Synthesis of 5-nitro-3,4-dihydropyrimidin-2(1H)-ones catalyzed by metal salts. Retro-Henry reaction with formation of N,N′-disubstituted ureas

Article abstract of DOI:10.1134/S1070428007010113

Three-component condensation of α-nitroacetophenone with aromatic aldehydes and urea in the presence of iron(III), cobalt(II), nickel(II), and copper(II) salts as catalyst led to the formation of 4,6-diaryl-5-nitro-3,4- dihydropyrimidin-2(1H)-ones and N-b

Full text of DOI:10.1134/S1070428007010113

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2007, Vol. 43, No. 1, pp. 90–95. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © V.F. Sedova, V.P. Krivopalov, O.P. Shkurko, 2007, published in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 1, pp. 87–91.
Synthesis of 5-Nitro-3,4-dihydropyrimidin-2(1H)-ones
Catalyzed by Metal Salts. Retro-Henry Reaction
with Formation of N,N'-Disubstituted Ureas
V. F. Sedova, V. P. Krivopalov, and O. P. Shkurko
Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 9, Novosibirsk, 630090 Russia
e-mail: oshk@nioch.nsc.ru
Received May 14, 2005
Abstract—Three-component condensation of α-nitroacetophenone with aromatic aldehydes and urea in the
presence of iron(III), cobalt(II), nickel(II), and copper(II) salts as catalyst led to the formation of 4,6-diaryl-5-
nitro-3,4-dihydropyrimidin-2(1H)-ones and N-benzoyl-N'-(1-aryl-2-nitroethyl)ureas. The latter were formed as
a result of retro-nitroaldol (retro-Henry) reaction of intermediate 4,6-diaryl-6-hydroxy-5-nitro-3,4,5,6-tetra-
hydropyrimidin-2(1H)-ones.
DOI: 10.1134/S1070428007010113
5-Alkoxycarbonyl- and amido-substituted 3,4-dihy-
dropyrimidin-2(1H)-ones exhibit pronounced biologic-
al activity: nifedipine-like calcium channel blockers,
antihypertensive agents, and α-adrenergic and neuro-
peptide antagonists were found among these com-
pounds [1]. 3,4-Dihydropyrimidin-2(1H)-one deriva-
tives are commonly synthesized by three-component
condensation of aldehydes with urea and β-dicarbonyl
compounds in boiling alcohol in the presence of a cata-
lytic amount of mineral acids (Biginelli reaction) [2].
In the recent time, numerous attempts were made to
modify the Biginelli reaction conditions by using vari-
ous aprotic Lewis acids as catalysts, carrying out the
reaction in various solvents and under solvent-free
conditions, and applying microwave irradiation [3, 4].
We previously synthesized a series of 4,6-diaryl-5-
nitro-3,4-dihydropyrimidin-2(1H)-ones I using α-nitro-
acetophenone instead of β-dicarbonyl compound in the
Scheme 1.
H
Ar
H
Ar
O
NO2
H
NO2
H
O
O
HN
HN
Catalyst
+
+
ArCHO
NO2
O
Ph
OH
Ph
H2N
NH2
Ph
O
N
H
NH2
IV
IIa–IId
V
Ar
NO2
Ph
HN
–H2O
O
N
H
Ia–Id
O
O
Ar
Catalyst
NO2
Ph
N
H
N
H
IIIa–IIId
Ar = RC6H4, R = H (a), m-O2N (b), m-F (c), p-MeO (d); catalyst = FeCl3 ·6H2O, CoCl2 ·6H2O, NiCl2 ·6H2O,
CuSO4 ·5H2O, Cu(OAc)2 ·H2O.
90

SYNTHESIS OF 5-NITRO-3,4-DIHYDROPYRIMIDIN-2(1H)-ONES
91
Scheme 2.
[C6H5]+
F1
–H
F2
–46 [NO2]
–121 [C6H5CONH2]
m/z 77
[M]+
F4
[C6H5CO]+
m/z 105
–47 [H], [NO2]
–105 [C6H5CO]
–120 [C6H5CONH]
F3
F5
–121 [C6H5CONH2]
Biginelli reaction with substituted benzaldehydes and
urea under standard conditions (EtOH, HCl), and the
products showed antiarrythmic activity [5].
nitro compounds [8]. The other fragment ions (F2–F5)
originate from subsequent decomposition of ions F1
and F2 ([M – HNO2]+); no ion peak with m/z 46 [NO2]+
or 30 [NO]+ was found in the spectra, and the most
abundant fragment ions were [PhCO]+ (m/z 105, 100%)
and [C6H5]+ (m/z 77, 62–86%) (Scheme 2).
