Transition metal-free addition of dithiocarbamates to alkynes: One-pot regioselective synthesis of S-vinyl dithiocarbamates under solvent-free conditions

Article abstract of DOI:10.1007/s00706-013-1112-6

A convenient, green, and efficient procedure for the synthesis of S-vinyl dithiocarbamates by a simple one-pot three-component condensation of an amine, carbon disulfide, and alkynes is described in the absence of any transition metal catalyst and under solvent-free conditions. This clean and improved method selectively furnishes the corresponding (Z)-S-vinyl dithiocarbamates in good to excellent yields. The reaction is clean with simple product workup and is carried out at 80 C. Graphical Abstract: [Figure not available: see fulltext.]

Full text of DOI:10.1007/s00706-013-1112-6

Monatsh Chem (2014) 145:521–526
DOI 10.1007/s00706-013-1112-6
ORIGINAL PAPER
Transition metal-free addition of dithiocarbamates to alkynes:
one-pot regioselective synthesis of S-vinyl dithiocarbamates
under solvent-free conditions
•
Fezzeh Aryanasab Mohammad Reza Saidi
Received: 8 May 2013 / Accepted: 23 October 2013 / Published online: 14 November 2013
Ó Springer-Verlag Wien 2013
Abstract A convenient, green, and efficient procedure
for the synthesis of S-vinyl dithiocarbamates by a simple
one-pot three-component condensation of an amine, carbon
disulfide, and alkynes is described in the absence of any
transition metal catalyst and under solvent-free conditions.
This clean and improved method selectively furnishes the
corresponding (Z)-S-vinyl dithiocarbamates in good to
excellent yields. The reaction is clean with simple product
workup and is carried out at 80 °C.
quantities. Furthermore, the difficulty of their separation
leads to the possibility of product contamination [6–8].
Solvent-free organic reactions are of great interest because
of the elimination of using volatile, hazardous organic
solvents, the low costs, and simplicity of the procedure.
Solvent-free reactions are generally fast and give higher
selectivity and yields, which may offer advantages over
those occurring in organic solvents [3–5].
Organic dithiocarbamates have received much attention
because of their interesting chemistry and wide utility.
They have many potential applications as useful synthetic
intermediates [9–13], protecting groups in peptide synthe-
sis [14, 15], playing a pivotal role in agriculture [16, 17],
and providing intriguing biological activities [18, 19]. They
can be used as linkers in solid-phase organic synthesis [20,
21] and recently as a single precursor source for the
preparation of nanoparticles [22–24]. Furthermore, dithio-
carbamates are widely employed in medicinal chemistry
and have been used in cancer therapy [25–27]. They are
also used in the rubber industry as vulcanization acceler-
ators and in controlling radical polymerization techniques
[28]. Therefore, the synthesis of dithiocarbamates has
attracted a lot of attention recently.
Keywords Dithiocarbamates Á Solvent-free Á
Green chemistry Á Alkynes Á Regioselective
Introduction
During the last few decades, there has been significant
interest in developing green chemical processes by using
more environmentally benign chemicals, reagents, cata-
lysts, and solvents [1, 2]. Among the most promising ways
to reach this goal, solvent- and catalyst-free techniques
hold a strategic position [3–5]. An environmentally benign
and metal-free process is desired as a part of the require-
ments for industry. In addition, one of the most important
challenges for chemists is avoiding or reducing the use of
metals in chemical reactions. These metals are sometimes
toxic, and it is difficult to keep them properly in large
Conventional methods for the synthesis of dithiocarba-
mates involve reactions of amines with costly and toxic
reagents, such as thiophosgene or an isothiocyanate, which
are costly and toxic reagents and not environmentally
acceptable [29–31]. Our group has been engaged in the
development of new methodologies for the synthesis of
dithiocarbamates using a one-pot reaction of amines with
carbon disulfide and alkyl halides, a,b-unsaturated com-
pounds, or epoxides in water or in solvent-free conditions
