Dihydropyrimidones: As novel class of β-glucuronidase inhibitors

Article abstract of DOI:10.1016/j.bmc.2016.06.002

Dihydropyrimidones 1–37 were synthesized via a ‘one-pot’ three component reaction according to well-known Biginelli reaction by utilizing Cu(NO₃)₂·3H₂O as catalyst, and screened for their in vitro β-glucuronidase inhibitor

Full text of DOI:10.1016/j.bmc.2016.06.002

Accepted Manuscript
Dihydropyrimidones: As Novel Class of β-Glucuronidase Inhibitors
Farman Ali, Khalid Mohammed Khan, Uzma Salar, Sarosh Iqbal, Muhammad
Taha, Nor Hadiani Ismail, Shahnaz Perveen, Abdul Wadood, Mehreen Ghufran,
Basharat Ali
PII:
S0968-0896(16)30418-7
DOI:
http://dx.doi.org/10.1016/j.bmc.2016.06.002
BMC 13058
Reference:
Bioorganic & Medicinal Chemistry
To appear in:
Received Date:
Revised Date:
Accepted Date:
7 May 2016
31 May 2016
1 June 2016
Please cite this article as: Ali, F., Khan, K.M., Salar, U., Iqbal, S., Taha, M., Ismail, N.H., Perveen, S., Wadood, A.,
Ghufran, M., Ali, B., Dihydropyrimidones: As Novel Class of β-Glucuronidase Inhibitors, Bioorganic & Medicinal
Chemistry (2016), doi: http://dx.doi.org/10.1016/j.bmc.2016.06.002
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Dihydropyrimidones: As Novel Class of β-Glucuronidase Inhibitors
Farman Ali,a Khalid Mohammed Khan,a Uzma Salar,a Sarosh Iqbal,a Muhammad Taha,b,c Nor
Hadiani Ismail,b Shahnaz Perveen,d Abdul Wadood,e Mehreen Ghufrane, Basharat Alia
aH. E. J. Research Institute of Chemistry, International Center for Chemical and Biological
Sciences, University of Karachi, Karachi-75270, Pakistan
bAtta-ur-Rahman Institute for Natural Product Discovery, Universiti Teknologi MARA (UiTM),
Puncak Alam Campus, 42300 Bandar Puncak Alam, Selangor D. E., Malaysia
cFaculty of Applied Science, Universiti Teknologi MARA, Shah Alam 40450, Selangor D. E.,
Malaysia
dPCSIR Laboratories Complex, Karachi, Shahrah-e-Dr. Salimuzzaman Siddiqui, Karachi-75280,
Pakistan
eDepartment of Biochemistry, Computational Medicinal Chemistry Laboratory, UCSS, Abdul
Wali Khan University Mardan, Pakistan
Abstract
Dihydropyrimidones 1-37 were synthesized via a “one-pot” three component reaction according
to well-known Biginelli reaction by utilizing Cu(NO3)2.3H2O as catalyst, and screened for their
in vitro β-glucuronidase inhibitory activity. It is worth mentioning that amongst the active
molecules, compounds 8 (IC50 = 28.16 ± .056 μM), 9 (IC50 = 18.16 ± 0.41 μM), 10 (IC50 = 22.14
± 0.43 μM), 13 (IC50 = 34.16 ± 0.65 μM), 14 (IC50 = 17.60 ± 0.35 μM), 15 (IC50 = 15.19 ± 0.30
μM), 16 (IC50 = 27.16 ± 0.48 μM), 17 (IC50 = 48.16 ± 1.06 μM), 22 (IC50 = 40.16 ± 0.85 μM), 23
(IC50 = 44.16 ± 0.86 μM), 24 (IC50 = 47.16 ± 0.92 μM), 25 (IC50 = 18.19 ± 0.34 μM), 26 (IC50 =
33.14 ± 0.68 μM), 27 (IC50 = 44.16 ± 0.94 μM), 28 (IC50 = 24.16 ± 0.50 μM), 29 (IC50 = 34.24 ±
0.47 μM), 31 (IC50 = 14.11 ± 0.21 μM) and 32 (IC50 = 9.38 ± 0.15 μM) found to be more potent
than the standard D-saccharic acid 1,4-lactone (IC50 = 48.4 ± 1.25 μM). Molecular docking study
was conducted to establish the structure-activity relationship (SAR) which demonstrated that a
number of structural features of dihydropyrimidone derivatives were involved to exhibit the
inhibitory potential. All compounds were characterized by spectroscopic techniques such as 1H-,
13C-NMR, EIMS and HREI-MS.
*Corresponding Author: khalid.khan@iccs.edu, hassaan2@super.net.pk, Tel.: 0092-21-34824910; Fax: 0092-21-
34819018
1

Keywords: Synthesis; Dihydropyrimidone; β-Glucuronidase; In vitro; Molecular docking;
Structure-activity relationship.
Introduction
β-Glucuronidase (EC 3.2.1.31) enzyme exists in anaerobic Escherichia, Bacteroides, Clostridia
and Peptostreptococcus genera and responsible to catalyzes the breakage of β-glucuronosyl-O-
bonds [1]. It is also present in many human body fluids and organs such as bile, kidney, serum,
spleen and urine [2-3]. Enhanced activity of β-glucuronidase leads to a variety of pathological
conditions including epilepsy [4], renal diseases [5], urinary tract infection [6-9], transplantation
rejection [10] and neoplasm of bladder, breast, larynx and testes [11,12].
Pyrimidine and pyrimidone are six-membered, heterocyclic, and aromatic organic compounds
containing two nitrogen atoms at position 1 and 3 [13]. In 1893, the Pietro Biginelli discovered
the synthesis of multi-functionalized dihydropyrimidones by a simple one-pot multicomponent
reaction [14]. Pyrimidine and pyrimidine ring containing compounds possess a diverse spectrum
of biological activities such as antitumor, antiviral, antibacterial, anti-inflammatory and
antihypertensive activities [15-18]. Recently, pyrimidine derivatives have been reported as potent
inhibitors of the enzymes responsible for diabetes, and particularly, pyrimidine-fused
heterocycles, which are identified as specific α-glucosidase inhibitors [19]. Dihydropyrimidines
derivatives also used as the calcium channel blockers, α-adrenergic antagonists as well as HIV
gp-120-CD4 inhibitors, and α-1a-antagonists [20-22].
Our research group had identified a number of heterocyclic compounds for their pharmacological
activities [23-29] and already published many heterocycles as potential class of β-glucuronidase
inhibitors [30-36]. Since, we have reported the β-glucuronidase inhibitory activity of 2-
arylquinazolin-4(3H)-ones [1], being structurally similar to this class, we decided to explore
dihydropyrimidones as potential β-glucuronidase inhibitors (Figure-1). Thus, this manuscript
describes the syntheses of dihydropyrimidones derivatives 1-37 and evaluation for their β-
glucuronidase inhibition studies. To the best of our knowledge, this class of compounds never
reported before for β-glucuronidase inhibitory activity.
2

