Ruthenium-Catalyzed Oxidative Cross-Coupling Reaction of Activated Olefins with Vinyl Boronates for the Synthesis of (E, E)-1,3-Dienes

Article abstract of DOI:10.1021/acs.joc.0c02823

An oxidative cross-coupling reaction between activated olefins and vinyl boronate derivatives has been developed for the highly stereoselective construction of synthetically useful (E,E)-1,3-dienes. The highlight of this reaction is that exclusive stereoselectivity (only E,E-isomer) was achieved from a base-free, ligand-free, and mild catalytic condition with a less expensive [RuCl2(p-cymene)]2 catalyst.

Full text of DOI:10.1021/acs.joc.0c02823

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Article
Ruthenium-Catalyzed Oxidative Cross-Coupling Reaction of
Activated Olefins with Vinyl Boronates for the Synthesis of (E,E)‑1,3-
Dienes
Dattatraya H. Dethe,* Nagabhushana C. Beeralingappa, and Amar Uike
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ABSTRACT: An oxidative cross-coupling reaction between
activated olefins and vinyl boronate derivatives has been developed
for the highly stereoselective construction of synthetically useful
(E,E)-1,3-dienes. The highlight of this reaction is that exclusive
stereoselectivity (only E,E-isomer) was achieved from a base-free,
ligand-free, and mild catalytic condition with a less expensive
[RuCl2(p-cymene)]2 catalyst.
synthesis. Poor stereoselectivity of the oxidative Heck reaction
coupled with skyrocketing prices of palladium has led to an
increased need to develop more sustainable strategies for such
kinds of carbon−carbon-bond formations. Herein, we report a
new catalytic system for the cross-coupling reaction of
organoboron compounds with activated olefins to afford
conjugated 1,3-dienes in a highly stereoselective manner
using the commercially available, less expensive [RuCl2(p-
cymene)]2 catalyst and Cu(OAc)2 as a reoxidant for the
ruthenium(0) species under base- and ligand-free conditions
(Scheme 22:).
INTRODUCTION
■
Palladium-catalyzed arylation of olefins has been routinely used
as powerful carbon−carbon bond forming reactions (Scheme
11:a) since its discovery in the early 1970s, which triggered the
era of natural product synthesis and medicinal chemistry.1−6
Substituted 1,3-dienes are valuable synthetic intermediates in
organic chemistry, which also feature as structural motifs in
numerous natural products and medicinally important
molecules.7 Indeed, these conjugated dienes serve as building
blocks for fabricating the complexity in chemical trans-
formations such as cross-coupling reactions, cycloadditions,
ene-reaction, and metathesis, including recently developed
asymmetric hydrofunctionalizations, difunctionalizations, etc.
It is well-understood that the syntheses of stereo- and regio-
defined conjugated dienes are often influenced by the
geometry of olefins involved in the reaction.8 Hence,
innumerable synthetic strategies have been explored for the
stereoselective construction of substituted 1,3-dienes.9 Oxida-
tive boron Heck reactions are known to be efficient, require
mild reaction conditions, show good functional group
tolerance, and are capable of coupling challenging substrates
such as highly substituted or cyclic olefins, many of which are
reluctant to undergo normal Heck coupling.10 In this regard,
many oxidative Heck reactions of phenyl boronates with
activated olefins have been developed,11−14 but there is only
one report in the literature on oxidative Heck reaction using
alkenyl boranes by Jung et al. (Scheme 11:b).15 Although this
protocol developed by Jung et al. provides access to dienes in
very good yields, it gives poor stereoselectivity when
acrylonitrile and styrenes are used as coupling partners. The
major problem in oxidative Heck coupling is that poor
stereoselectivity was observed for these reactions. To over-
come these stereoselective problems, sterically hindered
acrylates (activated olefins) such as tertiary butyl acrylate
were used. This limits the substrate scope and its application in
RESULTS AND DISCUSSION
■
An optimization study revealed that the couplings of
organoborane derivatives with various acrylates were found
to be beneficial in terms of functional group tolerance and
yield. To begin with, the cross-coupling reaction was
performed using trans-2-phenyl vinyl boronic ester 1a and
methyl acrylate 2a in trifluoroethanol at 80 °C for 12 h with 5
mol % [RuCl2(p-cymene)]2 as the catalyst, 2 equivalents of
Cu(OAc)2 as the oxidant, and 15 mol % AgSbF6 as an additive.
The desired 1,3-diene 3aa was obtained in 28% yield as a single
E,E-isomer (Table 1, entry 1). Change of the solvent to
CH3CN, t-AmOH, or NMP (entries 2−4) did not produce
better results. Change of the solvent to dichloromethane
afforded the coupling product in 35% at 40 °C (entry 5),
whereas replacement with toluene generated the cross-coupled
Received: November 26, 2020
Published: February 4, 2021
https://dx.doi.org/10.1021/acs.joc.0c02823
© 2021 American Chemical Society
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Scheme 1
Scheme 2. This Work
Table 1. Optimization of Reaction Conditions
e
entry
solvent
additive (15 mol %)
oxidant (2 equiv)
yield [%]
1
2
3
4
5
6
TFE
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
AgSbF6
NH4PF6
NH4PF6
AgOAc
Ag2CO3
Cu(OAc)2·H2O
Cu(OAc)2·H2O
Cu(OAc)2·H2O
Cu(OAc)2·H2O
Cu(OAc)2·H2O
Cu(OAc)2·H2O
Cu(OAc)2·H2O
Cu(OAc)2·H2O
Cu(OAc)2·H2O
KOAc
Cu(OAc)2·H2O
Cu(OAc)2·H2O
Cu(OAc)2·H2O
Cu(OAc)2·H2O
AgOAc
28
trace
16
25
35
65
42
45
88
12
75
48
trace
0
CH3CN
t-AmOH
NMP
DCM
toluene
toluene
DCE
DCE
DCE
DCE
toluene
DCE
a
7
8
b
9
10
11
12
13
14
15
DCE
DCE
DCE
DCE
16
0
0
c
16
17
Cu(OAc)2·H2O
d
AgSbF6
a
b
c
d
Reaction Conditions. Reaction at 110 °C. Reaction at 60 °C. The reaction was performed without AgSbF6. The reaction was performed
e
without Cu(OAc)2·H2O. Isolated yield of 3aa.
product in 65% yield at 80 °C (entry 6). An increase in the
temperature to 110 °C resulted in a lower yield probably due
to decomposition of the starting material (entry 7). Use of 1,2-
dichloroethane as a solvent afforded 45% of the desired
product at 60 °C (entry 8), and to our delight, when the
temperature was increased to 80 °C, the yield increased to 88%
(entry 9). When the reaction was conducted by replacing
AgSbF6 with a variety of additives, the reaction was found to be
sluggish, but in the case of NH4PF6, diene 3 was obtained in
75% yield at 80 °C using 1,2-dichloroethane as a solvent (entry
11). Change of the solvent to toluene and using NH4PF6 as an
additive at 80 °C afforded the desired coupling product in only
48% yield (entry 12). It was found that similar reactivity in
terms of rate and yield was observed when boronate esters
were replaced with corresponding boronic acids. It is
noteworthy to mention that the reaction did not occur when
carried out in the absence of either AgSbF6 (entry 16) or
Cu(OAc)2 (entry 17), revealing that Cu(OAc)2 as a reoxidant
and AgSbF6 as an additive were necessary for the reaction.
The scopes of the alkenyl boronates and the acrylates were
subsequently examined. As shown in Scheme 3, phenyl and
(4′-methyl) phenyl-substituted vinyl boronates 1a,b reacted
well with methyl (2a), butyl (2b), and cyclohexyl (2c)
acrylates independently to afford the corresponding cross-
coupled products 3aa−bc in very good yields and excellent
stereoselectivity. Notably, halogen-containing vinyl boronate
derivatives such as 1c−e showed their chemoselective
reactivity for the coupling reaction under a reactive catalytic
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a
Scheme 3. Reaction of Various Acrylates with Different Organoboron Derivatives
a
Reaction conditions: 1 (1 equiv), 2 (1 equiv), [Ru(p-cymene)Cl2]2 (5 mol %), AgSbF6 (15 mol %), and Cu(OAc)2·H2O (2 equiv) at 80 °C in
1,2-DCE (3.0 mL), under argon for 12 h. Cy, cyclohexyl.
system to generate corresponding coupling products 3cb−eb
without affecting the labile carbon−halogen (C−Br) bond,
which can be utilized for further functionalization. Phenyl-
boronic acid 1f on reaction with various acrylates 2b−e
generated the corresponding cross-coupled products 3fb−fe in
very good yields and excellent stereoselectivity. Sterically
crowded cyclohexenyl boronate ester 1g reacted smoothly with
various acrylates 2a−c, f to generate corresponding dienes
3ga−gc, gf, respectively, in very good yields. Cyclopentenyl
boronate ester 1h underwent a coupling reaction with methyl
acrylate 2a to afford 3ha in 80% yield. Allyl boronate ester 1i
underwent a coupling reaction with methyl (2a) and
cyclohexyl acrylate (2c) individually to afford 3ia and 3ic in
70% and 73% yields, respectively. Vinyl boronate ester 1j on
reaction with n-butyl acrylate (2b) generated the single isomer
3jb in 75% yield. Interestingly, cyclopropyl vinyl boronate ester
1k furnished dienes 3kb and 3kc in 78 and 75% yields,
respectively, without affecting its highly strained cyclopropyl
ring. It is important to highlight that the coupling reaction of
highly strained cyclopropane ring derivatives is likely to
undergo ring cleavage under a palladium catalytic system.16
Also, electron-withdrawing acetoxy-substituted vinyl boronate
ester 1l reacted with n-butyl acrylate (2b) to generate
functionalized diene 3lb in 82% yield. Highly activated vinyl
boronate derivative 1m underwent a coupling reaction with
cyclohexyl acrylate (2c) to afford the coupled product 3mc in
84% yield. Interestingly, the introduction of an ester side chain
has no effect on product selectivity. Markedly, symmetric
diacrylate 2g reacted with vinyl boronate derivative 1m to form
the coupled product 3mg in a somewhat moderate yield
(68%). Also, these conjugate diesters (3mc, mg) represent the
structure of an important class, called muconate derivatives.17
This differentiable terminal functionality of conjugated
muconates can be eventually transformed into versatile
synthetic intermediates widely used in organic synthesis. To
date, no catalytic method has been developed for the
stereoselective construction of (E,E)-muconate derivatives.18
It is noteworthy to mention that when the coupling reaction
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Scheme 4. Reaction of Various Activated Olefins with Different Organoboron Derivatives
Scheme 5. : Reaction of Organoboron Derivatives with Enones Using NH4PF6
was carried out on a gram scale, similar results were obtained
without affecting productivity in terms of yield and stereo-
selectivity.
