Stannous chloride-promoted synthesis of S-allyl-N-aryl dithiocarbamates under solvent-free conditions

Article abstract of DOI:10.1080/00397911003611778

A highly efficient method of synthesis of S-allyl-N-aryl dithiocarbamates using SnCl2 as a catalyst under solvent-free conditions is described. The mild reaction conditions, high yields, and shorter reaction period illustrate the good synthetic utility of

Full text of DOI:10.1080/00397911003611778

This article was downloaded by: [171.67.34.69]
On: 24 March 2013, At: 23:52
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Synthetic Communications: An
International Journal for Rapid
Communication of Synthetic Organic
Chemistry
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/lsyc20
Stannous Chloride–Promoted Synthesis
of S-Allyl-N-aryl Dithiocarbamates under
Solvent-Free Conditions
Okram Mukherjee Singh a & Nepram Sushuma Devi a
a Department of Chemistry, Manipur University, Canchipur, Manipur,
India
Version of record first published: 02 Feb 2011.
To cite this article: Okram Mukherjee Singh & Nepram Sushuma Devi (2011): Stannous
Chloride–Promoted Synthesis of S-Allyl-N-aryl Dithiocarbamates under Solvent-Free Conditions,
Synthetic Communications: An International Journal for Rapid Communication of Synthetic Organic
Chemistry, 41:4, 516-522
To link to this article: http://dx.doi.org/10.1080/00397911003611778
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation
that the contents will be complete or accurate or up to date. The accuracy of any
instructions, formulae, and drug doses should be independently verified with primary
sources. The publisher shall not be liable for any loss, actions, claims, proceedings,
demand, or costs or damages whatsoever or howsoever caused arising directly or
indirectly in connection with or arising out of the use of this material.

Synthetic Communications1, 41: 516–522, 2011
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911003611778
STANNOUS CHLORIDE–PROMOTED SYNTHESIS OF
S-ALLYL-N-ARYL DITHIOCARBAMATES UNDER
SOLVENT-FREE CONDITIONS
Okram Mukherjee Singh and Nepram Sushuma Devi
Department of Chemistry, Manipur University, Canchipur, Manipur, India
Abstract A highly efficient method of synthesis of S-allyl-N-aryl dithiocarbamates using
SnCl2 as a catalyst under solvent-free conditions is described. The mild reaction conditions,
high yields, and shorter reaction period illustrate the good synthetic utility of this method.
Keywords Allyl; N-aryl dithiocarbamate; SnCl2; solvent-free
INTRODUCTION
Organic dithiocarbamates (dithiourethanes) are biologically important
compounds.[1] They are also considered as valuable synthetic intermediates.[2] Because
of the ability of dithiocarbamates to chelate with different metal ions, many of the
dithiocarbamates have found applications in inorganic analysis.[3] A number of these
dithiocarbamates have been used in the rubber industry as vulcanization accelera-
tors.[4] Their applications in the field of agriculture are unlimited.[5] They also possess
powerful fungicidal properties.[6] It is therefore of utmost importance that the
synthesis of dithiocarbamates should be achieved by a simple and effective method.
Several methods for the synthesis of dithiocarbamate have been reported in the
literature, and among them, condensation of primary and secondary amines with
costly and toxic reagents, such as thiophosgene and isothiocyanate, constitute the
most widely used general methods for the synthesis of this class of compounds.[7]
Direct thiocarboxylation of amines with carbon monoxide and sulfur to form urea
derivatives has also been reported.[8] Recently, a one-pot reaction of amines with
carbonyl sulfide, alkyl halide, or a,b-unsaturated compounds also has been
developed.[9] However, these reactions require very toxic reagents and harmful
Received August 20, 2009.
Address correspondence to Okram Mukherjee Singh, Department of Chemistry, Manipur
University, Canchipur 795003, Manipur, India. E-mail: ok_mukherjee@yahoo.co.in
516