O
R
O
N
Me
O
NH
NH
Me
N
H
O
R
1-37
IC50 = 0.6-198 µM
IC50 = 9.38-78.16 µM
Standard = D-Saccharic acid 1,4-lactone (IC50 = 48.4 ± 1.25 µM)
Figure-1
Results and Discussion
Chemistry
Substituted 4-aryl dihydropyrimidones 1-37 were synthesized via “one pot” three component
reaction by fusing urea, methyl acetoacetate and variety of aldehydes in the presence of copper
nitrate trihydrate as catalyst in solvent free condition at 80-90 ºC with constant stirring (Scheme-
1, Table-1). Heating and stirring were continued until everything turned solidify. Reaction
progress was checked by monitoring thin layer chromatography (TLC). After the completion of
reaction the solid product was washed extensively with the distilled water and recrystallized
from ethanol to afford the pure products. Structure of all synthetic compounds 1-37 were
characterized by different spectroscopic techniques 1H-, 13C-NMR, EIMS and HREI-MS.
Scheme-1: “One-pot” three component syntheses of dihydropyrimidone derivatives 1-37
Reaction starts with the chelation of copper nitrate trihydrate with the carbonyl carbon of aryl
aldehyde to enhance its electrophilicity, followed by the nucleophilic attack of amino group of
urea to form intermediate (a). Than intermediate (a) undergoes the E2 elimination reaction to
afford iminium ion as in intermediate (b) which undergo the nucleophilic addition reaction by
enol carbon to from intermediate (c). Electrophilic carbonyl carbon of acetyl group was attacked
3

by the terminal amino group to give rise a cyclize intermediate (d) which undergo dehydration
reaction to afford the dihydropyrimidone ring (Figure-2).
Figure-2: Mechanism for the syntheses of dihydropyrimidones
Characteristic Spectral Feature of Representative Compound (32)
1H- and 13C-NMR spectra of most active compound 32 against β-glucuronidase were recorded in
deuterated DMSO. In 1H-NMR spectrum, two downfield broad singlets of the acidic NH protons
appeared at H 9.30 and H 7.83, respectively. Downfield signals was due to the extensive
conjugation throughout the basic dihydropyrimidone ring system. H-3′ and H-5′ appeared at H
7.70 (d, J3',2/5',6' = 8.0 Hz), showed ortho coupling with H-2' and 6'. Its downfield chemical shift
was due to the electron withdrawing ortho CF3 group. H-2′ and H-6′ appeared at H 7.45 (d,
J2',3'/6',5' = 8.0 Hz) and showed ortho coupling with H-3' and 5'. Characteristic signal of methine
H-4 appeared as doublet at H 5.22 (d, J4,NH = 3.2 Hz), and showed coupling with NH. The OCH3
protons of methyl ester appeared as a singlet at H 3.52. The singlet of allylic CH3 appeared at H
2.25 (Figure-3).
4

Figure-3: 1H-NMR chemical shifts of compound 32.
In 13C-NMR broad-band decoupled spectrum in DMSO-d6 showed a total of 14 carbon signals,
including 2 methyl, 5 methine, and 7 quarternary carbons. The quaternary carbon of ester
carbonyl, was the most downfield signal appeared at C 165.6. The second most downfield signal
was appeared at C 151.9 corresponds to the quaternary carbon of carbonyl which is lying in
between the two nitrogens. Two quaternary carbon of vinylic C-6 and phenyl C-1ʹ appeared at C
149.3 and C 149.1, respectively. Four aromatic methine carbons appeared in theusual aromatic
region C 125-127 while aromatic quaternary C-4ʹ, ipso to triflouromethane group resonated at C
125.4. CF3 carbon and C-5 resonated at C 125.5 and C 98.3, respectively. Methoxy carbon of
methyl ester resonated at C 50.8. The most upfield allylic methyl carbon appeared at C 17.9
(Figure-4).
Figure-4: 13C-NMR chemical shifts of compound 32
EI-MS of compound 32 showed the molecular ion peak [M]+ at m/z 314. High resolution EI-MS
of compound 32 displayed M+ at m/z = 314.0897 with a composition of C14H13F3O3N2 (Calcd.
314.0878). Molecular ion undergo the loss of methyl radical to yield a cation, appeared at m/z
299. Similarly, loss of neutral fragment of -PhCF3 from molecular ion gave a radical cation at
m/z 169 which is also the base peak indicating its stability. A radical cation at m/z 145
5

correspond to the PhCF3 with the neutral loss of dihydropyrimidone ring. Loss of methoxy from
the molecular ion yielded a peak at m/z 283 which was further fragmented into radical cations at
m/z 255 and at m/z 240, respectively, after neutral loss of carbon monoxide and methyl radicals
(Figure-5).
Figure-5: Key EI-MS fragmentation of compound 32.
In Vitro β-Glucuronidase Inhibitory Activities
All synthetic dihydropyrimidones 1-37 were screened to check their in vitro β-glucuronidase
inhibitory activity. Excepts compounds 1, 7, 11, 12, 18, 34, 36 and 37, all demonstrated good to
moderate inhibitory potential in the range of IC50 = 9.38 ± 0.15-78.16 ± 1.47 μM as compared to
the standard D-saccharic acid 1,4-lactone (IC50 = 48.4 ± 1.25 μM) (Table-1).
Table-1: In vitro β-glucuronidase inhibitory activity of dihydropyrimidones 1-37
IC50 ± SEMa [M]
S. No.
1
R1
N.A.b
72.16 ±1.65
59.16 ± 1.22
2
3
6

59.16 ± 1.25
61.02 ± 1.40
4
5
54.16 ± 1.12
N.A.b
6
7
28.16 ± .056
8
18.16 ± 0.41
22.14 ± 0.43
9
10
N.A.b
N.A.b
11
12
13
34.16 ± 0.65
17.60 ± 0.35
15.19 ± 0.30
14
15
7

27.16 ± 0.48
16
48.16 ± 1.06
N.A.b
17
18
52.16 ±1.15
78.16 ± 1.47
19
20
55.16 ± 1.25
40.16 ± 0.85
21
22
44.16 ± 0.86
47.16 ± 0.92
18.19 ± 0.34
23
24
25
33.14 ± 0.68
44.16 ± 0.94
26
27
24.16 ± 0.50
28
34.24 ± 0.47
64.12 ± 1.30
29
30
14.11 ± 0.21
31
9.38 ± 0.15
32
33
49.13 ± 1.08
8