Furthermore, phenyl vinyl sulfone, 4c, was subjected to a
coupling reaction to deliver a single (E,E)-isomer of desired
dienes 5nc and 5hc in 76 and 70% yields, respectively. A
similar reactivity was observed when acrylamide, 4d, was
reacted with phenylboronic acid and cyclopentenyl boronate
ester to provide corresponding coupling products 5fd and 5hd
in 81 and 79% yields, respectively. Additionally, the desired
product (5ae) was obtained when (E)-methyl crotonate 4e
was subjected to a coupling reaction with boronate ester, albeit
with a moderate yield (65%), highlighting the broad scope of
an olefinic partner.
Moreover, this newly developed catalytic protocol is not
limited only to acrylates but also applicable to various activated
olefins such as acrylonitrile, vinyl ketones, vinyl sulfones, and
acrylamides (Scheme 4). Series of vinyl boronates (1b−d, 1f,g,
and 1m) were independently treated with acrylonitrile (4a) to
afford the desired products (5ba−da, 5fa, 5ga, and 5ma) in
good yields with excellent stereoselectivity. It is worth
mentioning that palladium-catalyzed Heck oxidative coupling
showed poor stereoselectivity especially with acrylonitriles.15,19
It was interesting to observe that when ethyl vinyl ketone, 4b,
was used as a coupling partner, it generated 1,3-dienes
embedded with an enone substituent in very good yields.
Interesting results were observed when coupling reactions
between vinyl boronates and α,β-unsaturated ketones were
carried out by replacing AgSbF6 with NH4PF6 (Scheme 5). An
unanticipated double-bond reduced product, 6ab, was formed
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Scheme 6. Competitive Experiments
Scheme 7. Plausible Mechanism
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for flash column chromatography. Neat compounds were used to
record IR spectra. NMR spectra were recorded on a Bruker Avance
400 (1H, 400 MHz; 13C, 100 MHz), Bruker Avance 500 (1H, 500
MHz; 13C, 125 MHz), or JEOL DELTA (ECX) 500 (1H, 500 MHz;
13C, 125 MHz). Mass spectrometric data were obtained using
WATERS-Q-Tof-Premier-HAB213 and WATERS-QTof-Premier-
ESI-MS instruments, and IR data were recorded from a PerkinElmer
FTIR spectrometer. The following abbreviations were used to explain
the multiplicities: s, singlet; d, doublet; t, triplet; q, quartet; spt,
septet; dd, doublet of doublet; ddd, doublet of a doublet of a doublet;
dt, doublet of a triplet; td, triplet of a doublet; m, multiplet; br, broad.
General Procedure for Ruthenium-Catalyzed Oxidative
Coupling Reaction between Activated Olefins and Vinyl
Boronate Esters. An 8 mL screw-cap vial was charged with
[RuCl2(p-cymene)]2 (15.5 mg, 0.025 mmol, 5.0 mol %), Cu(OAc)2·
H2O (200 mg, 1.0 mmol, 2.0 equiv), AgSbF6 (25.7 mg, 0.075 mmol,
15 mol %), and 1,2-dichloroethane (3.0 mL). Then, boronic ester (0.5
mmol, 1.0 equiv) and activated olefins (0.5 mmol, 1.0 equiv) [2.0
equivalents of acrylonitrile and methyl crotonate were used] were
added into the solution in sequence. The vial was sealed under N2 and
heated to 80 °C with stirring for 12 h (using an oil bath). After
cooling down, the mixture was diluted with ethyl acetate, filtered, and
concentrated to give the crude compound, which was directly purified
by column chromatography. [Note: A general procedure was followed
for the oxidative coupling reaction of boronic esters with vinyl ketone
in the presence of 30 mol % NH4PF6 (25 mg) in the place of
AgSbF6.]
Gram-Scale Synthesis of 3ac. A 100 mL screw-cap vial was
charged with [RuCl2(p-cymene)]2 (134 mg, 0.22 mmol, 5.0 mol %),
AgSbF6 (180 mg, 0.52 mmol, 12 mol %), and Cu(OAc)2·H2O (1.8 g,
8.72 mmol, 2.0 equiv) in 1,2-dichloroethane (25 mL) and stirred for 5
minutes at room temperature under a nitrogen atmosphere. Then,
phenyl-substituted vinyl boronate ester 1a (1.0 g, 4.4 mmol, 1.0
equiv) and cyclohexyl acrylate 2c (0.7 mL, 4.4 mmol, 1.0 equiv,
density = 0.975 g/mL) were added into the solution in sequence and
the vial was sealed under N2 and heated to 80 °C with stirring for 12 h
(using an oil bath). After cooling down, the mixture was diluted with
ethyl acetate, filtered, and concentrated to give the crude compound,
which was directly purified by column chromatography to obtain the
pure product 3ac (0.95 g, 3.7 mmol, 85%).
Competitive Reactions between 1b and 1c. An 8 mL screw-
cap vial was charged with [RuCl2(p-cymene)]2 (13 mg, 0.02 mmol,
5.0 mol %), Cu(OAc)2·H2O (160 mg, 0.8 mmol, 2.0 equiv), AgSbF6
(21 mg, 0.06 mmol, 15 mol %), and 1,2-dichloroethane (2.5 mL).
Then, boronic esters 1b (50 mg, 0.2 mmol, 0.5 equiv) and 1c (50 mg,
0.2 mmol, 0.5 equiv) followed by methyl acrylate (38 mg, 0.44 mmol,
1.1 equiv) were added into the solution in sequence. The vial was
sealed under N2 and heated to 80 °C with stirring for 4 h (using an oil
bath). After cooling down, the mixture was diluted with ethyl acetate,
filtered, and concentrated to give the crude compound, which was
directly purified by column chromatography using 0−5% EtOAc in
pet ether to afford a mixture of compounds 3ba and 3ca in a 1:0.4
ratio.
Parallel Reactions. Similarly, two parallel reactions were
performed with 0.2 mmol each of 1b and 1c for 4 h at 80 °C.
After cooling down, the reaction mixtures were mixed, diluted with
ethyl acetate, filtered, and concentrated to give the crude compound,
which was directly purified by column chromatography using 0−5%
EtOAc in pet ether to afford a mixture of compounds 3ba and 3ca in a
1:0.65 ratio.
in 70% yield when boronate ester 1a was reacted with ethyl
vinyl ketone 4b. This may be due to facile enol formation/
protonation in the case of enones in the presence of the NH4
ion, which restricts β-hydride elimination. To check the
generality of this reaction, various vinyl boronate esters were
subjected to a coupling reaction with ethyl/methyl vinyl
ketone; similar results were obtained and afforded coupling
products (6bb, ff, hb, nf) in moderate to good yields.
To determine the effect of substituents on the rate of the
coupling reaction, we performed intermolecular competitive
reactions between differently substituted vinyl boronates.
When (4-methyl)-phenyl (1b) and (4-fluoro)-phenyl (1c)
vinyl boronate and methyl acrylate were employed, the
electron-rich substrate reacted more predominantly with a
reactivity difference of almost 1:0.4 (Scheme 6a). Similarly, a
mixture of compounds 3ba and 3ca in a 1:0.65 ratio was
observed from parallel reactions (Scheme 6b). When a
competitive reaction between alkyl and phenyl-substituted
vinyl boronate esters was performed, phenyl-substituted vinyl
boronate reacted preferentially with a reactivity difference of
1:0.45 (Scheme 6c).
+
Based on a previous report,20 a plausible reaction
mechanism for the cross-coupling reaction of vinyl boronate
with activated olefins is depicted in Scheme 7. The catalytic
cycle is initiated by in situ-generated reactive ruthenium(II)
species A, which further undergoes transmetalation with vinyl
boronate ester B to provide an intermediate C. Coordination
followed by regioselective insertion of activated olefin to the
ruthenium−carbon bond of intermediate C would generate the
ruthenium(II) intermediate E. Subsequent β-hydride elimi-
nation of E leads to the formation of the stereoselective cross-
coupled product P, followed by reductive elimination of the
Ru(II) intermediate F, which results in the formation of the
Ru(0) intermediate G. In the presence of Cu(OAc)2, the
reduced [Ru(0)] species could undergo oxidation to
regenerate the ruthenium (II) cationic reactive complex A
for the next catalytic cycle. In the presence of NH4PF6, the
catalytic cycle follows path B to afford product Q. This
unanticipated result may be due to facile enol formation/
+
protonation in the case of enones in the presence of the NH4
ion, which restricts β-hydride elimination.
CONCLUSIONS
■
In summary, ruthenium-catalyzed oxidative cross-coupling
between vinyl boronates and activated olefins has been
developed for efficient and direct access to synthetically useful
(E,E)-1,3-dienes in a highly stereoselective manner. This
reaction features a base-free, mild reaction condition, easily
accessible starting materials, a broad substrate scope, and
excellent stereoselectivity. The present simplified methodology
for carbon−carbon bond formation is highly practical, holding
great promise for wide use in organic and medicinal chemistry.
