Basic Al2O3 promotes one-pot synthesis of thioethers via in situ generation and addition of β-acyloxy mercaptans to electron-deficient alkenes

Article abstract of DOI:10.1007/s13738-015-0777-7

Thioethers were synthesized under solvent-free conditions by reacting Michael acceptors with β-acyloxy mercaptans in situ generated from the reaction of epoxides and thioacids in the presence of basic Al₂O₃ in high yields.

Full text of DOI:10.1007/s13738-015-0777-7

J IRAN CHEM SOC (2016) 13:653–658
DOI 10.1007/s13738-015-0777-7
ORIGINAL PAPER
Basic Al2O3 promotes one‑pot synthesis of thioethers
via in situ generation and addition of β‑acyloxy mercaptans
to electron‑deficient alkenes
Mohammad Abbasi1 · Dariush Khalili2
Received: 8 August 2015 / Accepted: 2 November 2015 / Published online: 9 November 2015
© Iranian Chemical Society 2015
Abstract Thioethers were synthesized under solvent-
free conditions by reacting Michael acceptors with
β-acyloxy mercaptans in situ generated from the reaction
of epoxides and thioacids in the presence of basic Al2O3
in high yields.
this regards, different strategies including the hydrolysis
of Bunte salts in acidic conditions [3], the treatment of
elemental sulfur with aryl halides in the presence of cop-
per ferrite nanoparticle [4], the treatment of an alkyl hal-
ide with thiourea in the presence of a base [5, 6], basic
hydrolysis of S-alkylisothiouronium salts [7], the hydroly-
sis of 3-[bis(alkylthio)methylene]pentane-2,4-diones [8,
9], and 2-[bis(alkylthio)methylene]-3-oxo-N–O-tolylbu-
tanamides [10], and reduction of disulfides [11–13] have
been employed successfully to in situ generate thiols in
Michael addition reactions.
Keywords Thioethers · Epoxides · Thioacids · Michael
addition · Al2O3
Introduction
Until now, the solid-phase organic synthesis [14, 15]
and catalysis [16] have been the subject of intense exper-
imental studies in organic synthesis. It is now clear that
many reactions proceed more efficiently in the solid state
than in solution [17–20]. A large number of organic, inor-
ganic, or organic–inorganic hybrid materials have been
employed as solid surfaces to promote or catalyze vari-
ous organic reactions [16]. In this regard, alumina and
silica gel has been used to promote a variety of organic
reactions since many years ago [21–26]. In this goal, we
recently developed a procedure for the one-pot prepara-
tion of thia-Michael adducts of β-acyloxy mercaptans
using thioacids, epoxides, and electron-deficient alkenes
under solvent-free conditions [27, 28]. In this method, a
β-hydroxy thioester is synthesized from the reaction of a
thioacid and an epoxide on silica gel surface at first which
rearranges to the corresponding β-acyloxy mercaptan by
using a silica gel/Et3N combined catalyst. Several dif-
ferent experiments convinced us that this rearrangement
proceeds efficiently only in the absence of any solvent.
Now, we wish to introduce a modified procedure for one-
pot synthesize of thia-Michael adducts of β-acyloxy mer-
captans using heterogeneous basic Al2O3 without needing
any co-catalyst.
Thioethers are essential building blocks for construction
of organosulfur derivatives that have important roles in
materials science, biology and chemistry [1, 2]. There
are several commonly used methods for the synthesis of
thioethers. Alkylation of thiols with electron-deficient
alkenes which is known as thio or thia-Michael addi-
tion reaction is one of the most efficient methods for
synthesizing thioethers. The study of thia-Michael addi-
tion has been remained a topic of research to this day in
organic synthesis. The studies have been mainly limited
to the introduction of new catalysts and conditions for the
addition of thiols to structurally diverse Michael accep-
tors. Over the past few years, a handful of methods have
been developed to prepare thia-Michael adducts via addi-
tion of in situ generated thiols to different acceptors. In
* Mohammad Abbasi
abbassi@pgu.ac.ir
1
Chemistry Department, Faculty of Sciences, Persian Gulf
University, 75169 Bushehr, Iran
2
Department of Chemistry, College of Sciences, Shiraz
University, 71454 Shiraz, Iran
1 3

654
J IRAN CHEM SOC (2016) 13:653–658
regioselectively by attacking thioacid to the less-hindered
carbon atom of the terminal epoxide. Next, an intramo-
lecular S→O acyl group migration generates in situ the
corresponding β-acyloxy mercaptan intermediate which
subsequently undergoes conjugate addition with the elec-
tron-deficient alkene to produce the corresponding thia-
Michael adduct. The actual function and precise role of
basic Al2O3 are not clear to us. In our opinion, the last two
stages can be efficiently promoted by basic Al2O3. It accel-
erates the intramolecular S→O acyl group migration via
activations of carbonyl group and increasing the nucleo-
philic character of the attacking hydroxyl group by abstrac-
tion of its proton. Similarly, it can accelerate thia-Michael
addition by interaction with electron-withdrawing group of
Michael acceptor and increasing the nucleophilic character
of the −SH group.
