Gold-catalyzed partial hydrogenation of activated alkynes mediated by triphenylphosphine

Article abstract of DOI:10.1055/s-0040-1707395

Gold(I) can exhibit a cooperative effect with triphenylphosphine, accelerating the triphenylphosphine-mediated partial hydrogenation of activated alkynes. In this protocol, 3-arylpropiolates are selectively reduced to the Z -isomer when the aryl ring bears an electron-donor substituent, whereas 3-arylpropynones are reduced to the E-isomers.

Full text of DOI:10.1055/s-0040-1707395

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2020, 31, A–H
paper
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en
A. P. Cocoletzi-Xochitiotzi et al.
Paper
Synthesis
Gold-Catalyzed Partial Hydrogenation of Activated Alkynes
Mediated by Triphenylphosphine
Ana Patricia Cocoletzi-Xochitiotzia,b
Miguel Hernández-Hernándeza,b
Ignacio Medina-Mercadoa
Williams de Jesús Jiménez-Martíneza
Virginia Maricela Mastranzoa,b
IPrAuCl/AgSbF6 cat.
O
R
Ar
O
O
R
and/or
Ar
Ar
R
Ph3P, t-BuOH
MeCN, 60 °C
38–89%
16 examples
R = OEt, Ph
Susana Porcel*a
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0
0
0-0
0
0
1-7
9
5
4-7
4
7
9
a Instituto de Química, Universidad Nacional Autónoma de México,
Circuito Exterios s/n, Ciudad Universitaria, Ciudad de México
04510, México
sporcel@unam.mx
b Universidad Autónoma de Tlaxcala, Facultad de Ciencias Básicas,
Ingeniería y Tecnología, Calzada Apizaquito S/N 90300, Apizaco,
Tlaxclala, México
Received: 15.03.2020
Accepted after revision: 08.04.2020
Published online: 12.05.2020
ing-up.8 It is also possible to attain the E-isomer by catalytic
alkene isomerization from the Z-isomer, and in some in-
stances the direct formation of the E-isomer has been ob-
served.9 Although broadly employed, these methods suffer
from the use of molecular hydrogen, which entails storage
risks or hazardous reagents.
For these reasons we turned our attention to the phos-
phine-mediated partial hydrogenation of alkynes as an at-
tractive alternative. In particular, we got interested in
studying the effect of incorporating a gold catalyst to the re-
action, expecting to observe a cooperative effect with the
phosphine,10 due to the high alkynophilicity of gold
(Scheme 1).11
DOI: 10.1055/s-0040-1707395; Art ID: ss-2020-m0020-op
Abstract Gold(I) can exhibit a cooperative effect with triphenylphos-
phine, accelerating the triphenylphosphine-mediated partial hydroge-
nation of activated alkynes. In this protocol, 3-arylpropiolates are selec-
tively reduced to the Z-isomer when the aryl ring bears an electron-
donor substituent, whereas 3-arylpropynones are reduced to the E-iso-
mers.
Key words partial hydrogenation, alkynes, triphenylphosphine, gold,
catalysis
The high oxophilicity of phosphonium ions has been
used in organic chemistry to trigger valuable synthetic
transformations such as the Mitsunobu, Wittig, and Appel
reactions.1 Although less known, the same principle has
been applied to the synthesis of alkenes from alkynes. In
1969, Tebby and co-workers reported the synthesis of 1,2-
dideuterated olefins from activated alkynes, using triphen-
ylphosphine and deuterium oxide.2 The methodology was
later explored by Larpent, Trofimov, and Yeh and their co-
workers, who achieved good levels of stereoselectivity to-
ward E-alkenes.3 More recently the group of Whittaker re-
ported the reduction of alkynyl carbonyls leading to either
the E- or Z-stereoisomers by tuning the reaction condi-
tions.4 Classical methods to perform the partial hydrogena-
tion of alkynes to alkenes use homogeneous or heteroge-
neous catalysts under H2 atmosphere.5 This process gener-
ally delivers the Z-isomer, coming from the syn-addition of
H2.6 The same isomer can be preferentially obtained by ac-
tivating hydrogen with frustrated Lewis pairs, or by using
silanes or transfer hydrogenation reactions.7 On the other
hand, the E-isomer is conventionally prepared by the Birch
reduction, which employs alkali metals dissolved in ammo-
nia and limits the functional-group tolerance and the scal-
Previous work
PPh2
Ph3P or
O
O
Tebby
Larpent
Yeh
SO3Na
R1
R1
R2
R2
H2O
Trofimov
O
Ph3P, PhCO2H
H2O
Ph3P
H2O
O
R1
R1
Whittaker
R1
R2
O
R2
R2
This work
O
O
[Au] cat.