over several years [32–37]. Although these methods were
appropriate for the synthesis of a wide range of alkyl
dithiocarbamates, they were not effective for the synthesis
F. Aryanasab (&)
Department of Chemistry and Petrochemical Engineering,
Standard Research Institute (SRI), 31745-139 Karaj, Iran
e-mail: f_aryanasab@standard.ac.ir
M. R. Saidi
Department of Chemistry, Sharif University of Technology,
11365 Tehran, Iran
123

522
F. Aryanasab, M. R. Saidi
of vinyl or aryl derivatives. The methods for the synthesis
of vinyl and aryl dithiocarbamates are rather limited [38–
40]. Some of the procedures are involved with the Wittig
reaction of aldehydes with phosphonium ylides [41] or
reaction of the sodium salt of dithiocarbamic acid with
hypervalent iodine compounds [42–44]. Clearly, a simple
and green method for the synthesis of vinyl dithiocarba-
mates would be highly desirable. Recently, a new protocol
based on the Ullmann-type coupling of sodium dithiocar-
bamates with aryl iodides and vinyl bromides catalyzed by
CuI in the presence of a ligand, N,N-dimethylglycine, in
DMF has been reported by Liu and Bao [45]. Moreover,
Ranu et al. reported a procedure using copper nanoparticles
for the synthesis of aryl and styrenyl dithiocarbamates by a
one-pot three-component condensation of aryl/styrenyl
halides, carbon disulfide, and amines in water [46]. They
also reported a catalyst-free procedure for the synthesis of
S-aryl dithiocarbamates using aryldiazonium fluoroborate
in water at room temperature [47].
2. The results are summarized in Table 1. Various sec-
ondary amines reacted with alkynes/propargyl ethers and
gave the corresponding S-vinyl dithiocarbamates in good to
excellent yields. The proposed mechanism for this reaction
is shown in Scheme 2. It must be mentioned that when a
primary amine was used in this reaction, a complex mix-
ture was obtained.
As indicated in Table 1, the transformation was suitable
for a variety of terminal alkynes and gave only the anti-
Markonikov products. Also, it should be noted that the
reaction did not work with internal alkynes (Table 1, entry
18).
The reaction reached excellent double-bond selectivity,
and only the cis addition products were formed in all cases.
The double-bond stereochemistry was confirmed by 1H
NMR experiments. For example, the cis-stereochemistry of
(Z)-styryl pyrrolidine-1-carbodithioate (Table 1, entry 3)
was determined based on the coupling constants of the
methine protons at d = 7.53 (1H, d, J = 11.07 Hz) and
1
6.79 (1H, d, J = 11.07 Hz) ppm in the H NMR spectra
[44, 45]. The propargyl ethers were prepared directly from
the corresponding phenol, b-naphthol, or 7-hydroxycoum-
arin [51].
Results and discussion
As a part of our continuing studies on the development of
green chemical reactions by using water as the reaction
medium or by performing organic transformations under
solvent-free conditions [48–50], herein, we report a novel
and simple method for the synthesis of S-vinyl dithiocar-
bamates by a one-pot multicomponent condensation of
amines 1, carbon disulfide, and alkynes/propargyl ethers 2
(Scheme 1).
Conclusion
In conclusion, we have described a one-pot, efficient, and
highly stereoselective green synthetic protocol for the
synthesis of S-vinyl dithiocarbamates via a sequential
multicomponent process involving the reaction of amines
with carbon disulfide and alkynes/propargyl ethers. This
one-pot protocol avoids the use of transition metal catalyst
and toxic organic solvents by performing solvent-free
conditions. A clean and efficient reaction, simple isolation,
and purification of the product and application to a variety
of substrates render this method a practical one.
To optimize the reaction conditions, we first studied
the reaction of pyrrolidine with carbon disulfide and
phenylacetylene in different solvents such as dichloro-
ethane, toluene, THF, DMF, and water. This reaction was
also carried out without using any solvent. The best
product yield was obtained when the condensation was
performed under solvent-free conditions. Furthermore,
heating the reaction mixture at 80 °C for 14 h under
solvent-free conditions improved the yield of S-vinyl
dithiocarbamates.