Results and discussion
To optimize conditions, several equimolar mixtures of
thioacetic acid and phenyl glycidyl ether were separately
treated with different amounts of basic Al2O3 (from 10
to 100 mol %) at room temperature and 80 °C. All reac-
tions had not been completed within 0.5 h and other than
the desired β-hydroxy thioester product and unreacted
substrates, some unidentified byproducts were observed
on the TLC. However, another reaction of thioacetic
acid (1 mmol) and phenyl glycidyl ether (1 mmol) in the
absence of basic Al2O3 had been completed within 0.5 h
at 80 °C to generate the desired β-hydroxy thioester prod-
uct cleanly. Without any separation, the crude oily prod-
uct was then treated with n-butyl acrylate (1 mmol) under
solvent-free condition. There was no reaction between
them at room temperature or 80 °C within 24 h. Next, the
similar reaction in the presence of basic Al2O3 was stud-
ied. In the presence of 0.1–0.5 g of Al2O3, the outcomes of
the reactions were not satisfying. For example, using 0.3 g
of Al2O3, and stirring the solid–liquid two-phase reaction
mixture at room temperature, the conversion was uncom-
pleted after 24 h and the desired product was obtained
in only 48 % yield. However, using 0.6 g of basic Al2O3,
the liquid reacting substrates were completely absorbed
on the surface of Al2O3. The desired thia-Michael adduct
was obtained in 92 % yield when the resulting powder was
shaken by a mechanical shaker at room temperature for 4 h.
The reusability of the catalyst was also studied. Al2O3
was separated each time and after washing with EtOAc and
drying at 120 °C was reused in another similar reaction. No
significant decrease in catalyst activity was observed even
after seven recycled runs.
Conclusion
In conclusion, we have presented that basic Al2O3 is an
efficient catalyst for high-yielding one-pot synthesis of
functionalized thioethers from commercially available
thioacids, epoxides and electron-deficient alkenes in sol-
vent-free conditions. In this study, a β-hydroxy thioester
is generated cleanly by heating an epoxide with a thioacid
without needing any catalyst which is then treated with
an electron-deficient alkene on the basic Al2O3 surface to
obtain thia-Michael adducts of β-acyloxy mercaptans in
high yields. In comparison with the previous work [28],
this study demonstrated that basic Al2O3 is more efficient
than SiO2 and is as efficient as Et3N/SiO2 combined cata-
lyst to synthesize β-acyloxy thioethers using epoxides,
thioacids and electron-deficient alkenes. Advantageously,
it was recoverable and reusable at least for seven runs.
The optimized conditions were then applied for the
preparation of thia-Michael adducts of other β-hydroxy
thioesters using structurally diverse epoxides, thioacids
and electron-deficient alkenes. The results are presented in
Table 1.
Experimental
As the results show, the structurally diverse thia-Michael
adducts of β-acyloxy mercaptans have been produced in
high yields by this procedure. The reaction of structurally
diverse electron-deficient alkenes with β-hydroxy acetic
acid thioesters produced from thioacetic acid and different
epoxides proceeded to completion within 4 h, whereas the
similar reactions with β-hydroxy benzoic acid thioesters
proceeded much slowly and required 7 h to reach end-
point. However, the synthesis of β-acyloxy thioethers by
starting from styrene oxide under reaction conditions was
not synthetically rewarding and a complex mixture of uni-
dentified products was produced in all experiments.
General procedure
A mixture of an epoxide (2 mmol) and a thioacid (2 mmol) in
an Erlenmeyer flask (25 mL) was heated at 80 °C for 0.5 h.