Ph3P, t-BuOH
Ar
Ar
OEt
OEt
E or Z
Scheme 1 Partial hydrogenation of activated alkynes mediated by
phosphines
We started our investigation by examining the partial
hydrogenation of ethyl 3-phenylpropiolate, using the cou-
ple Ph3PAuCl/AgSbF6 as catalyst. Ethyl cinnamate was ob-
tained in 48% after heating at 60 °C for 30 hours in acetoni-
© 2020. Thieme. All rights reserved. Synthesis 2020, 31, A–H
Georg Thieme Verlag KG, Rüdigerstraße 14, 70469 Stuttgart, Germany

B
A. P. Cocoletzi-Xochitiotzi et al.
Paper
Synthesis
Table 1 Optimization of the Reaction Conditions for the Reduction of
cleaner, ethyl cinnamate being obtained in 79% yield after
24 hours (entry 3). In control experiments, using Ph3PAuCl
or AgSbF6 alone (entries 4 and 5) the yield lowered to 30%
and 36%, respectively. Similarly, in the absence of catalysts
the yield dropped to 20% (entry 6). The results displayed on
entries 4 to 6, point that gold accelerates the reduction me-
diated by triphenylphosphine whereas maintaining the ste-
reoselectivity observed in the absence of catalyst.
With the optimized conditions in hand we next studied
the scope of the reaction (Table 2). 3-Arylpropiolates bear-
ing electron-rich aryl moieties such us tolyl, anisyl, biphe-
nyl, and thiophenyl, behave similarly to 3-phenylpropiolate
furnishing the corresponding alkenes in yields ranging from
41% to 75% (Table 2, entries 2–5), with good Z-stereoselec-
tivity. On the other hand, 3-arylpropiolates bearing elec-
tron-deficient aryl moieties such us 4-nitrophenyl, 4-cy-
anophenyl, 4-acetophenyl, and pyridyl (entries 6, 7, 9 and
11, respectively) reacted faster (6–13 h) delivering the cor-
responding alkenes in comparatively better yields, but with
lower stereoselectivity. Conversely, 8a containing a (trifluo-
romethyl)phenyl group and 10a containing a 4-chlorophe-
nyl group, gave preferentially the Z-isomer in 82% and 89%
yields, respectively.
Ethyl 3-Phenylpropiolatea
O
O
O
Ph3P, cat.
Ph
Ph
OEt
solvent, 60 °C
Ph
OEt
OEt
1a
1b
1c
Entry Catalyst
Nucleophile
H2O
Time (h) Yield (%)b Z/Ec
1
2
3
4
5
6
Ph3PAuCl/AgSbF6
10/10 mol%)
30
30
24
24
24
24
48
77
79
30
36
20
1:0.08
1:0.03
1:0.03
1:0.17
1:0.16
1:0.03
(10 equiv)
IPrAuCl/AgSbF6
(5/6 mol%)
H2O
(10 equiv)
IPrAuCl/AgSbF6
(5/6 mol%)
t-BuOH
(10 equiv)
IPrAuCl
(5 mol%)
t-BuOH
(10 equiv)
AgSbF6
(10 mol%)
t-BuOH
(10 equiv)
–
t-BuOH
(10 equiv)
a 3-Phenylpropiolate: 2 mmol/mL.
b Isolated yield.
c Z/E ratio determined by 1H NMR analysis of the crude mixture.
trile (Table 1, entry 1). Interestingly, under these conditions
the Z-isomer was favored (Z/E: 1:0.08). In order to improve
the yield, we replaced Ph3P by the more electron-donating
In comparison, 3-arylpropynones were less reactive
than 3-arylpropiolates delivering the corresponding chal-
cones in moderated yields (38–62%) and requiring an in-
crease in the amount of Ph3P (1.5 equiv). In this case, the E-
isomer was the major compound for both 3-arylpro-
pynones containing electron-donating and -withdrawing
groups (Table 3).
ligand
IPr
[1,3-bis(2,6-diisopropylphenyl)imidazol-2-
ylidene] (entry 2). As a result, the catalyst loading could be
reduced to 5 mol%, and the yield increased to 77%. Next, we
replaced H2O by t-BuOH and observed that the reaction was
Table 2 Scope of 3-Arylpropiolatesa
IPrAuCl/AgSbF6
O
O
O
(5 mol%/6 mol%)
Ar
OEt
Ar
Ar
OEt
Ph3P (1.1 equiv)
t-BuOH (3 equiv)
MeCN, 60 °C
OEt
1a–11a
1b–11b
1c–11c
Entry
1
Substrate
Time (h)
Product
Yield (%)b
79
Z/Ec
O
O
24
24
1:0.09
OEt
OEt
1a
1b
Me
O
Me
O
2
3
41
75
1:0.05
1:0.02
OEt
OEt
2a
2b
MeO
O
MeO
O
24
OEt
OEt
3a
3b
© 2020. Thieme. All rights reserved. Synthesis 2020, 31, A–H