N.A.b
34
35
49.16 ± 1.10
N.A.b
36
37
N.A.b
Standardc = D-saccharic acid 1,4-lactone
48.4 ± 1.25
aIC50 (mean ± standard error of mean); N.A.b (Not Active); Standardc (Inhibitor for β-glucuronidase).
All persistent structural features in compounds such as dihydropyrimidone ring, methyl group,
and methyl ester moiety were definitely and cordially played their role in demonstrating the
inhibitory activity, however, the varying features such as the aryl ring with different substitution
pattern in all compounds were also responsible for the fluctuation in activity (Figure-6).
Figure-6
Limited structure-activity relationship (SAR) was rationalized by looking at the substitution
pattern at the aryl part (R). Compound 32 (IC50 = 9.38 ± 0.15 μM) having p-triflouromethyl
group at aryl part, found to be the five-fold more potent than the standard. It showed that being
polar in nature, triflouromethyl group might interacted with the active site of β-glucuronidase.
Another flouro group containing compound 31 (IC50 = 14.11 ± 0.21 μM) was found to be the
second most potent of this library which verify the involvement of flouro group in activity. On
comparison of the activity of 31 with the structurally similar compound 9 (IC50 = 18.16 ± 0.41
μM) which has an additional p-methoxy substituent at aryl part, a slight decreased inhibition was
observed which might be due to the presence of methoxy group. Methoxy group may cause less
polar interaction of flouro group or might create hindrance in interaction of flouro with the active
9

site. However, when methoxy come in close to flouro residue as in compound 10 (IC50 = 22.14 ±
0.43 μM) further decreased activity was obtained (Figure-7).
Figure-7
Compound 15 (IC50 = 15.19 ± 0.30 μM) having m-hydroxy group on aryl part, was found to be
more than three-fold active than the standard. Most probably its activity was driven by the
hydrogen bonding interaction made by the hydroxy group with the active site of the enzyme.
Switching of hydroxy group from m- to p- as in compound 14 (IC50 = 17.60 ± 0.35 μM) didn’t
affect the activity to much extent. It was observed that incorporation of groups like chloro and
methoxy as in compounds 16 (IC50 = 27.16 ± 0.48 μM) and 13 (IC50 = 34.16 ± 0.65 μM),
respectively, decline in the inhibition was observed which might be due to steric hindrance to
form hydrogen bond interaction by hydroxy group (Figure-8).
Figure-8
Amongst the potent compounds, derivatives having solely chloro group 27-29 also showed better
potential than the standard. It was found that dichloro substituted compound 28 (IC50 = 24.16 ±
10

0.50 μM) was found to demonstrate two-fold more activity than the standard might be due to
hydrophobic interaction made by the chloro groups with the active site. Mono chloro substituted
compounds such as 29 (IC50 = 34.24 ± 0.47 μM) and 27 (IC50 = 44.16 ± 0.94 μM) demonstrated
decreased activity than the dichloro substituted compound (Figure-9).
Figure-9
Compounds 22-25 have heterocyclic ring as “R” also revealed good inhibition than the standard
might be due to the π-π interaction with the active site of enzyme. Amongst these, derivative 25
(IC50 = 18.19 ± 0.34 μM) having thiophene group substituted at position 2 was found to have
superior activity. Interestingly, the structurally similar compound 24 (IC50 = 47.16 ± 0.92 μM)
which has the only difference of position to which it is attached to the rest of the molecule, a
sharp decline in the activity was observed. Activity of compound 25 can be compared with the
22 (IC50 = 40.16 ± 0.85 μM) which has a furan ring instead of thiophene, a reduced activity was
observed might be due to lesser π-π interaction by furan ring having more electronegative
oxygen atom. Similarly, compound 23 (IC50 = 44.16 ± 0.86 μM) also showed a comparable
activity to 22 (Figure-10).
11

Figure-10
From the limited SAR study, it was extracted that the compounds having groups which involved
to make polar interactions like hydrogen bonding, were more prone to inhibit than the
compounds involved to make hydrophobic interaction with the active site of the enzyme.
However, in order to get the more insights regarding the inhibition pattern by the compounds, a
molecular docking studies on the most potent compounds such as 32, 31, 15, 14 and 9 were
carried out which is discussed below.
Molecular Docking Studies
The molecular docking studies predicted that the compounds were well fitted in the binding
pocket of the enzyme. From the docking conformation of the most active compound 32 (IC50 =
9.38 ± 0.15 µM), it was observed that this compound forms five hydrogen bonds with the
residues Phe206, Asp207, His385, Asn450, Glu451, Tyr508 and Arg600 of the binding pocket of
the β-D-glucuronidase with excellent docking score (-16.2919). Asp207, Glu451, and Tyr508
were observed in creating hydrogen bonds with the hydrogen atom of the -NH moiety of the
compound. Asp207 and Arg-600 interacts through active H atoms with the lone pair of the
carbonyl oxygen of this compound (Figure-11). This strong bonding network of the compound
might be one of the reasons for good inhibitory activity of the compound against β-D-
glucuronidase enzyme.
12

Figure-11: Binding mode of compound 32 in the active site of the β-D-glucuronidase.
The second most active compound 31 (IC50 = 14.11 ± 0.21 µM) also showed good docking score
(-14.9956) as well as significant interactions with the active residues of the target enzyme.
Phe206 displayed polar interaction with the carbonyl oxygen atom of the compound. Tyr508
demonstrated polar interaction with the -NH moiety of the compound and also forms
hydrophobic interaction with the compound. Arg600 displayed hydrogen bonding with the
carbonyl oxygen atom of the compound (Figure-12). The high potency of this compound may be
due to the presence of electron rich groups that are exposed to polar interactions.
13

Figure-12: Binding mode of compound 31 in the active site of the β-D-glucuronidase.
The third most active compound 15 (IC50 = 15.19 ± 0.30 µM) showed high docking score (-
14.5926) as well as good interactions with active site residues of the target protein. His385 and
Asn450 exhibited polar interactions with hydroxyl (-OH) moiety of the compound. Arg600
demonstrated hydrogen bonding donor interaction with carbonyl oxygen atom of the same
compound (Figure-13). The presence of the meta-OH group which is chemically more active,
might be one of the reasons of its strong inhibition activity.
Figure-13: Binding mode of compound 15 in the active site of the β-D-glucuronidase.
14

Similarly, compound 14 (IC50= 17.60 ± 0.35 µM) also has an OH group at para position showed
the docking score (-13.7533) and important interactions with the active residues of the binding
pocket (Figure-14). Asp207, His385, and Asn450 showed polar interactions with the hydroxyl
group of the compound. Arg600 displayed polar interaction with the carbonyl oxygen moiety of
the same compound. The position of OH group (meta or para) showed a minor role in molecular
docking study.
Figure-14: Binding mode of compound 14 in the active site of the β-D-glucuronidase.
The compound 9 (IC50 = 18.16 ± 0.41 µM) showed docking score (-13.3387). It was observed it
has two polar interactions with the Asp207 and Tyr511 residues (Figure-15). Asp207
demonstrated hydrogen bonding with the oxygen atom of the compound while Tyr511 formed
polar interaction with the carbonyl oxygen atom of the compound. The good inhibitory activity
might be due to the high electron cloud of lone pairs of the available electronegative groups.
15

