, J =
16.0 Hz, CH), 6.56 (0.6 H, d, J = 16.0 Hz, CH), 6.71 (0.6 H,
d, J = 16.0 Hz, CH), 7.27–7.34 (4 H, m, ArH), 13.41 (0.6 H,
s, OH). 13C NMR (100 MHz, CDCl3): d = 14.04, 14.22,
20.32, 28.56, 61.02, 61.81, 63.72, 76.61, 101.10, 121.67,
122.15, 127.06, 127.77, 128.66, 128.79, 129.09, 132.50,
134.07, 134.48, 136.58, 168.27, 172.53, 175.02, 201.13. MS
(70 eV): m/z (%) = 216.1146 (100) [M+], 268.0679 (38)
[M+ + 2], 240.0554 (40), 224.0598 (80), 220.0288 (74),
207.0022 (42), 205.0052 (98). HRMS (70 eV): m/z calcd for
C14H15ClO3: 266.0704; found: 216.1146.
(6) Okuro, K.; Furuune, M.; Miura, M.; Nomura, M. J. Org.
Chem. 1993, 58, 7606.
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(e) Ma, D.; Cai, Q. Org. Lett. 2003, 5, 3799. (f) Ma, D.;
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(11) Typical Procedure: A two-necked flask was charged with
vinyl bromide (0.5 mmol), CuI (0.05 mmol), L-proline (0.1
mmol), and Cs2CO3 (1.0 mmol), evacuated, and backfilled
with nitrogen. The activated methylene compound (1.0
mmol) and DMSO (2 g) were added under nitrogen. The
flask was immersed in a pre-heated oil bath, and the reaction
mixture was stirred at 90 °C until the conversion was
complete (detected by TLC). The cooled mixture was
purified by column chromatography on silica gel (PE–
EtOAc, 10:1 to 5:1) to provide the desired product.
(E)-3-Styrylpentane-2,4-dione (Table 2, entry 1): IR
(film): 3429.1, 3062.4, 3029.7, 2927.2, 1709.1, 1600.9,
1495.2, 1450.2, 1357.4, 1204.9, 1143.7, 1025.8, 976.2,
751.0, 699.4 cm–1. 1H NMR (400 MHz, CDCl3): d = 2.21 (6
H, s, CH3), 6.41 (1 H, d, J = 16.4 Hz, CH), 6.74 (1 H, d, J =
(E)-Diethyl-2-(4-chlorostyryl)malonate (Table 2, entry 7):
IR (film): 2983.7, 2934.6, 1732.7, 1492.2, 1465.7, 1446.6,
1369.5, 1256.7, 1151.2, 1094.7, 1035.1, 968.7, 821.9 cm–1.
1H NMR (400 MHz, CDCl3): d = 1.29 (6 H, t, J = 7.2 Hz,
CH3), 4.16–4.26 (5 H, m, CH2, CH), 6.40 (1 H, dd, J = 16.0,
8.8 Hz, CH), 6.55 (1 H, d, J = 16.0 Hz, CH), 7.28–7.35 (4 H,
Synlett 2006, No. 11, 1719–1723 © Thieme Stuttgart · New York

LETTER
Coupling Reactions of Vinyl Bromides with Activated Methylene Compounds
1723
m, ArH). 13C NMR (100 MHz, CDCl3): d = 13.89, 55.66,
(E)-Diethyl-2-(4-methylstyryl)malonate (Table 2, entry
10): IR (film): 2982.2, 2937.9, 1732.6, 1513.8, 1463.9,
1446.3, 1368.5, 1293.0, 1257.3, 1177.2, 1096.2, 1032.1,
968.5, 862.0, 812.0 cm–1. 1H NMR (400 MHz, CDCl3): d =
1.28 (6 H, t, J = 7.2 Hz, CH3), 2.33 (3 H, s, CH3), 4.16 (1 H,
d, J = 9.2 Hz, CH), 4.23 (4 H, q, J = 7.2 Hz, CH2), 6.42 (1
H, dd, J = 16.0, 9.2 Hz, CH), 6.55 (1 H, d, J = 16.0 Hz, CH),
7.13 (2 H, d, J = 8.0 Hz, ArH), 7.31 (2 H, d, J = 8.0 Hz,
ArH). 13C NMR (100 MHz, CDCl3): d = 14.01, 21.19, 55.94,
61.73, 119.79, 126.50, 129.22, 133.31, 134.89, 137.95,
168.12. MS (70 eV): m/z (%) =(100) [M+], 204.1147 (26),
203.1071 (28), 157.0647 (21), 129.0698 (51). HRMS (70
eV): m/z calcd for C16H20O4: 276.1356; found: 276.1363.
