Reaction of 2-(2-oxo-2-arylethylidene)-2,3-dihydropyrimidine-4(1H)-ones with aldehydes

Article abstract of DOI:10.1134/S1070363214050156

2-(2-Oxo-2-arylethylidene)-2,3-dihydropyrimidine-4(1H)-ones react with aromatic and heteroaromatic aldehydes to form the unsaturated ketones, whereas in the case of 3- and 4-benzaldehydes the corresponding trans-2- styrylpyrimidine-4(3H)-ones were obtained. A possible mechanism of hydrolytic cleavage of the product of condensation of 2-(2-oxo-2-phenylethylidene)-2,3- dihydropyrimidine-4(1H)-one with paraformaldehyde under acid catalysis and mechanochemical activation has been discussed.

Full text of DOI:10.1134/S1070363214050156

ISSN 1070-3632, Russian Journal of General Chemistry, 2014, Vol. 84, No. 5, pp. 869–874. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © A.A. Yavolovskii, L.V. Grishchuk, E.I. Bevzyuk, Yu.E. Ivanov, D.E. Stepanov, S.M. Pluzhnik-Gladyr, G.L. Kamalov, 2014,
published in Zhurnal Obshchei Khimii, 2014, Vol. 84, No. 5, pp. 777–781.
Reaction of 2-(2-Oxo-2-arylethylidene)-
2,3-dihydropyrimidine-4(1H)-ones with Aldehydes
A. A. Yavolovskiia, L. V. Grishchukb, E. I. Bevzyukb, Yu. E. Ivanova,
D. E. Stepanova, S. M. Pluzhnik-Gladyra, and G. L. Kamalova
a Bogatskii Physico-Chemical Institute, National Academy of Sciences of Ukraine,
Lyustdorfskaya doroga 86, Odessa, 65080 Ukraine
е-mail: sergey_pluzhnik@ukr.net
b Mechnikov Odessa National University, Odessa, Ukraine
Received August 8, 2013
Abstract—2-(2-Oxo-2-arylethylidene)-2,3-dihydropyrimidine-4(1H)-ones react with aromatic and hetero-
aromatic aldehydes to form the unsaturated ketones, whereas in the case of 3- and 4-benzaldehydes the
corresponding trans-2-styrylpyrimidine-4(3H)-ones were obtained. A possible mechanism of hydrolytic
cleavage of the product of condensation of 2-(2-oxo-2-phenylethylidene)-2,3-dihydropyrimidine-4(1H)-one
with paraformaldehyde under acid catalysis and mechanochemical activation has been discussed.
Keywords: pyrimidinone, pyrimidine, benzaldehyde, condensation
DOI: 10.1134/S1070363214050156
Only a few pyrimidine derivatives have been con-
sidered CH nucleophiles in condensation with carbonyl
compounds. Most of the studies reported so far have
been devoted to synthesis of 5-ylidene and 5,5'-
ylidenebishydroxypyrimidines from barbituric acids
and their derivatives [1]. Nevertheless, recently efficient
methods to prepare a series of styrylpyrimidines from
benzaldehydes and methylpyrimidines have been
developed [2–4] due to emerging interest towards
investigation of photophysical and photochemical
properties of heterocyclic analogs of stilbene [5].
conditions (refluxing in acetic acid in the presence of
catalytic amounts of p-toluenesulfonic acid mono-
hydrate) resulted in trans-2-styrylpyrimidine-4(3H)-
ones IIIa and IIIb, respectively (Scheme 1).
The high-boiling benzaldehyde, nicotinic aldehyde,
and furfural could be used simultaneously as solvents
in the reaction with pyrimidines Ia, Ib.
Short-run heating of compounds Ia, Ib with excess
of the corresponding aldehydes at 160–170°C gave
unsaturated ketones IIa, IIc–IIf with yields of 30–82%
(Scheme 2).