C
A. P. Cocoletzi-Xochitiotzi et al.
Paper
Synthesis
Table 2 (continued)
Entry
Substrate
Time (h)
Product
Yield (%)b
Z/Ec
O
O
OEt
4
24
62
1:0.01
OEt
4b
4a
5a
O
O
S
5
6
24
57
83
1:0.04
0.62:1
OEt
S
OEt
5b
O
O
OEt
O2N
7
OEt
O2N
6a
6b/c
O
O
NC
OEt
7
13
43
0.93:1
OEt
NC
7a
7b/c
CF3
O
CF3
O
8
9
13
82
73
89
63
1:0.05
1:0.4
OEt
OEt
8a
8b
O
O
Ac
OEt
13
OEt
Ac
9b/c
9a
Cl
O
Cl
O
10
11
36
1:0.09
0.93:1
OEt
OEt
OEt
10a
10b
O
O
6d
N
OEt
N
11a
11b/c
a 3-Arylpropiolate: 2 mmol/mL.
b Isolated yield.
c Z/E ratio determined by 1H NMR analysis of the crude mixture.
d Reaction performed at r.t.
The mechanism of the partial hydrogenation of activat-
ed alkynes mediated by phosphines, has been proposed to
proceed through initial attack of the phosphine to the triple
bond to form a zwitterionic intermediate that suffers the
attack of an oxygen nucleophile (usually water) collapsing
in triphenylphosphine oxide and the alkene.3,4
oxygen of the carbonyl moiety (Scheme 2). Subsequently t-
BuOH attacks the atom of phosphonium to form intermedi-
ate II that breaks into triphenylphosphine oxide and the Z-
alkene. In the case of 3-arylpropiolates substituted with
electron-withdrawing groups (nitrophenyl, 4-cyanophenyl,
4-acetophenyl, and pyridyl), the isomerization of the alkene
is favored by the reversible addition of the phosphine.3a,4
The last is true except in the case of (trifluoromethyl)phe-
In our case, we propose that the role of gold is to stabi-
lize the zwitterionic intermediate by coordination with the
Thieme. All rights reserved. Synthesis 2020, 31, A–H

D
A. P. Cocoletzi-Xochitiotzi et al.
Paper
Synthesis
Table 3 Scope of 3-Arylpropynonesa
O
Ph3P
R1
IPrAuCl/AgSbF6
(5 mol%/6 mol%)
O
AuL+
O
R2
Ar
Ar
Ph
Ph
Ph3P (1.5 equiv)
t-BuOH (10 equiv)
CH3CN, 60 °C, 24 h
12a–16a
12c–16c
OAuL
R1
R2
PPh3+
Entry
1
Product
Yield (%)b [Z/E]c
•
R2
O
R1
O
AuL
O
R2
R1
Ph3P
H
+
Ph
43 [0.1:1]
Ph3HP
O
AuL+
I
II
O
H
12c
Ph3P=O
O
Ph
2
3
53 [0.13:1]
62 [0.05:1]
Ph3P
R1
Me
13c
+PPh3
O
O
O
R1
R1
–
R2
R2
R2
O
Ph3P
Ph
III
NC
Scheme 2 Mechanistic proposal of the gold catalyzed partial hydroge-
nation of 3-arylpropiolates mediated by triphenylphosphine
14c
O
cation. Gold complexes were synthesized according to reported pro-
cedures1 and stored under a N2 atmosphere. Reactions were moni-
tored by TLC using TLC Alugram G/UV254 0.20 mm. Chromatography
purifications were performed using flash grade silica gel (SDS Chro-
matogel 60 Acc, 40–60 m). NMR spectra were recorded at 25 °C on a
Jeol Eclipse 300 Mz, Bruker Fourier 300 Mz, and Varian Unity Inova
500 MHz spectrometers. Chemical shifts are reported in ppm. High-
resolution mass spectra (HRMS) were recorded on a Jeol JMS-T100LC
AccuTOF spectrometer using polyethylene glycol as internal standard.
Melting points were determined using a Reichert microscope appara-
tus and are uncorrected.
Ph
4
5
38 [0.03:1]
49 [0.05:1]
O2N
15c
O
Ph
Cl
16c
a 3-Arylpropynone: 2 mmol/mL.
b Isolated yield.
c Z/E ratio determined by 1H NMR analysis of the crude mixture.