During this period, the starting epoxide had been completely
consumed. Next, an electron-deficient alkene (2 mmol) and
basic Al2O3 (1.2 g) were added to Erlenmeyer flask and the
resulting powder was shaken at room temperature using a
mechanical shaker. After consumption of β-hydroxy thi-
oester (4–7 h), the reaction was worked up by addition of
EtOAc (3 × 3 mL) to mixture and filtration. The correspond-
ing thia-Michael adducts were obtained in high yields after
purification by column chromatography on silica gel.
A
proposed reaction mechanism is shown in
Scheme 1. At first, the β-hydroxy thioester is produced
1 3

J IRAN CHEM SOC (2016) 13:653–658
655
OCOR1
Table 1 Synthesis of thioethers
via addition of in situ generated
β-acyloxy mercaptans to
R2
30 min
1)
2)
R1COSH
S
+
product (4a-r)
O
Al
R2
EWG
2O3,
EWG
R1 CH
Ph
:
3 (1a);
R2 CH OPh
(1b)
CH
electron-deficient alkenes
:
CH
2OCH(CH3)2 (2c);
CH CH=CH
2 (2d)
2
(2a);
3 (2b);
2
EWG: CO C H -n
COCH
CN
3 (3b), (3c)
(3a),
2
4
9
Entry
R1
R2
EWG
Product
Yield
OCOCH3
S
1
1a
1a
1a
1a
1a
1a
1a
2a
2a
2a
2b
2b
2b
2c
3a
3b
3c
3a
3b
3c
3a
4a
4b
4c
4d
4e
4f
92
90
94
87
84
87
89
-n
H
CO2C4
9
PhOH2C
PhOH2C
PhOH2C
OCOCH3
S
2
COCH3
CN
OCOCH3
S
3
OCOCH3
S
7
-n
H
CO2C4
9
OCOCH3
S
8
COCH3
OCOCH3
S
9
CN
OCOCH3
S
13
4g
-n
H
CO2C4
9
CHOCH
(CH3)2
2
OCOCH3
S
15
1a
2d
3a
H -
n
4h
90
CH2=CHCH2OCH2
CO2C4
9
OCOCH3
S
16
4
1a
1b
1b
1b
1b
2d
2a
2a
2a
2b
3c
3a
3b
3c
3a
4i
85
90
84
93
86
CH2=CHCH2OCH2
OCOPh
CN
4j
S
-n
H
PhOH2C
CO2C4
9
OCOPh
5
4k
4l
S
PhOH2C
COCH3
CN
OCOPh
6
S
PhOH2C
OCOPh
S
10
4m
-n
H
CO2C4
9
OCOPh
S
11
12
14
1b
1b
1b
2b
2b
2c
3b
3c
3a
4n
4o
4p
85
82
87
COCH3
OCOPh
S
CN
OCOPh
S
-n
H
CHOCH
CO2C4
(CH3)2
2
9
OCOPh
S
17
18
1b
2d
3a
H -n 4q
91
90
CH2=CHCH2OCH2
CH2=CHCH2OCH2
CO2C4
CN
9
OCOPh
S
1b
2d
3c
4r
1 3

656
J IRAN CHEM SOC (2016) 13:653–658
5.01–4.89 (m, 1H), 4.02 (t, J = 6.6 Hz, 2H), 2.91–2.49 (m,
6H), 1.97 (s, 3H), 1.56–1.50 (m, 2H), 1.34–1.17 (m, 2H),
1.23 (d, J = 6.3 Hz, 3H), 0.85 (t, J = 7.3 Hz,3H); 13C NMR
(62.5 MHz, CDCl3) δ: 171.8, 170.4, 69.9, 64.6, 37.4, 34.8,
30.6, 27.6, 21.2, 19.2, 19.1, 13.7; IR (neat): ν (cm−1) = 1735
(C = O ester); Anal. Calcd for (C12H22O4S): C, 54.93; H,
8.45; S, 12.22. Found: C, 55.05; H, 8.56; S, 12.05.
1‑Methyl‑2‑[(3‑oxobutyl)sulfanyl]ethyl
acetate
1
(4e) Colorless oil; H NMR (250 MHz, CDCl3) δ: 4.97–
4.87 (m, 1H), 2.63–2.50 (m, 6H), 2.10 (s, 3H), 1.97 (s. 3H),
1.24 (d, J = 6.3 Hz, 3H); 13C NMR (62.5 MHz, CDCl3)
δ: 206.6, 170.4, 69.9, 43.6, 37.6, 30.0, 26.3,21.2, 19.1;