In continuation of our studies on synthesis of 2-
alkylidenepyrimidines [6–8], herein we discuss some
features of interaction of 2-(2-oxo-2-arylethylidene)-
pyrimidines Ia and Ib with aromatic and hetero-
aromatic aldehydes.
Unlike aromatic aldehydes, paraformaldehyde could
react with pyrimidine Ia in the solid phase in the
presence of acid without heating. Mechanochemical
activation of compound Ia mixed with paraformal-
dehyde in the presence of catalytic amount of p-toluene-
sulfonic acid monohydrate afforded the derivative IV
with good yield.
Addition of the corresponding aldehyde to the
exocyclic double bond of Ia, Ib was accompanied with
the subsequent dehydration. Structure of the reaction
products was determined by nature of the substituent in
the starting benzaldehyde.
The optimal molar ratio compound Ia to p-
toluenesulfonic acid monohydrate was of 4 : 1.
Decreasing the acid content led to slowing down the
reaction, or even to reaction stopping. When the
amount of p-toluenesulfonic acid monohydrate was up
to >20%, hydrolytic cleavage of compound IV
occurred to give symmetrically substituted propane V.
In particular, reaction of pyrimidine Ia with benzal-
dehyde and 4-bromobenzaldehyde afforded arylidene-
ketones IIa and IIb, respectively, whereas the reac-
tions with 3- and 4-nitrobenzaldehydes under similar
869

870
YAVOLOVSKII et al.
Scheme 1.
O
N
R
O
HN
CHO
CH3
R
O
O
HN
IIa, IIb
CH3COOH
O
N
NH CH3
HN
CHO
Ia
O2N
CH3
O2N
IIIa, IIIb
R = H (IIa), Br (IIb), 3-NO2 (IIIa), 4-NO2 (IIIb).
Scheme 2.
O
O
O
NH
O
NH
ArCHO
N
CH3
NH CH3
R
Ar
R
Ia, Ib
IIа, IIc−IIf
R = H (Ia), NO2 (Ib); R = H, Ar = Ph (IIa); R = H, Ar = 3-Py (IIc); R = H, Ar = 2-Fur (IId); R = NO2, Ar = Ph (IIe); R =
NO2, Ar = 2-Fur (IIf).
The latter could be preparatively obtained both in
solution and in the solid phase under mechanical
activation in the presence of equimolar amount of the
acid (Scheme 3).
membered tetrahedral intermediates A should have
facilitated cleavage of the C–C bond to form N-
benzoyl derivative B followed by hydrolysis yielding
benzoic acid and, finally, compound V (X = H). We
believe that in that reaction the pyrimidine ring acted
as a peculiar agent promoting dissociation of the
C–benzoyl bond (Scheme 4).
Examples of the carbon-carbon bond cleavage
under mild conditions have been reported in the cases
of certain β-dicarbonyl compounds [9], including the
side reactions accompanying alkylation of 2-mercapto-
3-ureidopyridines and 5-amino-6-mercaptopyrimidines
halo-β-diketones [10, 11].
EXPERIMENTAL
The solvents were purified by standard proceduress
[12]. TLC analysis was performed with Silufol UV-
254 plates, eluting with chloroform–acetonitrile–
heptane (5 : 2 : 1) or chloroform–acetonitrile–methanol
(5 : 2 : 1) mixture. Solid phase synthesis was
performed in the electromechanical sealed vibrating
mortar KM–1 (Germany). 1H NMR spectra were
In the studied case, the ease of bispyrimidine IV
transformation into compound V could be due to the
acid catalysis (Scheme 4) of successive stages of
intramolecular of heterocycle nitrogen atom to the
benzoyl group. On the other hand, the strain in the six-
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REACTION OF 2-(2-OXO-2-ARYLETHYLIDENE)-2,3-DIHYDROPYRIMIDINE-4(1H)-ONES
871
Scheme 3.