(E)-3-(4-Methoxystyryl)pentane-2,4-dione(Table 2, entry
11): IR (film): 3055.4, 2913.6, 1443.6, 1071.7, 748.8, 692.1
cm–1. 1H NMR (400 MHz, CDCl3): d = 2.21 (6 H, s, CH3),
2.96 (3 H, s, CH3), 6.35 (1 H, d, J = 16.0 Hz, CH), 6.59 (1
H, d, J = 16.0 Hz, CH), 6.89–6.91 (2 H, m, ArH), 7.35–7.37
(2 H, m, ArH), 16.68 (1 H, s, OH). 13C NMR (100 MHz,
CDCl3): d = 24.24, 55.34, 111.47, 114.14, 120.57, 127.29,
130.23, 133.88, 140.17, 191.10. MS (70 eV): m/z (%) =
232.1099 (100) [M+], 204.0782 (63), 133.0648 (37). HRMS
(70 eV): m/z calcd for C14H16O3: 232.1094; found: 232.1099.
(E)-3-(1-Phenylprop-1-en-2-yl)pentane-2,4-dione
(Table 2, entry 13): IR (film): 3055.4, 2913.6, 1443.6,
1071.7, 748.8, 692.1 cm–1. 1H NMR (400 MHz, CDCl3): d =
1.99 (2 H, s, CH3), 2.05 (3 H, d, J = 1.2 Hz, CH3), 2.13 (4 H,
s, CH3), 6.42 (0.65 H, s, CH), 6.52 (0.35 H, s, CH), 7.18–
7.40 (5 H, m, ArH), 16.40 (0.65 H, s, OH), 16.50 (0.35 H, s,
OH). 13C NMR (100 MHz, CDCl3): d = 20.31, 22.84, 23.17,
27.05, 113.13, 118.18, 126.83, 126.92, 127.73, 128.25,
128.45, 128.64, 131.01, 132.60, 133.04, 133.46, 137.03,
137.34, 189.87, 190.14. MS (70 eV): m/z (%) = 216.1146
(100) [M+], 201.0912 (87), 173.0961 (25). HRMS (70 eV):
m/z calcd for C14H16O2: 216.1145; found: 216.1146.
61.33, 121.49, 127.71, 128.59, 133.65, 134.50, 167.73. MS
(70 eV): m/z (%) = 296.0818 (100) [M+], 298.0784 (32)
[M+ + 2], 224.0600(80), 223.0522 (35), 178.0181 (40).
HRMS (70 eV): m/z calcd for C15H17ClO4: 296.0810; found:
296.0818.
(E)-3-(4-Methylstyryl)pentane-2,4-dione (Table 2, entry
8): IR (film): 3055.4, 2913.6, 1443.6, 1071.7, 748.8, 692.1
cm–1. 1H NMR (400 MHz, CDCl3): d = 2.21 (6 H, s, CH3),
2.36 (3 H, s, CH3), 6.38 (1 H, d, J = 16.0 Hz, CH), 6.68 (1
H, d, J = 16.0 Hz, CH), 7.16 (2 H, d, J = 8.0 Hz, ArH), 7.16
(2 H, d, J = 8.0 Hz, ArH), 16.71 (1 H, s, OH). 13C NMR (100
MHz, CDCl3): d = 21.18, 24.23, 111.40, 121.72, 125.99,
129.36, 134.17, 134.24, 137.61, 191.13. MS (70 eV): m/z
(%) = 216.1148 (100) [M+], 201.0912 (61). HRMS (70 eV):
m/z calcd for C14H16O3: 216.1145; found: 216.1148.
(E)-Ethyl-2-acetyl-4-p-tolylbut-3-enoate (Table 2, entry
9): IR (film): 3459.1, 2981.7, 2923.5, 2868.0, 1721.8,
1639.5, 1604.2, 1513.6, 1369.4, 1245.6, 1061.4, 1019.3,
968.6, 860.4, 817.5 cm–1. 1H NMR (400 MHz, CDCl3): d =
1.29 (1.2 H, t, J = 7.2 Hz, CH3), 1.34 (1.8 H, t, J = 7.2 Hz,
CH3), 2.21 (1.8 H, s, CH3), 2.27 (1.2 H, s, CH3), 2.34 (3 H,
s, CH3), 4.23 (0.8 H, q, J = 7.2 Hz, CH2), 4.24 (0.3 H, s, CH),
4.28 (1.2 H, q, J = 7.2 Hz, CH2), 6.36 (0.4 H, dd, J = 16.0,
8.8 Hz, CH), 6.54 (0.4 H, d, J = 16.0 Hz, CH), 6.55 (0.6 H,
d, J = 16.0 Hz, CH), 6.68 (0.6 H, d, J = 16.0 Hz, CH), 7.13
(2 H, d, J = 8.0 Hz, ArH), 7.29–7.31 (2 H, m, ArH), 13.34
(0.6 H, s, OH). 13C NMR (100 MHz, CDCl3): d = 14.02,
14.19, 20.23, 21.10, 21.17, 28.38, 60.85, 61.61, 63.91,
101.33, 119.90, 120.58, 125.82, 126.46, 129.22, 129.27,
130.66, 133.24, 135.22, 135.25, 136.85, 138.10, 168.51,
172.67, 174.32, 201.51. MS (70 eV): m/z (%) = 246.1254
(72) [M+], 204.1145 (38), 200.0832 (77), 185.0596 (100),
158.0727 (27). HRMS (70 eV): m/z calcd for C15H18O3:
246.1250; found: 246.1254.
Synlett 2006, No. 11, 1719–1723 © Thieme Stuttgart · New York