Figure-15: Binding mode of compound 9 in the active site of the β-D-glucuronidase.
Conclusion
Synthetic dihydropyrimidones 1-37 were first time reported to possess in vitro β-glucuronidase
inhibitory activity and all compounds showed good inhibitory potential in the range of IC50
=
9.38 ± 0.15-78.16 ± 1.47 μM compared to the standard drug D-saccharic acid 1,4-lactone (IC50 =
48.4 ± 1.25 μM). Molecular docking study was carried out in order to establish the structure-
activity relationship. As a result of this study compounds 8-10, 13-17, 22-29, 31 and 32 were
identified as lead molecules for further research in order to get a powerful inhibitor for β-
glucuronidase.
Experimental
Materials and Methods
Reagents were purchased from Sigma-Aldrich, USA. All reagents and solvents were of
analytical grade and used as received. Thin layer chromatography was performed on pre-coated
silica gel, GF-254 (Merck, Germany). Spots were visualized under ultraviolet light at 254 and
366 nm. Melting points of the compounds were determined on BUCHI-M560 melting point
apparatus. Mass spectra were recorded under on MAT 312 and MAT 113D mass spectrometers.
16

13
The 1H, C-NMR were recorded on a Bruker AM spectrometers, operating at 300, 400 and 500
MHz. The chemical shift values are presented in ppm (δ), relative to tetramethylsilane (TMS) as
an internal standard and the coupling constant (J) are in Hz.
General Experimental Procedure for the Syntheses of Dihydropyrimidones 1-37
Urea (1 mmol), ethylacetoacetate (1.2 mmol), substituted aryl aldehyde (1 mmol) and copper
nitrate trihydrate (10 mol %) as catalyst were taken in a 100 mL round-bottomed flask and
heated at 80-90 ºC with constant stirring. Completion of the reaction was checked by periodic
TLC. After the reaction completion, the solid reaction mixture was washed with excess of
distilled water and recrystallized from ethanol to afford pure products in high yields.
Bioassay
β-Glucuronidase Inhibition Study
The bioassay protocol is used as reported by Taha et al [37]. β-Glucuronidase (E.C. 3.2.1.31,
from bovine liver, G-0251) and p-nitrophenyl-b-D-glucuronide (N-1627) were purchased from
Sigma-Aldrich USA. Anhydrous sodium carbonate and all other analytical grade reagents were
obtained from Merck, Germany. Solvents and reagents were of reagent grade and used directly
without purification.
β-Glucuronidase activity was determined by measuring the absorbance at 405 nm of p-
nitrophenol formed from the substrate by the spectrophotometric method. The total reaction
volume was 250 µL. DMSO (100%) was used to dissolve the compound (5 µL) which become
2% in the final assay (250 µL) and the same conditions were used for standard (D-saccharic acid
1,4-lactone). The reaction mixture contained 185 µL of 0.1 M acetate buffer, 5 µL of test
°
compound solution, 10 µL of enzyme solution was incubated at 37 C for 30 minutes. The plates
were read on a multiplate reader (SpectraMax plus 384, USA) at 405 nm after the addition of 50
µL of 0.4 mM p-nitrophenyl-β-D-glucuronide. All assays were carried in triplicate.
Molecular Docking Studies
The three dimensional (3D) structures of the dihydropyrimidones derivatives were generated by
using the builder tool of the molecular operating environment (MOE) (www.chemcomp.com).
17

Each compound was 3D protonated, then energy minimization was done by the default
parameters of the MOE (gradient: 0.05, Force Field: MMFF94X). All compounds were then
saved in separate database i-e mdb file and used for molecular docking. The 3D crystal structure
of human β-D-glucuronidase (PDB code 1BHG) [38] was retrieved from the protein databank for
docking studies. The B-chain of protein and hetero-atoms including cofactors were removed
from the original protein data bank file. Hydrogen atoms were added to the enzyme structure by
3D protonation and then energy minimization was carried out by using the default parameters of
the MOE (gradient: 0.05, Force Field: MMFF94X). The active residues of the binding pocket
were found out by the site-finder module and dihydropyrimidones inhibitors were allowed to
dock with the active residues of the human β-D-glucuronidase by the most default parameters.
All binding interactions of the compounds in the receptor were predicted by using the Pymol
software.
Methyl 6-methyl-2-oxo-4 phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxylate (1)
Yield: 89%; M.P.: 210-212 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.19 (s, 1H, NH), 7.73 (s, 1H,
NH), 7.33 (t, J3'(2',4') = J5'(4',6') = 7.6 Hz, 2H, H-3', 5'), 7.24 (m, 3H, H-2', 4', 6'), 5.13 (d, J4,NH = 3.2
Hz, 1H, H-4), 3.52 (s, 3H, OCH3), 2.23 (s, 3H, CH3); 13C-NMR (75 MHz, DMSO-d6): 165.8,
152.1, 148.6, 144.6, 128.4, 128.4, 127.2, 126.1, 126.1, 98.9, 53.7, 50.77,17.8; EIMS m/z (% rel.
abund.): M+ 246 (26), 231 (51), 187 (49), 169 (100); HREI-MS Calcd for C13H14O3N2: m/z =
246.1004, Found 246.0992.
Methyl 4-(4ʹ-ethoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (2)
Yield: 85%; M.P.: 212-214 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.15 (s, 1H, NH), 7.66 (s, 1H,
NH), 7.12 (d, J2',3'/6',5' = 8.4 Hz, 2H, H-2', 6'), 6.85 (d, J3',2'/5',6' = 8.4 Hz, 2H, H-3', 5'), 5.07 (d,
J4,NH = 2.8 Hz, 1H, H-4), 3.99 (q, 2H, OCH2CH3), 3.51 (s, 3H, OCH3), 2.22 (s, 3H, CH3), 1.30 (t,
13
JCH3/CH2 = 7.2 Hz, 3H, OCH2CH3); C-NMR (75 MHz, DMSO-d6): 165.8, 157.71, 152.16,
148.2, 136.6, 127.3, 127.3, 114.2, 114.2, 99.2, 62.9, 53.1, 50.7, 17.7, 14.6; EIMS m/z (% rel.
abund.): 290 (M+, 27), 275 (100), 230.9 (73), 169 (92); HREI-MS Calcd for C15H18O4N2: m/z =
290.1267, Found 290.1254.
Methyl 4-(4ʹ-methoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate
(3)
18

