BRITSUN et al.
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the carbonyl group of thioamides Id–If giving
intermediates V. The latter apparently suffer intra-
molecular attack of the thioamide group on the carbonyl
leading to the formation of 1,2-dihydro-pyridine-2-thiones
VIa–VIc.
cooled, and thionepyran VIa–VIc was separated by
filtration.
1-Methyl-5-(N-methylaminothiocarbonyl)-4,6-
diphenyl-1,2-dihydropyridine-2-thione (VIa). Yield
0.717 g (41%), mp 324–326°C (from DMSO). IR spec-
trum, ν, cm–1: 1320, 1360, 1430, 1490, 1580, 3050, 3400.
1H NMR spectrum, δ, ppm (J, Hz): 2.83 d (3H, NHCH3,
J 4.0), 3.35 s (3H, CH3-1), 6.72 s (1H, H3), 7.48–7.58 m
(8Harom.), 8.01 m (2Harom.),8.93 br.s (1H, NH). 13C NMR
spectrum, δ, ppm: 32.6 (HNCH3), 35.22 (CH3-1), 86.7
(C3), 122.1 (Ar), 126.8 (Ar), 128.2 (Ar), 128.6 (Ar), 128.9
(Ar), 130.0 (Ar), 130.5 (Ar), 134.8 (Ar), 137.1 (Ar), 139.1
(Ar), 161.3 (C6), 181.6 (C=S), 187.5 (C2). Found, %:
C 68.30; H 5.31; N 8.07; S 18.03. C20H18N2S2. Calculated,
%: C 68.54; H 5.18; N 7.99; S 18.29.
EXPERIMENTAL
NMR spectra of solutions of compounds in DMSO-
d6 were registered on a spectrometer Varian-300 at
operating frequencies 300 (1H) and 75 MHz (13C), internal
reference TMS. IR spectra were recorded on UR-20
instrument from KBr pellets.
2-Methyl-7-R-4H-pyrido[1,2-a]pyrimidine-4-
thiones IVa–IVc. A solution of 10 mmol of 3-oxo-N-
arylpropanethioamides Ia–Ic and 10 mmol of 2-amino-
5-R-pyridine IIa–IIc in 7 ml of AcOH was heated for
4 h at 100°C, cooled, and thione IVa–IVc was separated
by filtration.
1-Methyl-5-(N-methylaminothiocarbonyl)-4,6-
bis-(4-methoxyphenyl)-1,2-dihydropyridine-2-
thione (VIb). Yield 0.676 g (33%), mp 295–297°C (from
DMSO). IR spectrum, ν, cm–1: 1330, 1360, 1420, 1500,
2-Methyl-4H-pyrido[1,2-a]pyrimidine-4-thione
(IVa). Yield 1.144 g (65%), mp 156–158°C (fromAcOH)
(158°C [7]). IR spectrum, ν, cm–1: 1260, 1310, 1380, 1420,
1
1570, 3050, 3400. H NMR spectrum, δ, ppm (J, Hz):
2.85 d (3H, NHCH3, J 3.8), 3.45 s (3H, CH3-1), 3.82 s
(3H, CH3O), 3.84 s (3H, CH3O), 6.65 s (1H, H3), 6.97 d
(2H, p-C6H4, J 8.1), 7.19 d (2H, p-C6H4, J 8.3), 7.39 d
(2H, p-C6H4, J 8.1), 7.99 d (2H, p-C6H4, J 8.3), 8.82 q
(1H, NH, J 3.8). Found, %: C 64.10; H 5.65; N 6.57.
C22H22N2O2S2. Calculated, %: C 64.36; H 5.40; N 6.82.
1
1590, 3100. H NMR spectrum, δ, ppm (J, Hz): 2.45 s
(3H, CH3-2), 7.56 s (1H, H3), 7.64 m (1Harom.), 7.85 d
(1H, H9, J 8.7), 8.11 m (1Harom.), 10.10 d (1H, H6, J 7.5).