EXPERIMENTAL SECTION
Competitive Reactions between 1a and 1k. An 8 mL screw-
cap vial was charged with [RuCl2(p-cymene)]2 (13 mg, 0.02 mmol,
5.0 mol %), Cu(OAc)2·H2O (160 mg, 0.8 mmol, 2.0 equiv), AgSbF6
(21 mg, 0.06 mmol, 15 mol %), and 1,2-dichloroethane (2.5 mL).
Then, boronic esters 1a (55 mg, 0.24 mmol, 0.5 equiv) and 1k (43
mg, 0.24 mmol, 0.5 equiv) followed by methyl acrylate (38 mg, 0.44
mmol, 1.1 equiv) were added into the solution in sequence. The vial
was sealed under N2 and heated to 80 °C with stirring for 4 h (using
an oil bath). After cooling down, the mixture was diluted with ethyl
acetate, filtered, and concentrated to give the crude compound, which
■
General Aspects. Experiments involving moisture- and air-
sensitive components were performed in oven-dried glassware.
Commercial solvents and reagents were used without further
purification unless otherwise noted. Yields refer to chromato-
graphically pure compounds, unless otherwise stated. Reactions
were monitored by thin-layer chromatography (TLC) carried out
on 0.25 mm Merck silica gel plates (60F-254) using UV light as a
visualizing agent and p-anisaldehyde and heat as developing agents.
Merck silica gel (particle size 100−200 and 230−400 mesh) was used
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was directly purified by column chromatography using 0−5% EtOAc
in pet ether to afford a mixture of compounds 3aa and 3ka in a 1:0.45
ratio.
TOF) m/z: [M + Na]+ calcd for C18H22O2Na 293.1517; found
293.1520. IR (neat): vmax/cm−1 2937, 1708, 1448, 1234, 1132, 1009,
846, 808.
(2E,4E)-Methyl 5-Phenylpenta-2,4-dienoate (3aa). Following
the general procedure, 3aa was purified by silica column
chromatography (hexane/EtOAc at a 20:1 ratio), obtained as a
white solid (77 mg, 88%). 1H NMR (500 MHz, CDCl3) δ 7.49−7.42
(m, 3H), 7.38−7.28 (m, 3H), 6.93−6.83 (m, 2H), 5.99 (d, J = 15.3
Hz, 1H), 3.77 (s, 3H). 13C NMR {1H} (125 MHz, CDCl3) δ 167.6,
144.9, 140.7, 136.1, 129.2, 128.9 (2C), 127.3 (2C), 126.3, 120.9, 51.7.
HRMS (ESI-TOF) m/z: [M + H]+ calcd for C12H13O2 189.0916;
found 189.0910. IR (neat): vmax/cm−1 2926, 1717, 1628, 1439, 1450,
1321, 1344, 1242, 1172, 1137, 995.
(2E,4E)-Methyl 5-p-Tolylpenta-2,4-dienoate (3ba). Following
the general procedure, 3ba was purified by silica column
chromatography (hexane/EtOAc at a 20:1 ratio), obtained as a
white solid (81 mg, 86%). 1H NMR (400 MHz, CDCl3) δ 7.44 (dd, J
= 9.8, 15.3 Hz, 1H), 7.37−7.33 (m, 2H), 7.17−7.13 (m, 2H), 6.90−
6.77 (m, 2H), 5.96 (d, J = 15.3 Hz, 1H), 3.76 (s, 3H), 2.35 (s, 3H).
13C NMR{1H} (100 MHz, CDCl3) δ 167.6, 145.1, 140.7, 139.4,
133.4, 129.6(2C), 127.2(2C), 125.3, 120.3, 51.6, 21.4. HRMS (ESI-
TOF) m/z: [M + H]+ calcd for C13H15O2 203.1072; found 203.1070.
IR (neat): vmax/cm−1 2924, 1711, 1605, 1622, 1434, 1350, 1318, 1243,
1171, 1132, 1010, 840, 806.
(2E,4E)-Butyl 5-(4-Fluorophenyl)penta-2,4-dienoate (3cb).
Following the general procedure, 3cb was purified by silica column
chromatography (hexane/EtOAc at a 30:1 ratio), obtained as a white
solid (83 mg, 67%). 1H NMR (500 MHz, CDCl3) δ 7.49−7.34 (m, 3
H), 7.03 (t, J = 8.6 Hz, 2 H), 6.93−6.69 (m, 2 H), 5.97 (d, J = 15.5
Hz, 1 H), 4.16 (t, J = 6.6 Hz, 2 H), 1.69−1.63 (m, 2 H), 1.46−1.37
(m, 2 H), 0.95 (t, J = 7.4 Hz, 3 H). 13C NMR {1H} (125 MHz,
CDCl3) δ 167.2, 144.4, 139.0, 128.9, 128.9, 126.1, 121.5, 116.0, 115.9,
64.4, 30.9, 19.3, 13.8. HRMS (ESI-TOF) m/z: [M + Na]+ calcd for
C15H17O2FNa 271.1110; found 271.1119. IR (neat): vmax/cm−1 2978,
2865, 1712, 1676, 1614, 1628, 1598, 1235, 1029, 1012.
(2E,4E)-Butyl 5-(4-Bromophenyl)penta-2,4-dienoate (3db).
Following the general procedure, 3db was purified by silica column
chromatography (hexane/ EtOAc at a 30:1 ratio), obtained as a white
solid (95 mg, 62%). 1H NMR (400 MHz, CDCl3) δ 7.49−7.43 (m, J
= 7.9 Hz, 2H), 7.43−7.35 (m, 1H), 7.33−7.27 (m, J = 8.5 Hz, 2H),
6.89−6.76 (m, 2H), 5.99 (d, J = 15.3 Hz, 1H), 4.16 (t, J = 6.7 Hz,
2H), 1.70−1.61 (m, 2H), 1.41 (qd, J = 7.4, 15.0 Hz, 2H), 0.94 (t, J =
7.3 Hz, 3H). 13C NMR {1H} (100 MHz, CDCl3) δ 167.1, 144.1,
138.9, 135.0, 132.1 (2C), 128.6 (2C), 127.0, 123.0, 122.1, 64.5, 30.8,
19.3, 13.8. HRMS (ESI-TOF) m/z: [M + Na]+ calcd for
C15H17O2BrNa 331.0310; found 331.0315. IR (neat): vmax/cm−1
3047, 3027, 3006, 2253, 1897, 1663, 1702, 1623, 1474, 1464, 1358,
1277, 1241, 1157, 1175, 1018, 1009.
(2E,4E)-Butyl 5-(4-Bromo-3-methoxyphenyl)penta-2,4-dien-
oate (3eb). Following the general procedure, 3eb was purified by
silica column chromatography (hexane/EtOAc at a 30:1 ratio),
obtained as a white solid (127 mg, 75%). 1H NMR (400 MHz,
CDCl3) δ 7.67 (d, J = 1.8 Hz, 1 H), 7.43−7.31 (m, 2 H), 6.86 (d, J =
8.5 Hz, 1 H), 6.80−6.67 (m, 2 H), 5.95 (d, J = 15.3 Hz, 1 H), 4.15 (t,
J = 6.7 Hz, 2 H), 3.90 (s, 3 H), 1.68−1.62 (m, 2 H), 1.44−1.37 (m, 2
H), 0.96−0.92 (m, 3 H). 13C NMR {1H} (125 MHz, CDCl3) δ 167.2,
156.5, 144.4, 138.4, 131.7, 130.4, 127.9, 125.5, 121.2, 112.3, 112.0,
64.4, 56.4, 30.9, 19.3, 13.8. HRMS (ESI-TOF) m/z: [M + Na]+ calcd
for C16H19O3BrNa 361.0415; found 361.0413. IR (neat): vmax/cm−1
2924, 2852,1713, 1625, 1593, 1496, 1461, 1378, 1338, 1280, 1262,
1174, 1131, 1054, 1019, 996, 871, 501, 458, 418.
(2E,4E)-Butyl 5-Phenylpenta-2,4-dienoate (3ab). Following
the general procedure, 3ab was purified by silica column
chromatography (hexane/EtOAc at a 20:1 ratio), obtained as a
1
white solid (100 mg, 86%). H NMR (400 MHz, CDCl3) δ 7.48−
7.38 (m, 3 H), 7.37−7.26 (m, 3 H), 6.95−6.78 (m, 2 H), 5.98 (d, J =
15.3 Hz, 1 H), 4.16 (t, J = 6.7 Hz, 2 H), 1.70−1.61 (m, 2 H), 1.41
(qd, J = 7.4, 15.1 Hz, 2 H), 0.95 (t, J = 7.3 Hz, 3 H). 13C NMR{1H}
(125 MHz, CDCl3) δ 167.2, 144.6, 140.4, 136.1, 129.1, 128.9, 127.3,
126.3, 121.5, 64.4, 30.9, 19.3, 13.8. HRMS (ESI-TOF) m/z: [M +
H]+ calcd for C15H19O2 231.1385; found 231.1382. IR (neat): vmax
/
cm−1 3049, 3009, 2964, 2927, 2857, 1699, 1604, 1621, 1314, 1243,
1135, 1020.