Yield: 86%; M.P.: 192-194 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.15 (s, 1H, NH), 7.66 (s, 1H,
NH), 7.13 (d, J2',3'/6',5' = 8.4 Hz, 2H, H-2', 6'), 6.87 (d, J 3',2'/5',6' = 8.4 Hz, 2H, H-3', 5'), 5.07 (d,
J4,NH = 3.2 Hz, 1H, H-4), 3.70 (s, 3H, OCH3), 3.51 (s, 3H, OCH3), 2.23 (s, 3H, CH3); 13C-NMR
(100 MHz, DMSO-d6): 165.8, 158.4, 152.1, 148.2, 136.8, 127.2, 127.2, 113.7, 113.7, 99.2,
55.0, 53.1, 50.6, 17.4; EIMS m/z (% rel. abund.): 276 (M+, 34), 261 (95), 217 (100), 169 (92);
HREI-MS Calcd for C14H16O4N2: m/z = 276.1110, Found 276.1107.
Methyl 4-(2ʹ-methoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate
(4)
Yield: 86%; M.P.: 285-287 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.12 (s, 1H, NH), 7.22 (d, J6',5'
= 8.0 Hz, 1H, H-6'), 7.20 (s, 1H, NH), 7.02 (m, 2H, H-3', 5'), 6.86 (t, J4'(3',5') = 7.2 Hz, 1H, H-4'),
5.46 (d, J4,NH = 2.8 Hz, 1H, H-4), 3.78 (s, 3H, OCH3), 3.45 (s, 3H, OCH3), 2.27 (s, 3H, CH3);
13C-NMR (125 MHz, DMSO-d6): 165.8, 156.5, 152.2, 149.2, 131.2, 128.7, 126.7, 120.1, 111.2,
97.2, 55.4, 50.7, 48.7, 17.7; EIMS m/z (% rel. abund.): 276 (M+, 33), 261 (80) 169 (100); HREI-
MS Calcd for C14H16O4N2: m/z = 276.1110, Found 276.1102.
Methyl
4-(2ʹ,5ʹ-dimethoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (5)
Yield: 80%; M.P.: 230-232 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.14 (s, 1H, NH), 7.24 (s, 1H,
NH), 6.92 (d, J3',4' = 8.0 Hz, 1H, H-3'), 6.80 (d, J4',3 ' = 8.0 Hz, 1H, H-4'), 6.54 (s, 1H, H-6'), 5.41
(s, 1H, H-4), 3.73 (s, 3H, OCH3), 3.64 (s, 3H, OCH3), 3.47 (s, 3H, COOCH3), 2.26 (s, 3H, CH3);
13C-NMR (100 MHz, DMSO-d6): 165.7, 152.9, 152.2, 150.7, 149.2, 132.5, 113.8, 112.3, 111.9,
97.3, 56.0, 55.3, 50.7, 48.9, 17.7; EIMS m/z (% rel. abund.): 306 (M+, 49), 169 (100), 137 (42);
HREI-MS Calcd for C15H18O5N2: m/z = 306.1216, Found 306.1221.
Methyl
4-(2ʹ,3ʹ-dimethoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (6)
º
Yield: 88%; M.P.:227-229 C; 1H-NMR (400 MHz, DMSO-d6) δ 9.13 (s, 1H, NH), 7.34 (s, 1H,
NH), 6.99 (m, 2H, H-5', 6'), 6.72 (d, J4',5' = 6.7 Hz, 1H, H-4'), 5.46 (s, 1H, H-4), 3.78 (s, 3H,
13
OCH3), 3.75 (s, 3H, OCH3), 3.45 (s, 3H, OCH3), 2.25 (s, 3H, CH3); C-NMR (100 MHz,
DMSO-d6): 165.7, 152.3, 151.7, 148.7, 145.8, 137.4, 123.7, 119.2, 112.0, 98.1, 60.0, 55.6, 50.5,
19

49.0, 17.8; EIMS m/z (% rel. abund.): 306 (M+, 13), 169 (93); HREI-MS Calcd for C15H18O5N2:
m/z = 306.1216, Found 306.1212.
Methyl
4-(3ʹ,4ʹ-dimethoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (7)
Yield: 83%; M.P.: 150-152 ºC; 1H-NMR (300 MHz, DMSO-d6) δ 9.17 (s, 1H, NH), 7.68 (s, 1H,
NH), 6.88 (s, 1H, H-2'), 6.86 (d, J6',5' = 6.0 Hz, 1H, H-6'), 6.70 (d, J5',6' = 6.0 Hz, 1H, H-5'), 5.09
(d, J4,NH = 3.0 Hz, 1H, H-4), 3.70 (s, 6H, 2OCH3), 3.53 (s, 3H, OCH3), 2.24 (s, 3H, CH3); 13C-
NMR (100 MHz, DMSO-d6): 165.8, 152.1, 148.5, 148.3, 148.0, 137.0, 117.7, 111.7, 110.4,
99.0, 55.5, 55.4, 53.3, 50.7, 17.7; EIMS m/z (% rel. abund.): 306 (M+, 56), 291 (72), 169 (100);
HREI-MS Calcd for C15H18O5N2: m/z = 306.1216, Found 306.1209.
Methyl 4-(4ʹ-acetoxy-3ʹ-methoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (8)
º
1
Yield: 82%; M.P.: 209-211 C; H-NMR (300 MHz, DMSO-6) δ 9.24 (s, 1H, NH), 7.77 (s, 1H,
NH), 7.02 (d, J5',6' = J6',5' = 6.0 Hz, 2H, H-5', 6'), 6.77 (s, 1H, H-2'), 5.15 (d, J4,NH = 3.0 Hz, 1H, H-
4), 3.73 (s, 3H, OCH3), 3.55 (s, 3H, OCH3), 2.25 (s, 3H, OCOCH3), 2.23 (s, 3H, CH3); 13C-NMR
(75 MHz, DMSO-d6): 168.5, 165.7, 152.0, 150.5, 148.8, 143.3, 138.3, 122.7, 117.5, 110.9,
98.6, 55.5, 53.4, 50.7, 20.3, 17.7; EIMS m/z (% rel. abund.): 334 (M+, 11), 292 (90), 169 (100),
137 (44); HREI-MS Calcd for C16H18O6N2: m/z = 334.1165, Found 334.1175.
Methyl
4-(2ʹ-fluoro-4ʹ-methoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (9)
Yield: 86%; M.P.: 224-226 ºC; 1H-NMR (300 MHz, DMSO-d6) δ 9.22 (s, 1H, NH), 7.62 (s, 1H,
NH), 7.13 (d, J5',6' = 8.7 Hz, 1H, H-5'), 6.76 (d, J6',5' = 7.2 Hz, 1H, H-6'), 6.72 (s, 1H, H-3'), 5.34
(d, J4,NH = 1.8 Hz, 1H, H-4), 3.72 (s, 3H, OCH3), 3.46 (s, 3H, OCH3), 2.24 (s, 3H, CH3); 13C-
NMR (100 MHz, DMSO-d6): 165.5, 161.2, 159.9, 151.6, 148.8, 129.2, 123.5, 110.4, 101.5,
97.5, 55.5, 50.7, 48.2, 17.8; EIMS m/z (% rel. abund.): 294 (M+, 8), 279 (71), 169 (71), 44.1
(100); HREI-MS Calcd for C14H15FO4N2: m/z = 294.1016, Found 294.0993.
Methyl
4-(4ʹ-fluoro-3ʹ-methoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (10)
20

