Dimer of 5-methyl-3-isoxazolyl isothiocyanate

Full text of DOI:10.1007/s10593-007-0230-7

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Chemistry of Heterocyclic Compounds, Vol. 43, No. 11, 2007
DIMER OF 5-METHYL-3-ISOXAZOLYL
ISOTHIOCYANATE
A. N. Proshin1, A. N. Pushin1, and M. V. Makarov2
Keywords: dimer, isoxazolyl isothiocyanate, thiadiazole, cyclization.
In a search for physiologically active compounds among 1,2,4-thiadiazole derivatives, we prepared
5-methyl-3-isoxazolyl isothiocyanate (1) by the reaction of 3-amino-5-methylisoxazole with thiophosgene. The
structure of the product was supported by the preparation of products of its reactions with amines and established
using the 1H and 13C NMR spectral data.
At room temperature, isothiocyanate 1 gradually crystallizes to give 2, which is the product of a [4+2]
cycloaddition:
N
N
C
C
S
S
S
N
Me
+
Me
Me
N
N
N
N
O
O
O
Me
1
S
N
O
2
An NMR and X-ray diffraction structure investigation supported the structure assigned for the dimer of
5-methyl-3-isoxazolyl isothiocyanate 2.
Dimer 2 monomerizes in CDCl3 solution. Spectra of both the monomer and dimer were found in the
1H NMR spectra. Eventually, we obtained the hydrolysis products.
Molecular structure of 2
__________________________________________________________________________________________
1Institute of Physiologically Active Compounds, Russian Academy of Sciences, Chernogolovka 142432,
Moscow Region, Russia; e-mail: proshin@ipac.ac.ru. 2A. N. Nesmeyanov Institute of Organoelement
Compounds, Russian Academy of Sciences, 119991 Moscow, Russia. Translated from Khimiya
Geterotsiklicheskikh Soedinenii, No. 11, pp. 1738-1739, November, 2007. Original article submitted
May 31, 2007.
0009-3122/07/4311-1483©2007 Springer Science+Business Media, Inc.
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The H and 13C NMR spectra were taken on a Bruker DPX-200 spectrometer at 200 and 50 MHz,
respectively, in CDCl3 with TMS as the internal standard.
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The H and 13C NMR spectra were taken on a Bruker DPX-200 spectrometer at 200 and 50 MHz,
respectively, in CDCl3 with TMS as the internal standard.
5-Methylisoxazolyl 3-isothiocyanate (1). A solution of 3-amino-5-methylisoxazole (49.05 g, 0.5 mol)
in methylene chloride (300 ml) was added dropwise to a rapidly stirred solution of a mixture thiophosgene
(42.2 ml, 0.55 mol) and sodium bicarbonate (92.4 g, 1.1 mol) in water (200 ml) cooled to 0°C over 1 h. The
reaction mixture was stirred for an additional 30 min. The organic phase was removed, washed with two 100-ml
portions of saturated aqueous sodium chloride, dried over sodium sulfate, and evaporated. The oil obtained was
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distilled, taking the fraction at 39-41°C (1 mm Hg) to give 36.8 g (53%). H NMR spectrum, δ, ppm (J, Hz):
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6.00 (1H, q, J = 0.8, H-4); 2.50 (3H, d, J = 0.8, CH3). C NMR spectrum, δ, ppm: 172.9 (C-5); 153.1 (C-3);
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145.4 (NCS); 100.1 (C-4); 13.2 (CH3). The signals were assigned relative to proton-coupled C NMR spectra.
Found, %: C 42.61; H 2.53; N 20.21. C5H4N2OS. Calculated, %: C 42.85; H 2.88; N 19.99.
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Dimer of 5-methylisoxazolyl 3-isothiocyanate (2). H NMR spectrum, δ, ppm (J, Hz): 6.25 (1H, q,
J = 0.8, CH); 6.15 (1H, q, J = 0.8, CH); 2.70 (3H, d, J = 0.8, CH3); 2.60 (3H, d, J = 0.8, CH3). Found, %:
C 42.44; H 2.49; N 20.13. C10H8N4O2S2. Calculated, %r: 42.85; H 2.88; N 19.99.
The synthesis of 5-(disubstituted amino)-3-(2-oxopropyl)[1,2,4]thiadiazoles starting from our new
product, 5-methyl-3-isoxazolyl isothiocyanate will be the subject of a separate communication.
This work was carried out with the financial support of grant of Department of Chemistry and Material
Sciences, Russian Academy of Sciences.
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