Regioselective hydrocarbonylation of phenylacetylene to α,β-unsaturated esters and thioesters with Fe(CO)5and Mo(CO)6

Article abstract of DOI:10.1016/j.jorganchem.2016.01.025

A highly regioselective hydrocarbonylation of phenylacetylene with thiols and alcohols was developed using metal carbonyls/diazabicyclo[2.2.2]octane (DABCO) system at 100?°C in DMF. The use of Mo(CO)₆and thiols in the presence of DABCO was applied as an efficient Pd-free method for hydrothiocarbonylation of phenylacetylene into trans-α,β-cinamyl thioesters in excellent yields (88–98%). Similar reaction using Fe(CO)₅/ROH/DABCO system resulted into high yield synthesis of trans-α,β-cinamyl esters (87–98%). These reactions were conducted under mild reaction conditions without the need to use gaseous CO or any phosphine ligand and palladium catalyst.

Full text of DOI:10.1016/j.jorganchem.2016.01.025

Accepted Manuscript
Regioselective hydrocarbonylation of phenylacetylene to α,β- unsaturated esters and
thioesters with Fe(CO) and Mo(CO)
5
6
Nasser Iranpoor, Habib Firouzabadi, Asma Riazi, Keyvan Pedrood
PII:
S0022-328X(16)30025-0
10.1016/j.jorganchem.2016.01.025
JOM 19376
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 18 August 2015
Revised Date: 20 January 2016
Accepted Date: 21 January 2016
Please cite this article as: N. Iranpoor, H. Firouzabadi, A. Riazi, K. Pedrood, Regioselective
hydrocarbonylation of phenylacetylene to α,β- unsaturated esters and thioesters with Fe(CO) and
5
Mo(CO) , Journal of Organometallic Chemistry (2016), doi: 10.1016/j.jorganchem.2016.01.025.
6
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ACCEPTED MANUSCRIPT
Graphical abstract
Regioselective hydrocarbonylation of phenylacetylene to α,β- unsaturated
esters and thioesters with Fe(CO)5 and Mo(CO)6
N. Iranpoor, *,a H. Firouzabadi, *,a A. Riazi, a and K. Pedrooda
Chemistry Department, College of Sciences, Shiraz University, Shiraz, Iran
O
Fe(CO)5, DABCO, X=O
OR
°C, DMF
100
87-98%
O
RXH
Mo(CO)6, DABCO, X=S
C, DMF
SR
88-98%
°
100

ACCEPTED MANUSCRIPT
Regioselective hydrocarbonylation of phenylacetylene to α,β- unsaturated esters
and thioesters with Fe(CO)5 and Mo(CO)6
Nasser Iranpoor*,a, HabibFirouzabadi*,a, AsmaRiazia, KeyvanPedrooda
aChemistry Department, College of Sciences, Shiraz University, Shiraz, Iran
Corresponding authors. Tel.: +98 711 2287600; fax: +98 711 2280926; e-mailaddresses: iranpoor@chem.susc.ac.ir
(N. Iranpoor), firouzabadi@chem.susc.ac.ir (H.Firouzabadi)
Abstract:A highly regioselective hydrocarbonylation of phenylacetylene with thiols and alcohols was
developed using metal carbonyls/ diazabicyclo[2.2.2]octane (DABCO) system at 100 °C in DMF. The use
of Mo(CO)6 and thiols in the presence of DABCO was applied as an efficient Pd-free method for
hydrothiocarbonylation of phenylacetylene into trans-α,β-cinamyl thioesters in excellent yields (88-98%).
Similar reaction using Fe(CO)5/ROH/DABCO system resulted into high yield synthesis of trans-α,β-
cinamyl esters (87-98%). These reactions were conducted under mild reaction conditions without the need
to use gaseous CO or any phosphine ligand and palladium catalyst.
Keywords:
Hydroalkoxycarbonylation;Hydrothiocarbonylation;
Phenylacetylene;Fe(CO)5;
Mo(CO)6;diazabicyclo[2.2.2]octane (DABCO)
1. Introduction
Transition-metal catalyzed carbonylation is widely recognized as an important and attractive route for
carbonyl-forming reactions in organic synthesis. In this regards, the oxidative carbonylation of terminal
acetylenes is considered a practical approach for synthesis of α,β-unsaturated carboxylic acids and their
derivatives [1,2]. Synthesis of cinnamic acid and its esters as important intermediates for the production of
pharmaceuticals, fragrances, light-sensitive and electrically conductive materials and agrochemicals is still
an important research subject [3]. For the first time, Reppe [4] reported the carbonylation of alkynes and
alkenes in the presence of Ni(CO)4 to produce unsaturated and saturated carboxylic acids and esters
respectively. These reactions were performed under sever operating conditions (472–573 K and 10–100
MPa pressure) using reactor setup and the use of volatile and unstable material as catalyst. After that,
various protocols for hydroesterification of alkyne were developed using CO as source of the carbonyl
group in the presence of different catalytic systems such as Pd(OAc)2/PPh3/p-TsOH [5],
Pd(OAc)2/pyridine-2-carboxylic acid/PPh3 [5], Pd(OAc)2/dppb/H2 [6], Pd(OAc)2/dppb/BSA [7]. Recently,
Mathur and co-workers [8] have reported the high yield synthesis of α,β-vinylester by the photochemical
reaction of terminal acetylene with alcohols and gaseous carbon monoxide in the presence of iron
pentacarbonyl as catalyst.
In comparison with hydroalkoxycarbonylation of terminal acetylenes with alcohols catalyzed by
transition metals to give α,β- unsaturated esters, the reports on this reaction in the presence of thiols to give
α,β- unsaturated thioesters are considerably less. The problem with this reaction in the presence of thiols is
the poisoning of transition metal catalysts with organosulfure compounds. In this regard, a series of
transition metal-catalyzed carbonylation–addition reactions of thiols to acetylenes in the presence of CO
leading to α,β-unsaturated thioesters has been developed [9–12]. Later works on thiocarbonylation of
acetylens have been performed using gaseous CO or CO/H2 at high pressure of 3MPa to 600 psi at 110-120
oC [10, 11a, 12]. Apart from high pressure, these hydrocarbonylation reactions of alkynes, suffer from
limitation of the use of CO as a highly lethal gas with a main concern of its handling [13]. In continuation
of our recent work on the use of metal carbonyls as suitable source of CO gas in carbonylation reaction[14],
1