Experimental
With optimized reaction conditions in hand, the scope
and limitation of this simple process were explored by
using a range of amines 1 and alkynes or propargyl ethers
FT-IR spectra were recorded on a Midac spectrophotom-
eter (US). NMR spectra were recorded in CDCl3 solutions
at RT on a Bruker 500-MHz spectrometer (TMS was used
Scheme 1
S
Solvent-free
R1R2NH
CS2
R3
R1R2N
+
+
S
R3
80 °C
1
2
3
123

Transition metal-free addition of dithiocarbamates to alkynes
523
Table 1 Synthesis of various
(Z)-S-vinyl dithiocarbamates
Entry
1
Amine
Alkyne
Product
Yield /%
90
3a [46]
1a
2a
2a
2
3
3b [44]
3c [44]
88.5
60
1b
1c
2a
2a
4
5
3d
3e
71
87
1d
1a
2b
2b
6
7
1b
1c
3f
99
77
2b
2b
3g
8
9
1d
1a
3h
3i
92
99
2c
2c
10
11
12
13
1b
1c
1d
1a
3j
3k
3l
95
86
90
85
2c
2c
3m
2d
2d
14
1b
3n
95
15
16
1c
1a
2d
3o
3p
71
55
2e
2f
17
18
1c
3q
60
0
1b
2g
123

524
F. Aryanasab, M. R. Saidi
Scheme 2
S
R1
N
R3
R2
One step
80 °C
R1
R2
Solvent-free
N
H
S
S
+
N
CS2
R2
R1
H
S
R3
d = 7.28–7.31 (m, 3H), 6.97 (m, 1H), 6.92 (d,
J = 7.9 Hz, 2H), 6.17 (dt, J = 10.0, 5.9 Hz, 1H), 6.68
(dd, J = 5.9, 1.3 Hz, 2H), 4.06 (q, J = 6.9 Hz, 2H),
3.77 (q, J = 6.9 Hz, 2H), 1.31–1.36 (m, 6H) ppm; 13C
NMR (125 MHz, CDCl3): d = 191.4, 158.7, 129.9,
127.0, 126.8, 121.4, 115.2, 65.9, 50.1, 47.5, 13.1,
11.9 ppm.
as an internal standard). All reagents were purchased from
Merck and Aldrich and used without further purification.
Typical procedure for the preparation of S-vinyl
dithiocarbamates
In a 50-cm3 round-bottom flask fitted with a magnetic stir bar
at room temperature, CS2 (2 mmol) was added slowly to
amine 1 (1 mmol) and stirred for 10 min. Then, alkyne 2
(1 mmol) was added, and the flask was placed in an oil bath
with 80 °C. After the completion of the reaction (monitored
by TLC), the reaction mixture was diluted with EtOAc, and
the organic layer was washed with H2O. The organic layer
was dried over anhydrous Na2SO4, and the solvent was
removed on the rotary evaporator to give a crude residue. The
residue was purified by recrystallization from ethanol or by
column chromatography if needed (EtOAc and petroleum
ether) to give the pure products. All compounds were char-
acterized on the basis of their NMR spectroscopic data.
(Z)-3-Phenoxyprop-1-en-1-yl piperidine-1-carbodithioate
(3g, C15H19NOS2)
Isolated by column chromatography. Rf = 0.47 (EtOAc/
petroleum ether, 1:4); 1H NMR (500 MHz, CDCl3):
d = 7.29–7.35 (m, 3H), 6.97–7.04 (m, 2H), 6.94 (d,
J = 8.1 Hz, 1H), 6.20 (dt, J = 10.0, 6.0 Hz, 1H), 4.60
(dd, J = 6.0, 1.2 Hz, 2H), 4.33 (m, 2H), 3.93 (m, 2H), 1.74
(m, 6H) ppm; 13C NMR (125 MHz, CDCl3): d = 191.4,
158.7, 157.9, 129.9, 127.0, 126.8, 121.4, 115.1, 65.9, 53.2,
52.2, 26.6, 25.8, 24.3 ppm.
(Z)-3-Phenoxyprop-1-en-1-yl azepane-1-carbodithioate
(3h, C16H21NOS2)
Pale brown solid isolated by recrystallization from etha-
(Z)-Styryl azepane-1-carbodithioate (3d, C15H19NS2)
Isolated by column chromatography. Rf = 0.33 (EtOAc/
petroleum ether, 1:2); 1H NMR (500 MHz, CDCl3):
d = 7.58 (d, J = 11.1 Hz, 1H), 7.49 (d, J = 7.5 Hz, 2H),
7.39 (m, 2H), 7.30 (m, 1H), 6.84 (d, J = 11.1 Hz, 1H),
4.24 (t, J = 6.1 Hz, 2H), 3.96 (t, J = 6.1 Hz, 2H), 1.91 (m,
4H), 1.61 (m, 4H) ppm; 13C NMR (125 MHz, CDCl3):
d = 193.0, 136.9, 132.5, 129.2, 128.9, 128.7, 124.7, 56.4,
53.4, 28.3, 27.4, 27.0, 26.8, 26.5 ppm.
