EXPERIMENTAL
1H NMR spectra were recorded on a Bruker WM-250 (250 MHz) spectrometer with TMS as internal
standard. Monitoring of the course of the reaction and the purity of the products was carried out by TLC on
Silufol UV-254 plates with ethyl acetate eluent and revealed using UV light. The 1,2,4-triazine 4-oxides 1 were
synthesized according to the method [16].
Reaction of 1,2,4-Triazine 4-Oxides 1a,b with 1,3-Dimethylbarbituric Acid. (General Method). A
solution of the 6-aryl-1,2,4-triazine 4-oxide 1 (4 mmol) and 1,3-dimethylbarbituric acid (624 mg, 4 mmol) in
acetic acid (30 ml) was refluxed for 30 min. The precipitate formed on cooling was filtered off and recrystallized
from ethanol.
1-Hydroxy-6-(1,3-dimethyl-2,4,6(1H,3H,5H)-trioxopyrimidyl-5-idene)-3-phenyl-1,4,5-triazahexa-
1
1,3-diene (4a). Yield 1120 mg (85%); mp 255-257°C. H NMR spectrum, δ, ppm (J, Hz): 3.16 (3H, s, NCH3);
3.20 (3H, s, NCH3); 7.4 (3H, m); 7.8 (2H, m); 8.38 (1H, s); 8.44 (1H, d, J = 11.6); 12.80 (1H, s, OH); 14.13 (1H,
d, J = 11.6, NH). Found, %: C 54.89; H 4.49; N 21.34. C15H15N5O4. Calculated, %: C 54.71; H 4.59; N 21.27.
1-Hydroxy-6-(1,3-dimethyl-2,4,6(1H,3H,5H)-trioxopyrimidyl-5-idene)-3-(4-tolyl)-1,4,5-triazahexa-
1
1,3-diene (4b). Yield 1100 mg (80%); mp >270°C. H NMR spectrum, δ, ppm (J, Hz): 2.38 (3H, s, CH3); 3.20
(3H, s, NCH3); 3.23 (3H, s, NCH3); 7.22 (3H, m); 7.67 (2H, m); 8.32 (1H, s); 8.46 (1H, d, J = 11.1); 12.68 (1H,
s, OH); 14.15 (1H, d, J = 11.1, NH). Found, %: C 55.80; H 5.18; N 20.56. C16H18N5O4. Calculated, %: C 55.97;
H 4.99; N 20.40.
1-Hydroxy-6-(1,3-dioxoindan-2-ylidene)-3-phenyl-1,4,5-triazahexa-1,3-diene (5a). A solution of the
6-phenyl-1,2,4-triazine 4-oxide 1a (4 mmol) and indanedione (584 mg, 4 mmol) in trifluoroacetic acid was
allowed to stand at room temperature for 14 days, after which it was diluted with water and the residue was
1
recrystallized from ethanol. Yield 700 mg (55%); mp 180-181°C. H NMR spectrum, δ, ppm (J, Hz): 7.4 (3H,
m); 7.76 (s, 4H, indane); 7.8 (2H, m); 8.15 (1H, d, J = 11.0); 8.46 (1H, s); 12.9 (1H, s, OH); 14.0 (1H, d,
J = 11.0, NH). Found, %: C 67.55; H 4.26; N 13.02. C18H13N3O3. Calculated, %: C 67.71; H 4.10; N 13.16.
Reaction of the 1,2,4-Triazine 4-Oxides 1a,b with Ethylmagnesium Bromide. (General Method). A
solution of ethylmagnesium bromide in THF (obtained from 2 mmol of Mg and 2.5 mmol of bromoethane) was
added to the triazine 4-oxide 1 (1 mmol) with vigorous stirring. The solution formed was evaporated, water
(∼20 ml) was added, and the mixture was refluxed for 5-10 min, cooled to room temperature, and the precipitate
was filtered off.
5-Ethyl-4-hydroxy-6-phenyl-4,5-dihydro-1,2,4-triazine(6a). Yield 70 mg (35%); mp 195-197°C.
1H NMR spectrum, δ, ppm (J, Hz): 0.97 (3H, t, CH3CH2); 1.65 and 2.05 (both 1H, m, CH3CH2); 5.23 (1H, t,
H-5); 7.43 (3H, m); 7.79 (2H, m); 8.35 (1H, s, H-3). Found, %: C 64.89; H 6.49; N 20.54. C11H13N3O.
Calculated, %: C 65.01; H 6.45; N 20.67.
5-Ethyl-4-hydroxy-6-tolyl-4,5-dihydro-1,2,4-triazine(6b). Yield 140 mg (65%); mp 250-253°C
(decomp.). 1H NMR spectrum, δ, ppm (J, Hz): 0.85 (3H, t, CH3CH2); 1.65 and 2.00 (both 1H, m, CH3CH2); 2.36
(3H, s, CH3); 5.41 (1H, t, H-5); 7.32 (2H, d); 7.78 (2H, d); 9.14 (1H, s, H-3). Found, %: C 66.21; H 7.09;
N 19.18. C12H15N3O. Calculated, %: C 66.34; H 6.96; N 19.34.
5-Ethyl-4-hydroxy-6-(4-methoxyphenyl)-4,5-dihydro-1,2,4-triazine (6c). Yield 120 mg (50%);
mp 213-215°C. 1H NMR spectrum, δ, ppm (J, Hz): 0.88 (3H, t, CH3CH2); 1.65 and 2.05 (both 1H, m, CH3CH2);
3.80 (3H, s, CH3); 4.98 (1H, t, H-5); 6.93 (2H, d); 7.70 (2H, d); 8.12 (1H, s, H-3). Found, %: C 61.88; H 6.34;
N 17.82. C12H15N3O2. Calculated, %: C 61.79; H 6.48; N 18.01.
This work was carried out with financial support of the RFFI (grant No. 02-03-32627) and the Ural
Science Research Center (grant CRDF REC-005).
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