we now report an efficient Pd and phosphine-free method for the preparation of esters and thioesters of
ACCEPTED MANUSCRIPT
cinnamate from the reaction of phenylacetylene with alcohols and thiols using Fe(CO)5 and Mo(CO)6 as
source of carbonyl group respectively.
2. Results and discussion
As mentioned above, the regioselective synthesis of gem- or trans-α,β-unsaturated esters have been
achieved by direct carbonylation of phenylacetylene with alcohols in the presence of large amounts of
gaseous carbon monoxide, catalyzed by transition metals in the presence of suitable ligands [1a]. In order to
avoid using gaseous carbon monoxide, we decided to study the possibility of using metal carbonyls such as
Fe(CO)5, W(CO)6, Cr(CO)6, and Mo(CO)5 for this important transformation. Initially, we selected iron
pentacarbonyl as source of CO in the reaction with phenylacetylene as a model reaction. For the
optimization of the reaction conditions, we first performed the hydroalkoxycarbonylation of
phenylacetylene with ethanol in the presence of Fe(CO)5 and the effect of different parameters were
studied. In order to make easier and increase the possibility of CO releasing from Fe(CO)5, we added some
nitrogen compounds such as diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene
(DBU) and n-Pr3N. Initially, DBU was utilized to replace the CO group to form the DBU-iron carbonyl
complex. The reaction was carried out at 100 °C in DMF as solvent and the desired product was obtained in
moderate yield (Table 1, entry 1). Then DBU was substituted by DABCO and n-Pr3N. The best result was
obtained when we used DABCO as the complexing agent. Decreasing the amount of DABCO from three
equimolar to two and one equimolar amount increased the reaction time from 0.5 h (Table 1, entry 3) to
2.5h and 6h respectively and also led to the production of side products (Table 1, entries 6,7). In the
absence of DABCO, the performance of the reaction was not good and only 10% of the corresponding ester
was obtained after 24h. We also studied the effect of different amount of alcohol on the progress of the
reaction and observed that when the amount of ethanol was decreased from 4 to 2 and 1 equimolar, the
reactions did not complete even after 12 h (Table 1, entries 3, 8, 9). The effect of other solvents such as
diglyme, DMSO, xylene and toluene was also studied, but none of them were found to be as suitable as
DMF. From this study, the result of entry 3 was found to be the optimum condition for this reaction. The
effect of using catalytic amounts of Fe(CO)5 was also investigated and observed that the reaction was not
completed if its amount was reduced from 1.0 to 0.5 equivalent and nearly half of the starting material was
recovered unchanged (Table 1, entry 14). Increasing the reaction temperature from 100 °C to 120°C did not
have significant effect on the progress of the reaction.
Table 1. Optimization of different parameters for hydroalkoxycarbonylation of phenylacetylene.a
O
Base, Solvent
Temp.
O
Ethanol Fe(CO)5
Entry
1
Base
Solvent
DMF
DMF
DMF
TBAB
TBAB
DMF
DMF
DMF
DMF
Temp. (° C)
100
Time (h)
Yield (%)b
DBU
2
10
0.5
3
47
56
95
52
70
75
65
25
40
2
n-Pr3N
100
3
DABCO
n-Pr3N
100
4
110
5
DABCO
DABCO
DABCO
DABCO
DABCO
110
3
6c
7c
8d
9d
100
2.5
6
100
100
12
12
100
2

10
11
12
13
14
15
16
17
18e
19
K2CO3
NaOH
2
2
60
61
ACCEPTDEMDF MANUSC1R00IPT
DMF
100
Cs2CO3
DABCO
DABCO
DABCO
None
DMF
100
4
72
DMSO
diglyme
toluene
DMF
100
6
27
100
2.5
12
24
24
10
0.3
48
Reflux
100
36
10
DABCO
DABCO
DABCO
xylene
DMF
100
Trace
10
100
DMF
120
98
a Reaction conditions: 1.0 mmol of phenylacetylene, 1.0 mmol of Fe(CO)5, ethanol (4 mmol), Base (3 mmol), 2 mL of solvent.
b Isolated yield.
cThe amount of DABCO are 2.0 and 1.0 mmol for entries 6 and 7 respectively.
dThe amount of ethanol are 1.0 and 2.0 mmol for entries 8 and 9 respectively .
e The reaction was performed using 0.5 equivalent of Fe(CO)5.
After optimizing the conditions for the reaction of phenylacetylene and ethanol with Fe(CO)5, we then
replaced Fe(CO)5 with other metal carbonyls such as W(CO)6, Mo(CO)6 and Cr(CO)6. The results of this
study are shown in Table 2 (Entries 1-4). According to these results, the reaction in the presence of metal
carbonyls other than Fe(CO)5 did not give the desired carbonylated product (I). This reaction in the
presence of M(CO)6 [M=Cr, Mo, W] led to the formation of 1,5-diphenyl-1,4-pentadiyn-3-one (Table 2,
product II) and when Cr(CO)6 was used as CO source, small amounts of cinnamaldehyde was also formed.
Moreover, when we investigated the hydroalkoxycarbonylation reaction of phenylacetylene in the presence
of Pd(II), it was observed that the added catalyst doesn't have significant effect on the reaction time and
yield% of the obtained product(Table 2, entry 5).
Table 2. Reaction of phenylacetylene with with ethanol in the presence of different metal carbonyls.a
O
O
O
DABCO, M(CO)x, 2h
Ethanol
°
Ph
O
Ph
H
DMF, Base, 100 C
Ph
Ph
(I)
(II)
Isolated yield (%)
95%b of I
(III)
Entry
M(CO)x
Fe(CO)5
Mo(CO)6
W(CO)6
Cr(CO)6
Catalyst/ Base
None/DABCO
None/DABCO
None/DABCO -
None/DABCO
1
2
3
4
50% of II
35% of II
55% of II+30% of III
94% of I
5
Fe(CO)5
Pd(OAc)2/DABCO
a Reaction conditions: 1.0 mmol of phenylacetylene, 1.0 mmol of M(CO)x, 1.0 mmol of ethanol, 3.0 mmol of DABCO, 1.0 mmol of base and 2
mL of DMF at 100 °C.
b The reaction time is 30 min.
Having the optimized conditions, we then used different alcohols in the esterification reaction of
phenylacetylene (Table 3). A wide range of alcohols including primary and secondary aliphatic alcohols
reacted to give the desired product in high to excellent yields. The reaction of phenylacetylene and phenol
derivatives did not proceed well to give the corresponding ester while the reaction with benzyl alcohol and
4-chlorobenzyl alcohol was performed completely and both reactions led to their corresponding vicinal α,β-
vinylesters in excellent yields. The results of the carbonylation of phenylacetylene with different alcohols
are summarized in Table 3. The obtained results of hydroalkoxycarbonylation of phenylacetylene with
different alcohols showed excellent control of the regioselectivity for all of the products
.
3

