1560
M. M. Burbuliene, R. Dobrovolskaite and P. Vainilavicius
Vol 43
ml) was heated at reflux for 4 hours. The solvent was removed
under reduced pressure, the residue was triturated with methanol
and collected by filtration to give brownish powder, which was
crystallized from acetic acid as white crystals of 3, 0.24 g (50%),
248-250°. The residue was crystallized from ethoxyethane to
give dusty 4, 0.136 g (16%), mp 228-230°.
for 15 min. After being cooled to room temperature, the solid
was collected by filtration, washed with methanol and
crystallized from tetrahydrofuran to yield 0.43 g (76%), mp 154-
156°; ir: 1782 (C2=O), 1714 (NHCO) 1673 (C5=O) cm-1; 1H nmr
(DMSO-d6): ꢀ 2.12 (s, 3H, CH3), 4.78 (s, 2H, N-CH2), 6.82 (s,
1H, CH-5), 7.51-7.53 (m, 3H, Ph-H), 8.03-8.06 (m, 2H, Ph-H),
11.02 (s, 1H, NH) ppm.
N-Benzyl-2-(2-benzylamino-4-oxo-6-phenyl-4H-pyrimidin-3-
yl)-acetamide (4).
Anal. Calcd. for C14H12N4O3 (284.28): C, 59.15; H, 4.25; N,
19.71. Found: C, 59.45; H, 4.27; N, 19.66.
Method 1. A mixture of hydrazide 2 (0.29 g, 1 mmole) and
benzylamine (7 ml) was maintained at 155-160° for 5 hours and
left to cool to room temperature. The solid was filtered, washed
with methanol and crystallized from ethoxyethane to give 4,
0.18 g (42%), mp 228-230°; ir: 3444, 3254 (NH), 1668 (C4=O),
1648 (CONH) cm-1; 1H nmr (DMSO-d6): ꢀ 4.36 (d, 2H,
CONHCH2, J = 6.0 Hz), 4.69 (d, 2H, NHCH2, J = 5.03 Hz), 4.74
(s, 2H, N-CH2), 6.30 (s, 1H, CH-5), 7.23-7.44, (m, 13H, Ph-H),
7.95-7.97 (m, 3H, Ph-H+NH), 8.72 (t, 1H, CONH, J = 6.0 Hz)
ppm.
N-(2,5-Dioxo-7-phenyl-2,3-dihydro-5H-imidazo[1,2-a]pyrimidin-
1-yl)-2-benzamide (6b).
A mixture of compound 3 (0.48 g, 2 mmoles) and benzoyl
chloride (0.28 g, 2 mmoles) in pyridine (15 ml) was refluxed for
2 hours. Pyridine was removed under reduced pressure, the
residue was diluted with water, neutralized with acetic acid,
filtered and crystallized from methanol to give 6b as white
plates, 0.85 g (59%), mp 168-170°; ir: 3163 (NH), 1782 (C2=O),
1
1713 (NHCO), 1670 (C5=O) cm-1; H nmr (DMSO- d6): ꢀ 4.91
Anal. Calcd. for C26H24N4O2 (424.50): C, 73.56; H, 5.70; N,
13.20. Found: C, 73.29; H, 5.54; N, 13.45.
(s, 2H, N-CH2), 6.86 (s, 1H, CH-5), 7.47-8.05 (m, 10H, Ph-H),
11.72 (s, 1H, NH) ppm.
Method 2. A mixture of ester 1 (0.29 g, 1 mmole) and
benzylamine (7 ml) was maintained at 155-160° for 5 hours and
worked as above to yield 4, mp 228-230°, 0.28 g (67%).
Anal. Calcd. for C19H14N4O3 (346.34): C, 65.89; H, 4.07; N,
16.18. Found: C, 65.99; H, 4.14; N, 16.01.
N-Benzyl-2-(2-methylsulfanyl-4-oxo-6-phenyl-4H-pyrimidin-3-
yl)-acetamide (7).
General Procedure for the Synthesis of 1-[(Benzyl-
idene)-amino]-7-phenyl-1H-imidazo[1,2-a]pyrimidine-2,5-
dione (5a, 5b).
Method 1. A mixture of ester 1 (0.58 g, 2 mmoles) and
benzylamine (0.23 g, 2.1 mmoles) was maintained at 120-125°
temperature for 8 hours. The reaction mixture then was cooled,
triturated with acidified water, extracted with chloroform. The
chloroform solution was dried over sodium sulfate, filtered and
evaporated to give the unreacted ester 1, 0.04 g (7%), mp 130-
131°. The residual after extraction was crystallized from
isopropanol to give 7 as colorless crystals, 0.34 g (47%), mp
205-207°; ir: 3466, 3280 (NH), 1677 (C4=O), 1657 (CONH)
A mixture of compound 3 (0.48 g, 2 mmoles) and aromatic
aldehyde (2 mmoles) in acetic acid (15 ml) was heated at reflux
for 15 min. An excess of solvent was removed under reduced
pressure, the resulting precipitate was collected by filtration,
washed with methanol and crystallized from acetic acid to give
5a or 5b.