(2E,4E)-Butyl 5-p-Tolylpenta-2,4-dienoate (3bb). Following
the general procedure, 3bb was purified by silica column
chromatography (hexane/EtOAc at a 20:1 ratio), obtained as a
white solid (115 mg, 85%). 1H NMR (400 MHz, CDCl3) δ 7.42 (dd,
J = 9.2, 15.3 Hz, 1H), 7.38−7.31 (m, J = 7.9 Hz, 2H), 7.20−7.11 (m, J
= 7.9 Hz, 2H), 6.91−6.76 (m, 2H), 5.95 (d, J = 15.3 Hz, 1H), 4.16 (t,
J = 6.7 Hz, 2H), 2.35 (s, 3H), 1.71−1.61 (m, 2H), 1.47−1.36 (m,
2H), 0.95 (t, J = 7.3 Hz, 3H). 13C NMR {1H} (100 MHz, CDCl3) δ
167.3, 144.8, 140.5, 139.3, 133.4, 129.6(2C), 127.2(2C), 125.4, 120.8,
64.3, 30.9, 21.4, 19.3, 13.8. HRMS (ESI-TOF) m/z: [M + H]+ calcd
for C16H21O2 245.1542; found 245.1544. IR (neat): vmax/cm−1 2958,
1709, 1626, 1343, 1449, 1240, 1174, 1133, 1064.
(E)-Butyl Cinnamate (3fb). Following the general procedure, 3fb
was purified by silica column chromatography (hexane/EtOAc at a
1
40:1 ratio), obtained as a white solid (77 mg, 80%). H NMR (500
MHz, CDCl3) δ 7.65 (d, J = 16.0 Hz, 1 H), 7.49 (br. s., 2 H), 7.34
(br. s., 3 H), 6.41 (d, J = 16.0 Hz, 1 H), 4.17 (s, 2 H), 1.68 (s, 2 H),
1.42 (s, 2 H), 0.92 (s, 3 H). 13C NMR {1H} (125 MHz, CDCl3) δ
167.2, 144.6, 134.6, 130.3, 128.9, 128.1, 118.4, 64.5, 30.8, 19.3, 13.8.
HRMS (ESI-TOF) m/z: [M + H]+ calcd for C13H17O2 205.1229;
found 205.1227. IR (neat): vmax/cm−1 2926, 1720, 1626, 1440, 1452,
1321, 1344, 1242, 1176, 1141.
(2E,4E)-Cyclohexyl 5-Phenylpenta-2,4-dienoate (3ac). Fol-
lowing the general procedure, 3ac was purified by silica column
chromatography (hexane/EtOAc at a 30:1 ratio), obtained as a white
(E)-Cyclohexylcinnamate (3fc). Following the general proce-
1
dure, 3fc was purified by silica column chromatography (hexane/
solid (106 mg, 83%). H NMR (500 MHz, CDCl3) δ 7.49−7.38 (m,
1
EtOAc at a 40:1 ratio), obtained as a white solid (81 mg, 82%). H
3 H), 7.38−7.32 (m, 2 H), 7.32−7.26 (m, 1 H), 6.93−6.81 (m, 2 H),
5.98 (d, J = 15.5 Hz, 1 H), 4.90−4.79 (m, 1 H), 1.95−1.84 (m, 2 H),
1.81−1.69 (m, 2 H), 1.59−1.52 (m, 1 H), 1.52−1.34 (m, 4 H), 1.33−
1.24 (m, 1 H). 13C NMR {1H} (100 MHz, CDCl3) δ 166.6, 144.3,
140.2, 136.2, 129.0, 128.9, 127.2, 126.4, 122.1, 72.6, 31.8, 25.5, 23.9.
HRMS (ESI-TOF) m/z: [M + H]+ calcd for C17H21O2 257.1542;
found 257.1540. IR (neat): vmax/cm−1 2917, 2849, 1706, 1627, 1465,
1237, 1134, 740.
NMR (500 MHz, CDCl3) δ 7.66 (d, J = 16.0 Hz, 1 H), 7.55−7.44
(m, 2 H), 7.42−7.29 (m, 3 H), 6.43 (d, J = 16.0 Hz, 1 H), 4.96−4.81
(m, 1 H), 1.92 (dd, J = 4.6, 12.6 Hz, 2 H), 1.82−1.70 (m, 2 H), 1.62−
1.45 (m, 3 H), 1.45−1.35 (m, 2 H), 1.33−1.26 (m, 1 H). 13C NMR
{1H} (125 MHz, CDCl3) δ 166.5, 144.3, 134.7, 130.2, 128.9, 128.1,
119.0, 72.8, 31.8, 25.5, 23.9. HRMS (ESI-TOF) m/z: [M + H]+ calcd
for C15H19O2 231.1385; found 231.1389. IR (neat): vmax/cm−1 2924,
1717, 1615, 1622, 1434, 1350, 1316, 1243, 1171, 1135, 1010, 840,
806.
(E)-Isobutyl Cinnamate (3fd). Following the general procedure,
3fd was purified by silica column chromatography (hexane/EtOAc at
a 40:1 ratio), obtained as a white solid (100 mg, 74%). 1H NMR (500
MHz, CDCl3) δ 7.68 (d, J = 16.0 Hz, 1 H), 7.57−7.48 (m, 2 H),
7.42−7.33 (m, 3 H), 6.45 (d, J = 16.0 Hz, 1 H), 3.99 (d, J = 6.9 Hz, 2
H), 2.01 (td, J = 6.8, 13.3 Hz, 1 H), 0.98 (d, J = 6.9 Hz, 6 H). 13C
NMR {1H} (125 MHz, CDCl3) δ 167.2, 144.6, 134.6, 130.3, 128.9,
128.1, 118.4, 70.8, 27.9, 19.2. HRMS (ESI-TOF) m/z: [M + H]+
(2E,4E)-Cyclohexyl 5-p-Tolylpenta-2,4-dienoate (3bc). Fol-
lowing the general procedure, 3bc was purified by silica column
chromatography (hexane/EtOAc at a 30:1 ratio), obtained as a white
1
solid (108 mg, 80%). H NMR (500 MHz, CDCl3) δ 7.41 (dd, J =
10.0, 15.2 Hz, 1 H), 7.37−7.32 (m, J = 8.0 Hz, 2 H), 7.18−7.13 (m, J
= 8.0 Hz, 2 H), 6.90−6.74 (m, 2 H), 5.95 (d, J = 14.9 Hz, 1 H),
4.91−4.72 (m, 1 H), 2.35 (s, 3 H), 1.93−1.84 (m, 2 H), 1.75 (dd, J =
4.0, 9.2 Hz, 2 H), 1.63−1.52 (m, 2 H), 1.47−1.37 (m, 4 H). 13C
NMR {1H} (125 MHz, CDCl3) δ 166.7, 144.6, 140.3, 139.3, 133.5,
129.6, 127.2, 125.5, 121.5, 72.6, 31.8, 25.5, 23.9, 21.4. HRMS (ESI-
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−1
calcd for C13H17O2 205.1229; found 205.1232. IR (neat): vmax/cm
2964, 2927, 2857, 1718, 1621, 1314, 1243, 1135, 1020.
(m, 2H), 5.76 (d, J = 15.5 Hz, 1H), 3.72 (s, 3H), 1.83 (d, J = 6.3 Hz,
3H). 13C NMR {1H} (125 MHz, CDCl3) δ 167.8, 145.2, 139.5, 129.8,
118.6, 51.5, 18.7. HRMS (ESI-TOF) m/z: [M + H]+ calcd for
C7H11O2 127.0759; found 127.0760. IR (neat): vmax/cm−1 3483,
2955, 2925, 2853, 1724, 1650, 1437, 1309, 1271, 1172, 1200, 1029,
982, 858, 813, 633, 723, 541.
(E)-Benzyl Cinnamate (3fe). Following the general procedure,
3fe was purified by silica column chromatography (hexane/EtOAc at
a 30:1 ratio), obtained as a white solid (115 mg, 68%). 1H NMR (400
MHz, CDCl3) δ 7.74 (d, J = 15.9 Hz, 1 H), 7.58−7.49 (m, 2 H),
7.49−7.28 (m, 8 H), 6.50 (d, J = 15.9 Hz, 1 H), 5.26 (s, 2 H). 13C
NMR {1H} (100 MHz, CDCl3) δ 166.9, 145.3, 136.2, 134.4, 130.5,
129.0, 128.7, 128.4, 128.2, 118.0, 66.5. HRMS (ESI-TOF) m/z: [M +
(2E,4E)-Cyclohexyl Hexa-2,4-dienoate (3ic). Following the
general procedure, 3ic was purified by silica column chromatography
(hexane/EtOAc at a 20:1 ratio), obtained as a colorless oil (71 mg,
H]+ calcd for C16H15O2 239.1072; found 239.1069. IR (neat): vmax
/
73%). H NMR (500 MHz, CDCl3) δ 7.22 (dd, J = 10.3, 15.3 Hz,
1
cm−1 2958, 1709, 1626, 1343, 1449, 1240, 1174, 1133, 1064.
1H), 6.28−6.07 (m, 2H), 5.76 (d, J = 15.3 Hz, 1H), 4.92−4.77 (m,
1H), 1.90−1.82 (m, 5H), 1.72 (dd, J = 5.2, 7.7 Hz, 2H), 1.62−1.35
(m, 6H). 13C NMR {1H} (100 MHz, CDCl3) δ 166.9, 144.7, 139.0,
129.9, 119.8, 72.4, 31.8 (2C), 25.5, 23.9 (2C), 18.7. HRMS (ESI-
TOF) m/z: [M + H]+ calcd for C12H19O2 195.1385; found 195.1389.
IR (neat): vmax/cm−1 3025, 2934, 2661, 1712, 1629, 1450, 1435, 1350,
1318, 1286, 1167, 1039, 1018.