O
O
.
p-TolSO3H H2O
NH
N
NH
<20%
N
O
O
O
CH3
CH3
O
HN
(CH2O)n
N
H
CH3
IV
H
N
H
N
O
O
Ia
.
p-TolSO3H H2O
N
N
equimolar
CH3
CH3
V
Scheme 4.
O
O
O
+
HN
HN
HN
X
X
X
N
O
CH3
N
CH3
Ph
N
CH3
Ph
OH
H+
Ph
OH
Y
Y
Y
+
O
O
O
N
Y
N
HN
X
X
X
N
CH3
Ph
OH
_H+
CH3
N
CH3
N
H2O
_PhCOOH
O
Ph
Y
Y
A
B
O
NH
X = PhCO (IV), H (V),
Y =
.
N
CH3
registered with the Varian WXP-300 spectrometer
(299.9 MHz). Mass spectra were recorded using the
MX 1321 mass spectrometer (70 eV, the ion source
temperature 220°C). Mass spectrum (fast atom
bombardment) of IV was obtained with the VG
Analitycal 7070 ED instrument.
2-[1-Benzoyl-2-phenylvinyl]-6-methylpyrimidine-
4(3H)-one (IIa). a. A mixture of 0.5 g of pyrimidine
Ia, 0.5 g of freshly distilled benzaldehyde, and 0.08 g
of р-TolSO3H·H2O in 10 mL of acetic acid was
refluxed during 8 h. After the solvent was distilled off,
the solid residue was washed with small amount of
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YAVOLOVSKII et al.
methanol and recrystallized from ethanol. Yield 0.3 g
(43%), mp 235–237°C. 1Н NMR spectrum (DMSO-d6),
δ, ppm (J, Hz): 12.58 br.s (1H, NH), 7.99 s (1H,
CHolefin), 7.88 d (2H, CHAr, J 7.5), 7.60 t (1Н, CHAr,
J 7.5), 7.48 t (2H, CHAr, J 7.5), 7.33–7.27 m (5H,
CHAr), 6.22 s (1H, CHpyrimidine), 2.06 s (3H, CH3). Mass
spectrum, m/e (Irel,%): 316(30), 287(100), 259(6), 211
(86), 204(10), 178(7), 128(28), 110(6) 101(7), 84(38),
77(90). Found, %: С 75.86; Н 5.14; N 8.86.
С20Н16N2О2. Calculated, %: С 75.93; Н5.10; N 8.85.
2-[1-Benzoyl-2-(2-furyl)vinyl]-6-methylpyrimidine-
4(3H)-one (IId). A mixture of 1 g of pyrimidine Ia
and 5 mL of freshly distilled furfural was heated
during 1 h. The precipitate was filtered off and washed
with benzene on the filter. Yield 1.1 g (82%), mp 240–
242°C. 1Н NMR spectrum (DMSO-d6), δ, ppm (J, Hz):
12.32 br.s (1H, NH), 7.87 d (2H, CHAr, J 6.0), 7.86 s
(1H, CHolefin), 7.63 d (1H, CHfuryl, J 1.5), 7.61 t (1H,
CHAr, J 6.0), 7.49 t (2H, CHAr, J 6.0), 6.74 d (1H,
CHfuryl, J 3.0), 6.54 d.d (1H, CHfuryl, J 3.0, 1.5), 6.20 s
(1H, CHpyrimidine), 2.07 s (3H, CH3). Mass spectrum,
m/e (Irel, %): 306(57), 277(32), 251(26), 224(22), 201
(17), 198(13), 175(12), 118(13), 105(63), 84(23), 77
(100). Found, %: С 70.51; Н 4.70; N 9.11. С18Н14N2О3.
Calculated, %: С 70.58; Н 4.61; N 9.15.
b. A mixture of 1 g of pyrimidine Ia and 5 mL of
freshly distilled benzaldehyde was heated during 1 h at
160–170°C. After cooling, the precipitate was filtered
off, washed with benzene, and dried in air. Yield 0.5 g
(36%), mp 235–237°C.