S-ALLYL-N-ARYL DITHIOCARBAMATES
517
Scheme 1. One-pot, three-component synthesis of S-allyl-N-aryl-dithiocarbamate 2a.
organic solvents such as dimethylformamide (DMF), dimethylsulfoxide (DMSO),
and methanol in the presence of catalyst.
With the increasing interest in developing environmentally benign reactions,
organic transformations under solvent-free conditions are ideal processes in organic
chemistry. We now report an efficient, novel, and green procedure for the synthesis
of sulfur allylated N-aryl dithiocarbamates under solvent-free conditions using
SnCl2 ꢀ 2H2O as the catalyst. The methodology represents a one pot, three-
component, solvent-free, green synthetic protocol.
Initially, we examined the three-component reaction using aniline (6 mmol),
CS2 (6 mmol), and allylbromide (3 mmol) with SnCl2 ꢀ 2H2O (0.01 mmol) as catalyst
under solvent-free conditions, which afforded the S-allylated dithiocarbamate 2a in
93% yield (Scheme 1).
Next, we evaluated the scope of this catalytic system by employing a wide
range of metal salts. The reaction of aniline, CS2, and allylbromide was carried
out as a template using different salts as catalysts. The yields of products under
different catalysts are summarized in Table 1. The best yield was obtained using
SnCl2 ꢀ 2H2O, and duration of the reaction was only 20 min, whereas in the other
catalytic systems the duration for completion was in the range of 3–5 h to get the
maximum yield (Table 1).
Thus, we optimized the reaction using SnCl2 ꢀ 2H2O (0.01 mmol) as the catalyst
and stirring the reaction mixture at room temperature for 20 min only. The gener-
ality of the present method was extended to different substituted aromatic amines
Table 1. Synthesis S-allyl-N-phenyl dithiocarbamate using different catalystsa
Entry
Catalyst
Time
Yield (%)
1
2
3
4
5
SnCl2
CuCl2
FeCl3
ZnCl2
AlCl3
20 min
3 h
4 h
93
80
81
70
75
6 h
5 h
aReaction conditions: solvent-free, aniline (6 mmol), CS2 (6 mmol), allyl bromide (3 mmol), and catalyst
(0.01 mmol).

518
O. M. SINGH AND N. S. DEVI
Table 2. Stannous chloride–promoted allylated dithiocarbamatesa
Entry
R1
R2
R3
R4
Product
Yield (%)b
Mp (ꢁC)
1
2
3
4
5
6
7
8
9
H
CH3
C2H5
Cl
H
H
H
CH3
C2H5
CH3
H
H
H
2a
2b
2c
2d
2e
2f
93
92
95
89
91
94
95
93
91
185
157
145
163
201
115
215
135
115
H
H
H
H
Cl
C2H5
Cl
CH3
H
H
H
H
H
H
H
2g
2h
2i
CH3
C2H5
H
CH3
C2H5
CH3
CH3
H
aReaction conditions: solvent-free, aniline (6 mmol), CS2 (6 mmol), allyl=crotyl bromide (3 mmol), and
catalyst (0.01 mmol).
bIsolated yields.
and substituted allyl bromide. As can be seen from Table 2, various substituted
anilines, CS2, and allyl=crotyl bromide were treated under the solvent-free, multi-
component reactions to yield the corresponding S-allyl-N-aryl dithiocarbamates
2a–i in good to excellent yields.
In summary, we have described a novel, highly efficient, and entirely green
protocol for one-pot preparation of S-allyl-N-aryl dithiocarbamates catalyzed by
stannous chloride under solvent-free conditions. The shorter reaction time and good
to excellent yield of the desired products are the advantages of this synthetic protocol.
EXPERIMENTAL
Melting points are uncorrected and were determined in capillary tubes on an
1
apparatus containing silicon oil. H and 13C NMR spectra were recorded on a
Bruker instrument (AC 300 MHz) in CDCl3 using tetramethylsilane (TMS) as an
internal standard. Fourier transform–infrared (FT-IR) spectra were recorded on a
Mattson instrument, model Shimadzu IR-408. The microanalyses were performed
on a Perkin-Elmer 240B elemental analyzer. Chromatography was performed
on SiO2. The mass spectra were recorded on a Jeol JMSD-300 spectrometer.
General Experimental Procedure for the Preparation of
Compound 2a–i
To a mixture of CS2 (8 mmol) and allyl=crotyl bromide (6 mmol), an aromatic
amine (5 mmol) was added in the presence of a catalytic amount of SnCl2 ꢀ 2H2O