(E)-Butyl Penta-2,4-dienoate (3jb). Following the general
procedure, 3jb was purified by silica column chromatography
(hexane/EtOAc at a 20:1 ratio), obtained as a colorless oil (54 mg,
75%). 1H NMR (500 MHz, CDCl3) δ 7.29−7.22 (m, 1H), 6.50−6.40
(m, 1H), 5.90 (d, J = 15.5 Hz, 1H), 5.60 (d, J = 17.0 Hz, 1H), 5.48
(d, J = 10.5 Hz, 1H), 4.15 (t, J = 6.7 Hz, 2H), 1.67−1.61 (m, 2H),
1.40 (m, J = 7.5 Hz, 2H), 0.94 (t, J = 7.4 Hz, 3H). 13C NMR {1H}
(100 MHz, CDCl3) δ 167.0, 144.6, 134.8, 125.5, 122.3, 64.4, 30.8,
19.2, 13.8. HRMS (ESI-TOF) m/z: [M + H]+ calcd for C9H15O2
155.1072; found 155.1075. IR (neat): vmax/cm−1 2960, 2928, 2854,
1713, 1601, 1643, 1445, 1267, 1144.
(2E,4E)-Butyl 5-Cyclopropylpenta-2,4-dienoate (3kb). Fol-
lowing the general procedure, 3kb was purified by silica column
chromatography (hexane/EtOAc at a 20:1 ratio), obtained as a
colorless oil (76 mg, 78%). 1H NMR (400 MHz, CDCl3) δ 7.20 (dd, J
= 11.6, 15.3 Hz, 1 H), 6.24 (dd, J = 11.0, 15.3 Hz, 1 H), 5.73 (d, J =
15.3 Hz, 1 H), 5.59 (dd, J = 9.5, 15.0 Hz, 1 H), 4.11 (t, J = 6.7 Hz, 2
H), 1.65−1.59 (m, 2 H), 1.53−1.44 (m, 1 H), 1.42−1.33 (m, 2 H),
0.95−0.83 (m, 5 H), 0.56−0.45 (m, 2 H). 13C NMR {1H} (100 MHz,
CDCl3) δ 167.6, 148.8, 144.8, 125.8, 118.0, 64.1, 30.8, 19.2, 15.0,
13.8, 8.4(2C). HRMS (ESI-TOF) m/z: [M + H]+ calcd for C12H19O2
195.1385; found 195.1386. IR (neat): vmax/cm−1 3084, 3006, 1934,
2960, 2873, 1712, 1637, 1456, 1388, 1302, 1243, 1126, 1150.
(2E,4E)-Cyclohexyl 5-Cyclopropylpenta-2,4-dienoate (3kc).
Following the general procedure, 3kc was purified by silica column
chromatography (hexane/EtOAc at a 20:1 ratio), obtained as a
colorless oil (83 mg, 75%). 1H NMR (500 MHz, CDCl3) δ 7.19 (dd, J
= 11.2, 15.2 Hz, 1 H), 6.24 (dd, J = 10.9, 14.9 Hz, 1 H), 5.73 (d, J =
15.5 Hz, 1 H), 5.59 (dd, J = 9.5, 15.2 Hz, 1 H), 4.85−4.75 (m, 1 H),
1.91−1.79 (m, 2 H), 1.72 (dd, J = 3.4, 9.2 Hz, 2 H), 1.55−1.47 (m, 2
H), 1.45−1.32 (m, 4 H), 1.30−1.24 (m, 1 H), 0.89−0.84 (m, 2 H),
0.54−0.49 (m, 2 H). 13C NMR {1H} (125 MHz, CDCl3) δ 167.0,
148.5, 144.6, 125.9, 118.7, 72.3, 31.8, 25.5, 23.9, 14.9, 8.4. HRMS
(ESI-TOF) m/z: [M + Na]+ calcd for C14H20O2Na 243.1361; found
243.1366. IR (neat): vmax/cm−1 3085, 3008, 2918, 2850, 2252, 1701,
1636, 1453, 1382, 1257, 1300, 1242, 1151.
(2E,4E)-Butyl 6-Acetoxyhexa-2,4-dienoate (3lb). Following
the general procedure, 3lb was purified by silica column
chromatography (hexane/EtOAc at a 7:1 ratio), obtained as a
colorless oil (93 mg, 82%). 1H NMR (400 MHz, CDCl3) δ 7.24 (dd, J
= 11.0, 15.9 Hz, 1H), 6.37 (dd, J = 11.6, 15.3 Hz, 1H), 6.11 (td, J =
5.8, 15.3 Hz, 1H), 5.90 (d, J = 15.9 Hz, 1H), 4.66 (d, J = 6.1 Hz, 2H),
4.14 (t, J = 6.7 Hz, 2H), 2.08 (s, 3H), 1.70−1.61 (m, 2H), 1.39 (m, J
= 7.5, 2H), 0.95−0.90 (m, 3H). 13C NMR {1H} (100 MHz, CDCl3) δ
170.7, 166.9, 143.1, 135.2, 130.8, 122.7, 64.5, 63.9, 30.8, 20.9, 19.2,
13.8. HRMS (ESI-TOF) m/z: [M + H]+ calcd for C12H19O4
227.1283; found 227.1285. IR (neat): vmax/cm−1 2959, 2927, 2874,
1746, 1715, 1621, 1650, 1455, 1364, 1382, 1234, 1182, 1139, 1077,
1026, 1001.
(2E)-Methyl 3-Cyclohexenylacrylate (3ga). Following the
general procedure, 3ga was purified by silica column chromatography
(hexane/EtOAc at a 10:1 ratio), obtained as a colorless oil (61 mg,
81%). 1H NMR (500 MHz, CDCl3) δ 7.28 (d, J = 15.9 Hz, 1H), 6.16
(t, J = 3.9 Hz, 1H), 5.76 (d, J = 15.8 Hz, 1H), 3.73 (s, 3H), 2.20 (d, J
= 3.4 Hz, 2H), 2.15−2.11 (m, 2H), 1.71−1.66 (m, 2H), 1.64−1.59
(m, 2H). 13C NMR {1H}(100 MHz, CDCl3) δ 168.2, 148.4, 139.0,
135.0, 114.2, 51.5, 26.5, 24.2, 22.1 (2C). HRMS (ESI-TOF) m/z: [M
+ H]+ calcd for C10H15O2 167.1072; found 167.1080. IR (neat): vmax
/
cm−1 2928, 2856, 1721, 1628, 1435, 1378, 1309, 1269, 1167, 1136,
1073, 982.
(2E)-Butyl 3-Cyclohexenylacrylate (3gb). Following the
general procedure, 3gb was purified by silica column chromatography
(hexane/EtOAc at a 10:1 ratio), obtained as a colorless oil (83 mg,
80%). 1H NMR (400 MHz, CDCl3) δ 7.26 (d, J = 15.9 Hz, 1 H), 6.15
(t, J = 4.0 Hz, 1 H), 5.75 (d, J = 15.3 Hz, 1 H), 4.13 (t, J = 6.7 Hz, 2
H), 2.23−2.09 (m, 4 H), 1.70−1.59 (m, 6 H), 1.45−1.34 (m, 2 H),
0.93 (t, J = 7.3 Hz, 3 H). 13C NMR {1H} (100 MHz, CDCl3) δ 167.9,
148.1, 138.8, 135.0, 114.7, 64.1, 30.9, 26.5, 24.2, 22.1 (2C), 22.1, 19.3,
13.8. HRMS (ESI-TOF) m/z: [M + H]+ calcd for C13H21O2
209.1542; found 209.1538. IR (neat): vmax/cm−1 2957, 2931, 2863,
1716, 1630, 1458, 1286, 1164.
(2E)-Cyclohexyl 3-Cyclohexenylacrylate (3gc). Following the
general procedure, 3gc was purified by silica column chromatography
(hexane/EtOAc at a 10:1 ratio), obtained as a colorless oil (96 mg,
82%). 1H NMR (400 MHz, CDCl3) δ7.23 (s, 1 H), 6.14 (br. s., 1 H),
5.74 (d, J = 15.9 Hz, 1 H), 4.87−4.75 (m, 1 H), 2.24−2.08 (m, 4 H),
1.87 (dd, J = 4.0, 10.1 Hz, 2 H), 1.78−1.66 (m, 4 H), 1.66−1.56 (m,
3 H), 1.49−1.26 (m, 5 H). 13C NMR {1H} (100 MHz, CDCl3) δ
167.2, 147.8, 138.6, 135.0, 115.3, 72.4, 31.9 (2C), 26.5, 25.5, 24.2,
23.9 (2C), 22.2 (2C). HRMS (ESI-TOF) m/z: [M + Na]+ calcd for
C15H22O2Na 257.1517; found 257.1512. IR (neat): vmax/cm−1 3025,
2934, 2859, 2661, 1712, 1629, 1450, 1435, 1350, 1318, 1301, 1286,
1167, 1039, 1018, 925.
(2E)-tert-Butyl 3-Cyclohexenylacrylate (3gf). Following the
general procedure, 3gf was purified by silica column chromatography
(hexane/EtOAc at a 10:1 ratio), obtained as a colorless oil (86 mg,
83%). 1H NMR (400 MHz, CDCl3) δ 7.17 (d, J = 15.9 Hz, 1H), 6.11
(t, J = 4.3 Hz, 1H), 5.68 (d, J = 15.9 Hz, 1H), 2.21−2.15 (m, 2H),
2.11 (t, J = 6.1 Hz, 2H), 1.71−1.63 (m, 2H), 1.63−1.57 (m, 2H),
1.48 (s, 9H). 13C NMR {1H} (100 MHz, CDCl3) δ 167.2, 147.2,
138.1, 135.0, 116.5, 80.0, 28.3 (3C), 26.5, 24.3, 22.2 (2C). HRMS
(ESI-TOF) m/z: [M + Na]+ calcd for C13H20O2Na 231.1361; found
231.1360. IR (neat): vmax/cm−1 2976, 2931, 2861, 1705, 1631, 1619,
1455, 1435, 1367, 1316, 1287, 1268, 1149, 1098, 982.