ꢀ
nol; IR (KBr): m = 3,197, 3,172, 2,990, 2,902, 2,839,
2,487, 2,339, 2,024, 1,903, 1,638, 1,513, 1,430, 1,379,
1
676, 619 cm-1; H NMR (500 MHz, CDCl3): d = 7.27
(m, 3H), 6.95 (t, J = 7.3 Hz, 1H), 6.91 (d, J = 8.2 Hz,
2H), 6.15 (dt, J = 10.0, 6.0 Hz, 1H), 4.66 (dd, J = 6.1,
1.3 Hz, 2H), 4.20 (t, J = 6.0 Hz, 2H), 3.91 (t, J = 6.1 Hz,
2H), 1.87 (m, 4H), 1.60 (m, 4H) ppm; 13C NMR
(125 MHz, CDCl3): d = 192.1, 158.7, 129.9, 127.0,
126.8, 121.4, 115.1, 65.9, 56.1, 53.5, 28.3, 27.9, 27.0,
26.5 ppm.
(Z)-3-Phenoxyprop-1-en-1-yl pyrrolidine-1-carbodithioate
(3e, C14H17NOS2)
Isolated by column chromatography. Rf = 0.76 (EtOAc/
petroleum ether, 1:4); 1H NMR (500 MHz, CDCl3):
d = 7.36 (d, J = 10.0 Hz, 1H), 7.30 (t, 3H), 6.91–6.97
(m, 2H), 6.15 (d, J = 10.0 Hz, 1H), 4.67 (d, 2H), 3.90 (t,
2H), 3.70 (t, 2H), 2.10 (m, 2H), 2.00 (m, 2H) ppm; 13C
NMR (125 MHz, CDCl3): d = 188.5, 158.0, 129.0, 127.0,
126.5, 121.0, 115.0, 60.0, 55.7, 51.1, 26.2, 24.4 ppm.
(Z)-3-(Naphthalen-2-yloxy)prop-1-en-1-yl pyrrolidine-1-
carbodithioate (3i, C18H19NOS2)
Isolated by column chromatography. Rf = 0.41 (EtOAc/
petroleum ether, 1:4); 1H NMR (500 MHz, CDCl3):
d = 7.77 (m, 3H), 7.47 (m, 1H), 7.38 (m, 2H), 7.19 (m,
2H), 6.24 (dt, J = 10.0, 5.9 Hz, 1H), 4.81 (dd, J = 5.9,
1.2 Hz, 2H), 3.98 (t, J = 6.9 Hz, 2H), 3.72 (t, J = 6.9 Hz,
2H), 2.09 (m, 2H), 2.01 (m, 2H) ppm; 13C NMR
(125 MHz, CDCl3): d = 188.5, 156.6, 134.9, 129.9,
129.5, 128.0, 127.3, 126.8, 126.7, 124.2, 119.3, 107.4,
68.6, 55.5, 51.3, 26.4, 24.6 ppm.
(Z)-3-Phenoxyprop-1-en-1-yl azepane-1-carbodithioate
(3f, C14H19NOS2)
Isolated by column chromatography. Rf = 0.65 (EtOAc/
petroleum ether, 1:4); 1H NMR (500 MHz, CDCl3):
123

Transition metal-free addition of dithiocarbamates to alkynes
525
(Z)-3-(Naphthalen-2-yloxy)prop-1-en-1-yl
J = 7.0 Hz, 2H), 3.78 (q, J = 7.0 Hz, 2H), 1.34 (t,
J = 7.0 Hz, 3H), 1.29 (t, J = 7.0 Hz, 3H) ppm; 13C
NMR (125 MHz, CDCl3): d = 190.8, 161.8, 161.4, 156.1,
143.8, 129.3, 127.9, 125.5, 113.6, 113.3, 113.2, 102.2,
66.4, 50.2, 47.6, 13.1, 11.9 ppm.