Found, %: C 61.20; H 4.33; N 16.17; S 18.40. C9H8N2S.
Calculated, %: C 61.34; H 4.58; N 15.90; S 18.19.
1-Methyl-5-(N-methylaminothiocarbonyl)-4,6-
bis-(4-chlorophenyl)-1,2-dihydro-pyridine-2-thione
(VIc). Yield 0.564 g (27%), mp 291−293°C (from
DMSO). IR spectrum, ν, cm–1: 1320, 1360, 1440, 1490,
1550, 1600, 3000, 3400. 1H NMR spectrum, δ, ppm
(J, Hz): 2.87 d (3H, NHCH3, J 4.1), 3.38 s (3H, CH3-1),
6.77 s (1H, H3), 7.47 d (2H, p-C6H4, J 8.1), 7.53 d (2H,
p-C6H4, J 8.4), 7.62 d (2H, p-C6H4, J 8.1), 8.08 d (2H,
p-C6H4, J 8.4), 9.29 q (1H, NH, J 4.1). Found, %:
C 56.99; H 4.10; N 6.47. C20H16Cl2N2S2. Calculated, %:
C 57.28; H 3.85; N 6.68.
2,7-Dimethyl-4H-pyrido[1,2-a]pyrimidine-4-
thione (IVb).Yield 1.007 g (53%), mp 140–142°C (from
ethanol). IR spectrum, ν, cm–1: 1260, 1280, 1320, 1430,
1500, 1590, 3100. 1H NMR spectrum, δ, ppm (J, Hz):
2.42 s (3H, CH3-2), 2.54 s (3H, CH3-7), 7.57 s (1H, H3),
7.80 d (1H, H9, J 8.8), 8.02 d (1H, H8, J 8.8), 9.92 s (1H,
H6). Found, %: C 62.94; H 5.53; N 14.57. C10H10N2S.
Calculated, %: C 63.13; H 5.30; N 14.72.
2-Methyl-7-bromo-4H-pyrido[1,2-a]pyrimidine-
4-thione (IVc). Yield 1.53 g (60%), mp 198–200°C (from
AcOH). IR spectrum, ν, cm–1: 1250, 1310, 1430, 1540,
REFERENCES
1
1590, 3100. H NMR spectrum, δ, ppm (J, Hz): 2.44 s
(3H, CH -2), 7.59 s (1H, H3), 7.79 d (1H, H9, J 8.9),
1. Britsun, V.N., Borisevich, A.N., Samoilenko, L.S., and
Lozinskii, M.O., Zh. Org. Khim., 2005, vol. 41, p. 292.
2. Britsun, V.N., Borisevich, A.N., Samoilenko, L.S., and
Lozinskii, M.O., Zh. Org. Khim., 2005, vol. 41, p. 759.
3. Britsun, V.N., Borisevich,A.N., Samoilenko, L.S., Cherne-
ga, A.N., and Lozinskii, M.O., Izv. Akad. Nauk, Ser. Khim.,
2005, vol. 3, p. 757.
4. Britsun, V.N., Bazavova, I.M., Bodnar, V.N., Chernega,A.N.,
and Lozinskii, M.O., Khim. Geterotsikl. Soedin., 2005,
vol. 1, p. 120.
3
8.22 d (1H, H8, J 8.9), 10.19 s (1H, H6). Found, %: C
42.14; H 2.50; N 11.17. C9H7BrN2S. Calculated, %: C
42.37; H 2.77; N 10.98.
1-Methyl-5-(N-methylaminothiocarbonyl)-4,6-
diaryl-1,2-dihydropyridine-2-thiones VIa–VIc.
A solution of 10 mmol of 3-oxo-N-methyl-3-arylpropane-
thioamides Id–If and 10 mmol of 2-amino-5-R-pyridine
IIa–IIc in 7 ml of AcOH was heated for 12 h at 100°C,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 2 2007