S-ALLYL-N-ARYL DITHIOCARBAMATES
519
(0.5 mmol). The reaction mixture was stirred at room temperature under vigorous
magnetic stirring for 10–30 min. Then the organic materials were extracted with
chloroform or ethyl acetate (2 ꢂ 10 mL). The combined organic phases were washed
with water and dried over anhydrous sodium sulfate. The solvent was evaporated,
and white crystals of allylated dithiocarbamates were found at the bottom of the
flask. Analytically pure products could be obtained by simple crystallization using
either diethyl ether or ethylacetate, and thus column chromatography was not
required.
CHARACTERIZATION DATA
S-Allyl-N-phenyl Dithiocarbamate (2a)
1
Mp 185 ꢁC; IR (KBr) (n max): 1235, 1600, 3137 cmꢃ1, H NMR (DMSO-d6,
300 MHz) d 3.91–3.93 (d, J ¼ 6.2 Hz, 2H), 5.03, 5.12 (m, 2H), 5.96–6.01 (m, 1H),
6.79–7.01 (m, 5H); 13C NMR (DMSO-d6, 75.5 MHz) 51.7, 124.3, 126.1, 128.3,
129.1, 133.1, 139.3, 199.9; MS: m=z ¼ 209 (Mþ). Anal. calcd. for C10H11NS2: C,
57.38; H, 5.30; N, 6.69. Found: C, 57.37; H, 5.33; N, 6.67.
S-Allyl-N-(2,6-dimethylphenyl)dithiocarbamate (2b)
Mp 157 ꢁC; IR (KBr) (n max): 1237, 1569, 3137 cmꢃ1 1H NMR (CDCl3,
;
300 MHz) d 2.63 (s, 6H), 4.14–4.15 (d, J ¼ 6 Hz, 2H), 5.31–5.33 (m, 2H), 6.05–6.15
(m, 1H), 7.08–7.10 (d, J ¼ 5.4 Hz, 2H), 7.18–7.22 (m, 1H); 13C NMR (CDCl3,
75.5 MHz) 19.4, 51.9, 124.5, 126.2, 128.6, 129.3, 131.2, 132.1, 199.5; MS: m=z ¼
237 (Mþ). Anal. calcd. for C12H15NS2: C, 60.72; H, 6.37; N, 5.90. Found: C, 60.71;
H, 6.39; N, 5.89.
S-Allyl-N-(2,6-diethylphenyl)dithiocarbamate (2c)
Mp 145 ꢁC; IR (KBr) (n max): 1276, 1573, 3145 cmꢃ1 1H NMR (CDCl3,
;
300 MHz) d 1.31–1.35 (t, J ¼ 9 Hz, 6H), 3.01–3.03 (d, J ¼ 6 Hz, 4H), 4.14–4.16
(d, J ¼ 5.4 Hz, 2H), 5.27–5.29 (d, J ¼ 5.4 Hz, 2H), 6.04–6.13 (m, 1H), 7.18–7.20
(d, J ¼ 5.4 Hz, 2H), 7.31–7.35 (m, 1H), 10.38 (1H, br, NH); 13C NMR (CDCl3,
75.5 MHz) 15.5, 24.8, 53.9, 125.17, 126.75, 127.77, 129.6, 130.0, 138.5, 199.7; MS:
m=z ¼ 265 (Mþ). Anal. calcd. for C14H19NS2: C, 63.35; H, 7.21; N, 5.28. Found:
C, 63.51; H, 7.19; N, 5.29.
S-Allyl-N-(2-chloro-6-methylphenyl)dithiocarbamate (2d)
Mp 163 ꢁC; IR (KBr) (n max): 1275, 1579, 3147 cmꢃ1 1H NMR (CDCl3,
;
300 MHz) d 2.61 (s, 3H), 4.11–4.15 (d, J ¼ 5.4 Hz, 2H), 5.33–5.35 (m, 2H),
6.01–6.13 (m, 1H), 7.29–7.7.39 (m, 3H); 13C NMR (CDCl3, 75.5 MHz) 19.1, 51.5,
124.1, 126.5, 128.9, 129.1, 131.7, 132.3, 140.7, 199.9; MS: m=z ¼ 257 (Mþ). Anal.
calcd. for C11H12NS2Cl: C, 51.25; H, 4.69; N, 5.43. Found: C, 51.51; H, 4.19; N, 5.45.

