catalyst with diethyl ether (20 ml). The catalyst was filtered off, and the solvent distilled. After separation by
column chromatography salicylaldehyde (0.006 g, conversion 98%) and 2-methyl-2H-chromene-3-carbaldehyde
(4) (0.182 g, 50%) were isolated.
1H NMR spectrum (CDCl3–CCl4), δ, ppm (J, Hz): 1.35 (3H, d, J11,2 = 6.6, 11-CH3); 5.38 (1H, q,
J2,11 = 6.6, H-2); 6.83 (1H, br. d, J9,8 = 8.3, H-9); 6.90 (1H, ddd, J7,6 = 7.5, J7,8 = 7.5, J7,9 = 1.0, H-7); 7.13 (1H,
br. s, H-4); 7.15 (1H, dd, J6,7 = 7.5, J6,8 = 1.7, H-6); 7.26 (1H, ddd, J8,9 = 8.3, J8,7 = 7.5, J8,6 = 1.7, H-8); 9.51 (1H,
s, H-12). 13C NMR spectrum (CDCl3–CCl4), δ, ppm: 69.74 (d, C-2); 136.27 (s, C-3); 139.80 (d, C-4); 119.83 (s,
C-5); 129.00 (d, C-6); 121.44 (d, C-7); 133.27 (d, C-8); 117.33 (d, C-9); 154.51 (s, C-10); 19.93 (q, C-11);
189.38 (d, C-12). Found, m/z 174.0673 [M]+. C11H10O2. Calculated: M = 174.0675.
Interaction of 5-Methoxybenzimidazole-2-thiol (5) with Methyl Vinyl Ketone in the Presence of
Zeolite Csβ. 5-Methoxybenzimidazole-2-thiol (5) (0.309 g, 1.72 mmol) in methanol (10 ml) was added to basic
zeolite Csβ (0.05 g). The solvent was distilled off. MVK (0.1 g, 1.43 mmol) was added to the mixture. The
reaction mixture was maintained at room temperature for 60 h, then extracted from the catalyst with ethyl
acetate (25 ml). The catalyst was filtered off and the solvent evaporated. The reaction mixture was dissolved in
chloroform (20 ml) and left at 0oC for 1 day. Crystalline compound 5 (0.168 g) precipitated from the solution,
and the crystals were filtered off. The solvent was distilled from the filtrate, the solid residue (0.127 g) contained
a mixture of compound 5 and 4-[5-methoxy-3-(3-oxobutyl)-2-thioxo-2,3-dihydro-1H-benzimidazol-1-yl]butan-
2-one (6) in a ratio of 1:9.4. Conversion of the initial compound 5 was 43%, yield of thione 6 on reacted thiol 5
was 50%.
1H NMR spectrum (CDCl3–CCl4), δ, ppm (J, Hz): 2.14 and 2.15 (6H, s, 13-CH3, 17-CH3); 3.03 and 3.07
(4H, t, J = 6.7, -CH2COCH3, H-11,15); 3.84 (3H, s, 18-CH3); 4.43 and 4.44 (4H, t, J = 6.7, -CH2CH2COCH3,
H-10,14); 6.77 (1H, dd, J6,7 = 8.8, J6,4 = 2.3, H-6); 6.88 (1H, d, J4,6 = 2.3, H-4); 7.20 (1H, d, J7,6 = 8.8, H-7). 13C
NMR spectrum (CDCl3–CCl4), δ, ppm: 168.52 (s, C-2); 94.92 (d, C-4); 156.85 (s, C-5); 110.31 (d, C-6); 109.97
(d, C-7); 126.07 (s, C-8); 132.62 (s, C-9); 39.09 and 39.22 (t, C-10,14); 41.16 and 41.24 (t, C-11,15); 205.43
and 205.53 (s, C-12,16); 30.12 (q, C-13,17); 55.84 (q, C-18). Found: m/z 320.1185 [M]+. C16H20N2O3S.
Calculated: M = 320.1189.
Interaction of Methyl Vinyl Ketone with 1,2,4-Triazole-3-thiol (7) in the Presence of Zeolite Csβ.
Compound 7 (0.12 g, 1.19 mmol) was added to zeolite Csβ (0.05 g ), diethyl ether (20 ml) was added to the
mixture, and the suspension was stirred for 30 min. The solvent was distilled. MVK (0.08 g, 1.14 mmol) was
added to the reaction mixture. The mixture was maintained at room temperature for 60 h, and extracted from the
catalyst with ethyl acetate (20 ml). The catalyst was filtered off, and the solvent evaporated. After separation by
column chromatography a mixture (0.08 g) containing the initial thiol 7 (0.004 g, conversion 97%) and
5-methyl-6,7-dihydro-5H-[1,2,4-triazolo[3,4-b][1,3]thiazin-5-ol (10) (0.076 g, yield on reacted MVK was 39%),
and also a mixture (0.036 g) containing 4-(3-mercapto-4H-1,2,4-triazol-4-yl)butan-2-one (8) (0.005 g) (yield on
reacted MVK 3%) and 4-([3-[(3-oxobutyl)thio]-4H-1,2,4-triazol-4-yl]butan-2-one (9) (yield on reacted MVK
was 11%).
1
4-(3-Mercapto-4H-1,2,4-triazol-4-yl)butan-2-one (8). H NMR spectrum (CDCl3–CCl4), δ, ppm (J,
Hz): 2.13 (3H, s, 9-CH3); 3.00 (2H, t, J7,6 = 6.0, –CH2COCH3, H-7); 4.36 (2H, t, J6,7 = 6.0, –CH2CH2COCH3,
H-6); 8.06 (1H, s, H-3). The closeness of the chemical shifts of the H-6 proton signal in compound 8 and the
signals of the H-10 and H-14 protons of thione 6 indicate the addition of MVK to the nitrogen atom and not
sulfur in thione 8. Found: m/z 171.0462 [M]+. C6H9N3OS. Calculated: M = 171.0461.
1
4-[3-[(3-Oxobutyl)thio]-4H-1,2,4-triazol-4-yl]butan-2-one (9). H NMR spectrum (CDCl3–CCl4), δ, ppm
(J, Hz): 2.14 and 2.15 (6H, s, 9-CH3, 13-CH3); 2.90 (2H, t, J7,6 = 7.0, H-7); 2.99 (2H, t, J11,10 = 6.0, –CH2COCH3,
H-11); 3.23 (2H, t, J6,7 = 7.0, -CH2CH2COCH3, H-6); 4.33 (2H, t, J10,11 = 7.0, -CH2CH2COCH3, H-10); 7.98 (1H, s,
H-3). 13C NMR spectrum (CDCl3–CCl4), δ, ppm: 144.71 (d, C-3); 160.65 (s, C-5); 25.50 (t, C-6); 43.76 and 43.88 (t,
C-7,11); 204.38 and 205.85 (s, C-8,12); 29.90 and 29.93 (q, C-9,13); 42.24 (t, C-10). Found: m/z 241.088 [M]+.
C10H15N3O2S. Calculated: M = 241.088.
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