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Table 3. Reaction of alcohols with phenylacetylene in the presence of iron pentacarbonyl.a
O
OR
DABCO, DMF
ROH Fe(CO)5
100 oC, 30 min
Entry
1
Alcohol
Product
O
Yield (%)b
98
(CH3)2CHOH
O
(1a)
O
O
2
CH3OH
96
(1b)
O
O
3
4
CH3CH2OH
95
94
(1c)
O
OEt
O
EtO(CH2)2OH
(1d)
O
O
5
CH3(CH2)3CH2OH
95
(1e)
O
6
7
(CH2)4CHOH
(CH2)6CHOH
O
90
90
(1f)
O
O
(1g)
O
O
8
4-biphenylCH2OH
89
(1h)
O
O
9
CH3(CH2)6CH2OH
4-ClPhCH2OH
PhCH2OH
96
87
90
(1i)
O
O
10
11
Cl (1j)
(1k)
O
O
a Reaction conditions: 1.0 mmol of phenylacetylene, 1.0 mmol of Fe(CO)5, 4.0 mmol of alcohol, 2.0 mmol of DABCO, and 2 mL of DMF at
100 °C.
b Isolated yield.
In continuation, we extended the applicability of this method for one-pot regioselective
hydrothiocarbonylation of phenylacetylene. For this purpose, we selected the reaction of phenylacetylene
4

and benzyl mercaptan as a model reaction and studied the effect of different parameters such as the type
ACCEPTED MANUSCRIPT
and the amount of metal carbonyl, as well as the base as complexing agent, solvent and also temperature.
The obtained results are shown in Table 4. Our observation showed that, the best result was obtained when
the reaction was done with Mo(CO)6 and DABCO in DMF at 100 °C.
Table 4. Optimization of different parameters for hydrothiocarbonylation reaction of phenylacetylene.a
O
SH
Base,Sovent
Temp.
SCH2Ph
Mo(CO)6
Entry
1
Base (mmol)
DBU
Solvent
DMF
Temp. (° C)
100
Time (h)
Yieldb (%)
55
4
2
NBD
DMF
100
0.5
82
3
DABCO
DMF
100
15 min
92
4
5
n
-Pr3N
TBAB
TBAB
DMF
DMF
DMF
DMSO
diglyme
xylene
toluene
DMF
100
100
100
100
100
100
100
100
8
6
52
70
92
60
45
35
45
Trace
Trace
15c
95
DABCO
DABCO
DABCO
DABCO
DABCO
DABCO
DABCO
DABCO
DABCO
DABCO
6c
7c
8d
9
45 min
2
2
6
3
24
24
12
10 min
10
11
12
13
14
reflux
100
120
DMF
a Reaction conditions: 1.0 mmol of phenylacetylene, 1.0 mmol of Mo(CO)6, benzyl mercaptan (2.0 mmol), base (3.0 mmol), 2 mL of solvent.
b Isolated yield.
cThe amount of DABCO are 2.0 and 1.0 mmol for entries 6 and 7 respectively.
dThe amount of benzyl mercaptan is 1.0 mmol for entries 8.
e The reaction was performed using 0.5 equivalents of Mo(CO)6.
As the obtained results show, similar reaction in the presence of other metal carbonyls, M(CO)6 (M =
Cr, W), and Fe(CO)5 gave the desired product in lower yield (Table 5, Entries 2-4). For comparison, we
also synthesized Mo(CO)5DABCO complex and reacted it (one equimolar) with benzyl mercaptan under
the optimized condition. The corresponding thioester was isolated in excellent yield (Table 5, Entry 5). This
experiment shows that this complex can also be used as another solid source of generating CO for this
transformation.
Table 5. Effect of different metal carbonyl in the reaction of phenylacetylene with benzyl mercaptan under the optimized
condition.a
O
DABCO, M(CO)x, 2h
SCH2Ph
SH
DMF,100 o
C
Entry
M(CO)x
Mo(CO)6
Fe(CO)5
W(CO)6
Cr(CO)6
Isolated Yield(%)
1
2
3
4
92b
Trace
45
35
91c
5
Mo(CO)5DABCO
aReaction conditions: 1.0 mmol of phenylacetylene, 1.0 mmol of M(CO)x, 2.0 mmol of benzyl mercaptan, 3.0 mmol of DABCO and 2 mL of
DMF at 100 °C.
bThe reaction time is 15 min.
c The reaction time is 60 min.
The optimized conditions were then applied for the thiocarbonylation of phenylacetylene with different
alkyl- and aryl thiols. The results are summarized in Table 6. Hydrothiocarbonylation of phenylacetylene
with alkyl thiols was found to be very fast and completed after 5 min. However, similar reaction of
phenylacetylene with benzyl mercaptan and thiophenol were completed after 15 min.
5