2-[1-(4-Nitrobenzoyl)-2-phenylvinyl]-6-methyl-
pyrimidine-4(3H)-one (IId). A mixture of 0.5 g of
pyrimidine Ib and 3 mL of freshly distilled benzal-
dehyde was heated during 5 h. After cooling, the
reaction mixture was diluted with 3 mL of benzene,
and the reaction product was precipitated with heptane.
The solvents were decanted. Gummy precipitate was
triturated with methanol, and the crystals formed were
filtered off and dried in air. Yield 0.2 g (30%), mp
2-[1-Benzoyl-2-(4-bromophenyl)vinyl]-6-methyl-
pyrimidine-4(3H)-one (IIb). A mixture of 0.2 g of Ia,
0.3 g of p-bromobenzaldehyde, and 0.03 g of р-
TolSO3H·H2O in 10 mL of acetic acid was refluxed
during 14 h. After the solvent was distilled off, the
solid residue was washed with methanol and
recrystallized from ethanol. Yield 0.1g (27%), mp
1
231–232°C. Н NMR spectrum (DMSO-d6), δ, ppm
(J, Hz): 12.58 br.s (1H, NH), 7.95 s (1H, CHolefin), 7.86
d (2H, CHAr, J 7.5), 7.61 t (1H, CHAr, J 7.5), 7.51 d
(2H, CHAr, J 8.4), 7.48 t (2H, CHAr, J 7.5), 7.26 d (2H,
CHAr, J 8.4), 6.22 s (1H, CHpyrimidine), 2.06 s (3H, CH3).
Mass spectrum, m/e (Irel, %): 394(20), 367(63), 291
(19), 287(12), 211(63), 206(10), 143(12), 127(14), 110
(7), 105(62), 100(8), 77(100). Found, %: С 60.69; Н
3.87; N 7.05. С20Н15BrN2О2. Calculated, %: С 60.78;
Н 3.83; N 7.09.
1
170–180°C. Н NMR spectrum (DMSO-d6), δ, ppm
(J, Hz): 12.80 br.s (1H, NH), 8.30 d (2H, CHAr, J 9.0),
8.12 d (2H, CHAr, J 9.0), 8.0 s (1H, CHolefin), 7.36–7.26
m (5H, CHAr), 6.25 s (1H, CHpyrimidine), 2.05 s (3H,
CH3). Mass spectrum, m/e (Irel, %): 361(42), 333(100),
287(12), 273(7), 256(17), 211(38), 150(12), 128(24),
110(6), 104(24), 92(8), 84(50), 77(20). Found, %: С
66.41; Н 4.22; N 11.59. С20Н15N3О4. Calculated, %: С
66.48; Н 4.18; N 11.63.
2-(1-Benzoyl-2-pyridin-3-yl-vinyl)-6-methyl-
pyrimidine-4(3H)-one (IIc). A mixture of 0.4 g of Ia
and 1.1 mL of nicotinic aldehyde was heated during
1 h at 160–170°C. After cooling, the reaction mixture
was diluted with 4 mL of benzene, and then with 4 mL
of heptane. The resulting precipitate was filtered off
and washed with small amount of methanol. Yield 0.3 g
2-[1-(4-Nitrobenzoyl)-2-(2-furyl)vinyl]-6-methyl-
pyrimidine-4(3H)-one (IIe). A mixture of 0.3 g of
pyrimidine Ib and 4 mL of freshly distilled furfural
was refluxed during 1.5 h. The precipitate was filtered
off and washed with benzene on the filter. Yield 0.3 g
(77%), mp 250–252°C. 1Н NMR spectrum, (DMSO-d6),
δ, ppm (J, Hz): 12.45 br.s (1H, NH), 8.33 d (2H, CHAr,
J 9.0), 8.12 d (1H, CHAr, J 9.0), 7.95 s (1H, CHolefin),
7.64 d (1H, CHfuryl, J 1.5), 6.85 d (1H, CHfuryl, J 3.0),
6.57 d.d (1H, CHfuryl, J 3.0, 1.5), 6.23 s (1H, CHpyrimidine),
2.07 s (3H, CH3). Mass spectrum, m/e (Irel, %): 351
(100), 323(42), 310(7), 297(47), 280(12), 276(14), 269
(22), 201(33), 175(28), 150(37), 118(27), 104(47), 92
(17), 84(47), 77(46). Found, %: С61.48; Н 3.77; N
11.99. С18Н13N3О5. Calculated, %: С 61.54; Н 3.73; N
11.96.