520
O. M. SINGH AND N. S. DEVI
S-Allyl-N-(2-chloro-3-methylphenyl)dithiocarbamate (2e)
1
Mp 201 ꢁC; IR (KBr) (n max): 1273, 1587, 3149 cmꢃ1; H NMR (DMSO,
300 MHz) d 2.63 (s, 3H), 4.10–4.23 (d, J ¼ 5.4 Hz, 2H), 5.29–5.33 (m, 2H),
6.09–6.15 (m, 1H), 7.19–7.27 (m, 3H); 13CNMR (DMSO-d6, 75.5 MHz) 19.7,
51.3, 124.5, 126.7, 128.3, 129.1, 131.9, 133.1, 140.9, 199.7; MS: m=z ¼ 257 (Mþ).
Anal. calcd. for C11H12NS2Cl: C, 51.25; H, 4.69; N, 5.43. Found: C, 51.33; H,
4.59; N, 5.47.
S-Allyl-N-(2-ethylphenyl)dithiocarbamate (2f)
Mp 115 ꢁC; IR (KBr) (n max): 1275, 1589, 3149 cmꢃ1 1H NMR (CDCl3,
;
300 MHz) d 1.31–133 (t, J ¼ 9 Hz, 3H), 3.03–3.05 (q, 2H), 4.11–4.14 (d, J ¼ 5.4 Hz,
2H), 5.59–6.13 (m, 2H), 6.07–6.11 (m, 1H), 7.29–7.37 (m, 4H); 13C NMR (CDCl3,
75.5 MHz) 15.5, 24.9, 51.5, 125.17, 126.75, 127.77, 129.6, 130.0, 133.1, 136.1,
138.5, 199.7; MS: m=z ¼ 237 (Mþ). Anal. calcd. for C12H15NS2: C, 60.72; H, 6.37;
N, 5.90. Found: C, 60.51; H, 6.19; N, 5.99.
S-Allyl-N-(2-chlorophenyl)dithiocarbamate (2g)
1
Mp 215 ꢁC; IR (KBr) (n max): 1279, 1587, 3147 cmꢃ1; H NMR (DMSO-d6,
300 MHz) d 4.14–4.16 (d, J ¼ 5.4 Hz, 2H), 5.27–5.29 (d, J ¼ 5.4 Hz, 2H), 6.04–6.13
(m, 1H), 7.18–7.25 (m, 4H), 10.38 (1H, br, NH); 13C NMR (DMSO-d6,
75.5 MHz) 53.9, 125.1, 126.7, 127.2, 127.9 129.6, 130.0, 136.3, 138.5, 199.9; MS:
m=z ¼ 243 (Mþ). Anal. calcd. for C10H10NS2Cl: C, 49.27; H, 4.13; N, 5.75. Found:
C, 49.31; H, 4.19; N, 5.79.
But-3-en-2-yl-(2,6-dimethylphenyl)dithiocarbamate (2h)
Mp 135 ꢁC; IR (KBr) (n max): 1275, 1589, 3145 cmꢃ1 1H NMR (CDCl3,
;
300 MHz) d 1.62–1.63 (d, J ¼ 4.2 Hz, 3H), 2.64–2.68 (s, 6H), 4.07–4.09 (d, J ¼ 5.1 Hz,
2H), 5.03–5.12 (m, 1H), 5.65–5.80 (m, 1H), 7.07–7.09 (d, J ¼ 5.7 Hz, 2H), 7.17–7.27
(m, 1H); 13C NMR (CDCl3, 75.5 MHz) 17.8, 19.8, 52.1, 119.5, 129.2, 129.9, 131.8,
132.9, 137.5, 199.7; MS: m=z ¼ 251 (Mþ). Anal. calcd. for C13H17NS2: C, 62.11;
H, 6.82; N, 5.57. Found: C, 62.51; H, 6.79; N, 5.59.
But-3-en-2-yl-(2,6-diethylphenyl)dithiocarbamate (2i)
Mp 115 ꢁC; IR (KBr) (n max): 1269, 1591, 3153 cmꢃ1 1H NMR (CDCl3,
;
300 MHz) d 1.31–1.35 (t, J ¼ 7.5 Hz, 6H), 1.61–1.63 (d, J ¼ 4.2 Hz, 3H), 3.01–3.03
(d, J ¼ 6 Hz, 4H), 4.14–4.16 (m, 1H), 5.27–5.29 (m, 2H), 6.04–6.13 (m, 1H),
7.18–7.20 (d, J ¼ 5.4 Hz, 2H), 7.31–7.35 (m, 1H), 10.38 (1H, br, NH); 13C NMR
(CDCl3, 75.5 MHz) 17.5, 19.3, 24.8, 53.9, 119.5, 129.5, 129.9, 131.7, 132.9, 137.9,
199.7; MS: m=z ¼ 279 (Mþ). Anal. calcd. for C15H21NS2: C, 64.47; H, 7.57; N,
5.01. Found: C, 64.51; H, 7.59; N, 5.09.