Yield: 80%; M.P.: 214-216 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.22 (s, 1H, NH), 7.73 (s, 1H,
NH), 7.15 (d, J6',5' = 10.8 Hz, 1H, H-6'), 7.02 (d, J5',6' = 8.0 Hz, 1H, H-5'), 6.73 (br.s, 1H, H-2'),
5.12 (s, 1H, H-4), 3.79 (s, 3H, OCH3), 3.53 (s, 3H, COOCH3), 2.24 (s, 3H, CH3); 13C-NMR (75
MHz, DMSO-d6): 165.7, 152.2, 149.0, 148.8, 146.8, 141.3, 117.9, 115.7, 112.1, 98.5, 55.8,
53.3, 50.7, 17.7; EIMS m/z (% rel. abund.): 294 (M+, 32), 279 (41), 169 (100); HREI-MS Calcd
for C14H15FO4N2: m/z = 294.1016, Found 294.1003.
Methyl 4-(3ʹ-bromo-4ʹ,5ʹ-dimethoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-
5-carboxylate (11)
Yield: 83%; M.P.: 223-225 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.25 (s, 1H, NH), 7.75 (s, 1H,
NH), 6.92 (d, J2',6' = J6',2' = 4.8 Hz, 2H, H-2', 6'), 5.11 (d, J4,NH = 3.2 Hz, 1H, H-4), 3.78 (s, 3H,
OCH3), 3.70 (s, 3H, OCH3), 3.56 (s, 3H, OCH3), 2.25 (s, 3H, CH3); 13C-NMR (75 MHz, DMSO-
d6): 165.6, 153.2, 151.9, 149.1, 144.8, 141.8, 121.1, 116.4, 110.7, 98.2, 59.9, 55.9, 53.1, 50.8,
17.8; EIMS m/z (% rel. abund.): 384 (M+, 40), 386 (M + 2, 38), 305 (61), 169 (100); HREI-MS
Calcd for C15H17BrO5N2: m/z = 384.0321, Found 384.0337.
Methyl 4-(3ʹ-(benzyloxy)-4ʹ-methoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-
5-carboxylate (12)
Yield: 80%; M.P.: 148-151 ºC; 1H-NMR (300 MHz, DMSO-d6) δ 9.16 (s, 1H, NH), 7.67 (s, 1H,
NH), 7.41 (m, 5H, H-2'', 3'', 4'', 5'', 6''), 6.92 (s, 1H, H-2'), 6.92 (d, J6',5' = 9.0 Hz, 1H, H-6'), 6.74
(d, J5',6' = 9.0 Hz, 1H, H-5'), 5.05 (s, 1H, H-4), 5.01 (s, 2H, OCH2Ph), 3.72 (s, 3H, OCH3), 3.49
(s, 3H, OCH3), 2.22 (s, 3H, CH3); 13C-NMR (100 MHz, DMSO-d6): 165.7, 152.1, 148.4, 147.5,
137.0, 136.9, 128.3, 128.3, 127.8, 127.8, 118.4, 112.2, 112.2, 112.0, 112.0, 98.9, 70.0, 55.6, 53.2,
50.6, 17.7; EIMS m/z (% rel. abund.): 382 (M+, 27), 291 (85), 169 (61), 91 (100); HREI-MS
Calcd for C21H22O5N2: m/z = 382.1529, Found 382.1512.
Methyl
4-(4ʹ-hydroxy-3ʹ,5ʹ-dimethoxyphenyl)-6-methyl-2-oxo-1,2,3,4-
tetrahydropyrimidine-5-carboxylate (13)
Yield: 82%; M.P.: 200-202 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.12 (s, 1H, OH), 8.29 (s, 1H,
NH), 7.62 (s, 1H, NH), 6.46 (s, 2H, H-2', 6'), 5.06 (d, J4,NH = 2.4 Hz, 1H, H-4), 3.69 (s, 6H,
2OCH3), 3.54 (s, 3H, OCH3), 2.23 (s, 3H, CH3); 13C-NMR (75 MHz, DMSO-d6): 165.8, 152.1,
21

148.2, 148.2, 147.7, 135.0, 134.7, 103.8, 103.8, 99.0, 55.9, 55.9, 53.6, 50.6, 17.7; EIMS m/z (%
rel. abund.): 322 (M+, 37), 291 (27), 169 (100), 137 (95); HREI-MS Calcd for C15H18O6N2: m/z =
322.1165, Found 322.1173.
Methyl 4-(4ʹ-hydroxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate
(14)
Yield: 82%; M.P.: 231-233 ºC; 1H-NMR (300 MHz, DMSO-d6) δ 9.32 (s, 1H, OH), 9.12 (s, 1H,
NH), 7.62 (s, 1H, NH), 7.02 (d, J2',3'/6',5' = 8.4 Hz, 2H, H-2', 6'), 6.68 (d, J3',2'/5',6' = 8.4 Hz, 2H, H-
3', 5'), 5.02 (d, J4,NH = 3.3 Hz, 1H, H-4), 3.50 (s, 3H, OCH3), 2.22 (s, 3H, CH3); 13C-NMR (100
MHz, DMSO-d6): 165.9, 156.5, 152.2, 148.1, 135.2, 127.3, 127.3, 115.0, 115.0, 99.4, 53.2,
50.7, 17.8; EIMS m/z (% rel. abund.): 262 (M+, 15), 247 (72), 169 (100); HREI-MS Calcd for
C13H14O4N2: m/z = 262.0954, Found 262.0948.
Methyl 4-(3ʹ-hydroxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate
(15)
Yield: 78%; M.P.: 220-222 ºC; 1H-NMR (300 MHz, DMSO-d6) δ 9.35 (s, 1H, OH), 9.17 (s, 1H,
NH), 7.68 (s, 1H, NH), 7.10 (t, J5'(4',6') = 8.1 Hz, 1H, H-5'), 6.66 (m, 3H, H-2', 4' ,6'), 5.04 (d,
J4,NH = 3.0 Hz, 1H, H-4), 3.53 (s, 3H, OCH3), 2.22 (s, 3H, CH3); 13C-NMR (100 MHz, DMSO-
d6): 165.8, 157.3, 152.1, 148.3, 146.0, 129.3, 116.7, 114.2, 112.9, 99.0, 53.6, 50.7, 17.7; EIMS
m/z (% rel. abund.): 262 (M+, 24), 230 (31), 169 (100); HREI-MS Calcd for C13H14O4N2: m/z =
262.0954, Found 262.0963.
Methyl
4-(3ʹ-chloro-4ʹ-hydroxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (16)
Yield: 82%; M.P.: 262-264 ºC; 1H-NMR (300 MHz, DMSO-d6) δ 10.12 (s, 1H, OH), 9.20 (s, 1H,
NH), 7.69 (s, 1H, NH), 7.12 (s, 1H, H-2'), 6.99 (d, J6', 5' = 9.0 Hz, 1H, H-6'), 6.90 (d, J5', 6' = 6.0,
1H, H-5'), 5.03 (d, J4,NH = 3.0 Hz, 1H, H-4), 3.52 (s, 3H, OCH3), 2.23 (s, 3H, CH3); 13C-NMR
(100 MHz, DMSO-d6): 165.8, 152.2, 152.0, 148.6, 136.6, 127.6, 125.8, 119.3, 116.6, 98.8,
52.9, 50.8, 17.8; EIMS m/z (% rel. abund.): 296 (M+, 22), 298 (M + 2, 7), 281 (51), 169 (100),
137 (58); HREI-MS Calcd for C13H13ClO4N2: m/z = 296.0564, Found 296.0563.
22