IR (neat): ν (cm−1) = 1740 (C = O ester), 1717 (C = O
ketone); Anal. Calcd for (C9H16O3S): C, 52.91; H, 7.89; S,
15.70. Found: C, 52.70; H, 7.96; S, 15.64.
Scheme 1 A proposed reaction pathway
Butyl 3‑{[2‑(acetyloxy)‑3‑phenoxypropyl]sulfanyl}pro‑
1
panoate (4a) Colorless oil; H NMR (250 MHz, CDCl3)
δ: 7.21–7.13 (m, 2H), 6.88–6.71 (m, 3H), 5.22–5.12 (m,
1H), 4.11–4.50 (m, 2H), 3.99 (t, J = 6.6 Hz, 2H), 2.88–
2.69 (m, 4H), 2.54–2.48 (m, 2H), 1.98 (s, 3H), 1.56–1.45
(m, 2H), 1.34–1.17 (m, 2H), 0.83 (t, J = 7.3 Hz, 3H); 13C
NMR (62.5 MHz, CDCl3) δ: 171.7, 170.3, 158.4, 129.5,
121.3, 114.6, 71.4, 67.2, 64.5, 34.7, 32.2, 30.6, 27.6, 21.0,
19.1, 13.7; IR (neat): ν (cm−1) = 1735 (C = O ester), 1597
(C = C aromatic); Anal. Calcd for (C18H26O5S): C, 60.99;
H, 7.39; S, 9.05. Found: C, 60.76; H, 7.51; S, 8.90.
2‑[(2‑Cyanoethyl)sulfanyl]‑1‑methylethyl
acetate
1
(4f) Colorless oil; H NMR (250 MHz, CDCl3) δ: 4.96–
4.87 (m, 1H), 2.81–2.72 (m, 2H), 2.68–2.58 (m, 4H), 1.99
(s, 3H), 1.26 (d, J = 6.3 Hz, 3H); 13C NMR (62.5 MHz,
CDCl3) δ: 170.3, 118.3, 69.6, 37.2, 27.9, 21.1, 19.0, 18.7;
IR (neat): ν (cm−1) = 2242 (CN), 1739 (C = O ester);
Anal. Calcd for (C8H13NO2S): C, 51.31; H, 7.00; S, 17.12.
Found: C, 51.46; H, 7.16; S, 17.01.
2‑[(3‑Oxobutyl)sulfanyl]‑1‑(phenoxymethyl)ethyl ace‑
1
tate (4b) Colorless oil; H NMR (250 MHz, CDCl3) δ:
Butyl
3‑{[2‑(acetyloxy)‑3‑isopropoxypropyl]sulfanyl}
7.24–7.17 (m, 2H), 6.91–6.81 (m, 3H), 5.21–5.12 (m, 1H),
4.09–4.05 (m, 2H), 2.88–2.61 (m, 6H), 2.06 (s, 3H), 2.01
(s, 3H); 13C NMR (62.5 MHz, CDCl3) δ: 206.5, 170.4,
158.4, 129.5, 121.2, 114.6, 71.4, 67.2, 43.4, 32.4, 30.0,
26.3, 21.1; IR (neat): ν (cm−1) = 1740 (C = O ester), 1717
(C = O ketone), 1597 (C = C aromatic); Anal. Calcd for
(C15H20O4S): C, 60.79; H, 6.80; S, 10.82. Found: C, 60.66;
H, 6.96; S, 11.04.
propanoate (4g) Colorless oil; 1H NMR (250 MHz,
CDCl3) δ: 4.97–4.91 (m, 1H), 4.02 (t, J = 6.6 Hz, 2H),
3.54–3.43 (m, 3H), 2.78–2.64 (m, 4H), 2.56–2.50 (m,
2H), 2.00 (s, 3H), 1.57–1.46 (m, 2H), 1.32–1.24 (m, 2H),
1.06 (d, J = 6.2 Hz, 6H), 0.86 (t, J = 7.3 Hz, 3H); 13C
NMR (62.5 MHz, CDCl3) δ: 171.5, 170.0, 72.1, 72.0,
67.3, 64.2, 33.4, 32.1, 30.4, 27.4, 21.8, 20.8, 18.9, 13.5;
IR (neat): ν (cm−1) = 1735 (C = O ester); Anal. Calcd for
(C15H28O5S): C, 56.22; H, 8.81; S, 10.01. Found: C, 56.06;
H, 8.96; S, 10.04.