S-ALLYL-N-ARYL DITHIOCARBAMATES
521
ACKNOWLEDGMENTS
O. M. S. is thankful to the Council of Scientific and Industrial Research
(Project No. 01(2387)=10=EMR-II) for financial assistance. We also thank Sophisti-
cated Analytical Instrument Facility (SAIF), Central Drug Research Institute,
Lucknow, and SAIF, North Eastern Hill University, Shillong, for the spectral
recordings.
REFERENCES
1. (a) Dhooghe, M.; De Kime, N. Synthetic approaches towards 2-iminothiazolidine: An
overview. Tetrahedron 2006, 62, 513–535; (b) Fernandez, J. M. G.; Mellet, C. O.; Blanco,
J. L. J.; Mota, J. F.; Gadelle, A.; Coste-Sarguet, A.; Defaye, J. Isothiocyanates and cyclic
thiocarbamates of a,a0-trehalose, sucrose, and cyclomaltooligosaccharides. Carbohydr. Res.
1995, 268, 57–71.
2. (a) Boas, U.; Jakobsen, M. H. A new synthesis of aliphatic isothiocyanates from primary
amines, convenient for in situ use. J. Chem. Soc., Chem. Commun. 1995, 1995–1996; (b)
Elgemeie, G. H.; Sayed, S. H. Synthesis and chemistry of dithiols. Synthesis 2001, 1747–
1772; (c) Mukherjee, A. K.; Ashare, R. Isothiocyanates in the chemistry of heterocycles.
Chem. Rev. 1991, 91, 1–24; (d) Boas, U.; Gertz, H.; Christensen, J. B.; Heegaard, P. M. H.
Facile synthesis of aliphatic isothiocyanates and thioureas on solid phase using peptide
coupling reagents. Tetrahedron Lett. 2004, 45, 269–272.
3. Delepine, M. Sulphur and nitrogen compounds derived from carbon disulphide, XII:
Metallic thiosulfocarbamates. Bull. Soc. Chim. France 1908, 4(3), 643.
4. (a) Nieuwenhuizen, P. J.; Ethlers, A. W.; Haasnoot, J. G.; Janse, S. R.; Reedijk, J.;
Baerends, E. J. The mechanism of zinc(II)-dithiocarbamate-accelerated vulcanization
uncovered: Theoretical and experimental evidence. J. Am. Chem. Soc. 1999, 121, 163–168;
(b) Thorn, G. D.; Ludwig, R. A. The Dithiocarbamates and Related Compounds; Elsevier:
Amsterdam, 1962.
5. (a) Mizuno, T.; Nishiguchi, I.; Okushi, T.; Hirashima, T. Facile synthesis of S-alkyl thiocar-
bamates through reaction of carbamoyl lithium with elemental sulphur. Tetrahedron Lett.
1991, 32, 6867–6868; (b) Chen, Y. S.; Schuphan, I.; Casida, J. E. S-Chloroallyl thiocarbamate
herbicides: Mouse hepatic microsomal oxygenase and rat metabolism of cis- and trans-
[14C:O]. J. Agric. Food Chem. 1979, 27, 709–712; (c) Rafin, C.; Veignie, E.; Sancholle, M.;