With a view to elucidate whether analogous modifi-
cations could be applied to the synthesis of nitrodihy-
dropyrimidinones I to raise their yields, we examined
three-component condensation of α-nitroacetophenone
with aromatic aldehydes IIa–IId and urea in the pres-
ence of inorganic iron(III), cobalt(II), nickel(II), and
copper(II) salts as catalyst [4]. In the condensation of
α-nitroacetophenone with benzaldehyde (IIa) and urea
in the presence of FeCl3·6H2O in boiling ethanol, we
isolated two products, the expected nitrodihydropyri-
midinone Ia and N-benzoyl-N'-(2-nitro-1-phenyl-
ethyl)urea (IIIa). The reactions with other aromatic
aldehydes IIb–IId also led to the formation of mix-
tures of two products, dihydropyrimidinones Ib–Id and
N,N'-disubstituted ureas IIIb–IIId (Scheme 1). How-
ever, their overall yield did not exceed 45% (see table).
1
Apart from aromatic proton signals, the H NMR
spectra of compounds III contained five one-proton
signals. Two downfield signals were assigned to the
N1H (s) and N3H protons (d, J = 8.4– 8.8 Hz); the
intensity of these signals decreased upon addition of
CD3OD to solutions of IIIb and IIIc in DMSO-d6. The
remaining three signals in the region δ 5.0–6.0 ppm did
not change their intensity upon addition of CD3OD
over a period of 24 h and were assigned to CH protons.
Two slightly distorted doublets of doublets at δ 5.00–
5.50 ppm are likely to belong to protons in the
CH2NO2 group (AB system, JAB = 13.1–13.9 Hz). The
vicinal coupling constants between 5-HA and 5-HB, on
The structure of disubstituted ureas IIIa–IIId was
determined on the basis of their spectral parameters
and analytical data. Compounds IIIa–IIIc showed in
the IR spectra (KBr) two absorption bands at 1694–
1690 and 1674–1660 cm–1 due to stretching vibrations
of the carbonyl groups, while the spectrum of IIId
contained one absorption band at 1684 cm–1; stretching
vibrations of the NH groups appeared at 3335–
3244 cm–1. In the IR spectrum of IIIc recorded in
mineral oil we observed two NH stretching vibration
bands at 3261 and 3332 cm–1, while bands assignable
to OH vibrations were absent. All compounds IIIa–
IIId characteristically displayed absorption bands at
1566–1546 and 1383–1378 cm–1 belonging, respec-
tively, to asymmetric and symmetric stretching vibra-
tions of the aliphatic nitro group.
Condensation of α-nitroacetophenone with aromatic alde-
hydes IIa–IId and urea (reactant ratio 1:1:2) in the pres-
ence of metal salts MXn
a
Initial
Yield of I,b
Yield, %
aldehyde Catalyst MXn
no.
% [5]
I
III
FeCl3·6H2O
FeCl3·6H2O
FeCl3·6H2O
FeCl3·6H2O
CoCl2·6H2O
CuSO4·5H2O
Cu(OAc)2 ·H2O
CoCl2·6H2O
NiCl2·6H2O
27
27
16
09
08
05
22
21
17
24
28
63
62
57
58
IIa
IIb
IIc
16
13
IId
IIb
IIb
IIb
IIbc
IIbc
06
–
–
Traces
Traces
The mass spectra of IIIa–IIId lack molecular ion
peaks [M]+; the heaviest fragment ion has an m/z value
and elemental composition (determined from the high-
resolution spectra) corresponding to loss of the nitro
group, [M – NO2]+ (F1), which is typical of aliphatic
a
25 mol % of MXn, EtOH, 3 drops of concentrated hydrochloric
acid, reflux.
Concentrated hydrochloric acid, 2-propanol, reflux.
In acetonitrile; compound Ib was detected in the reaction mixture
by TLC (Silufol, CHCl3–EtOH, 15:1).
b
c
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 1 2007

SEDOVA et al.