(2E)-Methyl 3-Cyclopentenylacrylate (3ha). Following the
general procedure, 3ha was purified by silica column chromatography
(hexane/EtOAc at a 10:1 ratio), obtained as a colorless oil (55 mg,
80%). 1H NMR (400 MHz, CDCl3) δ 7.49 (d, J = 15.9 Hz, 1H), 6.16
(s, 1H), 5.72 (d, J = 15.9 Hz, 1H), 3.74 (s, 3H), 2.51−2.40 (m, 4H),
2.00−1.91 (m, 2H). 13C NMR {1H} (100 MHz, CDCl3) δ 168.0,
141.5, 141.2, 140.8, 117.8, 51.6, 33.6, 30.8, 23.1. HRMS (ESI-TOF)
m/z: [M + H]+ calcd for C9H13O2 153.0916; found 153.0916. IR
(neat): vmax/cm−1 2924, 2849, 1720, 1630, 1434, 1308, 1272, 1221,
1191, 1166, 1038, 980.
(2E,4E)-Methyl Hexa-2,4-dienoate (3ia). Following the general
procedure, 3ia was purified by silica column chromatography
(hexane/EtOAc at a 20:1 ratio), obtained as a colorless oil (44 mg,
70%). 1H NMR (500 MHz, CDCl3) δ 7.27−7.20 (m, 1H), 6.22−6.08
(2E,4E)-Cyclohexyl Ethyl Hexa-2,4-dienedioate (3mc). Fol-
lowing the general procedure, 3mc was purified by silica column
chromatography (hexane/EtOAc at a 5:1 ratio), obtained as a
1
colorless oil (106 mg, 84%). H NMR (400 MHz,CDCl3) δ 7.36−
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7.19 (m, 2H), 6.28−6.09 (m, 2H), 4.90−4.73 (m, 1H), 4.22 (q, J =
6.9 Hz, 2H), 1.86 (dd, J = 4.3, 9.2 Hz, 2H), 1.73 (dd, J = 3.7, 9.2 Hz,
2H), 1.60−1.32 (m, 6H), 1.29 (t, J = 7.3 Hz, 3H). 13C NMR {1H}
(100 MHz, CDCl3) δ 166.0, 165.4, 141.0, 140.5, 131.7 (2C), 128.3,
73.3, 60.9, 31.7, 25.4, 23.8 (2C), 14.3. HRMS (ESI-TOF) m/z: [M +
Na]+ calcd for C14H20O4Na 275.1259; found 275.1252. IR (neat):
C9H12N 134.0970; found 134.0970. IR (neat): vmax/cm−1 3058, 2927,
2857, 2215, 1738, 1626, 1598, 1448, 1434, 1378, 965.
(2E,4E)-Ethyl 5-Cyanopenta-2,4-dienoate (5ma). Following
the general procedure, 5ma was purified by silica column
chromatography (hexane/EtOAc at a 10:1 ratio), obtained as a
colorless oil (66 mg, 75%). 1H NMR (500 MHz,CDCl3) δ 7.24 (dd, J
= 11.5, 15.5 Hz, 1H), 7.07 (dd, J = 11.2, 15.8 Hz, 1H), 6.19 (d, J =
14.3 Hz, 1H), 5.70 (d, J = 15.5 Hz, 1H), 4.24 (q, J = 6.9 Hz, 2H),
1.30 (t, J = 7.2 Hz, 3H). 13C NMR {1H} (100 MHz, CDCl3) δ 165.4,
147.1, 139.5, 129.6, 116.9, 106.1, 61.3, 14.3. HRMS (ESI-TOF) m/z:
[M + H]+ calcd for C8H10NO2 152.0712; found 152.0715. IR (neat):
v
max/cm−1 3400, 3066, 2938, 2861, 1699, 1611, 1456, 1446, 1310,
1251, 1167, 1027, 1015, 935.
(2E,4E)-9-(Acryloyloxy)nonyl Ethyl Hexa-2,4-dienedioate
(3mg). Following the general procedure, 3mg was purified by silica
column chromatography (hexane/EtOAc at a 6:1 ratio), obtained as a
v
max/cm−1 3404, 3028, 3054, 2987, 2960, 2926, 2855, 2255, 2217,
1
colorless oil (124 mg, 68%). H NMR (500 MHz, CDCl3) δ 7.27 (s,
1710, 1670, 1636, 1263, 1183, 1001, 910.
1H), 7.31 (s, 1H), 6.38 (d, J = 17.1 Hz, 1H), 6.24−5.97 (m, 3H),
5.79 (d, J = 10.4 Hz, 1H), 4.22 (q, J = 7.1 Hz, 2H), 4.14 (q, J = 7.3
Hz, 4H), 1.71−1.62 (m, 4H), 1.35−1.27 (m, 13H). 13C NMR {1H}
(100 MHz, CDCl3) δ 166.4, 166.1, 166.0, 140.9 (2C), 130.6, 128.7,
128.5 (2C), 65.1, 64.7, 61.0, 29.5, 29.4, 29.3, 29.2, 28.7, 26.0 (2C),
14.3. HRMS (ESI-TOF) m/z: [M + H]+ calcd for C20H31O6
367.2121; found 367.2128. IR (neat): vmax/cm−1 3070, 2928, 2855,
1721, 1703, 1613, 1473, 1313, 1295, 1260, 1240, 1021.
(2E,4E)-5-p-Tolylpenta-2,4-dienenitrile (5ba). Following the
general procedure, 5ba was purified by silica column chromatography
(hexane/EtOAc at a 30:1 ratio), obtained as a white solid (70 mg,
83%). 1H NMR (400 MHz, CDCl3) δ 7.34 (d, J = 7.9 Hz, 2H), 7.18−
7.09 (m, 3H), 6.87−6.76 (m, 2H), 5.39 (d, J = 15.9 Hz, 1H), 2.35 (s,
3H). 13C NMR {1H} (100 MHz, CDCl3) δ 150.6, 141.5, 140.1, 132.6,
129.8 (2C), 127.5 (2C), 124.6, 118.6, 97.6, 21.5. HRMS (ESI-TOF)
m/z: [M + H]+ calcd for C12H12N 170.0970; found 170.0971. IR
(neat): vmax/cm−1 3028, 3049,2924, 2856,2254, 2209, 1732, 1605,
1623, 1593, 1454, 1310, 1286, 1153, 968, 995, 980.
(1E)-1-Cyclohexenylpent-1-en-3-one (5gb). Following the
general procedure, 5gb was purified by silica column chromatography
(hexane/EtOAc at a 20:1 ratio), obtained as a colorless oil (60 mg,
73%). 1H NMR (400 MHz, CDCl3) δ 7.14 (d, J = 15.9 Hz, 1H), 6.19
(t, J = 4.3 Hz, 1H), 6.06 (d, J = 16.5 Hz, 1H), 2.58 (q, J = 7.3 Hz,
2H), 2.24−2.17 (m, 2H), 2.16−2.11 (m, 2H), 1.72−1.65 (m, 2H),
1.64−1.59 (m, 2H), 1.10 (t, J = 7.3 Hz, 3H). 13C NMR {1H} (100
MHz, CDCl3) δ 201.7, 146.0, 139.7, 135.3, 123.1, 33.7, 26.7, 24.3,
22.1(2C), 8.5. HRMS (ESI-TOF) m/z: [M + Na]+ calcd for
C11H16ONa 187.1099; found 187.1096. IR (neat): vmax/cm−1 2931,
2860, 1688, 1664, 1625, 1598, 1434, 1458, 1375, 1278, 1194, 1120,
1049, 1035.
(1E)-1-Cyclopentenylpent-1-en-3-one (5hb). Following the
general procedure, 5hb was purified by silica column chromatography
(hexane/EtOAc at a 20:1 ratio), obtained as a colorless oil (56 mg,
74%). 1H NMR (500 MHz, CDCl3) δ7.37 (d, J = 16.0 Hz, 1 H), 6.21
(br. s., 1 H), 6.01 (d, J = 16.0 Hz, 1 H), 2.59 (q, J = 7.4 Hz, 2 H),
2.51−2.41 (m, 4 H), 2.02−1.88 (m, 2 H), 1.11 (t, J = 7.4 Hz, 3 H).
13C NMR {1H} (125 MHz, CDCl3) δ 201.8, 141.9, 141.5, 138.6,
126.6, 33.7, 33.6, 30.9, 23.2, 8.4. HRMS (ESI-TOF) m/z: [M + H]+
calcd for C10H15O 151.1123; found 151.1122. IR (neat): vmax/cm−1
3372, 3039, 2924, 2954, 2851, 1690, 1668, 1612, 1590, 1460, 1411,
1375, 1189, 1119, 1037.
(4E,6E)-7-Cyclopropylhepta-4,6-dien-3-one (5kb). Following
the general procedure, 5kb was purified by silica column
chromatography (hexane/EtOAc at a 20:1 ratio), obtained as a
colorless oil (56 mg, 75%). 1H NMR (400 MHz, CDCl3) δ 7.10 (dd, J
= 11.3, 15.4 Hz, 1H), 6.25 (dd, J = 10.9, 15.0 Hz, 1H), 6.04 (d, J =
15.4 Hz, 1H), 5.64 (dd, J = 9.5, 15.0 Hz, 1H), 2.54 (q, J = 7.4 Hz,
2H), 1.54−1.46 (m, 1H), 1.09 (t, J = 7.2 Hz, 3H), 0.91−0.86 (m,
2H), 0.56−0.51 (m, 2H). 13C NMR {1H} (100 MHz, CDCl3) δ
201.5, 149.8, 142.7, 126.6, 126.4, 33.7, 15.2, 8.6, 8.4(2C). HRMS
(ESI-TOF) m/z: [M + Li]+ calcd for C10H14OLi 157.1205; found
157.1208. IR (neat): vmax/cm−1 3085, 3007, 2975, 2927, 2855, 1897,
1715, 1688, 1662, 1632, 1595, 1455, 1377, 1281, 1201, 1033, 1049,
997, 950, 861.