2‑[(2‑Cyanoethyl)sulfanyl]‑1‑(phenoxymethyl)ethyl
acetate (4c) Colorless oil; 1H NMR (250 MHz, CDCl3) δ:
7.23–7.16 (m, 2H), 6.91–6.80 (m, 3H), 5.17–5.09 (m, 1H),
4.11–4.01 (m, 2H), 2.93–2.69 (m, 4H), 2.56–2.51 (m, 2H),
2.00 (s, 3H); 13C NMR (62.5 MHz, CDCl3) δ: 170.3, 158.3,
129.6, 121.4, 118.6, 114.7, 71.1, 67.2, 32.0, 27.9, 21.0,
18.6; IR (neat): ν (cm−1) = 2242 (CN), 1740 (C = O ester),
1597 (C = C aromatic); Anal. Calcd for (C14H17NO3S): C,
60.19; H, 6.13; S, 11.48. Found: C, 60.31; H, 6.16; S, 11.24.
Butyl
3‑{[2‑(acetyloxy)‑3‑(allyloxy)propyl]sulfanyl}
propanoate (4h) Colorless oil; 1H NMR (250 MHz,
CDCl3) δ: 5.89–5.73 (m, 1H), 5.23–4.94 (m, 3H), 4.02
(t, J = 6.6 Hz, 2H), 3.95–3.92 (m, 2H), 3.58–3.46 (m,
2H), 2.80–2.61 (m, 4H), 2.57–2.50 (m, 2H), 2.01 (s, 3H),
1.60–1.49 (m, 2H), 1.38–1.24 (m, 2H) 0.68 (t, J = 7.3 Hz,
3H); 13C NMR (62.5 MHz, CDCl3) δ: 171.7, 170.2, 134.3,
117.1, 72.1, 71.9, 69.3, 64.4, 34.7, 32.2, 30.5, 27.5, 21.0,
19.0, 13.6; IR (neat): ν (cm−1) = 1735 (C = O ester), 1647
(C = C alkene); Anal. Calcd for (C15H26O5S): C, 56.58; H,
8.23; S, 10.07. Found: C, 56.66; H, 8.16; S, 10.14.
Butyl
3‑{[2‑(acetyloxy)propyl]sulfanyl}propanoate
(4d) Colorless oil; 1H NMR (250 MHz, CDCl3) δ:
1 3

J IRAN CHEM SOC (2016) 13:653–658
657
2‑(Allyloxy)‑1‑{[(2‑cyanoethyl)sulfanyl]methyl}ethyl
acetate (4i) Colorless oil; 1H NMR (250 MHz, CDCl3) δ:
5.90–5.74 (m, 1H), 5.25–5.19 (m, 2H), 4.99–4.94 (m, 1H),
3.97–3.93 (m, 2H), 3.62–3.50 (m, 2H), 2.86–2.71 (m, 4H),
2.65–2.59 (m, 2H), 2.02 (s, 3H); 13C NMR (62.5 MHz,
CDCl3) δ: 170.4, 134.2, 118.2, 117.4, 72.2, 71.7, 69.1,
32.1, 27.9, 21.1, 19.7; IR (neat): ν (cm−1) = 2242 (CN),
1740 (C = O ester), 1647 (C = C alkene); Anal. Calcd
for (C11H17NO3S): C, 54.30; H, 7.04; S, 13.18. Found: C,
54.21; H, 7.16; S, 13.14.
for (C19H19NO3S): C, 66.84; H, 5.61; S, 9.39. Found: C,
66.89; H, 5.46; S, 9.44.
2‑[(3‑Butoxy‑3‑oxopropyl)sulfanyl]‑1‑methylethyl ben‑
zoate (4m) Colorless oil; 1H NMR (250 MHz, CDCl3) δ:
7.96–7.92 (m, 2H), 7.47–7.40 (m, 1H), 7.35–7.28 (m, 2H),
5.16–5.11 (m, 1H), 3.97 (t, J = 6.6 Hz, 2H), 2.76–2.61
(m, 2H), 2.54–2.48 (m, 2H), 1.50–1.43 (m, 2H), 1.34 (d,
J = 6.3 Hz, 3H), 1.32–1.14 (m, 2H), 0.81 (t, J = 7.2 Hz Hz,
3H); 13C NMR (62.5 MHz, CDCl3) δ: 171.7, 165.8, 132.9,
130.3, 129.5, 128.6, 70.6, 64.4, 37.4, 34.9, 30.5, 27.7,
19.1, 13.6; IR (neat): ν (cm−1) = 1735 (C = O ester), 1720
(C = O conjugated ester); Anal. Calcd for (C17H24O4S): C,
62.93; H, 7.46; S, 9.88. Found: C, 63.06; H, 7.29; S, 9.84.