1
(54%), mp 214–215°C. Н NMR spectrum (DMSO-
d6), δ, ppm (J, Hz): 12.43 br.s (1H, NH), 8.54 s (1H,
CHpyridine), 8.45 d (1H, CHpyridine, J 6.0), 8.02 s (1H,
CHolefin), 7.88 d (2H, CHAr, J 6.0), 7.66–7.58 m (2H,
CHAr, CHpyridine), 7.49 t (2H, CHAr, J 6.0), 7.31 d.d
(1H, CHpyridine, J 6.0, 3.0), 6.27 s (1H, CHpyrimidine), 2.10
s (3H, CH3). Mass spectrum, m/e (Irel, %): 317 (32),
289(51), 288(55), 287(45), 211(48), 129(12), 105(62),
84(27), 77(100). Found, %: С 75.86; Н 5.15; N 8.88.
С20Н16N2О2. Calculated, %: С 75.93; Н 5.10; N 8.85.
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REACTION OF 2-(2-OXO-2-ARYLETHYLIDENE)-2,3-DIHYDROPYRIMIDINE-4(1H)-ONES
873
1,3-Bis(4-methyl-6-oxo-1,6-dihydropyrimidin-2-
yl)propane (V). a. Synthesis was performed similarly
to that of IV from 0.9 g of pyrimidine Ia, 0.25 g of
paraformaldehyde, and 0.75 g of р-TolSO3H·H2O. The
reaction product was dissolved in water and filtered.
The filtrate was neutralized with sodium carbonate and
evaporated on a rotary evaporator to dryness. The solid
residue was extracted three times with chloroform–
methanol mixture (1 : 1). The combined extracts were
evaporated to dryness; the residue was washed with
hot benzene and recrystallized from methanol–dioxane
mixture (1 : 3). Yield 0.33 g (64%), mp 273–275°C.
1Н NMR spectrum (DMSO-d6), δ, ppm (J, Hz): 12.20
br.s (2H, 2NH), 5.99 s (2H, 2CHpyrimidine), 2.54 t (4H,
2CH2, J 7.2), 2.12 s (6H, 2CH3), 2.03 t (2H, CH2,
J 7.2). Mass spectrum, m/e (Irel, %): 260(6), 137(100),
124(71), 105(7), 84(18). Found, %: С 59.89; Н 6.25; N
21.57. С13Н16N4О2. Calculated, %: С 59.99; Н 6.20; N
21.52.
2-[2-(3-Nitrophenyl)vinyl]-6-methylpyrimidine-
4(3H)-one (IIIa). A mixture of 1.0 g of pyrimidine Ia,
0.99 g of m-nitrobenzaldehyde, and 0.17 g of р-
TolSO3H·H2O was refluxed in 50 mL of acetic acid
during 28 h. The resulting precipitate was filtered off,
washed sequentially with methanol, water, and methanol.