1-((1E,3E)-Nona-1,3-dienylsulfonyl)benzene (5nc). Following
the general procedure, 5nc was purified by silica column
chromatography (hexane/EtOAc at a 3:1 ratio), obtained as a white
solid (92 mg, 70%). 1H NMR (500 MHz, CDCl3) δ 7.88 (dd, J = 0.9,
8.2 Hz, 2H), 7.62−7.56 (m, 1H), 7.56−7.47 (m, 2H), 7.24 (dd, J =
10.9, 14.7 Hz, 1H), 6.29−6.20 (m, 2H), 6.09 (dd, J = 10.9, 15.2 Hz,
1H), 2.16 (q, J = 7.1 Hz, 2H), 1.41 (q, J = 7.3 Hz, 2H), 1.30−1.25
(m, 4H), 0.87 (t, J = 6.9 Hz, 3H). 13C NMR {1H} (125 MHz,
CDCl3) δ 148.1, 143.1, 141.2, 133.2, 129.3 (2C), 127.6 (2C), 127.5,
126.1, 33.1, 31.4, 28.2, 22.5, 14.1. HRMS (ESI-TOF) m/z: [M + H]+
calcd for C15H21SO2 265.1262; found 265.1260. IR (neat): vmax/cm−1
3404, 3028, 3054, 2987, 2960, 2926, 2855, 2255, 2217, 1710, 1670,
1636, 1263, 1183, 1001, 910.
(2E,4E)-5-(4-Bromophenyl)penta-2,4-dienenitrile (5ca). Fol-
lowing the general procedure, 5ca was purified by silica column
chromatography (hexane/EtOAc at a 30:1 ratio), obtained as a white
1
solid (80 mg, 68%). H NMR (500 MHz, CDCl3) δ 7.49 (d, J = 8.6
Hz, 2H), 7.31 (d, J = 8.6 Hz, 2H), 7.12 (ddd, J = 2.6, 7.3, 16 Hz, 1H),
6.85−6.74 (m, 2H), 5.45 (d, J = 16.0 Hz, 1H). 13C NMR {1H} (125
MHz, CDCl3) δ 150.0, 140.0, 134.3, 132.2 (2C), 128.8 (2C), 126.1,
123.9, 118.2, 99.1. HRMS (ESI-TOF) m/z: [M + H]+ calcd for
C11H9NBr 233.9918; found 233.9925. IR (neat): vmax/cm−1 3051,
3019, 2923, 2853, 2253, 2211, 1911, 1737, 1620, 1597, 1579, 1486,
1467, 1402, 1274, 1150, 1099, 1007, 1071, 983, 948.
(2E,4E)-5-(4-Fluorophenyl)penta-2,4-dienenitrile (5da). Fol-
lowing the general procedure, 5da was purified by silica column
chromatography (hexane/EtOAc at a 30:1 ratio), obtained as a white
solid (86 mg, 60%). 1H NMR (500 MHz, CDCl3) δ 7.43 (dd, J = 5.4,
8.4 Hz, 2H), 7.13 (dd, J = 10.7, 15.9 Hz, 1H), 7.06 (t, J = 8.6 Hz,
2H), 6.84 (d, J = 15.6 Hz, 1H), 6.73 (dd, J = 10.8, 15.5 Hz, 1H), 5.43
(d, J = 15.9 Hz, 1H). 13C NMR {1H} (125 MHz, CDCl3) δ 164.5,
1
3
162.6 (d, JCF = 262.5 Hz), 150.2, 140.1, 131.6, 129.2 (2C, d, JCF
=
2
8.75 Hz) 125.3, 118.3, 116.3, 116.1 (2C, d, JCF = 21.2 Hz), 98.4.
HRMS (ESI-TOF) m/z: [M + H]+ calcd for C11H9NF 174.0719;
found 174.0720. IR (neat): vmax/cm−1 2911, 2883, 2212, 1726, 1671,
1616, 1402,1288, 1219, 1151, 1172, 1047, 983.
Cinnamonitrile (5fa). Following the general procedure, 5fa was
purified by silica column chromatography (hexane/EtOAc at a 30:1
1
ratio), obtained as a white solid (77 mg, 85%). H NMR (500 MHz,
CDCl3) δ 7.47−7.35 (m, 6 H), 5.87 (d, J = 17.2 Hz, 1 H). 13C NMR
{1H} (125 MHz, CDCl3) δ 150.7, 133.6, 131.3, 129.2, 127.4, 118.2,
96.4. HRMS (ESI-TOF) m/z: [M + H]+ calcd for C9H10N 132.0813;
found 132.0818. IR(neat): vmax/cm−1 2929, 2856, 1628, 1439, 1450,
1324, 1342, 1240, 1172, 1137, 1031.
(2E)-3-Cyclohexenylacrylonitrile (5ga). Following the general
procedure, 5ga was purified by silica column chromatography
(hexane/EtOAc at a 30:1 ratio), obtained as a colorless oil (62 mg,
78%). 1H NMR (500 MHz, CDCl3) δ 6.98 (d, J = 16.4 Hz, 1 H), 6.14
(t, J = 4.2 Hz, 1 H), 5.17 (d, J = 16.3 Hz, 1 H), 2.24−2.19 (m, 2 H),
2.09−2.04 (m, 2 H), 1.71−1.66 (m, 2 H), 1.61 (td, J = 2.6, 8.4 Hz, 2
H). 13C NMR {1H} (100 MHz, CDCl3) δ 153.8, 140.0, 134.7, 92.4,
26.4, 23.5, 21.8, 21.8. HRMS (ESI-TOF) m/z: [M + H]+ calcd for
1-((1E)-2-Cyclopentenylvinylsulfonyl)benzene (5hc). Follow-
ing the general procedure, 5hc was purified by silica column
chromatography (hexane/EtOAc at a 3:1 ratio), obtained as a white
1
solid (89 mg, 76%). H NMR (400 MHz, CDCl3) δ 7.91−7.85 (m,
2H), 7.62−7.56 (m, 1H), 7.56−7.45 (m, 3H), 6.33−6.26 (m, 1H),
6.16 (dd, J = 0.8, 15.0 Hz, 1H), 2.53−2.44 (m, 2H), 2.38−2.32 (m,
2H), 1.94 (m, 2H). 13C NMR {1H} (100 MHz, CDCl3) δ 143.8,
141.2, 139.5, 138.9, 133.2, 129.3 (2C), 127.6 (2C), 126.9, 33.8, 30.9,
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Article
23.1. HRMS (ESI-TOF) m/z: [M + H]+ calcd for C13H15SO2
235.0793; found 235.0787. IR (neat): vmax/cm−1 3028, 3054, 2987,
2960, 2926, 2217, 1710, 1670, 1636, 1263.
1.05 (t, J = 7.4 Hz, 3H). 13C NMR {1H} (100 MHz, CDCl3) δ 211.4,
143.4, 123.7, 40.8, 35.9, 35.3, 32.5, 25.4, 23.4, 7.9. HRMS (ESI-TOF)
m/z: [M + H]+ calcd for C10H17O 153.1279; found 153.1280. IR
(neat): vmax/cm−1 3045, 2925, 2850, 1717, 1651, 1614, 1460, 1413,
1376, 1111, 978.
(E)-Undec-5-en-2-one (6nf). Following the general procedure,
6nf was purified by silica column chromatography (hexane/EtOAc at
a 20:1 ratio), obtained as a colorless oil (50 mg, 60%). 1H NMR (400
MHz, CDCl3) δ 5.49−5.27 (m, 2H), 2.49−2.42 (m, 2H), 2.23 (q, J =
6.7 Hz, 2H), 2.11 (s, 3H), 1.97−1.87 (m, 2H), 1.35−1.25 (m, 6H),
0.85 (t, J = 6.7 Hz, 3H). 13C NMR {1H} (100 MHz, CDCl3) δ 208.6,
131.7, 128.2, 43.7, 32.5, 31.4, 30.0, 29.2, 26.9, 22.6, 14.1. HRMS (ESI-
TOF) m/z: [M + H]+ calcd for C11H21O 169.1592; found 169.1593.
IR (neat): vmax/cm−1 2957, 2925, 2855, 1718, 1440, 1359, 1160, 969.
(E)-Cinnamamide (5fd). Following the general procedure, 5fd
was purified by silica column chromatography (hexane/EtOAc at a
1
1:4 ratio), obtained as a white solid (77 mg, 81%). H NMR (500
MHz, CDCl3) δ 7.65 (d, J = 15.6 Hz, 1 H), 7.57−7.45 (m, 2 H), 7.38
(br. s., 3 H), 6.45 (d, J = 15.8 Hz, 1 H), 5.58 (br. s., 2 H). 13C NMR
{1H} (125 MHz, CDCl3) δ 166.7, 141.7, 133.6, 129.1, 127.9, 127.0,
118.5. HRMS (ESI-TOF) m/z: [M + Na]+ calcd for C9H9NONa
170.0582; found 170.0586. IR (neat): vmax/cm−1 2926, 1665, 1594,
1439, 1450, 1321, 1344, 1241, 1173, 1139, 1035.
(2E)-3-Cyclopentenylacrylamide (5hd). Following the general
procedure, 5hd was purified by silica column chromatography
(hexane/EtOAc at a 1:4 ratio), obtained as a sticky solid (54 mg,
79%). 1H NMR (400 MHz, CDCl3) δ 7.43 (d, J = 15.9 Hz, 1H), 6.13
(s, 1H), 5.73 (d, J = 15.3 Hz, 1H), 5.58 (br. s., 2H), 2.51−2.36 (m,
4H), 1.96 (m, J = 7.6 Hz, 2H). 13C NMR {1H} (100 MHz, CDCl3)
δ168.7, 141.2, 140.1, 138.8, 119.5, 33.5, 31.0, 23.2. HRMS (ESI-
TOF) m/z: [M + H]+ calcd for C8H12ON 138.0919; found 138.0914.