Methyl
(17)
6-methyl-4-(naphthalen-1ʹ-yl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate
Yield: 84%; M.P.: 235-237 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.26 (s, 1H, NH), 8.29 (d, J8',7'
= 8.4 Hz, 1H, H-8'), 7.94 (d, J5',6' = 8.0 Hz, 1H, H-5'), 7.83 (d, J4',3' = 8.0 Hz, 1H, H-4'), 7.73 (s,
1H, NH), 7.55 (m, 3H, H-3', 6', 7'), 7.37 (d, J2',3' = 6.8 Hz, 1H, H-2'), 6.03 (d, J4,NH = 3.2 Hz, 1H,
13
H-4), 3.36 (s, 3H, OCH3), 2.35 (s, 3H, CH3); C-NMR (100 MHz, DMSO-d6): 165.7, 159.5,
151.7, 149.1, 139.8, 133.5, 130.0, 128.4, 127.9, 126.0, 125.6, 123.9, 123.5, 98.7, 50.6,49.6, 17.8;
EIMS m/z (% rel. abund.): 296 (M+, 58), 237 (39), 169 (100); HREI-MS Calcd for C17H16O3N2:
m/z = 296.1161, Found 296.1148.
Methyl
(18)
6-methyl-4-(naphthalen-2ʹ-yl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate
Yield: 86%; M.P.: 276-278 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.25 (s, 1H, NH), 7.89 (m, 4H,
H-5', 6', 7', 8'), 7.65 (s, 1H, NH), 7.49 (m, 3H, H-1', 3', 4'), 5.31 (d, J4,NH = 2.8 Hz, 1H, H-4), 3.51
(s, 3H, OCH3), 2.28 (s, 3H, CH3); 13C-NMR (100 MHz, DMSO-d6): 165.8, 152.0, 148.9, 142.0,
132.7, 132.3, 128.3, 127.9, 127.4, 126.2, 125.9, 124.9, 124.4, 98.8, 54.1, 50.8, 17.9; EIMS m/z
(% rel. abund.): 296 (M+, 86), 237 (67), 169 (100); HREI-MS Calcd for C17H16O3N2: m/z =
296.1161, Found 276.1160.
Methyl 4-ethyl-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (19)
Yield: 80%; M.P.: 183-185 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 8.92 (s, 1H, NH), 7.27 (s, 1H,
NH), 4.01 (d, J4,NH = 3.6 Hz, 1H, H-4), 3.58 (s, 3H, OCH3), 2.15 (s, 3H, CH3), 1.41 (m, 2H,
CH2CH3), 0.79 (t, JCH3/CH2 = 7.2 Hz, CH2CH3); 13C-NMR (100 MHz, DMSO-d6): 165.9, 152.7,
148.5, 98.5, 51.3, 50.6, 29.5, 17.6, 8.3; EIMS m/z (% rel. abund.): 199 (M+, 1), 169 (100); HREI-
MS Calcd for C9H14O3N2: m/z = 198.1004, Found 198.0990.
Methyl 4-butyl-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (20)
Yield: 75%; M.P.: 178-180 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 8.92 (s, 1H, NH), 7.29 (s, 1H,
NH), 4.03 (d, J4,NH = 4.0 Hz, 1H, H-4), 3.58 (s, 3H, OCH3), 2.14 (s, 3H, CH3), 1.37 (t,
2H,CH2CH2CH2CH3), 1.23 (m, 4H, CH2CH2CH2CH3), 0.83 (t, JCH3/CH2 = 6.8 Hz, 3H,
CH2CH2CH2CH3); 13C-NMR (100 MHz, DMSO-d6): 165.9, 152.6, 148.3, 99.1, 50.6, 50.0, 36.3,
23

25.8, 21.9, 17.68, 13.88; EIMS m/z (% rel. abund.): 226 (M+, 2), 169 (100), 137 (70); HREI-MS
Calcd for C11H18O3N2: m/z = 226.1317, Found 226.1314.
Methyl 4-isobutyl-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (21)
Yield: 80%; M.P.: 180-182 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 8.94 (s, 1H, NH), 7.39 (s, 1H,
NH), 4.05 (d, J4,NH = 4.4 Hz, 1H, H-4), 3.58 (s, 3H, OCH3), 2.14 (s, 3H, CH3), 1.69 (m, 1H,
CH(CH3)2, 1.39 (m, 1H, CH2), 1.14 (m, 1H, CH2), 0.85 (d, J = 6.4 Hz, 6H, CH(CH3)2); 13C-NMR
(75 MHz, DMSO-d6): 165.8, 152.7, 148.3, 100.1, 50.7, 48.1, 45.9, 23.6, 22.8, 21.4, 17.7; EIMS
m/z (% rel. abund.): 226 (M+, 1), 169 (100), 137 (85); HREI-MS Calcd for C11H18O2N3: m/z =
226.1317, Found 226.1316.
Methyl 4-(furan-2ʹ-yl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (22)
Yield: 86%; M.P.: 236-238 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.25 (s, 1H, NH), 7.76 (s, 1H,
NH), 7.54 (s, 1H, H-5'), 6.34 (m, 1H, H-4'), 6.08 (d, J3',4' = 2.8 Hz, 1H, H-3'), 5.18 (d, J4,NH = 3.2
Hz, 1H, H-4), 3.55 (s, 3H, OCH3), 2.22 (s, 3H, CH3); 13C-NMR (100 MHz, DMSO-d6): 165.4,
155.8, 152.3, 149.6, 142.1, 110.3, 105.2, 96.5, 50.8, 47.6, 17.7; EIMS m/z (% rel. abund.): 236
(M+, 60), 177 (100); HREI-MS Calcd for C11H12O4N2: m/z = 236.0797, Found 236.0811.
Methyl
6-methyl-4-(5ʹ-methylfuran-2ʹ-yl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (23)
Yield: 82%; M.P.: 198-200 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.20 (s, 1H, NH), 7.72 (s, 1H,
NH), 5.92 (d, J3',4' = J4',3' = 1.6 Hz, 2H, H-3', 4'), 5.11 (d, J4,NH = 3.2 Hz, 1H, H-4), 3.55 (s, 3H,
13
OCH3), 2.22 (s, 3H, furan-CH3), 2.20 (s, 3H, CH3); C-NMR (75 MHz, DMSO-d6): 165.6,
154.0, 152.3, 150.7, 149.5, 106.3, 106.0, 96.5, 50.8, 47.5, 17.7, 13.3; EIMS m/z (% rel. abund.):
250 (M+, 58), 235 (75), 207 (100), 169 (52); HREI-MS Calcd for C12H14O4N2: m/z = 250.0954,
Found 250.0935.
Methyl 6-methyl-2-oxo-4-(thiophen-3ʹ-yl)-1,2,3,4-tetrahydropyrimidine-5-carboxylate (24)
Yield: 80%; M.P.: 237-239 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.18 (s, 1H, NH), 7.74 (s, 1H,
NH), 7.45 (m, 1H, H-4'), 7.14 (d, J2', 5' = 2.0 Hz, 1H, H-2'), 6.98 (dd, J5',2' = 0.4, J5',4' = 4.8 Hz, 1H,
H-5'), 5.19 (d, J4,NH = 3.2 Hz, 1H, H-4), 3.57 (s, 3H, OCH3), 2.21 (s, 3H, CH3); 13C-NMR (75
24