Postal, D.; Len, C.; Villa, P.; Ronco, G. Synthesis and antifungal activity of novel bisdithio-
carbamate derivatives of carbohydrates against Fusarium oxysporum f. sp. lini. J. Agric. Food
Chem. 2000, 48, 5283–5290; (d) Len, C.; Postal, D.; Ronco, G.; Villa, P.; Goubert, C.;
Jeufrault, E.; Mathon, B.; Simon, H. Synthesis of carbamic esters derivatives of itols:
Antifungal activity against various crop diseases. J. Agric. Food Chem. 1997, 45, 3–10.
6. Tisdale, W. H.; Williams, I. Disinfectant fungicides. U.S. Patent 197296, Sept. 1943.
7. (a) Tilles, H. Thiolcarbamates: Preparation and molar refractions. J. Am. Chem. Soc.
1959, 81, 714–727; (b) Chin-Hsien, W. Phase-transfer-catalysed preparation of S-alkyl thio-
carbamates. Synthesis 1981, 622–623; (c) L’abbe, G.; Leurs, S. Synthesis of fused
1,2,4-thiadiazolines by intramolecular cycloaddition–elimination reactions of 4-methyl-5-
(cyano tethered)imino-D2-1,2,3,4-thiatriazolines. Tetrahedron 1992, 48, 7505–7518.
8. (a) Franz, R. A.; Applegath, F. A new urea synthesis. I: The reaction of ammonia, carbon
monoxide, and sulfur. J. Org. Chem. 1961, 26, 3304–3306; (b) Franz, R. A.; Applegath, F.;
Morriss, F. V.; Baiocchi, F. A new synthesis of ureas, II: The reaction of primary aliphatic
amines with carbon monoxide and sulfur. J. Org. Chem. 1961, 26, 3306–3308.

522
O. M. SINGH AND N. S. DEVI
9. (a) Salvatore, R. N.; Sahab, S.; Jung, K. W. Mild and efficient synthesis of thiocarbonates
and thiocarbamates via a three-component coupling utilizing Cs2CO3 and TBAI. Tetra-
hedron Lett. 2001, 42, 2055–2058; (b) Buess, C. M. The reaction of dithiocarbamates
with acrylamide. J. Am. Chem. Soc. 1955, 77, 6613–6615; (c) Guo, B.; Ge, Z.; Chang, T.;
Li, R. Conjugated addition reaction of amine, carbon disulfide to electrophilic alkenes in
the presence of anhydrous potassium phosphate. Synth. Commun. 2001, 31, 3021–3025;
(d) Ziyaei-Halimjani, A.; Saidi, M. R. An efficient one-pot Michael addition of dithiocar-
bamate anion to a,b-unsaturated olefins mediated by lithium perchlorate. J. Sulfur Chem.
2005, 26, 149–153; (e) Busque, F.; March, P.-D.; Figueredo, M.; Font, J.; Gonzalez, L. A
study of the conjugate addition of thionucleophiles to 2(5H)-Furanones. Eur. J. Org. Chem.
2004, 1492–1499.