92
the one hand, and 4-H, on the other, depend on mutual
arrangement of these protons (3J = 8.0–8.5 and 4.4–5.4
Hz, respectively). The 4-H signal appears as a double
doublet of doublets or a multiplet at δ 5.50–6.00 ppm.
It should be noted that H–D exchange at the nitrogen
atoms in molecule IIIb (DMSO-d6–CD3OD) leads to
the transformation of the 4-H signal into a doublet of
doublets (J = 4.4, 8.4 Hz). When an NMR ampule
containing a solution of compound IIIb in DMSO-d6–
CD3OD was kept for a month at room temperature, the
appearance of the three CH signals and the intensity
of the 5-HA and 5-HB signals changed as a result of
deuterium exchange in the CH2NO2 fragment (1-H:
3-H:4-H:5-HA:5-HB = 0.17 :0.19:1:0.4:0.4). In this
case, hydrogen–deuterium exchange is facilitated due
to electron-acceptor effect of the nitro group.
dissociation of the C–C bond (retro-Henry reaction)
in acetone or tetrahydrofuran [10] in the presence of
quaternary ammonium bases [9, 11], Al2O3 [9], or SiO2
[6], and by the action of NaBH4 [12], Al/Hg [6], or
CuSO4/SiO2 [13]. The yield of the retro-nitroaldol re-
action products in the presence of CuSO4/SiO2 attains
75%. Analogous transformations were observed previ-
ously for aliphatic [9, 11, 14], cyclic [10, 12, 13], and
heterocyclic compounds [10, 15].
In our experiments, an iron salt present in the
reaction mixture could exert the same catalytic effect
on the decomposition of cyclic β-nitro alcohols V as
that of copper and other metal salts [10, 13]. Therefore,
by analogy with published data [13], we presume inter-
mediate formation of complex VI in which the metal
ion favors dissociation of the endocyclic C5–C6 bond
with formation of acyclic nitro derivatives, N-benzoyl-
N'-(1-aryl-2-nitroethyl)ureas III (Scheme 3). When the
reaction with m-nitrobenzaldehyde (IIb) was perform-
ed in the presence of 2 equiv of FeCl3·6H2O, the yield
of the retro-Henry reaction product did not increase
(IIIb, 8.4%).
9
R
7
H
11
NO2
4
HN
2
6
13
15
O
N
H
Scheme 3.
17
O
N
I
Ar
H
H
R
Ph
H
O
NH
H
Fe3+
O
N
O
9
11
Fe+
V
O
N
H
O
HN
O
Ph
O
O
7
N
O
6
H
NO2
Ar
15
N
N
13
H1
H 3
5
VI
17
O
O
Ar
III
H+
NO2
III
The 13C NMR spectra of compounds III were fully
consistent with the assumed structure. The spectra con-
tained signals from aromatic carbon atoms, downfield
signals from the carbonyl carbon atoms (C6, δC 168.27–
168.43 ppm; C2, δC 152.82–153.13 ppm), and upfield
signals from the C4 (δC 50.67–51.20 ppm) and C5
carbon atoms (δC 77.66–78.49 ppm).
Ph
N
H
N
H
H
The reaction of ArCHO with urea and α-(p-nitro-
phenoxy)acetophenone (VII) instead of α-nitroaceto-
phenone in the presence of FeCl3·6H2O gave neither
appreciable amount of 5-(4-nitrophenoxy)-4,6-di-
phenyl-3,4-dihydropyrimidin-2(1H)-ones nor other
compounds whose formation could indicate the occur-
rence of three-component condensation. From the
reaction mixture we isolated initial acetophenone VII
(90%). Presumably, the reason is reduced reactivity of
the α-methylene group in VII as compared to nitro-
acetophenone.