ACCEPTED MANUSCRIPT
Table 6.Hydrothiocarbonylation of phenylacetylene with different thiols in the presence of Mo(CO)6.a
O
DABCO, DMF
SR
Mo(CO)6
RSH
100 oC, 5-15 min
Entry
1
Thiol
Product
Yield (%)b
95
O
S
(CH3)2CHSH
(2a)
(2b)
O
2
3
CH3CH2SH
S
98
95
O
S
CH3(CH2)3CH2SH
(2c)
O
S
4
5
CH3(CH2)6CH2SH
PhSH
95
(2d)
O
88c
S
(2e)
O
S
6
7
PhCH2SH
92c
(2f)
O
S
CH3(CH2)2CH2SH
98
(2g)
a Reaction conditions: 1.0 mmol of phenylacetylene, 1.0 mmol of Mo(CO)6, thiol (2.0 mmol), DABCO (2mmol), 2 mL of DMF.
b Isolated yield.
c The reaction was completed after 15 min.
The proposed mechanism was shown in Scheme 1.We suggest that a transient molybdenum carbonyl
complex (A) can be resulted from the complexation of 1,4-diaza-bicyclo[2.2.2]octane (DABCO) with
Mo(CO)6 with rapid releasing of one CO. Then, the complex B is formed in the presence of nucleophile.
Transfer of sulfide group to CO can then occur with the addition of phenylacetylene to give the
intermediate D. In the next step, metal to ligand migration can produce the intermediate E. High
regioselectivity of this method depends greatly to this step in which metal migrates to the terminal
acetylenic carbon which is much less hindered. Finally, E is protonated through the reaction with BH+ (B =
DABCO) to generate the desired product.
L
N
CO
SHR
N
DMF, 100 o
-CO
C
N
-CO
L=
Mo(CO)6
N
Mo
Mo(CO)5
RSH
CO
CO
(B)
CO
(A)
L
CO
CO
O
CSR
L
L
CO
L
Mo
L=DABCO
O
Ph
CO
CO
SR
CO
Mo
Ph
(E)
Mo
RS
CO
H
CO
CO
Ph
CO
(D)
(C)
O
RS
Ph
6

ACCEPTED MANUSCRIPT
Scheme 1.Mechanism of hydrothiocarbonylationof phenylacetylenein the presence ofMo(CO)6 and DABCO
The obtained results from the reaction of Mo(CO)5 DABCO complex with benzyl mercatptan (Table 5,
Entry 5) can be considered as a support for the formation of the proposed intermediate complex (A) in this
mechanism.
In conclusion, we introduced an efficient method for the carbonylation of phenylacetylene with alcohols
and thiols in the presence of Fe(CO)5/DABCO and Mo(CO)6/DABCO system respectively. This method
allows access to a wide range of α,β-cinamylesters and thioesters in excellent yields without the need for
using any external gaseous CO. Overall, the hydroalkoxy and hydrothiocarbonylation reactions were
occurred under atmospheric pressure at relatively mild reaction temperature and relatively short reaction
times. The absence of any Pd catalyst and phosphine ligand can be considered as other advantages of this
method.
3. Experimental
3.1. General
FTIR spectra were run on a Shimadzu FTIR-8300 spectrophotometer.1H and C NMR spectra were
recorded on a Brucker Avance DPX-250 spectrometer using tetramethylsilane (TMS) as internal standard
in pure deuterated solvents. Chemical shifts are given in the δ scale in parts per million (ppm) and coupling
constants (J) in hertz. Singlet (s), doublet (d), triplet (t) and multiplet (m) are recorded. The reaction
monitoring was carried out on silica gel analytical sheets or by GC analysis using a 3-m length column
packed with DC-200 stationary phase. Column chromatography was carried out on a column of silica gel
60 Merck (230-240 mesh) in glass columns (2 or 3 cm diameter) using 15-20 g of silica gel per 1 g of the
crude mixture.
3.2. General procedure for hydroesterification of phenylacetylene with alcohols in the presence of
Fe(CO)5
A mixture of Fe(CO)5 (1.0 mmol), phenylacetylene (1.0 mmol), alcohol (4.0 mmol) and DABCO (3.0
°
mmol) in DMF (3 mL) was heated at 100 C. After completion of the reaction within 10-45 min, the
reaction mixture was cooled down to room temperature. Water was then added and extracted with ethyl
acetate (3 × 20 mL). Organic layer was dried over anhydrous Na2SO4. The crude organic mixture was then
purified by column chromatography over silica gel using petroleum ether/ ethyl acetate = 20:1 to obtain the
desired productin 85-98% (Table 3).
3.2.1. (E)-3-Phenyl-acrylic acid isopropyl ester (1a) [8]
1H NMR (250 MHz, CDCl3) δ= 7.68 (d, J= 16.2 Hz, 1H), 7.34-7.51(m, 5H), 6.32 (d, J= 16.2 Hz, 1H), 5.10
(m, 1H), 1.97 (d, J= 6.5 Hz, 6H); 13C NMR (62.9 MHz, CDCl3) δ= 171.2, 144.3, 118.8, 134.5, 130.1,
128.8, 128.0, 67.87, 22.05.Anal.Calcd for C12H14O2:C, 75.76; H, 7.42. Found: C, 75.88; H, 7.30.
3.2.2. (E)-3-Phenyl-acrylic acid methyl ester (1b) [15]
1H NMR (250 MHz, CDCl3) δ= 7.71 (d, J= 16.0 Hz, 1H), 7.21-7.43 (m, 5H), 6.45 (d, J= 16.0 Hz, 1H), 3.42
13
(s, 3H); C NMR (62.9 MHz, CDCl3) δ= 171.2, 144.3, 134.5, 130.1, 128.8, 118.8, 51.7.Anal.Calcd for
C10H10O2: C, 74.06; H, 6.21. Found: C, 74.13; H, 6.18.
3.2.3.(E)-3-Phenyl acrylic acid ethyl ester (1c) [16]
7