diethylcarbamodithioate (3j, C18H21NOS2)
Isolated by column chromatography. Rf = 0.64 (EtOAc/
petroleum ether, 1:4); 1H NMR (500 MHz, CDCl3):
d = 7.73–7.77 (m, 3H), 7.47 (t, J = 7.1 Hz, 1H),
7.32–7.37 (m, 2H), 7.16–7.21 (m, 2H), 6.24 (dt,
J = 10.0, 5.9 Hz, 1H), 4.78 (dd, J = 4.7, 1.1 Hz, 2H),
4.02 (t, J = 7.0 Hz, 2H), 3.73 (t, J = 7.0 Hz, 2H),
1.27–1.32 (m, 6H) ppm; 13C NMR (125 MHz, CDCl3):
d = 191.3, 156.7, 134.9, 129.9, 129.5, 128.1, 127.3, 127.1,
126.9, 126.8, 124.2, 119.3, 107.5, 66.1, 50.1, 47.6, 13.2,
12.0 ppm.
(Z)-3-[(2-Oxo-2H-chromen-6-yl)oxy]prop-1-en-1-yl piper-
idine-1-carbodithioate (3o, C18H19NO3S2)
Isolated by column chromatography. Rf = 0.31 (EtOAc/
petroleum ether, 1:2); 1H NMR (500 MHz, CDCl3):
d = 7.67 (d, J = 10.0 Hz, 1H), 7.41 (s, 1H), 7.31 (m, 1H),
6.81–6.85 (m, 2H), 6.27 (m, 1H), 6.11 (dt, J = 10.0, 5.9 Hz,
1H), 4.70 (d, J = 5.2 Hz, 2H), 3.98 (t, J = 6.7 Hz, 2H), 3.76
(t, J = 6.7 Hz, 2H), 1.73 (m, 6H) ppm; 13C NMR (125 MHz,
CDCl3): d = 190.8, 161.8, 156.2, 143.7, 129.2, 127.7, 125.8,
113.6, 113.4, 102.5, 66.4, 60.7, 56.6, 24.6, 21.4, 14.6 ppm.
(Z)-3-(Naphthalen-2-yloxy)prop-1-en-1-yl piperidine-1-
carbodithioate (3k, C19H21NOS2)
Isolated by column chromatography. Rf = 0.58 (EtOAc/
petroleum ether, 1:4); 1H NMR (500 MHz, CDCl3):
d = 7.77–7.81 (m, 3H), 7.48 (m, 1H), 7.35–7.40 (m, 2H),
7.18–7.23 (m, 2H), 6.28 (dt, J = 11.7, 5.8 Hz, 1H), 4.83
(dd, J = 6.1, 1.5 Hz, 2H), 4.34 (m, 2H), 3.93 (m, 2H), 1.74
(m, 6H) ppm; 13C NMR (125 MHz, CDCl3): d = 191.4,
156.7, 134.9, 129.9, 129.5, 128.1, 127.4, 127.1, 126.8,
124.5, 119.3, 107.5, 66.0, 56.3, 53.2, 26.6, 25.9, 24.6 ppm.
(Z)-3-Hydroxyprop-1-en-1-yl pyrrolidine-1-carbodithioate
(3p, C8H13NOS2)
Isolated by column chromatography. Rf = 0.30 (EtOAc/
petroleum ether, 1:2); 1H NMR (500 MHz, CDCl3):
d = 6.97 (d, J = 9.8, 1H), 6.02 (m, 1H), 4.56 (m, 2H),
3.94 (t, J = 7.0 Hz, 2H), 3.69 (t, J = 7.0 Hz, 2H), 2.2 (m,
4H) ppm; 13C NMR (125 MHz, CDCl3): d = 192.1, 166.0,
124.7, 60.8, 55.0, 52.0, 25.1, 23.2 ppm.