The formation of disubstituted ureas III in the
reaction under study may be rationalized according to
Scheme 1. The primary condensation product is N-sub-
stituted urea IV which undergoes heterocyclization to
hexahydropyrimidin-2-one V. The latter may be
regarded as a cyclic β-nitro alcohol. It is known that
dehydration of β-nitro alcohols usually gives nitrovinyl
derivatives [6, 7, 9] and that some compounds can
decompose into nitro and carbonyl compounds via
In the condensation with aldehyde IIb as an ex-
ample we examined the effect of other metal salts,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 1 2007

SYNTHESIS OF 5-NITRO-3,4-DIHYDROPYRIMIDIN-2(1H)-ONES
93
CoCl2· 6 H2O, NiCl2 · 6 H2O, CuSO4 · 5 H2O, and
Cu(OAc)2·H2O. The results are collected in table. It is
seen that all these metal ions are more efficient in the
retro-Henry reaction than Fe3+. The Cu(II)-catalyzed
reaction gave no pyrimidinone Ib (according to the
TLC data). In other experiments, the amount of the
corresponding product was also insignificant. In the
reaction catalyzed by CoCl2·6H2O, the yield of Ib was
5.9%, i.e., it was lower by a factor of almost 4 than the
yield of urea IIIb. The use of acetonitrile as solvent in
the Co2+ and Ni2+-catalyzed reactions led to a relatively
high yield of urea IIIb, while the concentration of
pyrimidine Ib in the reaction mixture was very small
(compound Ib was detected only by chromatography).
of α-nitroacetophenone, 15 mmol of aromatic aldehyde
IIa–IId, 30 mmol of urea, and 3.7 mmol of the corre-
sponding metal salt MXn in 30 ml of ethanol or aceto-
nitrile. The mixture was heated for 6 h under reflux
and cooled to room temperature, and the precipitate
was filtered off, washed with ethanol, water (2×10 ml),
and aqueous ethanol (1:1, 2×5 ml), dried, and recrys-
tallized. Compounds IIIa–IIId were thus isolated. The
filtrate was poured into 3 volumes of water, and oily
material separated and was ground with alcohol, and
the precipitate was filtered off, washed with aqueous
alcohol (1:1, 3×5 ml), and recryctallized. Compounds
Ia–Id were characterized by melting points, IR spec-
tra, and TLC data (cf. [5]).
Thus we were the first to demonstrate that the
three-component condensation of α-nitroacetophenone
with aromatic aldehydes and urea in the presence of
Fe3+, Co2+, Ni2+, and Cu2+ salts leads to the formation
of 4,6-diaryl-5-nitro-3,4-dihydropyrimidin-2(1H)-ones
and N-benzoyl-N'-(1-aryl-2-nitroethyl)ureas. The latter
are products of the retro-nitroaldol reaction of inter-
mediate cyclic β-nitro alcohols, 4,6-diaryl-6-hydroxy-
5-nitro-3,4,5,6-tetrahydropyrimidin-2(1H)-ones.
Cobalt(II), nickel(II), and copper(II) salts turned out to
be more effective catalysts in the retro-Henry reaction
than iron(III) salts. Therefore, the examined modifica-
tions of the cyclocondensation conditions could not
compete with the procedure proposed previously [5]
for the synthesis of nitrodihydropyrimidinones I (see
table). On the other hand, the reaction in the presence
of mineral salts may be used to obtain difficultly
accessible nitroethyl-substituted ureas.
5-Nitro-4,6-diphenyl-3,4-dihydropyrimidin-
2(1H)-one (Ia). mp 206–208°C (from EtOH) [5].
5-Nitro-4-(3-nitrophenyl)-6-phenyl-3,4-dihydro-
pyrimidin-2(1H)-one (Ib). mp 220–222°C (from
1
EtOH); published data [5]: mp 221–223°C. H NMR
spectrum (400 MHz), δ, ppm: 5.82 s (1H, 4-H), 7.38–
3
7.55 m (5H, Harom), 7.72 d.d (1H, 11-H, J10,11 = 7.2,
3
3J11,12 = 7.6 Hz), 7.89 d (1H, 10-H, J10,11 = 7.2 Hz),
3
8.19 d (1H, 12-H, J11,12 = 7.6 Hz), 8.27 s (1H, 8-H),
8.47 s (1H, 3-H), 10.19 s (1H, 1-H). 13C NMR spec-
trum (100 MHz), δC, ppm: 53.61 (C4), 121.34 (C8),
121.57 (C5), 122.96 (C10), 127.68 (C14, C18), 128.34
(C15, C17), 129.94 (C11), 130.57 (C16), 132.12 (C13),
132.93 (C12), 144.25 (C7), 148.02 (C9), 149.98 (C6),
150.29 (C2).