1H NMR (250 MHz, CDCl ) δ (ppm)= 7.59 (d, J= 16.2 Hz, 1H), 7.31-7.46 (m, 5H), 6.34 (d, J= 16.2 Hz,
ACCEPTED MANUSCRIPT
1H), 4.16 (q, 2H), 1.28 (t, J= 7.0 Hz, 3H); C NMR (62.9 MHz, CDCl3) δ= 167.1, 144.7, 134.5, 130.1,
3
13
128.8, 126.6, 118.4, 60.6, 14.4. Anal.Calcd for C11H12O2: C, 74.98; H, 6.86. Found: C, 74.91; H, 6.94.
3.2.4. (E)-3-Phenyl-acrylic acid 2-ethoxy-ethyl ester (1d)
1H NMR (250 MHz, CDCl3) δ = 7.64 (d, J= 16.0 Hz, 1H),7.29-7.47 (m, 5H), 6.42 (d, J= 16.0Hz, 1H), 4.27-
4.31 (t, J= 4.5 Hz, Jʹ= 5.0 Hz, 2H), 3.61-3.65(t, J= 5.0 Hz, 2H), 3.45-3.56 (q, 2H), 1.16 (t, J=7.0 Hz, 3H).
13C NMR (CDCl3) δ = 165.0, 142.8, 117.6, 134.9, 128.4, 127.7, 126.2, 69.6, 67.5, 62.7, 14.7.Anal.Calcd for
C13H16O3: C, 70.89; H, 7.32. Found: C, 70.74; H, 7.45.
3.2.5. (E)-3-Phenyl-acrylic acid pentyl ester (1e) [7]
1H NMR (250 MHz, CDCl3) δ = 7.61 (d, J= 16.0 Hz, 1H), 7.18-7.47 (m, 5H), 6.37 (d, J= 16.0Hz, 1H), 4.12
13
(t, J= 6.8 Hz, 2H), 1.58-1.66 (m, 2H), 1.25-1.34 (m, 2H), 1.18 (m,2H), 0.85 (t, J=7.0 Hz, 3H). C NMR
(CDCl3) δ = 167.2, 144.8, 134.5, 130.1, 128.8, 118.4, 72.7, 30.0, 24.0, 21.8, 15.9.Anal.Calcd for C14H18O2:
C, 77.03; H, 8.31. Found: C, 77.14; H, 8.26.
3.2.6. (E)-3-Phenyl-acrylic acid cyclopentyl ester (1f)[17]
1H NMR (250 MHz, CDCl3) δ = 7.67 (d, J= 16.0 Hz, 1H), 7.26-7.55(m, 5H), 6.44 (d, J= 16.0 Hz, 1H),
4.84-4.93 ( 5H, m ), 1.30-2.17 ( m, 12H ). 13C NMR (CDCl3) δ = 166.5, 144.2, 118.9, 134.5, 130.1, 128.8,
128.0, 72.7, 31.0, 21.0. Anal. Calcd for C14H16O2: C, 77.75; H, 7.46. Found: C, 77.84; H, 7.40.
3.2.7. (E)-3-Phenyl-acrylic acid cycloheptyl ester (1g) [18]
1H NMR (250 MHz, CDCl3) δ = 7.67 (d, J= 16.0 Hz, 1H), 7.26-7.55(m, 5H), 6.44 (d, J= 16.0 Hz, 1H),
4.84-4.93 ( 5H, m ), 1.30-2.17 ( m, 12H ). 13C NMR (CDCl3) δ = 166.5, 144.2, 118.9, 134.5, 130.1, 128.8,
128.0, 72.7, 31.7, 23.8, 23.7.Anal. Calcd for C16H20O2: C, 78.65; H, 8.25. Found: C, 78.42; H, 8.36.
3.2.8.(E)-3-Phenyl-acrylic acid biphenyl-4-ylmethyl ester (1h)
1H NMR (250 MHz, CDCl3) δ = 7.46 (d, J= 16.0 Hz, 1H), 7.27-7.39 (m, 14H), 6.42 (d, J= 16.0 Hz, 1H),
13
5.21 (s, 2H). C NMR (CDCl3) δ = 168.0, 145.4, 140.4, 139.6, 138.3, 135.8, 129.4, 129.0, 128.9, 128.4,
128.3, 128.0, 127.2, 117.1, 66.5.Anal.Calcd for C21H16O2: C, 83.98; H, 5.37. Found: C, 84.05; H, 5.25.
3.2.9. (E)-3-Phenyl-acrylic acid octyl ester(1i) [18]
1H NMR (250 MHz, CDCl3) δ = 7.60 (d, J= 16.0 Hz, 1H), 7.25-7.47 (m, 5H), 6.31 (d, J= 16.0Hz, 1H), 4.10
(t, J= 6.8 Hz, 2H), 1.58-1.64 (m, 2H), 1.40-1.45 (m, 2H), 1.25-1.34 (m, 6H), 1.20 (m,2H), 0.88 (t, J=7.0 Hz,
3H). 13C NMR (CDCl3) δ = 167.1, 144.5, 134.5, 130.2, 128.8, 128.0, 118.3, 64.7, 31.8, 29.2, 29.1,
28.7,25.9, 22.6, 14.0.Anal.Calcd for C17H24O2: C, 78.42; H, 9.29. Found: C, 78.63; H, 9.30.
3.2.10. (E)-3-Phenyl-acrylic acid 4-chloro-benzyl ester (1j) [19]
1H NMR (250 MHz, CDCl3) δ = 7.74 (d, J= 16.0 Hz, 1H), 7.29-7.52 (m, 9H), 6.48 (d, J= 16.0Hz, 1H), 5.21
(s, 2H).13C NMR (CDCl3) δ = 166.8, 145.2, 139.0, 134.9, 132.7, 129.1, 128.7, 128.4, 127.7, 126.2,
70.1.Anal.Calcd for C16H13O2: C, 70.46; H, 4.80. Found: C, 70.63; H, 4.87.
3.2.11. (E)-3-Phenyl-acrylic acid benzyl ester (1k) [20]
1H NMR (250 MHz, CDCl3) δ = 7.64 (d, J= 16.0 Hz, 1H), 7.26-7.29 (m, 10H), 6.39 (d, J= 16.0 Hz, 1H),
13
5.16 (s, 2H). C NMR (CDCl3) δ= 166.8, 145.2, 136.1, 134.3, 130.4, 128.9, 128.6, 128.3, 128.2, 128.1,
117.9, 66.4. Anal.Calcd for C16H14O2: C, 80.65; H, 5.92. Found: C, 80.75; H, 5.98.
8