Gold-Catalyzed Reduction of 3-Arylpropiolates; General Proce-
dure
To a suspension of Ph3P (0.252 mmol, 1.1 equiv), IPrAuCl (0.011
mmol, 0.05 equiv), and AgSbF6 (0.013 mmol, 0.06 equiv) in MeCN (0.5
mL) was added the corresponding 3-arylpropiolate (0.178–0.229
mmol, 1 equiv). The mixture was heated at 60 °C until TLC showed
complete consumption of the propiolate. The mixture was cooled to
r.t. and filtered through a pad of Celite. The residue obtained was fur-
ther purified by flash chromatography using mixtures of hexane/EtOAc
(100:1) as eluent.
nyl and 4-chlorophenyl groups, which led principally to the
Z-isomer, what we cannot explain at this point. A reversible
addition of the phosphine is also expected to occur in 3-
arylpropynones due to the presence of a second aryl ring fa-
voring the E-isomer.
In summary, we have shown for the first time that Au(I)
can exert a cooperative effect with triphenylphosphine, ac-
celerating in this case the partial reduction of activated
alkynes. As a result, Z-alkenes are obtained with good val-
ues of stereoselectivity, starting from 3-arylpropiolates
when the aryl moiety is electron-rich, and E-alkenes from
3-arylpropynones.
Ethyl (Z)-Cinnamate (1b)12
Yellowish oil; yield: 32.5 mg (79%).
IR (film): 1707, 1636 cm–1
.
1H NMR (300 MHz, CDCl3):  = 7.68–7.50 (m, 2 H), 7.35 (d, J = 6.6 Hz, 3
H), 6.95 (d, J = 12.6 Hz, 1 H), 5.95 (d, J = 12.6 Hz, 1 H), 4.18 (q, J = 7.1
Hz, 2 H), 1.24 (t, J = 7.1 Hz, 3 H).
13C NMR (75 MHz, CDCl3):  = 166.37 (C), 143.11 (CH), 135.02 (C),
129.81 (CH), 129.10 (CH), 128.12 (CH), 120.04 (CH), 60.45 (CH2),
14.23 (CH3).
All reactions were carried out under a N2 atmosphere using standard
Schlenk techniques. THF and MeCN were dried by standard methods
and freshly distilled prior to use. CDCl3 and commercial reagents were
purchased from Aldrich and used as received without further purifi-
© 2020. Thieme. All rights reserved. Synthesis 2020, 31, A–H

E
A. P. Cocoletzi-Xochitiotzi et al.
Paper
Synthesis
HRMS-DART: m/z calcd for C11H13O2 [M + H]+: 177.09155; found:
177.09193.
1H NMR (300 MHz, CDCl3):  = 8.17 (d, J = 8.7 Hz, 2 H), 7.66 (d, J = 8.7
Hz, 2 H), 7.00 (d, J = 12.6 Hz, 1 H), 6.12 (d, J = 12.6 Hz, 1 H, Zisom), 4.16
(q, J = 7.2 Hz, 2 H, Zisom), 1.23 (t, J = 7.2 Hz, 3 H).
Ethyl (Z)-4-Methylcinnamate (2b)13
Ethyl (E)-3-(4-Nitrophenyl)acrylate (6c)18
Yellowish oil; yield: 18.5 mg (41%).
White solid; mp 142–143 °C.
IR (KBr): 1708, 1643, 1334 cm–1
IR (film): 1717, 1628 cm–1
.
.
1H NMR (300 MHz, CDCl3):  = 7.52 (d, J = 8.1 Hz, 2 H), 7.16 (d, J = 8.0
Hz, 2 H), 6.90 (d, J = 12.6 Hz, 1 H), 5.89 (d, J = 12.7 Hz, 1 H), 4.18 (q, J =
7.1 Hz, 2 H), 2.36 (s, 3 H), 1.26 (t, J = 7.1 Hz, 3 H).
13C NMR (75 MHz, CDCl3):  = 166.44 (C=O), 143.27 (CH), 139.35 (C),
132.07 (C), 130.01 (CH), 128.81 (CH), 118.94 (CH), 60.30 (CH2), 21.49
(CH3), 14.23 (CH3).
1H NMR (300 MHz, CDCl3):  = 8.23 (d, J = 8.1 Hz, 2 H), 7.70 (d, J = 14.5
Hz, 1 H), 7.66 (d, J = 7.2 Hz, 2 H), 6.55 (d, J = 16.2 Hz, 1 H), 4.28 (q, J =
6.9 Hz, 2 H), 1.34 (t, J = 6.9 Hz, 3 H).
13C NMR (75 MHz, CDCl3):  = 166.11 (C), 148.58 (C), 141.70 (CH),
140.70 (C), 128.72 (CH), 124.27 (CH), 122.71 (CH), 61.11 (CH2), 14.38
(CH3).
HRMS-DART: m/z calcd for C12H15O2 [M + H]+: 191.10720; found:
191.10694.
