Med Chem Res
20 ml), the intermediate (13 and 14) was added and heated
on water bath for 20 min with continuous stirring. After
cooling, the solvent was evaporated under vacuum, and the
residue was suspended in water (25 ml). The resulting
suspension was acidified up to pH 1–3 using 2.5 M HCl.
The precipitated product (4a, 5a, 6a and 4b, 5b, 6b) was
filtered off, recrystallized with suitable solvent, and dried
under vacuum.
13C NMR (75 MHz, DMSO-d6): d 127.1 (C-20 and C-60),
129.5 (C-30 and C-50), 129.7 (C-40), 131.3 (C-10), 141.7 (C-
2), 151.9 (C-9), 162.4 (C-7), 175.8 (C-5); Anal. calcd. for
C10H7N5OS: C, 48.97; H, 2.88; N, 28.55. Found: C, 47.99;
H, 2.71; N, 28.21.
2-Benzyl-5-thioxo-5,6-dihydro-[1,2,4]triazolo[1,5-
a][1,3,5]triazin-7(4H)-one (5b)
2-Phenyl-[1,2,4]triazolo[1,5-a][1,3,5]triazin-5,7(4H,6H)-
dione (4a)
Yield: 55 %; mp: 246 °C (ethanol–water (5:1)); ESI–MS
m/z 242.3(M-1)?; 1H NMR (300 MHz, DMSO-d6): d
4.01(s, 2H, PhCH2), 7.23–7.29 (m, 5H, Ph), 12.99 (s, 1H,
NH), 14.10 (brs, 1H, NH); 13C NMR (75 MHz, DMSO-d6):
d 34.7 (CH2), 127.1 (C-40), 128.9 (C-20and C-60), 129.5 (C-
30 and C-50), 137.4 (C-10), 141.6 (C-2), 151.5 (C-9), 165.0
(C-7), 175.8 (C-5); Anal. calcd. for C11H9N5OS: C, 50.95;
H, 3.50; N, 27.01. Found: C, 50.24; H, 3.24; N, 26.51.
Yield: 54 %; mp: 318–319 °C (ethanol–water (5:1)), ESI–
MS m/z 228.2 (M-1)?; 1H NMR (300 MHz, DMSO-d6): d
7.52–7.54 (m, 3H, H-30, H-40, and H-50), 8.03–8.05 (m, 2H,
H-20 and H-60), 11.94 (s, 1H, NH), 12.90 (s, 1H, NH); 13C
NMR (75 MHz, DMSO-d6): d 127.0 (C-20 and C-60), 129.4
(C-30 and C-50), 130.0 (C-40), 131.0 (C-10), 143.9 (C-2),
149.3 (C-9), 152.5 (C-5), 162.2 (C-7); Anal. calcd. for
C10H7N5O2: C, 52.40; H, 3.08; N, 30.56. Found: C, 52.23;
H, 3.01; N, 30.21.
7-Phenyl-2-thioxo-2,3-dihydro-1H-pyrazolo[1,5-
a][1,3,5]triazin-4-one (6b)
Yield: 71 %; mp: 286–288 °C (ethanol–water (5:1)); ESI–
2-Benzyl-[1,2,4]triazolo[1,5-a][1,3,5]triazine-5,7(4H,6H)-
dione (5a)