3.3. General procedure for hydrothioesterification of phenylacetylene with thiols in the presence of
ACCEPTED MANUSCRIPT
Mo(CO)6
A flask was charged with phenylacetylene (1.0 mmol), thiol (2.0 mmol), DABCO (1.0 mmol), Mo(CO)6
(1.0 mmol) and 3 mL of DMF. The flask was then placed in an oil bath on a heater stirrer preset at 100 °C.
After 5-15 min, the reaction vessel was removed from the oil bath and allowed to cool to room temperature.
After addition of water,the reaction mixture was extracted with ethyl acetate (3 × 10 mL). The organic layer
was separated and dried by Na2SO4. Then, the solvent was removed by rotary evaporation under reduced
pressure. The residue was purified by using column chromatography or preparative TLC (silica gel, eluant:
n-hexane/ethyl acetate 20:1) to obtain the desired product in 88-98% (Table 6).
3.4. Preparation of Mo(CO)5DABCO complex
A round bottom flask was charged with DABCO (5.38 g,16.0 mmol), THF (30 mL) and Mo(CO)6 (1.06
g, 4.0 mmol). The mixture was refluxed for 5 h and then the solvent was evaporated under reduced pressure
to dryness to yield a brown solid that was purified by n-hexane. Evaporation of all volatile materials under
1
reduced pressure gave yellow crystals of the title compound (1.45 g; 84%). H NMR data (250 MHz,
13
CHCl3): δ= 2.75 (t, J= 9.2 Hz, 6H), 3.04 (t, J= 9.2 Hz, 6H). C NMR (CDCl3) δ= 47.3, 55.2, 204.0 (CO).
IR ѵmax/cm-1 =2047, 1960, 1929 and 1895 (CO); Anal. Calc. for C11H12N2O5Mo: C, 37.96; H, 3.45; N, 8.05;
Found: C, 38.30%; H, 3.36%; N, 7.82%;
3.5. Typical procedure for hydrothiocarbonylation of phenylacetylene with penthane-1-thiol in the
presence of Mo(CO)5DABCO
To a round-bottom flask, phenylacetylene (1.0 mmol, 0.102 g), penthane-1-thiol (180 mg, 2.0 mmol),
DABCO (3mmol, 0.336 g), Mo(CO)5DABCO, (1 mmol, 0.432 g) and 3 mL of DMF were added. The flask
was heated at 100 °C for 45 min and then cooled down to room temperature. The product was extracted
with ethyl acetate (3 × 20 mL) from the aqueous layer, and dried over anhydrous Na2SO4. Then the crude
organic mixture was purified by column chromatography over silica gel using petroleum ether/ ethyl
acetate = 20:1 to obtain 3-phenyl-thioacrylic acid S-pentylester(0.223 g, 95%).
3.5.1. (E)-3-Phenyl-thioacrylic acid S-isopropyl ester (2a) [21]
1H NMR (250 MHz, CDCl3) δ7.52 (d, J= 16.0 Hz, 1H), 7.31-7.40 (m, 5H); 6.38 (d, J= 16.2 Hz, 1H), 2.89
(m, 2H), 1.28 (d, J= 6.5 Hz, 6H). 13C NMR (CDCl3) δ 192.0, 145.8, 132.9, 129.0, 128.4, 128.0, 125.3, 30.0,
22.0.Anal.Calcd for C12H14OS: C, 69.86; H, 6.84. Found: C, 69.95; H, 6.80.
3.5.2. (E)-3-Phenyl-thioacrylic acid S-ethyl ester (2b) [22]
1H-NMR (250 MHz, CDCl3) δ 7.58 (d, J = 16.0 Hz,1H), 7.35-7.48 (m, 5H), 6.50 (d, J = 16.0 Hz, 1H), 2.91
13
(q, J = 7.5 Hz, 2H), 1.30 (t, J = 7.5 Hz, 3H); C NMR(CDCl3) δ 193.9, 140.1, 130.4, 128.9,128.3, 127.8,
125.0, 23.3, 14.8.Anal.Calcd for C11H12OS: C, 68.71; H, 6.29. Found: C, 68.54; H, 6.44.
3.5.3. (E)-3-Phenyl-thioacrylic acid S-pentyl ester (2c)
1H NMR (250 MHz, CDCl3) δ = 7.53 (d, J= 16.0 Hz, 1H), 7.23-7.47 (m, 5H), 6.64 (d, J= 16.0Hz, 1H), 2.93
13
(t, J= 7.5 Hz, 2H), 1.45-1.59 (m, 2H), 1.18-1.30 (m, 4H), 0.86 (t, J=7.0 Hz, 3H). C NMR (CDCl3) δ
190.0, 140.1, 130.4, 128.8, 128.4, 128.0, 125.1, 31.9, 29.2, 28.3, 22.2, 13.9.Anal.Calcd for C14H18OS: C,
71.75; H, 7.74. Found: C, 71.59; H, 7.90.
3.5.4. (E)-3-Phenyl-thioacrylic acid S-octyl ester (2d) [23]
9

