1814
ERKIN et al.
isomers of V. The IR spectrum contains strong bands
tains a weak band with a maximum at 280 nm (log
3.71) corresponding to n * transitions in the con-
assignable to stretching vibrations of carbonyl groups
1
at 1715 (NHCO) and 1685 cm (C4=O), and also to
jugated system of this resonance model. Preservation
of the shorter-wave but stronger band of the phenyl-
carbamoyl moiety with a maximum at 232 nm (log
4.31) is indicative of the less significant contribution
of structure B in which the charge delocalization is
inefficient to the stabilization of V (Fig. 2).
1
bending vibrations of NH groups at 1570 1540 cm
(Fig. 1). A considerable decrease in the intensity of
the stretching vibration bands of the double bonds in
1
the pyrimidine ring (1625 1615 cm ) suggests a sig-
nificant contribution of pseudo-p-quinoid structure A
to stabilization of V. Indeed, the UV spectrum con-
O
O
N
O
O
N
+
N
HN
N
H
HN
V
HO
+
N
HO
H
N
Me
Me
H
H
B
A
In contrast to phenylcarbamate III, its 5-bromo
derivative IV is incapable of intramolecular rearrange-
ment under the above conditions, which indirectly
confirms the isomerization of III involving 5-position
of the pyrimidine ring. Furthermore, compound IV
undergoes acid hydrolysis neither to bromopyrimidyl-
aminoethanol II not to 5-bromo-6-methyluracil. After
heating in concentrated HCl at 100 C for 1 h, com-
pound IV is recovered unchanged, according to chro-
matography and to a mixing test which showed no
melting point depression on mixing with the initial
sample of IV. Such a behavior may be caused by ex-
tremely low solubility of IV in water: even traces of
this compound were not detected in the filtrate.
2-(2-Hydroxyethyl)amino-6-methyl-4-oxodi-
hydro-3H-pyrimidine I and 2-(2-acetoxyethyl)-
amino-6-methyl-4-oxodihydro-3H-pyrimidine were
prepared as described in [1].
5-Bromo-2-(2-hydroxyethyl)amino-6-methyl-4-
oxodihydro-3H-pyrimidine II. A 1.6-g portion of
bromine was added dropwise with vigorous stirring to
a solution of 1.69 g of I in 20 ml of glacial acetic acid.
The resulting suspension was filtered off, and the
precipitate was dissolved in 10% aqueous NaOH,
reprecipitated with the calculated amount of acetic
acid, washed with water, and dried at 80 C for 10 h;
yield of compound II thus obtained 1.93 g (78%), mp
219 C (with decomposition) (published data: mp
1
236 C [7]), Rf 0.24 (A). H NMR spectrum, , ppm:
EXPERIMENTAL
2.22 s (3H, Me), 3.33 t (2H, CH2), 3.49 d (2H, CH2),
4.74 br.s (1H, OH), 6.67 br.s (1H, NHe), 11.03 br.s
(1H, NH). Found, %: C 33.72; H 5.89; N 16.54.
C7H10BrN3O2. Calculated, %: C 33.89; H 4.06; N
16.94.
The IR spectra were recorded on a Specord M-80
1
spectrometer (KBr pellets). The H NMR spectra were
taken on a Bruker AC-200 spectrometer (200.13 MHz)
in DMSO-d6, with residual proton signal of the solv-
ent as internal reference. The UV spectra were meas-
6-Methyl-4-oxo-2-[2-(phenylcarbamoyloxy)-
ethyl]aminodihydro-3H-pyrimidine III. A mixture
of 1.69 g of I and 1.31 g of freshly distilled phenyl iso-
cyanate in 3 ml of absolute DMF was heated at 120 C
for 2 h. Then the solvent was distilled off to dryness
in a vacuum, and the residue was crystallized by
adding 10 ml of absolute acetonitrile. The precipitate
was filtered off, recrystallized from ethanol, and
vacuum-dried over phosphorus pentoxide; yield of
compound III thus obtained 1.7 g (59%), mp 181 C,
4
ured with an SF-26 spectrophotometer from 10
solutions in methanol.
M
The elemental analysis was performed with a Per-
kin Elmer-240 CHN analyzer.
The purity of the compounds was checked by TLC
on Silufol UV-25 plates in the systems chloroform
methanol, 9 : 1 (A) and acetone hexane, 2 : 1, + two
drops of pyridine (B). The spots were developed by
UV light.
1
Rf 0.19 (B). H NMR spectrum, , ppm 2.02 s (3H,
The molecular weights were determined by the
Rast method.
Me), 3.58 d (2H, CH2), 4.20 t (2H, CH2), 5.36 s (1H,
CH), 6.42 br.s (1H, NHe), 6.90 7.47 m (5H, Ph),
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 11 2005
Erkin
