REACTIONS OF ETHYL OXAMATE AND DIALKYL OXALATES
721
Yield 1.31 g (66%), mp 190–192°C. 1H NMR spectrum,
δ, ppm: 3.90 s (3H, OCH3), 7.22–8.65 m (4H, C6H4),
8.12 s (1H, CONH2), 8.42 s (1H, CONH2), 12.30 s (1H,
NHCO) [9].
mixture was diluted with 50 ml of water and left
overnight. The separated precipitate was filtered off,
dried, and recrystallized from ethanol. Yield 1.83 g
(78%), mp 133–135°C.
b. Analogous procedure was carried out using
2-Carbamoyloxanilic acid ethyl ester (Va). a. In a
minimal quantity of glacial acetic acid was dissolved
1.36 g (0.01 mol) of amide Id, 1.4 ml (0.01 mol) of diethyl
oxalate was added, and the mixture was heated for
10 min. On cooling the reaction mixture was diluted with
50 ml of cold water and left overnight. The separated
precipitate was filtered off, dried, and recrystallized from
ethanol. Yield 2.07 g (87%), mp 135–137°C.
0.01 mol of diethyl oxalate. Yield 1.93 g (88%), mp 131–
1
133°C. H NMR spectrum, δ, ppm: 1.25 t (3H, CH3),
4.30 q (2H, CH2), 5.90 s (2H, NH2), 7.61 t (1H, H6),
7.72 d (1H, H8), 7.87 t (1H, H7), 8.19 d (1H, H5) [1].
Methyl 3-amino-4-oxo-3,4-dihydroquinazoline-2-
carboxylate (IIb) was obtained in the same way as
compound IIa by procedure b from 1.51 g (0.01 mol) of
amide Id and 1.02 g (0.01 mol) of dimethyl oxalate. Yield
b. In a minimal quantity of formic acid was dissolved
1.36 g (0.01 mol) of amide Id, 1.4 ml (0.01 mol) of diethyl
oxalate was added, and the mixture was heated for
10 min. On cooling the reaction mixture was diluted with
50 ml of cold water and left overnight. The separated
precipitate was filtered off, dried, and recrystallized from
ethanol. Yield 1.18 g (53%), mp 169–171°C. 1H NMR
spectrum, δ, ppm: 1.32 m (3H, CH3), 4.31 m (2H, CH2),
7.25–8.52 m (4H, C6H4), 7.80 C (1H, CONH2), 8.41 s
(1H, CONH2), 13.00 s (1H, NHCO) [10].
1
1.71 g (84%), mp 183–185°C. H NMR spectrum,
δ, ppm: 3.91 s (3H, OCH3), 5.90 s (2H, NH2), 7.60 t
(1H, H6), 7.71 d (1H, H8), 7.92 t (1H, H7), 8.18 d (1H,
H5).
Ethyl 4-oxo-3,4-dihydroquinazoline-2-carboxylate
(IIc) was obtained in the same way as compound IIa
both by procedure a from 1.36 g (0.01 mol) of amide Id
and 1.17 g (0.01 mol) of ethyl oxamate, yield 2.01 g
(92%), mp 181–183°C and procedure b using 0.01 mol
of diethyl oxalate. Yield 1.93 g (88%), mp 183–185°C.
1H NMR spectrum, δ, ppm: 1.25 t (3H, CH3), 4.28 q
(2H, CH2), 7.60–8.51 m (4H, C6H4), 12.60 s (1H, NH)
[7].
2-Carbamoyloxanilic acid methyl ester (Vb). In
a minimal quantity of 1,4-dioxane was dissolved 1.36 g
(0.01 mol) of amide Id, 1.02 g (0.01 mol) of dimethyl
oxalate was added, and the mixture was heated for 30
min. On cooling the reaction mixture was diluted with
50 ml of water. The separated precipitate was filtered
off, dried, and recrystallized from ethanol. Yield 1.65 g
Methyl 4-oxo-3,4-dihydroquinazoline-2-carboxy-
late (IId) was obtained in the same way as compound
IIa by procedure b from 1.36 g (0.01 mol) of amide ²d
and 1.02 g (0.01 mol) of dimethyl oxalate. Yield 1.72 g
1
(74%), mp 168–170°C. H NMR spectrum, δ, ppm:
1
(84%), mp 192–194°C. H NMR spectrum, δ, ppm:
3.87 s (3H, OCH3), 7.25–8.51 m (4H, C6H4), 7.82 s (1H,
CONH2), 8.37 s (1H, CONH2), 13.10 s (1H, NHCO).
3.80 s (3H, OCH3), 7.20–8.50 m (4H, C6H4), 13.05 s
(1H, NH).
3-Acetylamino-2-ethoxycarbonyl-4-oxo-3,4-
dihydroquinazoline (VI). In a minimal quantity of
glacial acetic acid was dissolved 0.01 mol (1.51 g) of
hydrazide Ia, 0.01 mol (1.4 ml) of triethylamine was
added, and at cooling also 1.2 ml (0.01 mol) of ethyl
oxalyl chloride. The reaction mixture was left standing
for 1 h, cooled, diluted with 50 ml of water, the separated
precipitate was filtered off, dried, and recrystallized from
ethanol. Yield 1.73 g (63%), mp 142–144°C. 1H NMR
spectrum, δ, ppm: 1.05 t (3H, CH3), 2.50 s (3H, COCH3),
4.05 q (2H, CH2), 7.05 t (1H, H6), 7.25 d (1H, H8),
7.50 t (1H, H7), 7.70 d (1H, H5), 11.55 br.s (1H, NHCO)
[4].
2-Carboxyoxanilic acid ethyl ester (III). In
a minimal quantity of glacial acetic acid was dissolved
1.37 g (0.01 mol) of anthranilic acid Ib, 1.17 g (0.01 mol)
of ethyl oxamate was added, and the mixture was heated
for 30 min. On cooling the reaction mixture was diluted
with 40 ml of cold water and left overnight. The separated
precipitate was filtered off, dried, and recrystallized from
1
ethanol. Yield 1.42 g (60%), mp 178–180°C. H NMR
spectrum, δ, ppm: 1.35 t (3H, CH3), 4.30 q (2H, CH2),
7.20–8.51 m (4H, C6H4), 12.50 s (1H, NHCO), 13.05
(1H, OH) [8].
2-Methoxycarbonyloxanilic acid amide (IV) was
prepared similarly to compound III from 1.51 g (0.01
mol) of ester Ic and 1.17 g (0.01 mol) of ethyl oxamate.
4-Oxo-3,4-dihydroquinazoline (VIIa). a. In a mini-
mal quantity of formic acid was heated for 30 min 1.36 g
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 5 2007