1H NMR (250 MHz, CDCl3) δ = 7.60 (d, J= 16.0 Hz, 1H), 7.30-7.47 (m, 5H), 6.78 (d, J= 16.0Hz, 1H), 2.98
ACCEPTED MANUSCRIPT
(t, J= 7.5 Hz, 2H), 1.86-1.98 (m, 2H), 1.26-1.38 (m, 10H), 0.92 (t, J=7.0 Hz, 3H). C NMR (CDCl3) δ
13
194.0, 148.8, 134.9, 128.4, 128.0, 127.8,125.1, 31.6, 29.9, 29.0, 28.9, 28.8, 22.9, 14.0.Anal.Calcd for
C17H24OS: C, 73.86; H, 8.75. Found: C, 73.93; H, 8.56.
3.5.5.(E)- 3-Phenyl-thioacrylic acid S-phenyl ester (2e) [24]
13
1H NMR (250 MHz, CDCl3) δ 7.50 (d, J= 16.0 Hz, 1H), 7.30-7.42 (m, 10H),6.41 (d, J= 16.0 Hz, 1H). C
NMR (CDCl3) δ=194.2, 145.2, 136.0, 134.9, 129.5, 129.4, 129.2, 128.4, 127.7,127.1, 124.9. Anal.Calcd for
C15H12OS: C,74.97; H, 5.03. Found: C, 74.75; H, 4.86.
3.5.6. (E)-3-Phenyl-thioacrylic acid S-benzyl ester(2f) [25]
1H NMR (250 MHz, CDCl3) δ 7.54 (d, J= 16.0 Hz, 1H), 7.26-7.36 (m, 10H), 6.39 (d, J= 16.0 Hz, 1H), 4.13
13
(s, 2H). C NMR (CDCl3) δ= 194.2, 145.2, 136.1, 134.3, 130.4, 129.4, 128.9, 128.6, 128.3, 128.2, 128.1,
37.4.Anal.Calcd for C16H14OS: C, 75.55; H, 5.55. Found: C, 75.37; H, 5.64.
3.5.7. (E)-3-Phenyl-thioacrylic acid S-butyl ester (2g) [26]
1H NMR (250 MHz, CDCl3) δ = 7.53 (d, J= 16.0 Hz, 1H), 7.23-7.47 (m, 5H), 6.64 (d, J= 16.0Hz, 1H), 2.93
13
(t, J= 7.5 Hz, 2H), 1.45-1.59 (m, 2H), 1.18-1.30 (m, 2H), 0.86 (t, J=7.0 Hz, 3H). C NMR (CDCl3) δ
194.0, 148.8, 134.9, 128.4, 127.7, 125.6, 32.0, 30.3, 24.0, 15.9.Anal.Calcd for C13H16OS: C, 70.87; H, 7.32.
Found: C, 70.63; H, 7.50.
Acknowledgments
The financial support of this work by the research council of Shiraz University and Iran National Elite
Foundation is acknowledged.
References
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3521-3526.
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M.Larhed, A. Hallberg, Drug Discovery Today 6 (2001) 406-416. (c) C. R. Strauss, R. W. Trainor,
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794-796
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829
11

Table 1. Optimization of different parameters for hydroalkoxycarbonylation of phenylacetylene.a
ACCEPTED MANUSCRIPT
O
Base, Solvent
Temp.
O
Ethanol Fe(CO)5
Entry
1
Base
DBU
Solvent
DMF
Temp. (° C)
100
Time (h)
Yield (%)b
47
2
10
0.5
3
2
n
-Pr3N
DABCO
-Pr3N
DMF
100
56
3
DMF
100
95
4
n
TBAB
TBAB
DMF
110
52
5
6c
7c
DABCO
DABCO
DABCO
DABCO
DABCO
K2CO3
110
3
70
100
2.5
6
75
DMF
100
65
8d
9d
10
11
12
13
14
15
16
17
18e
19
DMF
100
12
12
2
25
DMF
100
40
DMF
100
60
NaOH
DMF
100
2
61
Cs2CO3
DABCO
DABCO
DABCO
None
DMF
100
4
72
DMSO
diglyme
toluene
DMF
100
6
27
100
2.5
12
24
24
10
0.3
48
Reflux
100
36
10
DABCO
DABCO
DABCO
xylene
DMF
100
Trace
10
100
DMF
120
98
a Reaction conditions: 1.0 mmol of phenylacetylene, 1.0 mmol of Fe(CO)5, ethanol (4 mmol), Base (3 mmol), 2 mL of solvent.
b Isolated yield.
cThe amount of DABCO are 2.0 and 1.0 mmol for entries 6 and 7 respectively.
dThe amount of ethanol are 1.0 and 2.0 mmol for entries 8 and 9 respectively.
e The reaction was performed using 0.5 equivalent of Fe(CO)5.
Table 2. Reaction of phenylacetylene with with ethanol in the presence of different metal carbonyls.a
O
O
O
DABCO, M(CO)x, 2h
Ethanol
°
Ph
O
Ph
H
DMF, Base, 100 C
Ph
Ph
(II)
(I)
(III)
Entry
M(CO)x
Catalyst/ Base
None/DABCO
None/DABCO
None/DABCO -
None/DABCO
Isolated yield (%)
95%b of I
50% of II
35% of II
55% of II+30% of III
94% of I
1
2
3
4
Fe(CO)5
Mo(CO)6
W(CO)6
Cr(CO)6
5
Fe(CO)5
Pd(OAc)2/DABCO
a Reaction conditions: 1.0 mmol of phenylacetylene, 1.0 mmol of M(CO)x, 1.0 mmol of ethanol, 3.0 mmol of DABCO, 1.0 mmol of base and 2
mL of DMF at 100 °C.
b The reaction time is 30 min.
12