HRMS-DART: m/z calcd for C11H12NO4 [M + H]+: 222.07663; found:
222.07697.
Ethyl (Z)-3-(4-Methoxyphenyl)acrylate (3b)14
Ethyl (Z)-3-(4-Cyanophenyl)acrylate (7b)
Yellowish oil; yield: 33.5 mg (75%).
Yield of the E/Z mixture: 17.4 mg (43%).
IR (film): 1709, 1602, 1510 cm–1
.
1H NMR (300 MHz, CDCl3):  = 7.63 (s, 4 H), 6.96 (d, J = 12.3 Hz, 1 H),
6.09 (d, J = 12.3 Hz, 1 H), 4.15 (q, J = 7.2 Hz, 2 H, CH2), 1.24 (t, J = 7.2
Hz, 3 H, CH3).
1H NMR (300 MHz, CDCl3):  = 7.52 (d, J = 8.1 Hz, 2 H), 7.16 (d, J = 8.0
Hz, 2 H), 6.90 (d, J = 12.6 Hz, 1 H), 5.89 (d, J = 12.7 Hz, 1 H), 4.18 (q, J =
7.1 Hz, 2 H), 2.36 (s, 3 H), 1.26 (t, J = 7.1 Hz, 3 H).
13C NMR (75 MHz, CDCl3):  = 166.44 (C=O), 143.27 (CH), 139.35 (C),
132.07 (C), 130.01 (CH), 128.81 (CH), 118.94 (CH), 60.30 (CH2), 21.49
(CH3), 14.23 (CH3).
Ethyl (E)-3-(4-Cyanophenyl)acrylate (7c)19
White solid; mp 67–68 °C.
IR (KBr): 2223, 1706, 1634 cm–1
.
HRMS-DART: m/z calcd for C12H15O3 [M + H]+: 207.10212; found:
1H NMR (300 MHz, CDCl3):  = 7.71–7.55 (m, 5 H), 6.51 (d, J = 15.9 Hz,
1 H), 4.27 (q, J = 7.2 Hz, 2 H), 1.33 (t, J = 7.2 Hz, 3 H).
13C NMR (75 MHz, CDCl3):  = 166.24 (C), 142.23 (CH), 138.86 (C),
132.75 (CH), 128.48 (CH), 121.99 (CH), 118.74 (C), 113.46 (C), 61.05
(CH2), 14.39 (CH3).
207.10146.
Ethyl (Z)-3-(1-Naphthyl)acrylate (4b)15
Yellowish oil; yield: 25.1 mg (62%).
IR (film): 1701, 1586 cm–1
.
HRMS-DART: m/z calcd for C12H12NO2 [M + H]+: 202.08680; found:
202.08676.
1H NMR (300 MHz, CDCl3):  = 7.93–7.79 (m, 3 H), 7.56 (d, J = 12.4 Hz,
1 H), 7.5–7.41 (m, 4 H), 6.24 (d, J = 12.1 Hz, 1 H), 4.01 (q, J = 7.1 Hz, 2
H), 1.01 (t, J = 7.1 Hz, 3 H).
13C NMR (75 MHz, CDCl3):  = 166.03 (C), 141.99 (CH), 133.34 (C),
133.12 (C), 131.16 (C), 128.80 (CH), 128.62 (CH), 126.61 (CH), 126.33
(CH), 125.93 (CH), 125.08 (CH), 124.50 (CH), 122.89 (CH), 60.24 (CH2),
13.91 (CH3).
Ethyl (Z)-3-(4-Trifluoromethylphenyl)acrylate (8b)20
Yellowish oil; yield: 33.2 mg (82%).
IR (film): 1702, 1635 cm–1
.
1H NMR (300 MHz, CDCl3):  = 7.69–7.55 (m, 4 H), 6.98 (d, J = 12.6 Hz,
1 H), 6.06 (d, J = 12.6 Hz, 1 H), 4.17 (q, J = 7.2 Hz, 2 H), 1.24 (t, J = 7.2
Hz, 3 H).
HRMS-DART: m/z calcd for C15H15O2 [M + H]+: 227.10720; found:
227.10804.
13C NMR (75 MHz, CDCl3):  = 165.79 (C), 141.57 (CH), 138.60 (C),
Ethyl (Z)-3-(2-Thienyl)acrylate (5b)16
2
1
133.88 (C, q, JC,F = 19.4 Hz), 129.80 (CH), 124.13 (C, q, JC,F = 271.59
Yellow solid; yield: 23.3 mg (57%).
Hz), 125.03 (C, q, 3JC,F = 4.0 Hz), 122.23 (CH), 60.69 (CH2), 14.18 (CH3).
IR (KBr): 1705, 1610 cm–1
.
HRMS-DART: m/z calcd for C12H11F3O2 [M + H]+: 245.07894; found:
245.07848.