(Z)-3-(Naphthalen-2-yloxy)prop-1-en-1-yl azepane-1-
carbodithioate (3l, C20H23NOS2)
(Z)-Prop-1-ene-1,3-diyl bis(piperidine-1-carbodithioate)
(3q, C15H24N2S4)
Isolated by column chromatography. Rf = 0.69 (EtOAc/
petroleum ether, 1:4); 1H NMR (500 MHz, CDCl3):
d = 7.72–7.77 (m, 3H), 7.43 (m, 1H), 7.30–7.35 (m, 2H),
7.13–7.17 (m, 2H), 6.22 (dt, J = 9.9, 5.8 Hz, 1H), 4.78 (m,
2H), 4.20 (t, J = 6.0 Hz, 2H), 3.91 (t, J = 6.0 Hz, 2H),
1.87–1.89 (m, 2H), 1.58–1.61 (m, 6H) ppm; 13C NMR
(125 MHz, CDCl3): d = 192.2, 156.7, 134.9, 129.9, 129.5,
128.0, 127.2, 126.8, 124.1, 119.3, 107.4, 66.0, 56.1, 53.5,
28.3, 27.9, 26.9, 26.5 ppm.
Isolated by column chromatography. Rf = 0.22 (EtOAc/
petroleum ether, 1:3); 1H NMR (500 MHz, CDCl3):
d = 6.07 (m, 1H), 5.65 (m, 1H), 4.51 (m, 2H), 4.06 (m,
4H), 3.87 (m, 4H), 1.67 (m, 12H) ppm; 13C NMR
(125 MHz, CDCl3): d = 195.3, 193.8, 137.5, 130.8, 59.6,
52.8, 44, 26.5, 25.8, 24.6, 24.5 ppm.
Acknowledgments We are grateful to the Research Council of
Sharif University of Technology for financial support.
(Z)-3-[(2-Oxo-2H-chromen-6-yl)oxy]prop-1-en-1-yl
diethylcarbamodithioate (3m, C17H17NO3S2)
Isolated by column chromatography. Rf = 0.72 (EtOAc/
petroleum ether, 1:4); 1H NMR (500 MHz, CDCl3):
d = 7.65 (d, J = 9.9 Hz, 1H), 7.38 (s, 1H), 7.40 (m,
1H), 6.83–6.87 (m, 2H), 6.27 (m, 1H), 6.12 (dt, J = 9.9,
5.9 Hz, 1H), 4.70 (d, J = 5.1 Hz, 2H), 3.98 (t, J = 6.8 Hz,
2H), 3.76 (t, J = 6.8 Hz, 2H), 2.15 (m, 2H), 2.04 (m, 2H)
ppm; 13C NMR (125 MHz, CDCl3): d = 188.0, 161.0,
156.0, 143.7, 129.2, 127.7, 125.4, 113.7, 113.4, 102.5,
66.4, 55.6, 51.4, 26.4, 24.6 ppm.
References
1. Sheldon RA (2005) Green Chem 7:267
2. Ranu BC, Saha A, Dey R (2010) Curr Opin Drug Discov Dev
13:658
3. Tanaka K (2003) Solvent-free organic synthesis. Wiley, Germany
4. Tanaka K, Toda F (2000) Chem Rev 100:1025
5. Nagendrappa G (2002) Resonance 7:59
6. Zhou F, Ding M, Zhou J (2012) Org Biomol Chem 10:3178
7. Palisse A, Kirsch SF (2012) Org Biomol Chem 10:8041
´
8. Thome I, Bolm C (2012) Org Lett 14:1892
(Z)-3-[(2-oxo-2H-chromen-7-yl)oxy]prop-1-en-1-yl
diethylcarbamodithioate (3n, C17H19NO3S2)
White solid isolated by recrystallization from ethanol.