Table 3. Reaction of alcohols with phenylacetylene in the presence of iron pentacarbonyl.a
ACCEPTED MANUSCRIPT
O
OR
DABCO, DMF
ROH Fe(CO)5
100 oC, 30 min
Entry
1
Alcohol
Product
O
Yield (%)b
98
(CH3)2CHOH (1a)
O
(2a)
O
O
2
CH3OH (1b)
96
(2b)
O
O
3
4
CH3CH2OH (1c)
95
94
(2c)
O
OEt
O
EtO(CH2)2OH (1e)
(2d)
O
O
5
CH3(CH2)3CH2OH (1f)
95
(2e)
O
6
7
(CH2)4CHOH (1h)
(CH2)6CHOH (1i)
O
90
90
(2f)
O
O
(2g)
O
O
8
4-biphenylCH2OH (1j)
89
(2h)
O
O
9
CH3(CH2)6CH2OH (1k)
4-ClPhCH2OH (1l)
PhCH2OH (1m)
96
87
90
(2i)
O
O
10
11
Cl (2j)
(2k)
O
O
a Reaction conditions: 1.0 mmol of phenylacetylene, 1.0 mmol of Fe(CO)5, 4.0 mmol of alcohol, 2.0 mmol of DABCO, and 2 mL of DMF at
100 °C.
b Isolated yield.
13

ACCEPTED MANUSCRIPT
Table 4. Optimization of different parameters for hydrothiocarbonylation reaction of phenylacetylene.a
O
SH
Base,Sovent
Temp.
SCH2Ph
Mo(CO)6
Entry
1
Base (mmol)
DBU
Solvent
DMF
Temp. (° C)
100
Time (h)
Yieldb (%)
55
4
2
NBD
DMF
100
0.5
82
3
DABCO
DMF
100
15 min
92
4
5
n
-Pr3N
TBAB
TBAB
DMF
DMF
DMF
DMSO
diglyme
xylene
Toluene
DMF
100
100
100
100
100
100
100
100
8
6
52
70
92
60
45
35
45
Trace
Trace
15c
95
DABCO
DABCO
DABCO
DABCO
DABCO
DABCO
DABCO
DABCO
DABCO
DABCO
6c
7c
8d
9
45 min
2
2
6
3
24
24
12
10 min
10
11
12
13
14
reflux
100
120
DMF
a Reaction conditions: 1.0 mmol of phenylacetylene, 1.0 mmol of Mo(CO)6, benzyl mercaptan (2.0 mmol), base (3.0 mmol),
2 mL of solvent.
b Isolated yield.
cThe amount of DABCO are 2.0 and 1.0 mmol for entries 6 and 7 respectively.
dThe amount of benzyl mercaptane is 1.0 mmol for entries 8.
e The reaction was performed using 0.5 equivalents of Mo(CO)6.
Table 5. Effect of different metal carbonyl in the reaction of phenylacetylene with benzyl mercaptan under the
optimized condition.a
Entry
M(CO)x
Mo(CO)6
Fe(CO)5
W(CO)6
Cr(CO)6
Isolated Yield(%)
1
2
3
4
92%b
trace
45%
35
91%c
5
Mo(CO)5DABCO
a
Reaction conditions: 1.0 mmol of phenylacetylene, 1.0 mmol of M(CO)x, 2.0 mmol of benzyl mercaptan, 3.0 mmol of
DABCO and 2 mL of DMF at 100 °C.
bThe reaction time is 15 min.
c The reaction time is 60 min.
Table 6.Hydrothiocarbonylation of phenylacetylene with different thiols in the presence of Mo(CO)6.a
O
DABCO, DMF
SR
Mo(CO)6
RSH
100 oC, 5-15 min
Entry
1
Thiol
Product
Yield (%)b
95
O
S
(CH3)2CHSH
(2a)
(2b)
O
2
3
CH3CH2SH
S
98
95
O
S
CH3(CH2)3CH2SH
(2c)
14

ACCEPTED MANUSCRIPT
O
S
4
5
CH3(CH2)6CH2SH
95
(2d)
O
PhSH
88c
S
(2e)
(2f)
O
92c
98
S
6
7
PhCH2SH
O
S
CH3(CH2)2CH2SH
(2g)
a
Reaction conditions: 1.0 mmol of phenylacetylene, 1.0 mmol of Mo(CO)6, benzyl mercaptan (2.0 mmol), DABCO
(2mmol), 2 mL of DMF.
b Isolated yield.
c The reaction was completed after 15 min.
15

ACCEPTED MANUSCRIPT
Research highlight
‹ The carbonylation of alkyne was performed by using metal carbonyl/DABCO system.
‹ α,β-Cinamylesters and thioesters was obtained in excellent yields.
‹ These reactions were carried out in the absence of Pd catalyst and phosphine ligand.