2‑[(3‑Butoxy‑3‑oxopropyl)sulfanyl]‑1‑(phenoxymethyl)
1
ethyl benzoate (4j) Colorless oil; H NMR (250 MHz,
CDCl3) δ: 7.97–7.92 (m, 2H), 7.46–7.40 (m, 1H), 7.34–
7.28 (m, 2H), 7.17–7.12 (m, 2H), 6.87–6.80 (m, 3H),
5.44–5.36 (m, 1H), 4.26–4.13 (m, 2H), 3.97 (t, J = 6.6 Hz,
2H), 3.01–2.85 (m, 2H), 2.78 (t, J = 7.0 Hz, 2H), 2.52 (t,
J = 7.0 Hz, 2H),1.53–1.44 (m, 2H), 1.30–1.16 (m, 2H),
0.80 (t, J = 7.3 Hz, 3H); 13C NMR (62.5 MHz, CDCl3)
δ: 171.7, 165.9, 158.5, 133.2, 129.9, 129.8, 129.6, 128.4,
121.3, 114.8, 72.2, 67.3, 64.6, 34.8, 32.4, 30.6, 27.8, 19.1,
13.7; IR (neat): ν (cm−1) = 1735 (C = O ester), 1717
(C = O conjugated ester), 1597 (C = C aromatic); Anal.
Calcd for (C23H28O5S): C, 66.32; H, 6.78; S, 7.70. Found:
C, 66.56; H, 6.60; S, 7.81.
1‑Methyl‑2‑[(3‑oxobutyl)sulfanyl]ethyl
benzoate
1
(4n) Colorless oil; H NMR (250 MHz, CDCl3) δ: 7.98–
7.93 (m, 2H), 7.48–7.45 (m, 1H), 7.39–7.34 (m, 2H), 5.21–
5.18 (m, 1H), 2.79–2.65 (m, 6H), 2.07 (s, 3H), 1.36 (d,
J = 6.3 Hz, 3H); 13C NMR (62.5 MHz, CDCl3) δ: 206.5,
165.8, 132.9, 130.3, 129.5, 128.3, 70.6, 43.6, 37.7, 29.9,
26.4, 19.2; IR (neat): ν (cm−1) = 1717 (C = O ketone and
conjugated ester), 1601 (C = C aromatic); Anal. Calcd for
(C14H18O3S): C, 63.13; H, 6.81; S, 12.04. Found: C, 63.22;
H, 6.96; S, 11.99.
2‑[(3‑Oxobutyl)sulfanyl]‑1‑(phenoxymethyl)ethyl ben‑
1
zoate (4k) Colorless oil; H NMR (250 MHz, CDCl3)
2‑[(2‑Cyanoethyl)sulfanyl]‑1‑methylethyl
benzo‑
1
δ: 7.94–7.87 (m, 2H), 7.44–7.38 (m, 1H), 7.32–7.25 (m,
2H), 7.18–7.11 (m, 2H), 7.86–6.74 (m, 3H), 5.42–3.34
(m, 1H), 4.05–3.97 (m, 2H), 2.98–2.81 (m, 2H), 2.74–
2.68 (m, 2H), 2.61–2.55 (m, 2H), 1.96 (s, 3H); 13C NMR
(62.5 MHz, CDCl3) δ: 206.6, 166.0, 158.5, 133.3, 129.8,
129.6, 129.5, 128.5, 121.3, 114.8, 71.5, 67.3, 43.6, 33.0,
30.0, 26.5; IR (neat): ν (cm−1) = 1717 (C = O ketone and
conjugated ester), 1597 (C = C aromatic); Anal. Calcd for
(C20H22O4S): C, 67.01; H, 6.19; S, 8.95. Found: C, 66.86;
H, 6.16; S, 9.10.
ate (4o) Colorless oil; H NMR (250 MHz, CDCl3) δ:
7.96–7.89 (m, 2H), 7.49–7.43 (m, 1H), 7.38–7.29 (m, 2H),
5.21–5.09 (m, 1H), 2.83–2.64 (m, 4H), 2.57–2.53 (m, 2H),
1.35 (d, J = 6.3 Hz, 3H); 13C NMR (62.5 MHz, CDCl3) δ:
165.9, 133.1, 130.1, 129.5, 128.5, 118.3, 70.4, 37.3, 28.1,
19.5, 19.2; IR (neat): ν (cm−1) = 2242 (CN), 1717 (C = O
conjugated ester); Anal. Calcd for (C13H15NO2S): C, 62.62;
H, 6.06; S, 12.86. Found: C, 62.76; H, 5.96; S, 12.80.