4-(3-Fluorophenyl)-5-nitro-6-phenyl-3,4-dihy-
dropyrimidin-2(1H)-one (Ic). mp 202–204°C (from
1
EtOH); published data [5]: mp 203–205°C. H NMR
3
spectrum (400 MHz), δ, ppm: 5.69 d (1H, 4-H, J3,4
=
EXPERIMENTAL
3
3
3.4 Hz), 7.20 d.t (1H, 10-H, JHF = 8.0, J10,11 = 8.0,
3
4
4J8,10 = 2.1 Hz), 7.23 t.d (1H, 8-H, JHF = 10, J8,10
=
The IR spectra were recorded in KBr on a Bruker
Vector-22 spectrophotometer. The UV spectra of solu-
tions in ethanol were recorded on a Specord M-40
spectrophotometer. The mass spectra (electron impact,
70 eV) were obtained on a Finnigan MAT 8200 instru-
ment with direct sample admission into the ion source.
2.1, 4J8,12 = 1.0 Hz), 7.31 d (1H, 12-H, J11,12 = 7.2 Hz),
3
3
7.42–7.54 m (6H, C6H5, 11-H), 8.39 d (1H, 3-H, J3,4
=
3.4 Hz), 10.10 s (1H, 1-H). 13C NMR spectrum
2
(100 MHz), δC, ppm: 53.76 (C4), 113.35 d (C8, JCF
=
22.0 Hz), 114.86 d (C10, JCF = 21.0 Hz), 121.99 (C5),
122.22 d (C12, 4JCF = 2.0 Hz), 127.69 (C14, C18), 128.33
2
1
The H and 13C NMR spectra were measured on
(C15, C17), 129.86 (C16), 130.93 d (C11, JCF = 8.0 Hz),
3
Bruker AC-200 and AM-400 spectrometers from solu-
tions in DMSO-d6 using the solvent signals as refer-
ence (δ 2.50, δC 39.50 ppm). The purity of the products
was checked by TLC on Silufol UV-254 plates using
CHCl3–EtOH (15:1) as eluent.
132.28 (C13), 144.91 d (C7, 3JCF = 7.0 Hz), 149.81 (C6),
150.16 (C2), 162.25 d (C9, 1JCF = 223 Hz).
4-(4-Methoxyphenyl)-5-nitro-6-phenyl-3,4-dihy-
dropyrimidin-2(1H)-one (Id). mp 246–248°C (from
1
EtOH); published data [5]: mp 247–249°C. H NMR
General procedure for three-component con-
densation of α-nitroacetophenone with aromatic
aldehydes and urea. Three drops of concentrated
hydrochloric acid were added to a solution of 15 mmol
spectrum (200 MHz), δ, ppm: 3.77 s (3H, MeO),
3
5.60 d (1H, 4-H, J3,4 = 3.2 Hz), 6.98 d (2H, 9-H,
3
3
11-H, J8,9 = 8.6 Hz), 7.37 d (2H, 8-H, 12-H, J8,9
=
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 1 2007

SEDOVA et al.
94
8.6 Hz), 7.41–7.53 m (5H, C6H5), 8.31 d (1H, 3-H,
N-Benzoyl-N'-[1-(3-fluorophenyl)-2-nitroethyl]-
urea (IIIc). mp 186–187°C (from EtOH). UV spec-
trum, λmax, nm (logε): 206 (4.44), 236 (4.30), 269 sh
(3.51). IR spectrum, ν, cm–1: 3334, 3264 (NH); 1690,
3J3,4 = 3.2 Hz), 10.00 s (1H, 1-H).
N-Benzoyl-N'-(2-nitro-1-phenylethyl)urea (IIIa).