1-[(4-Methoxy-benzylidene)-amino]-7-phenyl-1H-imidazo-
[1,2-a]pyrimidine-2,5-dione (5a).
1
cm-1; H nmr (DMSO-d6): ꢀ 2.70 (s, 3H, SCH3), 4.35 (d, 2H,
NHCH2, J = 6.0 Hz), 4.74 (s, 2H, N-CH2), 6.85 (s, 1H, CH-5),
7.30-7.36 (m, 5H, Ph-H ), 7.52-7.54 (m, 3H, Ph-H), 8.14-8.16
(m, 2H, Ph-H), 8.82 (t, 1H, NH, J = 6.0 Hz) ppm.
This compound was obtained as colorless crystals, yield 0.62
1
g, (86%), mp 210-212°; ir: 1775 (C2=O), 1686 (C5=O) cm-1; H
nmr (DMSO-d6): ꢀ 3.88 (s, 3H, OCH3), 4.61 (s, 2H, N-CH2),
6.84 (s, 1H, CH-5), 7.15 (d, 2H, Ar-H, J = 9 Hz), 7.52-7.54 (m,
3H, Ar-H), 7.93 (d, 2H, Ar-H, J = 9 Hz), 8.07-8.11 (m, 2H, Ar-
H), 9.35 (s, 1H, CH) ppm.
Anal. Calcd. for C20H16N4O3 (360.37): C, 66.66; H, 4.48; N,
15.55. Found: C, 66.54; H, 4.31; N, 15.49.
Anal. Calcd. for C20H19N3O2S (365.45): C, 65.73; H, 5.24; N,
11.50. Found: C, 65.49; H, 5.19; N, 11.64.
Method 2. A mixture of ester 1 (0.58 g, 2 mmoles) and
benzylamine (0.23 g, 2.1 mmoles) was maintained at 120-125°
temperature for 3 hours and worked as above to give 7, 0.13 g
(18%), mp 205-207° and unreacted 1, 0.35 g (61%), mp 130-
131°.
Method 3. A mixture of ester 1 (0.58, 2 mmoles), benzyl-
amine (0.23 g, 2.1 mmoles) and dry dimethylformamide (10 ml)
was maintained at 120-125° temperature for 5 hours. After the
solvent was removed under reduced pressure, the remainder was
worked as above to yield 7, 0.09 g (12%), mp 205-207° and
unreacted ester 1, 0.38 g (66%).
1-[(4-Hydroxy-3-methoxy-benzylidene)-amino]-7-phenyl-1H-
imidazo[1,2-a]pyrimidine-2,5-dione (5b).
This compound was obtained as a white solid, 0.52 g (69%),
1
mp > 300°; ir: 3444 (OH), 1781 (C2=O), 1670 (C5=O) cm-1; H
nmr (DMSO-d6): ꢀ 3.88 (s, 3H, OCH3), 4.61 (s, 2H, N-CH2),
6.82 (s, 1H, CH-5), 6.96 (d, 1H, Ph-H, J = 8.1 Hz), 7.38 (d, 1H,
Ph-H, J = 8.1 Hz), 7.51-7.53 (m, 4H, Ph-H), 8.06-8.09 (m, 2H,
Ph-H), 9.20 (s, 1H, CH), 9.99 (br s, 1H, OH) ppm.
1-Benzyl-7-phenyl-1H-imidazo[1,2-a]pyrimidine-2,5-dione (8).
Anal. Calcd. for C20H16N4O4 (376.37): C, 63.82; H, 4.28; N,
14.89. Found: C, 63.75; H, 4.33; N, 15.01.
Method 1. A mixture of ester 1 (0.58, 2 mmoles) and
benzylamine (0.23 g, 2.1 mmoles) was maintained at 155-160°
temperature for 8 hours, then cooled, triturated with methanol,
the precipitate formed was filtered and crystallized from
isopropanol to yield 8 as a white powder, 0.33 g (52%), mp 177-
179°; ir: 1758 (C2=O), 1677 (C7=O) cm-1; 1H nmr ꢀ (DMSO-d6):
4.62 (s, 2H, N-CH2), 4.94 (s, 2H, N-CH2), 6.76 (s, 1H, CH-5),
N-(2,5-Dioxo-7-phenyl-2,3-dihydro-5H-imidazo[1,2-a]pyrimidin-
1-yl)-acetamide (6a).
A mixture of compound 3 (0.48 g, 2 mmoles) and acetic
anhydride (0.31 g, 3 mmoles) in acetic acid was heated at reflux