2‑[(3‑Butoxy‑3‑oxopropyl)sulfanyl]‑1‑(isopropoxymethyl)
1
ethyl benzoate (4p) Colorless oil; H NMR (250 MHz,
2‑[(2‑Cyanoethyl)sulfanyl]‑1‑(phenoxymethyl)ethyl
benzoate (4l) Colorless oil; 1H NMR (250 MHz,
CDCl3) δ: 7.96–7.91 (m, 2H), 7.49–7.43 (m, 1H), 7.36–
7.30 (m, 2H), 7.22–7.15 (m, 2H), 6.90–6.76 (m, 3H),
5.42–5.32 (m, 1H), 4.24–4.14 (m, 2H), 3.03–2.81 (m,
2H), 2.78–2.63 (m, 2H), 2.56–2.51 (m, 2H); 13C NMR
(62.5 MHz, CDCl3) δ: 166.1, 158.4, 133.4, 129.8, 129.7,
129.7, 128.5, 121.5, 118.4, 114.8, 72.0, 67.2, 32.2, 28.1,
18.8; IR (neat): ν (cm−1) = 2248 (CN), 1717 (C = O
conjugated ester), 1597 (C = C aromatic); Anal. Calcd
CDCl3) δ: 7.99–7.92 (m, 2H), 7.49–7.43 (m, 1H), 7.38–7.30
(m, 2H), 5.24–5.15 (m, 1H), 3.99 (t, J = 6.6 Hz, 2H), 3.69–
3.47 (m, 3H), 2.93–2.76 (m, 4H), 2.53 (t, J = 7.1 Hz, 2H),
1.56–1.44 (m, 2H), 1.34–1.19 (m, 2H), 1.06 (d, J = 6.1 Hz,
6H), 0.82 (t, J = 7.3, 3H); 13C NMR (62.5 MHz, CDCl3) δ:
171.5, 165.6, 132.9, 130.1, 129.5, 128.6, 72.9, 72.1, 67.5,
64.2, 34.7, 32.3, 30.5, 27.5, 21.9, 19.0, 13.6; IR (neat):
ν (cm−1) = 1735 (C = O ester), 1717 (C = O conjugated
ester); Anal. Calcd for (C20H30O5S): C, 62.80; H, 7.91; S,
8.38. Found: C, 62.63; H, 7.86; S, 8.50.
1 3

658
J IRAN CHEM SOC (2016) 13:653–658
3. Y.-M. Lin, G.-L. Lu, C. Cai, W.-B. Yi, RSC Adv. 5, 27107–
27111 (2015)
4. M. Gholinejad, H. Firouzabadi, New J. Chem. 39, 5953–5959
(2015)
5. H. Firouzabadi, N. Iranpoor, M. Abbasi, Adv. Synth. Catal. 351,
755–766 (2009)
6. H. Firouzabadi, N. Iranpoor, M. Abbasi, Tetrahedron 65, 5293–
5301 (2009)
7. Y. Zhao, Z.-M. Ge, T.-M. Cheng, R.-T. Li, Synlett 2007, 1529–
1532 (2007)
8. Y. Chai, D. Dong, Y. Ouyang, Y. Liang, Y. Wang, M. Li, Q. Liu,
Lett. Org. Chem. 4, 281–284 (2007)
2‑(Allyloxy)‑1‑{[(3‑butoxy‑3‑oxopropyl)sulfanyl]
