Vol. 31, No. 7 (2019)
Triton-B Catalyzed One Pot Multicomponent Synthesis of Isothiocyanates in Non-Aqueous Medium 1637
Several solvents like dimethyl sulphoxide, N,N-dimethyl
formamide, benzene, acetonitrile, dichloromethane, hexane,
heptanes, methanol, chloroform and acetone were examined
and found that dimethyl sulphoxide (DMSO) proved to be the
R = C6H5 (
C5H4N (
1
); C2H4Cl (
2
); C7H7 (
3
7
); C6H4NO2 (
4);
most suitable solvent for carrying out the transformation.
5); C6H11 ); C7H5O (
(6
); C6H4F ( );
8
Conclusion
Scheme-I: Synthesis of isothiocyantaes from corresponding amines
(reagents and conditions DMSO (anhyd.), Triton-B, CS2,
2-4 h)
In conclusion, a convenient and efficient protocol is developed
for the one pot two component coupling of a range of primary,
secondary and tertiary range amines via combination of Triton-
B and carbon disulphide. This reaction generates correspon-
ding isothiocyanates in excellent yields (80-99 %) at the room
temperature. Furthermore, this method offers substrate versatility,
good selectivity, high yields, high efficiency, excellent func-
tional group compatibility, operational simplicity, inexpensive
catalyst, easily available reagents and mild reaction conditions.
1
The synthesized trithiocarbonates was subjected to H
NMR, 13C NMR and mass spectroscopy for structure eluci-
dation. The novel one pot synthesis yields good to excellent
amount of isothiocyanates, both cyclic and acyclic substituent
at room temperature.
Isothiocyanatobenzene (1): Yield: 96 %; yellow oily
liquid. 1H NMR (CDCl3): δ 7.37-7.33 (m, 2H), 7.30-7.27 (m,
1H), 7.23-7.21 (m, 2H); MS (m/z): 135. Anal. calcd. (found)
% for C7H5NS: C, 62.19; H, 3.73; N, 10.36; S, 23.72.
1-Chloro-2-isothiocyanatoethane (2): Yield: 94 %;
yellow oily liquid. 1H NMR (CDCl3): δ 3.830 (t, J = 6.0 Hz,
2H), 3.69 (t, J = 6.0 Hz, 2H); MS (m/z): 121.5. Anal. calcd.
(found) % for C3H4NSCl: C, 29.63; H, 3.32; Cl, 29.16; N,
11.52; S, 26.37.
Isothiocyanatomethylbenzene (3):Yield: 97 %; yellow
oily liquid. 1H NMR (CDCl3): δ 7.42-7.31 (m, 5H), 4.72 (s,
2H); MS (m/z):149.Anal. calcd. (found) % for C8H7NS: C, 64.39;
H, 4.73; N, 9.39; S, 21.49.
ACKNOWLEDGEMENTS
The authors acknowledge Dr. Devdutt Chaturvedi from
Mahatma Gandhi Central university, Motihari, India for his
guidance and support.
CONFLICT OF INTEREST
The authors declare that there is no conflict of interests
regarding the publication of this article.
REFERENCES
1-Isothiocyanato-4-nitrobenzene (4):Yield: 94 %; yellow
oily liquid. 1H NMR (CDCl3): δ 8.26-8.22 (m, 2H), 7.36-7.33
(m, 2H); MS (m/z): 180.Anal. calcd. (found) % for C7H4N2O2S:
C, 46.66; H, 2.24; N, 15.55; O, 17.76; S, 17.80.
3-Isothiocyanatopyridine (5): Yield: 97 %; yellow oily
liquid. 1H NMR (CDCl3): δ 8.53 (s, 1H), 8.49 (d, J = 6.0 Hz,
1H), 7.52-7.49 (m, 1H), 7.31-3.28 (m, 1H); MS (m/z): 138.
Anal. calcd. (found) % for C6H4N2S: C, 52.92; H, 2.96; N, 20.57;
S, 23.55.