1H NMR (300 MHz, CDCl3):  = 7.44 (d, J = 5.1 Hz, 1 H), 7.37 (d, J = 3.3
Hz, 1 H), 7.02 (d, J = 12.4 Hz, 1 H), 6.98 (dd, J = 5.1, 3.7 Hz, 1 H), 5.68 (d,
J = 12.3 Hz, 1 H), 4.18 (q, J = 7.2 Hz, 2 H), 1.26 (t, J = 7.2 Hz, 3 H).
Ethyl (E)-3-(4-Trifluoromethylphenyl)acrylate (8c)20
13C NMR (75 MHz, CDCl3):  = 166.55 (C), 137.72 (C), 136.64 (CH),
135.74 (CH), 132.07 (CH), 126.64 (CH), 113.82 (CH), 60.36 (CH2),
14.45 (CH3).
Yellowish oil.
IR (film): 1712, 1641 cm–1
1H NMR (300 MHz, CDCl3):  = 7.69 (d, J = 16.1 Hz, 1 H), 7.63 (s, 4 H),
6.51 (d, J = 15.9 Hz, 1 H), 4.28 (q, J = 7.2 Hz, 2 H), 1.35 (t, J = 7.2 Hz, 3
.
HRMS-DART: m/z calcd for C9H11O2S [M + H]+: 183.04797; found:
183.04817.
H).
13C NMR (75 MHz, CDCl3):  = 166.55 (C), 142.83 (CH), 137.98 (C),
Ethyl (Z)-3-(4-Nitrophenyl)acrylate (6b)17
2
3
131.86 (C, q, JC,F = 32.9 Hz), 128.29 (CH), 125.99 (C, q, JC,F = 3.8 Hz),
Yield of E/Z mixture: 33.6 mg (83%).
123.97 (C, q, 1JC,F = 272.1 Hz), 121.01 (CH), 60.95 (CH2), 14.43 (CH3).
HRMS-DART: m/z calcd for C12H11F3O2 [M + H]+: 245.07894; found:
245.07901.
© 2020. Thieme. All rights reserved. Synthesis 2020, 31, A–H

F
A. P. Cocoletzi-Xochitiotzi et al.
Paper
Synthesis
Ethyl (E,Z)-3-(4-Acetylphenyl)acrylate (9b,c)21
E/Z mixture; yellowish oil; yield: 29.5 mg (73%).
Chalcone (12c)24
Yellowish oil; yield: 17.4 mg (43%).
IR (film): 1709, 1682, 1643, 1595 cm–1
.
IR (film): 1661, 1601, 1574 cm–1
.
1H NMR (300 MHz, CDCl3):  = 8.02–7.89 (m, 4 H E and Z), 7.69 (d, J =
16.1 Hz, 1 H E), 7.63–7.57 (m, 4 H E and Z), 6.98 (d, J = 12.6 Hz, 1 H Z),
6.52 (d, J = 16.0 Hz, 1 H E), 6.05 (d, J = 12.6 Hz, 1 H E), 4.28 (q, J = 7.1
Hz, 1 H E), 4.17 (q, J = 7.1 Hz, 1 H Z), 2.61 (s, 3 H E), 2.60 (s, 1 H Z), 1.34
(t, J = 7.1 Hz, 3 H E), 1.24 (t, J = 7.1 Hz, 3 H Z).
13C NMR (75 MHz, CDCl3):  = 197.69 (C, E), 197.44 (C, Z), 166.60 (C,
Z), 165.86 (C, E), 143.11 (CH, E), 143.78 (CH, Z), 139.73 (C, Z), 138.90
(C, E), 138.07 (C, E), 136.94 (C, Z), 128.70 (CH, Z), 128.96 (C, E), 128.22
(CH, Z), 128.07 (CH, E), 122.08 (CH, Z), 120.93 (CH, E), 118.74 (C),
113.46 (C), 60.88 (CH2, E), 60.64 (CH2, Z), 26.79 (CH3, Z), 26. 76 (CH3,
E), 14.39 (CH3, Z), 14.17 (CH3, E).
1H NMR (300 MHz, CDCl3):  = 8.06–8.00 (m, 2 H), 7.82 (d, J = 15.7 Hz,
1 H), 7.68–7.64 (m, 2 H), 7.61–7.48 (m, 4 H), 7.46–7.40 (m, 3 H).
13C NMR (75 MHz, CDCl3):  = 190.73, 145.01, 138.36, 135.04, 132.94,
130.70, 129.12, 128.78, 128.66, 128.60, 122.24.
HRMS-DART: m/z calcd for C15H13O [M + H]+: 209.09664; found:
209.09575.
4-Methylchalcone (13c)25
Yellowish oil; yield: 21.4 mg (53%).