methyl}ethyl benzoate (4q) Colorless oil; 1H NMR
(250 MHz, CDCl3) δ: 8.08–8.01 (m, 2H), 7.60–7.53 (m,
1H), 7.48–7.41 (m, 2H), 5.97–5.82 (m, 1H), 5.35–5.15 (m,
3H), 4.08 (t, J = 6.6 Hz, 2H), 4.07–4.03 (m, 2H), 3.82–3.70
(m, 2H), 3.01–2.84 (m, 4H), 2.65–2.59 (m, 2H), 1.66–1.54
(m, 2H), 1.44–1.29 (m, 2H), 0.84 (t, J = 7.3 Hz, 3H); 13C
NMR (62.5 MHz, CDCl3) δ: 171.8, 165.9, 134.4, 133.1,
130.0, 129.7, 128.4, 117.2, 72.7, 72.3, 69.5, 64.6, 34.8,
32.5, 30.6, 27.7, 19.1, 13.7;; IR (neat): ν (cm−1) = 1735
(C = O ester), 1717 (C = O conjugated ester), 1647 (C = C
alkene); Anal. Calcd for (C20H28O5S): C, 63.13; H, 7.42; S,
8.43. Found: C, 63.32; H, 7.31; S, 8.30.
9. C. Lin, X.-L. Zhao, Y. Ouyang, H.-F. Yu, D.-W. Dong, Chin. J.
Chem. 26, 1431–1434 (2008)
10. D. Dong, H. Yu, Y. Ouyang, Q. Liu, X. Bi, Y. Lu, Synlett 2006,
283–287 (2006)
11. B. Movassagh, Y. Zakinezhad, Z. Naturforsch. 61b, 47–49
(2006)
12. A. Bartolozzi, H. M. Foudoulakis, B. M. Cole, Synthesis 2008,
2023–2032 (2008)
13. B. C. Ranu, T. Mandal, Synlett 2004, 1239–1242 (2004)
14. K. Burgess, B. Yan. Solid-phase Org. Synth. (2002).
doi:10.1002/0471228249
15. F. Guillier, D. Orain, M. Bradley. Chem. Rev. 100, 2091–2158
(2000)
16. B. Basu, S. Paul, J. Catal. 2013, 1–20 (2013)
17. F. Toda, H. Takumi, M. Akehi, J. Chem. Soc. Chem. Commun.
1990, 1270–1271 (1990)
2‑(Allyloxy)‑1‑{[(2‑cyanoethyl)sulfanyl]methyl}ethyl
benzoate (4r) Colorless oil; 1H NMR (250 MHz, CDCl3)
δ: 7.97–7.86 (m, 2H), 7.47–7.40 (m, 1H), 7.35–7.27 (m,
2H), 5.85–5.69 (m, 1H), 5.23–5.03 (m, 3H), 3.94–3.85 (m,
2H), 3.69–3.57 (m, 2H), 2.93–2.77 (m, 2H), 2.75–2.69 (m,
2H), 2.56–2.51 (m,2H); 13C NMR (62.5 MHz, CDCl3) δ:
165.8, 133.7, 132.8, 129.8, 129.6, 128.5, 118.4, 117.2, 72.5,
72.2, 69.3, 32.2, 28.0, 18.7; IR (neat): ν (cm−1) = 2242
(CN), 1717 (C = O conjugated ester), 1647 (C = C alk-
ene); Anal. Calcd for (C16H19NO3S): C, 62.93; H, 6.27; S,
10.50. Found: C, 62.77; H, 6.17; S, 10.69.
18. F. Toda, K. Tanaka, S. Iwata. J. Org. Chem. 54, 3007–3009
(1989)
19. F. Toda, Acc. Chem. Res. 28, 480–486 (1995)
20. K. Tanaka, F. Toda, Chem. Rev. 100, 1025–1074 (2000)
21. P.J. Kropp, G.W. Breton, S.L. Craig, S.D. Crawford, W.F. Dur-
land Jr, J.E. Jones III, J.S. Raleigh, J. Org. Chem. 60, 4146–4152
(1995)
Acknowledgments We gratefully acknowledge the support of this
study by Persian Gulf University Research Council.
22. A.K. Banerjee, M.S. Laya Mimo, W.J. Vera Vegas, Russ. Chem.
Rev. 70, 971–990 (2001)
23. G. Sartori, R. Ballini, F. Bigi, G. Bosica, R. Maggi, P. Righi,
Chem. Rev. 104, 199–250 (2004)
24. S. Minakata, M. Komatsu, Chem. Rev. 109, 711–724 (2009)
25. G.H. Posner, Angew. Chem. Int. Ed. Engl. 17, 487–496 (1978)
26. P. Laszlo, Acc. Chem. Res. 19, 121–127 (1986)
27. M. Abbasi, Tetrahedron Lett. 53, 2608–2610 (2012)
28. M. Abbasi, Tetrahedron Lett. 53, 3683–3685 (2012)
References
1. R.J. Cremlyn, An Introduction to Organo-Sulfur Chemistry
(Wiley & Sons, NewYork, 1996)
2. J. Hassan, M. Sevignon, C. Gozzi, E. Schulz, M. Lemaire, Chem.
Rev. 102, 1359–1469 (2002)
1 3