1230
RAKHIMOV, AVDEEV
Yields of the S- and C-benzylation products (on the
the next day the reaction mixture was filtered. The
filtrate was concentrated, and precipitate was filtered
off and recrystallized from absolute ethanol. Yield 1.1 g
(40% on the reacted I), mp 182–183°С (decomp.). Н
NMR spectrum, δ, ppm: 4.26 m (2Н, СН2–С6H5), 5.96 s
(1Н, C=СН–), 6.92–7.45 m (10Н, НAr), 11.7 s (1Н,
NH). Found, %: N 8.78. C18H14N2O2S. Calculated, %:
N 8.69.
reacted I) are 40% (II) and 10% (IV), respectively.
The quantum-chemical analysis by АМ1 method
[2, 3] of S- and С-anions generated from I and III
respectively indicates a distinction in charges and
energy on the reaction centre of anions in comparison
with the corresponding anions from thiobarbituric acid.
1
Benzylidene group incorporation into the position 5
(anion А) leads to decrease in the electron density of
the thiolate anion in comparison with anion С and to
decrease in its reactivity. Benzylthiolate group
incorporation increases electron density on the carbon
atom in carbanion В in comparison with anion D and
makes possible С-benzylation.
5-Benzyl-2-(benzylthio)pyrimidine-4,6(1H,5H)-
dione (IV). To a suspension of 2 g (8.5 mmol) of III
in 30 ml of water–dioxane mixture (20 ml of dioxane
and 10 ml of water) was dropwise added a solution of
0.4 g (8.9 mmol) of sodium hydroxide in 10 ml of
water. The solid residue was fileterd off and to the
filtrate obtained was dropwise added a solution of
benzyl chloride (1.1 ml, 9.4 mmol) in 5 ml of dioxane.
This mixture was stirred for 2 h and then it was kept
overnight. At the next day the reaction mixture was
filtered. The filtrate was concentrated, and precipitate
was filtered off and recrystallized from absolute
O
O
H
H
N
N
_
_
_S
N
C
O
S
_
N
O
A
0.450
0.458
1
ethanol. Yield 0.28 g (10%), mp 185°С (decomp.). Н
E = –1345.5 kcal mol–1
E = –2693.8 kcal mol–1
NMR spectrum, δ, ppm: 3.22 s (1Н, O=C–СН–), 3.51 s
(1Н, C–СН–C6H5), 4.33 s (2H, S–CH2 ), 7.06–7.40 m
(10Н, НAr), 11.7 s (1Н, NH). Found, %: N 8.81.
C18H16N2O2S. Calculated, %: N 8.63.
O
O
H
S
H
0.535
H
S
H
0.528
_
_
_
_
N
C
N
C
1
N
O
N
O
The H NMR spectra were registered on a Varian
Mercury device (300 MHz) in DMSO-d6 relative to
internal HMDS. Melting points were determined in
accordance with procedure [4].
H
D
B
E = –1351.3 kcal mol–1
E = –2816.7 kcal mol–1
REFERENCES
(5Z)-5-Benzylidene-2-(benzylthio)pyrimidine-4,6-
(1H,5H)-dione (II). To a suspension of 5 g (21.5 mmol)
of I in 60 ml of water–dioxane mixture (50 ml of
dioxane and 10 ml of water) was added dropwise a
solution of 0.9 g (22.6 mmol) of sodium hydroxide in
40 ml of water. This mixture was stirred for 2 h to the
reaction mixture solidification. To the suspension
obtained was dropwise added a solution of benzyl
chloride (2.7 ml, 23.6 mmol) in 5 ml of dioxane. This
mixture was stirred for 3 h and left kept overnight. At
1. Rakhimov, A.I., Avdeev, S.А., and Le Thi Doan Chang,
Zh. Obshch. Khim., 2009, vol. 79, no. 2, p. 348.
2. Schmidt, M.W., Baldridge, K.K., and Boatz, J.A.,
J. Comput. Chem., 1993, vol. 14, p. 1347.
3. Voets, R., J. Comput. Chem., 1990, vol. 11, p. 269.
4. Stepin, B.D., Tekhnika laboratornogo eksperimenta v
khimii (Technique of Laboratory Experiment in
Chemistry), Moscow: Khimiya, 1999, p. 600.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 6 2009
Rakhimov