IR (film): 1661, 1599, 1574 cm–1
.
HRMS-DART: m/z calcd for C13H15NO3 [M + H]+: 219.10212; found:
219.10211.
1H NMR (300 MHz, CDCl3):  = 7.98–7.91 (m, 2 H), 7.81 (d, J = 15.7 Hz,
1 H), 7.68–7.63 (m, 2 H), 7.54 (d, J = 15.7 Hz, 1 H), 7.45–7.39 (m, 3 H),
7.31 (dt, J = 8.0, 0.7 Hz, 2 H), 2.44 (s, 3 H).
Ethyl (Z)-3-(4-Chlorophenyl)acrylate (10c)22
Z/E mixture; yellowish oil; yield: 36.1 mg (89%).
13C NMR (75 MHz, CDCl3):  = 190.19, 144.56, 143.80, 135.78, 135.16,
130.57, 129.49, 129.09, 128.81, 128.56, 122.25, 21.84.
HRMS-DART: m/z calcd for C16H15O [M + H]+: 223.11229; found:
IR (film): 1716, 1634 cm–1
.
223.11183.
1H NMR (300 MHz, CDCl3):  = 7.52–7.41 (m, 4 H E and Z), 7.32–7.20
(m, 5 H E and Z), 6.81 (d, J = 12.6 Hz, 1 H Z), 6.34 (d, J = 16.0 Hz, 1 H E),
5.89 (d, J = 12.6 Hz, 1 H E), 4.23 (q, J = 7.1 Hz, 1 H E), 4.10 (q, J = 7.1 Hz,
1 H Z), 1.30 (t, J = 7.1 Hz, 3 H E), 1.19 (t, J = 7.1 Hz, 3 H Z).
4-Cyanochalcone (14c)26
Yellowish solid; yield: 25.0 mg (62%).
13C NMR (125 MHz, CDCl3):  = 166.36 (C, E), 166.08 (C, Z), 143.10
(CH, E), 141.98 (C, Z), 135.04 (C, Z and E), 133.38 (C, Z and E), 131.30
(CH, Z), 129.80 (CH, E), 129.09 (CH, Z), 128.34 (CH, Z), 120.53 (CH, Z),
120.03 (CH, Z), 60.55 (CH2, Z), 60.44 (CH2, E), 14.25 (CH2, Z and E).
HRMS-DART: m/z calcd for C11H12ClO2 [M + H]+: 211.05258; found:
211.05307.
IR (KBr): 1661, 1592, 1573 cm–1
.
1H NMR (300 MHz, CDCl3):  = 8.12–8.06 (m, 2 H), 7.85 (d, J = 12.4 Hz,
1 H), 7.83–7.79 (m, 2 H), 7.69–7.62 (m, 2 H), 7.48 (d, J = 10.8 Hz, 1 H),
7.46–7.42 (m, 3 H).
13C NMR (75 MHz, CDCl3):  = 189.32, 146.75, 141.62, 134.49, 132.65,
131.32, 129.25, 129.01, 128.81, 121.30, 118.19, 116.11.
HRMS-DART: m/z calcd for C16H12NO [M + H]+: 234.09184; found:
234.09076.
Ethyl (Z)-3-(2-Pyridinyl)acrylate (11b)23
Colorless oil; yield: 20.0 mg (50%).
IR (film): 1722, 1638 cm–1
.
4-Nitrochalcone (15c)27
1H NMR (300 MHz, CDCl3):  = 8.52 (d, J = 4.6 Hz, 1 H), 7.69–7.46 (m, 2
H), 7.18–7.04 (m, 1 H), 6.88 (d, J = 12.5 Hz, 1 H), 6.07 (d, J = 12.5 Hz, 1
H), 4.14 (q, J = 7.1 Hz, 2 H), 1.19 (t, J = 7.1 Hz, 3 H).
13C NMR (75 MHz, CDCl3):  = 166.83 (C), 153.71 (C), 149.30 (CH),
139.81 (CH), 136.11 (CH), 124.50 (CH), 123.21 (CH), 123.15 (CH),
60.72 (CH2), 14.18 (CH3).
Yellowish solid; yield: 15.3 mg (38%).
IR (KBr): 1662, 1602, 1572 cm–1
.
1H NMR (300 MHz, CDCl3):  = 8.40–8.31 (m, 2 H), 8.18–8.10 (m, 2 H),
7.85 (d, J = 15.7 Hz, 1 H), 7.69–7.62 (m, 2 H), 7.49 (d, J = 15.1 Hz, 2 H),
7.45 (dd, J = 4.8, 1.5 Hz, 2 H).
13C NMR (75 MHz, CDCl3):  = 189.15, 150.19, 146.95, 143.17, 134.41,
131.38, 129.55, 129.25, 128.84, 124.00, 121.41.