Yield 0.6 g (55%), mp 270–273°C. 1Н NMR spectrum,
(DMSO-d6), δ, ppm (J, Hz): 12.39 s (1H, NH), 8.43 s
(1H, CHAr), 8.23 d (1H, CHAr, J 8.1), 8.08 d (1H,
CHAr, J 8.1), 7.95 d (1H, CHolefin, J 15.9), 7.74 t (1H,
CHAr, J 8.1), 7.08 d (1H, CHolefin, J 15.9), 6.13 s (1H,
CHpyrimidine), 2.24 s (3H, CH3). Mass spectrum, m/e (Irel,
%): 257(100), 240(10), 210(75), 182(18), 128(40), 110
(10), 101(20), 91(7), 84(85). Found, %: С 60.61; Н
4.36; N 16.38. С13Н11N3О3. Calculated, %: С 60.70; Н
4.31; N 16.33.
2-[2-(4-Nitrophenyl)vinyl]-6-methylpyrimidine-
4(3H)-one (IIIb) was prepared similarly, the reaction
1
time was 20 h. Yield 60%, mp >300°C. Н NMR
b. A mixture of 0.9 g of pyrimidine Ia, 0.25 g of
paraformaldehyde, and 0.75 g of р-TolSO3H·H2O was
dissolved in minimal amount of boiling ethanol. The
solution was heated during 15 h, and then the solvent
was evaporated on a rotary evaporator. The residue
was dissolved in water and filtered. The filtrate was
neutralized with sodium carbonate and evaporated on a
rotary evaporator to dryness. The solid residue was
extracted three times with chloroform–methanol
mixture (1 : 1). The combined extracts were evaporated
to dryness, the residue was washed with hot benzene
and recrystallized from methanol–dioxane mixture
(1 : 3). Yield 0.3 g (59%), mp 273–275°C.
spectrum, (DMSO-d6), δ, ppm (J, Hz): 12.46 s (1H,
NH), 8.28 d (2H, CHAr, J 8.7), 7.93 d (1H, CHolefin
J 15.9), 7.89 d (2H, CHAr, J 8.7), 7.09 d (1H, CHolefin
,
,
J 15.9), 6.14 s (1H, CHpyrimidine), 2.24 s (3H, CH3).
Mass spectrum, m/e (Irel, %): 257 (100), 240(27), 210
(78), 182(8), 128(22), 110(8), 101(12), 91(5), 84(75).
Found, %: С 60.59; Н 4.38; N.32. С13Н11N3О3. Cal-
culated, %: С 60.70; Н 4.31; N.33.
1,3-Bis(4-methyl-6-oxo-1,6-dihydropyrimidin-2-
yl)-1,3-dibenzoylpropane (IV). A mixture of 0.7 g of
Ia, 0.18 g of paraformaldehyde, and 0.12 g of р-
TolSO3H·H2O was stirred in the vibration mortar
during 17–20 h (reaction progress was monitored by
TLC). The reaction mixture was transferred onto a
glass filter, washed with water, and dried under water
jet pump vacuum. The precipitate was mixed with
70 mL of methylene chloride, and the solid part was
filtered off. The filtrate was diluted with 50 mL of
hexane and incubated for precipitate formation. The
precipitate was filtered off and dried on air. Yield 0.6 g
(83%), mp 135–140°C. 1Н NMR spectrum (DMSO-d6),
δ, ppm (J, Hz): 12.45 br.s (2H, 2NH), 8.08–7.47 m
(10Н, СНAr), 6.15 s (1.2H, 2CHpyrimidine), 5.99 s (0.8H,
2CHpyrimidine), 4.94–4.76 m (2H, 2CHСО), 2.63–2.59 m
(1H, CH2), 2.26 s (3.6Н, 2CH3), 2.20–2.06 m (1H,
CH2), 1.97 s (2.4H, 2CH3). Mass spectrum (FAB): m/e
469 [M + H]+. Found, %: С 69.17; Н 5.21; N 11.99.
С27Н24N4О4. Calculated, %: С 69.22; Н 5.16; N 11.96.
ACKNOWLEDGMENTS
This work was performed in the frame of target
complex program of basic research “Fundamental
problems of creating new substances and industrial
chemicals” of National Academy of Sciences of
Ukraine (project no. 16).
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