Br
Br
Ac2O
S
N
S
N
Me
Me
S
S
5
6
The structure of the obtained compound 3 was confirmed by comparative analysis of the 13C NMR
spectral data for the following compounds: compound 3, 3-methyl-1,3-thiazine-2-thione 5, 3-methyl-1,3-
thiazolidine-2-thione 6, and 3-acetyl-1,3-thiazolidine-2-thione (7) [3]. We established that for these compounds,
the chemical shift of the C(2) atom is found in the ~200 ppm region, which is typical of substances containing the
thione group [4]. Furthermore, in the proton-coupled 13C NMR spectra for compounds 3, 6, and 7, we observe a
spin–spin coupling constant of 3J(C(7)–H-4) = 0.7±0.2 Hz, which also suggests acetylation at the nitrogen atom.
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The C NMR spectra were recorded on a Burker CXP-200 spectrometer (50 MHz) in a 1:4 DMSO-d6–
CCl4 mixture, internal standard TMS.
3-Acetyl-5-bromomethyl-1,3-thiazolidine-2-thione (3). A. 5-Bromomethylthiazolidine-2-thione 2
(0.2 g, 0.01 mol) was added to acetic anhydride (4 ml) and heated for 15 min at 80°C with vigorous stirring. The
mixture was cooled down and the acetic anhydride was evaporated. The oil obtained was treated with water.
Obtained 2.3 g (96%) of compound 3; mp 76-77°C. Found, %: C 28.50; H 3.08; N 5.43. C6H8BrNOS2.
Calculated, %: C 28.35; H 3.17; N 5.51.
B. 5-Bromothiazine thione 1 (0.1 g, 0.005 mol) was added to acetic anhydride (10 ml) and heated with
vigorous stirring for 6 h at 80°C. The mixture was cooled down and the acetic anhydride was evaporated. The oil
obtained was treated with water. Obtained 1.1 g (92%) of compound 3; mp 75-76°C. 13C NMR spectrum,
δ, ppm: 200.51 (C(2)); 171.01 (C(7)); 59.34 (C(4)); 44.69 (C(5)); 34.76 (C(6)); 27.50 (CH3). Found, %: C 28.33;
H 3.13; N 5.58. C6H8BrNOS2. Calculated, %: C 28.35, H 3.17; N 5.51.
5-Bromo-3-methyl-3,4,5,6-tetrahydro-1,3-thiazine-2-thione (5). A solution of NaOH (1.44 g,
0.036 mol) in water (30 ml) was added dropwise to N-methyl-2,3-dibromopropylamine hydrobromide (11.23 g,
0.036 mol) in a minimal amount of water with stirring. This was extracted with ether (4 × 60 ml). The ether
extracts were combined, evaporated down to 150 ml, and then carbon disulfide (1.38 g, 1.1 ml, 0.038 mol) was
added. The reaction mixture was held for 24 hours at room temperature. The white precipitate formed was
13
filtered out and washed with water. Obtained 0.3 g (7%) of compound 5; mp 140-142°C. C NMR spectrum,
δ, ppm: 188.27 (C(2)); 58.69 (C(4)); 44.30 (CH3), 41.09 (C(5)); 39.94 (C(6)). Found, %: C 26.64; H 3.61; N 6.42.
C5H8BrNS2. Calculated, %: C 26.55; H 3.57; N 6.19.
5-Bromomethyl-3-methyl-1,3-thiazolidine-2-thione (6). The ether layer from the preceding
experiment was held for 6 days at room temperature; the precipitating crystals were filtered out and washed with
a small amount of water. Obtained 1.4 g of compound 6. The ether filtrate was evaporated down, washed with
water, and another 1.5 g of compound 6 was isolated. The precipitates were combined: yield 72%; mp 70-71°C.
13C NMR spectrum, δ, ppm: 193.88 (C(2)); 62.71 (C(4)); 43.95 (C(5)); 37.10 (CH3); 35.99 (C(6)). Found, %:
C 26.72; H 3.40; N 6.38. C5H8BrNS2. Calculated, %: C 26.55; H 3.57; N 6.19.
3-Acetyl-1,3-thiazolidine-2-thione (7) was obtained by acetylation of thiazolidine-2-thione by acetyl
chloride; mp 112-114°C (mp 111-114°C [3]). 13C NMR spectrum, δ, ppm: 202.64 (C(2)); 170.78 (C(7)); 56.08
(C(4)); 28.22 (C(5)); 26.74 (CH3).
This research was done with the financial support of the Russian Foundation for Basic Research (grants
No. 05-04-48794 and No. 05-03-08140 ofi-a).
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