HRMS-DART: m/z calcd for C10H12NO2 [M + H]+: 178.08680; found:
178.08607.
HRMS-DART: m/z calcd for C15H12NO3 [M + H]+: 254.08172; found:
254.08053.
Ethyl (E)-3-(2-Pyridinyl)acrylate (11c)18
Yellowish oil; yield: 5.2 mg (13%).
4-Chlorochalcone (16c)24
IR (film): 1709, 1644 cm–1
.
Yellowish solid; yield: 19.8 mg (49%).
1H NMR (300 MHz, CDCl3):  = 8.57 (d, J = 4.0 Hz, 1 H), 7.70–7.55 (m, 1
H), 7.61 (d, J = 15.8 Hz, 1 H), 7.36 (d, J = 7.9 Hz, 1 H), 7.19 (dd, J = 7.5,
4.5 Hz, 1 H), 6.84 (d, J = 15.7 Hz, 1 H), 4.20 (q, J = 7.1 Hz, 2 H), 1.26 (t,
J = 7.1 Hz, 3 H).
13C NMR (75 MHz, CDCl3):  = 166.80 (C), 153.05 (C), 150.19 (CH),
143.36 (CH), 136.81 (CH), 124.25 (CH), 124.13 (CH), 122.53 (CH),
60.72 (CH2), 14.34 (CH3).
IR (KBr): 1659, 1585, 1565 cm–1
1H NMR (300 MHz, CDCl3):  = 7.99–7.93 (m, 2 H), 7.82 (d, J = 15.7 Hz,
1 H), 7.68–7.59 (m, 2 H), 7.50 (d, J = 7.8 Hz, 1 H), 7.47–7.37 (m, 5 H).
13C NMR (75 MHz, CDCl3):  = 189.23, 145.43, 139.31, 136.59, 134.79,
130.85, 130.02, 129.11, 129.04, 128.62, 121.56.
.
HRMS-DART: m/z calcd for C15H12ClO [M + H]+: 243.05767; found:
243.05683.
HRMS-DART: m/z calcd for C10H12NO2 [M + H]+: 178.08680; found:
178.08650.
© 2020. Thieme. All rights reserved. Synthesis 2020, 31, A–H

G
A. P. Cocoletzi-Xochitiotzi et al.
Paper
Synthesis
Funding Information
Adv. Synth. Catal. 2012, 354, 1542. (d) Whittaker, A. M.; Lalic, G.
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Li, Z.-J.; Chen, B.; Tung, C.-H.; Wu, L.-Z. Chem. Commun. 2016,
52, 1800. (g) Szeto, K. C.; Sahyoun, W.; Merle, N.; Castelbou, J. L.;
Popoff, N.; Lefebvre, F.; Raynaud, J.; Godard, C.; Claver, C.;
Delevoye, L.; Gauvin, R. M.; Taoufik, M. Catal. Sci. Technol. 2016,
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Synth. Catal. 2016, 358, 1410. (i) Korytiaková, E.; Thiel, N. O.;
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48, 3592.
This work was supported by CONACyT (A1-S-7805) and DGAPA
(IN202017).
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Acknowledgment
The authors would like to thank M. A. Peña-González, E. Huerta-Sala-
zar, B. Quiroz-García, I. Chávez-Uribe, H. Ríos-Olivares, M. R. Patiño-
Maya, L. Velasco-Ibarra, F. Javier Pérez-Flores, M. C. García-González,
L. C. Márquez-Alonso, E. García-Ríos, and L. M. Rios-Ruiz for technical
support.
(8) Pasto, D. J. In Comprehensive Organic Synthesis, Vol. 8; Trost, B.
M.; Fleming, I., Ed.; Pergamon: Oxford, 1991, 471.
Supporting Information
(9) Selected examples: (a) Tani, K.; Iseki, A.; Yamagata, T. Chem.
Commun. 1999, 1821. (b) Trost, B. M.; Ball, Z. T.; Jöge, T. J. Am.
Chem. Soc. 2002, 124, 7922. (c) Trost, B. M.; Ball, Z. T.;
Laemmerhold, K. M. J. Am. Chem. Soc. 2005, 127, 10028.
(d) Trost, B. M.; Ball, Z. T. J. Am. Chem. Soc. 2005, 127, 17644.
(e) Reyes-Sánchez, A.; Cañavera-Buelvas, F.; Barrios-Francisco,
R.; Cifuentes-Vaca, O. L.; Flores-Alamo, M.; García, J. J. Organo-
metallics 2011, 30, 3340. (f) Radkowshi, K.; Sundararaju, B.;
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Supporting information for this article is available online at
https://doi.org/10.1055/s-0040-1707395.
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