9. Thorn GD, Ludwig RA (1962) The dithiocarbamates and related
compounds. Elsevier, Amsterdam
10. Saha A, Nasir Baig RB, Leazer J, Varma RS (2012) Chem
Commun 48:8889
11. Das P, Kumar CK, Kumar KN, Innus M, Iqbal J, Srinivas N
(2008) Tetrahedron Lett 49:992
12. Ziyaei-Halimehjani A, Marjani K, Ashouri A (2012) Tetrahedron
Lett 53:3490
1
M.p.: 115 °C; H NMR (500 MHz, CDCl3): d = 7.62 (d,
J = 9.4 Hz, 1H), 7.35 (d, J = 8.5 Hz, 1H), 7.30 (d,
J = 8.7 Hz, 1H), 6.82 (m, 2H), 6.23 (d, J = 9.4 Hz, 1H),
6.11 (m, 1H), 4.70 (dd, J = 5.9, 1.3 Hz, 2H), 4.04 (q,
123

526
F. Aryanasab, M. R. Saidi
13. Azizi N, Gholibeglo E, Dehghan Nayeri S (2012) Monatsh Chem
143:1171
30. Chin-Hsien W (1981) Synthesis 622
31. Walter W, Bode KD (1967) Angew Chem Int Ed 6:281
32. Azizi N, Aryanasab F, Saidi MR (2006) Org Lett 8:5275
33. Azizi N, Aryanasab F, Torkiyan L, Ziyaei A, Saidi MR (2006) J
Org Chem 71:3634
34. Azizi N, Ebrahimi F, Akbari E, Aryanasab F, Saidi MR (2007)
Synlett 2797
14. Greene TW, Wuts PGM (1999) Protecting groups in organic
synthesis, 3rd edn. Wiley Interscience, New York
15. Madalageri PM, Kotresh O (2012) J Chem Pharm Res 4:2697
16. Chauhan K, Sharma M, Singh P, Kumar V, Shukla PK, Siddiqi
MI, Chauhan PMS (2012) Med Chem Comm 3:1104
17. Qin Y, Liu S, Xing R, Yu H, Li K, Meng X, Li R, Li P (2012)
Carbohyd Polym 89:388
35. Azizi N, Pourhasan B, Aryanasab F, Saidi MR (2007) Synlett
1239
18. Hogarth G (2012) Mini-Rev Med Chem 12:1202
19. Tripathi RP, Khan AR, Setty BS, Bhaduri AP (1996) Acta Pharm
46:169
36. Aryanasab F, Ziyaei A, Saidi MR (2010) Tetrahedron Lett 51:790
37. Azizi N, Aryanasab F, Torkiyan L, Saidi MR (2011) Synth
Commun 41:94
20. Morf P, Raimondi F, Nothofer HG, Schnyder B, Yasuda A,
Wessels JM, Jung TA (2006) Langmuir 22:658
21. Almeida I, Ferreira VC, Montemor MF, Abrantes LM, Viana AS
(2012) Electrochim Acta 83:311
22. Marx Nirmal A, Pandian K, Sivakumar K (2011) Appl Surf Sci
257:2745
23. Nyamen LD, Rajasekhar Pullabhotla VSR, Nejo AA, Ndifon PT,
Warner JH, Revaprasadu N (2012) Dalton Trans 41:8297
24. Sun JQ, Shen XP, Chen KM, Liu Q, Liu W (2008) Solid State
Commun 147:501
25. Cvek B (2012) Mini-Rev Med Chem 12:1173
26. Ding Q, Lin Y, Ding G, Liao F, Sanga X, Peng Y (2013) Beilstein
J Org Chem 9:460
38. Galli R (1987) J Org Chem 52:5349
39. Grunnwell JR (1970) J Org Chem 35:1500
40. Giboreau P, Morin C (1994) J Org Chem 59:1205
41. Huang ZZ, Wu LL (1996) Synth Commun 26:509
42. Chen ZC, Jin YY, Stand PJ (1987) J Org Chem 52:4117
43. Clifford AM, Lichty JG (1932) J Am Chem Soc 54:1163
44. Yan J, Chen ZC (1999) Synth Commun 29:2867
45. Liu Y, Bao W (2007) Tetrahedron Lett 48:4785
46. Bhadra S, Saha A, Ranu BC (2008) Green Chem 10:1224
47. Chatterjee T, Bhadra S, Ranu BC (2011) Green Chem 13:1837
48. Ziyaei A, Aryanasab F, Saidi MR (2009) Tetrahedron Lett
50:1441
49. Azizi N, Aryanasab F, Saidi MR (2006) Org Biomol Chem
4:4275
50. Aryanasab F, Saidi MR (2008) Synth Commun 38:4036
51. Vogel AI, Tatchell AR, Furnis BS, Hannaford AJ, Smith PWG
(1996) Vogel’s textbook of practical organic chemistry, 5th edn.
Wiley, New York, p 986
27. Buac D, Schmitt S, Ventro G, Kona FR, Dou QP (2012) Mini-
Rev Med Chem 12:1193
28. Alam MdN, Mandal SK, Debnath SC (2012) Rubber Chem
Technol 85:120
29. Tilles H (1959) J Am Chem Soc 81:714
123