mp 183–186°C (from EtOH). UV spectrum, λmax, nm
(logε): 203 (4.51), 235 (4.26), 270 sh (3.15). IR spec-
trum, ν, cm–1: 3287, 3244, 3131 (NH); 1690, 1660
1
1672 (C=O); 1545, 1536, 1379, 1353. H NMR spec-
2
trum (400 MHz), δ, ppm: 5.15 d.d (1H, 5-HA, JAB
=
3
2
1
13.6, J4,5 = 4.4 Hz), 5.31 d.d (1H, 5-HB, JAB = 13.6,
(C=O); 1554, 1529, 1504, 1383. H NMR spectrum
3J4,5 = 8.5 Hz), 5.69–5 80 m (1H, 4-H), 7.17 t (1H,
2
(400 MHz), δ, ppm: 5.11 d.d (1H, 5-HA, JAB = 13.6,
3
3
2
3J4,5 = 4.8 Hz), 5.25 d.d (1H, 5-HB, JAB = 13.6, 3J4,5
=
10-H, J10,11 = JHF = 8.4 Hz), 7.34 d (1H, 12-H,
3J11,12 = 7.7 Hz), 7.39 d (1H, 8-H, JHF = 10.3 Hz),
3
3
3
8.1 Hz), 5.69 d.d.d (1H, 4-H, J4,5A = 4.8, J4,5B = 8.1,
3
3J4, 3 = 8.4 Hz), 7.34 t (1H, 10-H, J10, 9 = J10, 11
=
3
3
7.45 m (1H, 11-H), 7.51 t (2H, 15-H, 17-H, J15,14
=
=
7.4 Hz), 7.41 t (2H, 9-H, 11-H, 3J9,8 = 3J9,10 = 7.4 Hz),
3J15,16 = 7.7 Hz), 7.62 t (1H, 16-H, J16,15 = J16,17
3
3
3
3
7.49 d (2H, 8-H, 12-H, J8, 9 = 7.4 Hz), 7.52 t (2H,
7.7 Hz), 7.99 d (2H, 14-H, 18-H, J14,15 = 7.7 Hz),
3
3
3
15-H, 17-H, J15, 14 = J15, 16 = 7.7 Hz), 7.63 t (1H,
16-H, 3J16,15, 3J16,17 = 7.7 Hz), 7.99 d (2H, 14-H, 18-H,
9.51 d (1H, 3-H, J3,4 = 8.8 Hz), 10.92 s (1H, 1-H).
13C NMR spectrum (100 MHz), δC, ppm: 50.83 (C4),
78.13 (C5), 113.86 d (C8, 2JCF = 22 Hz), 114.94 d (C10,
2JCF = 21 Hz), 123.03 (C12), 128.27 (C14, C18), 128.56
3J14,15 = 7.7 Hz), 9.49 d (1H, 3-H, J3,4 = 8.4 Hz),
3
10.84 s (1H, 1-H). 13C NMR spectrum (100 MHz), δC,
ppm: 51.20 (C4), 78.45 (C5), 126.64 (C8, C12), 127.94
(C10), 128.08 (C14, C18), 128.39 and 128.62 (C9, C11,
C15, C17), 132.23 (C13), 132.78 (C16), 137.61 (C7),
152.89 (C2), 168.30 (C6). Mass spectrum, m/z (Irel, %):
267 (17.3) [M – NO2]+, 266 (27.7) [M – HNO2]+, 161
(12.6), 146 (28.2), 145 (18.4), 105 (100), 77 (61.8).
Found, %: C 61.10; H 4.83; N 13.30. m/z 267.1133.
C16H15N3O4. Calculated, %: C 61.33; H 4.83; N 13.41.
(M – NO2) 267.1133 (C16H15N2O2).
(C15, C17), 130.79 d (C11, JCF = 8 Hz), 132.32 (C13),
3
132.98 (C16), 140.69 d (C7, JCF = 7 Hz), 153.13 (C2),
3
162.28 d (C9, JCF = 242 Hz), 168.43 (C6). Mass spec-
1
trum, m/z (Irel, %): 285 (28.0) [M – NO2]+, 284 (41.2)
[M – HNO2]+, 179 (13.3), 164 (26.6), 163 (17.7), 105
(100), 77 (76.3). Found, %: C 57.84; H 4.16; F 5.93;
N 12.58. m/z 285.1008. C16H14FN3O4. Calculated, %:
C 58.00; H 4.26; F 5.74; N 12.68. (M – NO2) 285.1039
(C16H14FN2O2).
N-Benzoyl-N'-[2-nitro-1-(3-nitrophenyl)ethyl]-
urea (IIIb). mp 199–200°C (from EtOH–dioxane). UV
spectrum, λmax, nm (logε): 208 (4.43), 237 (4.37),
263 sh (4.06). IR spectrum, ν, cm–1: 3253, 3168 (NH);
1695, 1674 (C=O); 1566, 1529, 1504, 1377, 1358.