1
MS m/z 243.0 (M-1)?; H NMR (300 MHz, DMSO-d6): d
6.39 (s, 1H, CH), 7.38–7.54 (m, 3H, H-30, H-40, and H-50),
7.88–8.00 (m, 2H, H-20 and H-60), 12.75 (s, 1H, NH), 13.56
(s, 1H, NH); 13C NMR (75 MHz, DMSO-d6): d 87.3 (C-8),
126.8 (C-30 and C-50), 129.4 (C-20 and C-60), 130.1 (C-40),
131.7 (C-10), 142.0 (C-7), 142.1 (C-9), 155.9 (C-4), 173.6
(C-2); Anal. calcd. for C11H8N4OS: C, 54.09; H, 3.30; N,
22.94. Found: C, 53.78; H, 3.24; N, 22.74.
Yield: 47 %; mp:[300 °C (ethanol–water (5:1)); ESI–MS
m/z 242.3 (M-1)?; 1H NMR (300 MHz, DMSO-d6): d 4.00
(s, 2H, PhCH2), 7.04–7.61 (m, 5H, Ar–H), 11.81 (s, 1H, NH),
12.69 (brs, 1H, NH); 13C NMR (75 MHz, DMSO-d6): d 34.8
(CH2), 127.04 (C-40), 128.8 (C-20 and C-60), 129.5 (C-30 and
C-50), 137.5 (C-10), 143.9 (C-2), 149.4 (C-9), 152.1 (C-7),
164.8 (C-5); Anal. calcd. for C11H9N5O2: C, 54.32; H, 3.73;
N, 28.79. Found: C, 53.88; H, 3.58; N, 28.07.
General procedure for the preparation of methylthio
analogues of 4b, 5b, 6b (4c, 5c, 6c)
7-Phenyl-1H-pyrazolo[1,5-a][1,3,5]triazin-2,4-dione (6a)
Yield: 55 %; mp: 312–314 °C(ethanol–water (5:1)); ESI–
To a stirred solution of 4b, 5b, and 6b (5 mmol) in 4 ml of
2.5 M NaOH, iodomethane (933 ll, 7.5 mmol) was added
and the stirring was continued for 30 min. A solid pre-
cipitate was observed which upon acidification (pH 1–3)
with 2.5 M HCl afforded another solid. The precipitated
solid was filtered, washed with ice cold water and recrys-
tallized from water–ethanol system.
1
MS m/z 227.1 (M-1)?; H NMR (300 MHz, DMSO-d6): d
6.30 (s, 1H, CH), 7.40–7.49 (m, 3H, H-30, H-40, and H-50),
7.92 (d, 2H, H-20 and H-60, J = 8.7 Hz), 11.61 (s, 1H, NH),
12.00 (s, 1H, NH). 13C NMR (75 MHz, DMSO-d6): d 85.9
(C-8), 126.0 (C-30 and C-50), 128.7 (C-20 and C-60), 129.2
(C-40), 131.5 (C-10), 141.7 (C-7), 144.2 (C-9), 148.3 (C-4),
155.0 (C-2); Anal. calcd. for C11H8N4O2: C, 57.89; H,
3.53; N, 24.55. Found: C, 57.05; H, 3.51; N, 24.11.
5-(Methylthio)-2-phenyl-[1,2,4]triazolo[1,5-
a][1,3,5]triazin-7(6H)-one (4c)
2-Phenyl-5-thioxo-5,6-dihydro-[1,2,4]triazolo[1,5-
a][1,3,5]triazin-7(4H)-one (4b)
Yield: 58 %; mp: 292–294 °C (ethanol–water (5:1)); ESI–
1
MS m/z 258.0 (M-1)?; H NMR (300 MHz, DMSO-d6): d
2.62 (s, 3H, SMe), 7.54–7.55 (m, 3H, H-30, H-40, and H-50),
8.03–8.06 (m, 2H, H-20 and H-60), 13.06 (brs, 1H, NH); 13C
NMR (75 MHz, DMSO-d6): d 13.9 (SMe), 127.1 (C-20 and
C-60), 129.4 (C-30and C-50), 130.4 (C-40), 131.0 (C-10),
143.8 (C-2), 157.9 (C-9), 163.1 (C-5), 165.3 (C-7); Anal.
Yield: 78 %; mp: 258–259 °C (ethanol); ESI–MS m/
z 244.1 (M-1)?; 1H NMR (300 MHz, DMSO-d6): d
7.53–7.55 (m, 3H, H-30, H-40, and H-50), 8.04–8.07 (m, 2H,
H-20 and H-60), 13.12 (s, 1H, NH), 14.31 (brs, 1H, NH);
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