1. V. Dufour, B. Alazzam, G. Ermel, M. Thepaut, A. Rossero, O. Tresse
and C. Baysse, Front. Cell. Infect. Microbiol., 2, 53 (2012);
2. G.A. Carter, J.L. Garraway, D.M. Spencer and R.L.Wain, Ann. Appl. Biol.,
51, 135 (1963);
3. G.H. Posner, C.-G. Cho, J.V. Green, Y. Zhang and P. Talalay, J. Med.
Chem., 37, 170 (1994);
4. J.T. Arnold, B.P. Wilkinson, S. Sharma and V.E. Steele, Cancer Res.,
55, 537 (1995).
Isothiocyanatocyclohexane (6):Yield: 95 %; yellow oily
liquid. 1H NMR (CDCl3): δ 3.71-3.66 (m, 1H), 1.89-1.87 (m,
2H), 1.75-1.61 (m, 4H), 1.54-1.42 (m, 1H), 1.40-1.37 (m, 3H);
MS (m/z): 141. Anal. calcd. (found) % for C7H11NS: C, 59.53;
H, 7.85; N, 9.92; S, 22.70.
5. A.M. Pintao, M.S. Pais, H. Coley, L.R. Kelland and I.R. Judson, Planta
Med., 61, 233 (1995);
6. S. Adsule, S. Banerjee, F. Ahmed, S. Padhye and F.H. Sarkar, Bioorg.
Med. Chem. Lett., 20, 1247 (2010);
7. C. Nastruzzi, R. Cortesi, E. Esposito, E. Menegatti, O. Leoni, R. Iori,
and S. Palmieri, J. Agric. Food Chem., 48, 3572 (2000);
8. G. Bian, W. Shan and W. Su, Chem. Res. Synop., 2005, 585 (2005);
9. X. Zhang, N. Neamati, Y. Lee, A. Orr, R.D. Brown, N. Whitaker, Y.
Pommier and T.R. Burke Jr., Bioorg. Med. Chem., 9, 1649 (2001);
10. S. Heckl, A. Sturzu, M. Regenbogen, A. Beck, G. Feil, A. Gharabaghi
and H. Echner, Med. Chem., 4, 348 (2008);
Benzoyl isothiocyanate (7): Yield: 94 %; yellow oily
liquid. 1H NMR (CDCl3): δ 7.89-7.82 (m,1H), 7.81-7.83 (m,
1H), 7.63-7.57 (m, 1H), 7.55-7.51 (m, 1H), 7.49-7.46 (m, 1H);
MS (m/z): 163. Anal. calcd. (found) % for C8H5NOS: C, 58.88;
H, 3.09; N, 8.58; O, 9.80; S, 19.65.
1-Fluoro-2-isothiocyanatobenzene (8):Yield: 97 %; yellow
oily liquid. 1H NMR (CDCl3): δ 7.24-7.219 (m,1H), 7.20-7.19
(m, 1H), 7.18-7.16 (m, 1H), 7.14-7.10 (m, 2H); MS (m/z): 153.
Anal. calcd. (found) % for C7H4NSF: C, 54.89; H, 2.63; F, 12.40;
N, 9.14; S, 20.93.
11. S. Dong and M. Roman, J. Am. Chem. Soc., 129, 13810 (2007);
12. H.-G. Lerchen, J. Baumgarten, N. Piel and V. Kolb-Bachofen, Angew.
Chem. Int. Ed., 38, 3680 (1999);
RESULTS AND DISCUSSION
13. G. Sommen, Synlett, 7, 1323 (2004);
14. A.K. Ghosh, G. Bilcer and G. Schiltz, Synthesis, 2203 (2001);
The synthesis of isothiocyanates is afforded by reacting
primary, secondary and tertiary amines in DMSO in carbon
disulphide environment in presence of Triton-B, a phase transfer
catalyst at room temperature for 2-4 h to afford trithiocarbo-
nates in a very good to excellent yields (80-99 %).