IR (neat): vmax/cm−1 3355, 3169, 2954, 2852, 2923, 1662, 1592, 1397,
1462, 1439, 1243, 1103, 1037.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.joc.0c02823.
■
sı
Copies of 1H and 13C spectra for all products and table
of results from kinetics NMR experiments (PDF)
(2E,4E)-Methyl 3-Methyl-5-phenylpenta-2,4-dienoate (5ae).
Following the general procedure, 5ae was purified by silica column
chromatography (hexane/EtOAc at a 20:1 ratio), obtained as a white
AUTHOR INFORMATION
Corresponding Author
■
1
solid (66 mg, 65%). H NMR (400 MHz, CDCl3) δ 7.48−7.41 (m,
2H), 7.37−7.31 (m, 2H), 7.31−7.25 (m, 1H), 6.94 (d, J = 16.5 Hz,
1H), 6.80 (d, J = 15.9 Hz, 1H), 5.90 (s, 1H), 3.72 (s, 3H), 2.40 (s,
3H). 13C NMR {1H} (100 MHz, CDCl3) δ 167.5, 152.5, 136.4, 134.3,
131.9, 128.9 (2C), 128.7, 127.1 (2C), 119.4, 51.2, 13.8. HRMS (ESI-
TOF) m/z: [M + H]+ calcd for C13H15O2 203.1072; found 203.1075.
IR (neat): vmax/cm−1 1712, 1609, 1433, 1357,1238, 1154, 960, 690.
(E)-7-Phenylhept-6-en-3-one (6ab). Following the general
procedure, 6ab was purified by silica column chromatography
(hexane/EtOAc at a 20:1 ratio), obtained as a white solid (68 mg,
70%). 1H NMR (400 MHz, CDCl3) δ 7.33−7.25 (m, 4H), 7.22−7.15
(m, 1H), 6.39 (d, J = 15.9 Hz, 1H), 6.18 (td, J = 6.7, 15.9 Hz, 1H),
2.61−2.54 (m, 2H), 2.52−2.39 (m, 4H), 1.06 (t, J = 7.3 Hz, 3H). 13C
NMR {1H} (100 MHz, CDCl3) δ 210.8, 137.5, 130.8, 129.1, 128.6
(2C), 127.2, 126.1 (2C), 41.9, 36.2, 27.3, 7.9. HRMS (ESI-TOF) m/
z: [M + H]+ calcd for C13H17O 189.1279; found 189.1282. IR (neat):
Dattatraya H. Dethe − Department of Chemistry, Indian
Institute of Technology Kanpur, Kanpur 208016, India;
orcid.org/0000-0003-2734-210X; Email: ddethe@
iitk.ac.in
Authors
Nagabhushana C. Beeralingappa − Department of Chemistry,
Indian Institute of Technology Kanpur, Kanpur 208016,
India
Amar Uike − Department of Chemistry, Indian Institute of
Technology Kanpur, Kanpur 208016, India
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.joc.0c02823
v
max/cm−1 3059, 3025, 2974, 2934, 2852, 1714, 1597, 1448, 1260,
Notes
1114, 1027.
The authors declare no competing financial interest.
(E)-7-p-Tolylhept-6-en-3-one (6bb). Following the general
procedure, 6bb was purified by silica column chromatography
(hexane/EtOAc at a 20:1 ratio), obtained as a white solid (76 mg,
75%). 1H NMR (400 MHz, CDCl3) δ 7.23−7.18 (m, J = 8.5 Hz, 2H),
7.11−7.05 (m, J = 7.9 Hz, 2H), 6.36 (d, J = 15.9 Hz, 1H), 6.13 (td, J
= 6.7, 15.9 Hz, 1H), 2.56 (d, J = 7.3 Hz, 2H), 2.50−2.40 (m, 4H),
2.31 (s, 3H), 1.05 (t, J = 7.3 Hz, 3H). 13C NMR {1H} (100 MHz,
CDCl3) δ 210.9, 136.9, 134.7, 130.6, 129.3 (2C), 128.0, 126.0 (2C),
42.0, 36.1, 27.3, 21.2, 7.9. HRMS (ESI-TOF) m/z: [M + H]+ calcd
for C14H19O 203.1436; found 203.1432. IR (neat): vmax/cm−1 3413,
3022, 2922, 2853, 1899, 1714, 1612, 1581, 1512, 1458, 1411, 1375,
1306, 1260, 1208, 1181, 1112, 1067, 1019.
ACKNOWLEDGMENTS
■
N.C.B. and A.U. thank UGC, New Delhi, for the award of a
research fellowship. Financial support from SERB Project No.
EMR/2017/001455 is gratefully acknowledged.
REFERENCES
■
(1) (a) Mizoroki, T.; Mori, K.; Ozaki, A. Arylation of Olefin with
Aryl Iodide Catalyzed by Palladium. Bull. Chem. Soc. Jpn. 1971, 44,
581. (b) Heck, R.; Nolley, J. P. Palladium-catalyzed vinylic hydrogen
substitution reactions with aryl, benzyl, and styryl halides. J. Org.
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4-Phenylbutan-2-one (6ff). Following the general procedure, 6ff
was purified by silica column chromatography (hexane/EtOAc at a
1
(2) For reviews of the Heck reaction, see (a) Diederich, F.; de
Meijere, A. Metal-Catalyzed Cross-Coupling Reactions; Wiley: New
York, 1998; Chapter 3. (b) Beletskaya, I. P.; Cheprakov, A. V. Heck
Reaction as a Sharpening Stone of Palladium Catalysis. Chem. Rev.
2000, 100, 3009. (c) Heck, R. F. Comprehensive Organic Synthesis;
Trost, B. M., Ed.; Pergamon: New York, 1991; Vol. 4. Chapter 4.3.
(d) Heck, R. F. Palladium-Catalyzed Vinylation of Organic Halides.
Org. React. 1982, 27, 345. (e) Crisp, G. T. Variations on a theme-
recent developments on the mechanism of the Heck reaction and
their implications for synthesis. Chem. Soc. Rev. 1998, 27, 427. (f) de
Meijere, A.; Meyer, F. E. Fine Feathers Make Fine Birds: The Heck
Reaction in Modern Garb. Angew. Chem. Int. Ed. Engl. 1995, 33, 2379.
(g) Jeffery, T.; Liebeskind, L. S. Advances in Metal-Organic Chemistry;
20:1 ratio), obtained as a colorless oil (60 mg, 65%). H NMR (500
MHz,CDCl3) δ 7.32−7.22 (m, 2 H), 7.22−7.11 (m, 3 H), 2.89 (t, J =
7.7 Hz, 2 H), 2.76 (t, J = 7.7 Hz, 2 H), 2.14 (s, 3 H). 13C NMR {1H}
(125 MHz, CDCl3) δ 207.0, 140.1, 127.6, 127.4, 125.2, 44.3, 29.2,
28.8. HRMS (ESI-TOF) m/z: [M + H]+ calcd for C10H13O 149.0966;
found 149.0969. IR (neat): vmax/cm−1 2931, 2860, 1720, 1664, 1625,
1588, 1458, 1375, 1278, 1194, 1120, 1049, 1035.
1-Cyclopentenylpentan-3-one (6hb). Following the general
procedure, 6hb was purified by silica column chromatography
(hexane/EtOAc at a 20:1 ratio), obtained as a colorless oil (50 mg,
65%). 1H NMR (500 MHz, CDCl3) δ 5.41−5.21 (m, 1H), 2.58−2.53
(m, 2H), 2.46−2.40 (m, 2H), 2.33 (t, J = 8.0 Hz, 2H), 2.27 (ddd, J =
2.3, 4.7, 9.6 Hz, 2H), 2.22 (t, J = 8.6 Hz, 2H), 1.87−1.80 (m, 2H),
3453
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JAI: London, 1996; Vol. 5, p 153. (h) Cabri, W.; Candiani, I. Recent
Developments and New Perspectives in the Heck Reaction. Acc.
Chem. Res. 1995, 28, 2.
(3) For example, see the following (a) Danishefsky, S. J.; Masters, J.
J.; Young, W. B.; Link, J. T.; Snyder, L. B.; Magee, T. V.; Jung, D. K.;
Isaacs, R. C. A.; Bornmann, W. G.; Alaimo, C. A.; Coburn, C. A.; Di
Grandi, M. J. Total Synthesis of Baccatin III and Taxol. J. Am. Chem.
Soc. 1996, 118, 2843. (b) Overman, L. E.; Ricca, D. J.; Tran, V. D.
First total synthesis of scopadulcic acid B. J. Am. Chem. Soc. 1993,
115, 2042.
(4) (a) Link, J. T.; Overman, L. E.; Diederich, F.; Stang, P. J. Metal-
Catalyzed Cross-Coupling Reactions; Wiley-VCH: New York, 1998;
Chapter 6. (b) Nicolaou, K. C.; Sorensen, E. J. Classics in Total
Synthesis; VCH: New York, 1996; Chapter 31. These authors refer to
the Heck reaction as “one of the true “power tools” of contemporary
organic synthesis”
(5) For example, see (a) Hedrick, J. L.; Labadie, J. W. ACS
Symposium Series 624; American Chemical Society: DC Washington,
1996; Chapters 1, 2, and 4. (b) Devries, R. A.; Vosejpka, P. C.; Ash,
M. L.; Herkes, F. E. Catalysis of Organic Reactions; Marcel Dekker:
New York, 1998; Chapter 37. (c) Tietze, L. F.; Kettschau, G.;
Heuschert, U.; Nordmann, G. Highly Efficient Synthesis of Linear
Pyrrole Oligomers by Two fold Heck Reactions. Chemistry 2001, 7,
368.
(c) Whitcombe, N. J.; Hii, K. K.; Gibson, S. E. Advances in the Heck
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