1H NMR spectrum (200 MHz), δ, ppm: 5.21 d.d (1H,
N-Benzoyl-N'-[1-(4-methoxyphenyl)-2-nitro-
ethyl]urea (IIId). mp 181–182°C (from EtOH). IR
spectrum, ν, cm–1: 3432, 3261 (NH); 1684 (C=O);
1556, 1533, 1515, 1379, 1354. H NMR spectrum
(200 MHz), δ, ppm: 3.74 s (3H, MeO), 5.04 d.d (1H,
1
2
3
5-HA, JAB = 13.1, J4,5 = 5.4 Hz), 5.19 d.d (1H, 5-HB,
2
3
5-HA, JAB = 13.9, J4,5 = 4.4 Hz), 5.40 d.d (1H, 5-HB,
2JAB = 13.1, J4,5 = 8.0 Hz), 5.60 d.d.d (1H, 4-H,
3
3
2JAB = 13.9, J4,5 = 8.4 Hz), 5.86 d.d.d (1H, 4-H,
3J4,5A = 5.4, J4,5B = 8.0, J3,4 = 8.7 Hz ), 6.95 d (2H,
3
3
3
3
3J4,5A = 4.4, J4,5B = 8.4, J3,4 = 8.6 Hz), 7.51 t (2H,
3
3
3
9-H, 11-H, J8,9 = 8.8 Hz), 7.40 d (2H, 8-H, 12-H,
15-H, 17-H, J15,14 = J15,16 = 7.3 Hz), 7.64 t (1H, 16-H,
3J8,9 = 8.8 Hz), 7.50 d.d (2H, 15-H, 17-H, J14,15
=
=
3
3J16,15 = J16,17 = 7.3 Hz), 7.71 t (1H, 11-H, J11,10
=
3
3
3
3
3J11,12 = 8.0 Hz), 7.92–8.04 m (3H, 10-H, 14-H, 18-H),
7.0 Hz, J15,16 = 7.3 Hz), 7.61 t.t (1H, 16-H, J16,15
3J16,17 = 7.3 Hz, J16,14 = J16,18 = 1.4 Hz), 7.97 d.d (2H,
4
4
3
4
8.19 d.d (1H, 12-H, J11,12 = 8.0, J8,12 = 1.5 Hz), 8.43 t
3
4
4
4
14-H, 18-H, J14,15 = 7.0 Hz, J14,16 = 1.4 Hz), 9.39 d
(1H, 8-H, J8,10 = J8,12 = 1.5 Hz), 9.61 d (1H, 3-H,
3J3,4 = 8.6 Hz), 10.89 s (1H, 1-H). 13C NMR spectrum
(50 MHz), δC, ppm: 50.67 (C4), 77.66 (C5), 121.80
(C8), 122.94 (C10), 128.18 (C14, C18), 128.48 (C15, C17),
130.20 (C11), 132.30 (C13), 132.90 (C16), 133.70 (C12),
140.20 (C7), 147.90 (C9), 153.08 (C2), 168.27 (C6).
Mass spectrum, m/z (Irel, %): 312 (42.2) [M – NO2]+,
311 (60.8) [M – HNO2]+, 206 (12.2), 191 (14.7), 190
(30.8), 105 (100), 77 (85.8). Found, %: C 53.38;
H 3.90; N 15.44. m/z 312.0984. C16H14N4O6. Calculat-
ed, %: C 53.63; H 3.94; N 15.64. (M – NO2) 312.0984
(C16N14N3O4).
3
13
(1H, 3-H, J3,4 = 8.7 Hz), 10.82 s (1H, 1-H). C NMR
spectrum (50 MHz), δC, ppm: 50.76 (C4), 55.07
(MeO), 78.49 (C5), 114.06 (C9, C11), 127.97 (C8, C12),
128.08 (C14, C18), 128.42 (C15, C17), 129.51 (C7),
132.25 (C13), 132.80 (C16), 152.82 (C2), 158.96 (C10),
168.29 (C6). Mass spectrum, m/z (Irel, %): 297 (13.8)
[M – NO2]+, 296 (51.0) [M – HNO2]+, 191 (6.0), 176
(97.3), 175 (61.6), 105 (100), 77 (78.7). Found, %:
C 59.31; H 4.95; N 12.10. m/z 296.1156. C17H17N3O5.
Calculated, %: C 59.47; H 4.99; N 12.24. (M – HNO2)
296.1161 (C17N16N2O3).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 1 2007

SYNTHESIS OF 5-NITRO-3,4-DIHYDROPYRIMIDIN-2(1H)-ONES
95
mi, Y., Nakajima, T., Ikeno, T., and Yamada, T., Syn-
thesis, 2004, p. 1947; see also references therein.
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