MHz, DMSO-d6): 165.7, 152.5, 148.7, 145.6, 126.6, 126.1, 120.7, 99.1, 50.8, 49.3, 17.7; EIMS
m/z (% rel. abund.): 252 (M+, 100), 193 (88), 169 (77); HREI-MS Calcd for C11H12O3N2S: m/z =
252.0569, Found 252.0572.
Methyl 6-methyl-2-oxo-4-(thiophen-2ʹ-yl)-1,2,3,4-tetrahydropyrimidine-5-carboxylate (25)
Yield: 80%; M.P.: 226-228 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.32 (s, 1H, NH), 7.90 (s, 1H,
NH), 7.34 (s, 1H, H-3'), 6.92 (s, 1H, H-5'), 6.88 (s, 1H, H-4'), 5.39 (s, 1H, H-4), 3.58 (s, 3H,
OCH3), 2.21 (s, 3H, CH3); 13C-NMR (100 MHz, DMSO-d6): 165.5, 152.2, 148.9, 148.7, 126.7,
124.6, 123.5, 99.6, 50.8, 49.3, 17.7; EIMS m/z (% rel. abund.): 252 (M+, 100), 193 (94), 169
(43); HREI-MS Calcd for C11H12O3N2S: m/z = 252.0569, Found 252.0561.
Methyl
6-methyl-4-(5ʹ-methylthiophen-2ʹ-yl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (26)
Yield: 80%; M.P.: 194-196 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.28 (s, 1H, NH), 7.82 (s, 1H,
NH), 6.64 (s, 1H, H-3'), 6.58 (s, 1H, H-4'), 5.29 (d, J4,NH = 2.8, 1H, H-4), 3.58 (s, 3H, OCH3),
2.34 (s, 3H, thiophene-CH3), 2.19 (s, 3H, CH3); 13C-NMR (100 MHz, DMSO-d6): 165.4, 152.1,
148.7, 146.1, 137.9, 124.6, 123.2, 99.5, 50.8, 49.3, 17.6, 14.8; EIMS m/z (% rel. abund.): 266
(M+, 100), 207 (93), 169 (50); HREI-MS Calcd for C12H14O3N2S: m/z = 266.0725, Found
266.0723.
Methyl
(27)
4-(2ʹ-chlorophenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate
Yield: 90%; M.P.: 226-228 ºC; 1H-NMR (300 MHz, DMSO-d6) δ 9.29 (s, 1H, NH), 7.69 (s, 1H,
NH), 7.40 (d, J3',4 ' = 7.2 Hz, 1H, H-3'), 7.31 (t, J4'(3',5') = 5.4 Hz, 1H, H-4'), 7.26 (m, 2H, H-5', 6'),
13
5.60 (d, J4,NH = 3.0 Hz, 1H, H-4), 3.44 (s, 3H, OCH3), 2.28 (s, 3H, CH3); C-NMR (75 MHz,
DMSO-d6): 165.4, 151.3, 149.4, 141.5, 131.6, 129.4, 128.6, 127.7, 126.8, 97.6, 51.3, 50.6, 17.6;
EIMS m/z (% rel. abund.): 279 (M+, 6), 281 (M+2, 3), 245 (46), 169 (100); HREI-MS Calcd for
C13H13O3N2Clm/z = 280.0615, Found 280.0602.
25

Methyl
4-(2ʹ,6ʹ-dichlorophenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (28)
Yield: 85%; M.P.: 292-294 ºC; 1H-NMR (300 MHz, DMSO-d6) δ 9.29 (s, 1H, NH), 7.57 (s, 1H,
NH), 7.41 (d, J3',4' = J5',4' = 7.8 Hz, 2H, H-3', 5'), 7.28 (t, J4'(3',5') = 7.8 Hz, 1H, H-4'), 6.14 (s, 1H,
H-4), 3.35 (s, 3H, OCH3), 2.15 (s, 3H, CH3); 13C-NMR (100 MHz, DMSO-d6): 165.4, 150.5,
149.7, 137.5, 135.1, 130.1, 130.0, 129.3, 129.3, 93.9, 52.2, 50.2, 17.8; EIMS m/z (% rel. abund.):
314 (M+, 2), 255 (37), 169 (100); HREI-MS Calcd for C13H12Cl2O3N2: m/z = 314.0225, Found
314.0217.
Methyl
(29)
4-(4ʹ-chlorophenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate
Yield: 82%; M.P.: 205-207 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.25 (s, 1H, NH), 7.77 (s, 1H,
NH), 7.38 (d, J3',2'/5',6' = 8.0 Hz, 2H, H-3', 5'), 7.24 (d, J2',3'/6',5' = 8.0, 2H, H-2', 6'), 5.12 (d, J4,NH
=
2.4 Hz, 1H, H-4), 3.51 (s, 3H, OCH3), 2.23 (s, 3H, CH3); 13C-NMR (100 MHz, DMSO-d6):
165.7, 151.9, 149.0, 143.6, 131.8, 129.7, 128.4, 128.1, 128.1, 98.6, 53.2, 50.8, 17.8; EIMS m/z
(% rel. abund.): 280 (M+, 17), 282 (M + 2, 5), 265 (39), 169 (100), 137 (95); HREI-MS Calcd for
C13H13ClO3N2: m/z = 280.0615, Found 280.0607.
Methyl
(30)
4-(4ʹ-bromophenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate
Yield: 82%; M.P.: 213-215 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.25 (s, 1H, NH), 7.77 (s, 1H,
NH), 7.52 (d, J3',2'/5',6' = 8.0 Hz, 2H, H-3', 5'), 7.18 (d, J2',3'/6',5' = 8.0 Hz, 2H, H-2', 6'), 5.10 (s, 1H,
H-4), 3.51 (s, 3H, OCH3), 2.23 (s, 3H, CH3); 13C-NMR (100 MHz, DMSO-d6): 165.6, 151.8,
148.9, 143.9, 131.3, 131.3, 128.4, 128.4, 120.2, 98.5, 53.2, 50.7, 17.7; EIMS m/z (% rel. abund.):
324 (M+, 15), 326 (M + 2, 15), 309 (30), 169 (100), 137 (80); HREI-MS Calcd for
C13H13BrO3N2: m/z = 324.0110, Found 324.0081.
Methyl
(31)
4-(2ʹ-fluorophenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate
Yield: 82%; M.P.: 255-257 ºC; 1H−NMR (400 MHz, DMSO−d6) δ 9.25 (s, 1H, NH), 7.68 (s, 1H,
NH), 7.31 (m, 2H, H-4', 5'), 7.15 (d, J3',4' = J6',5' = 8.0 Hz, 2H, H-3', 6'), 5.45 (d, J4,NH = 2.0 Hz,
26

13
1H, H-4), 3.46 (s, 3H, OCH3), 2.25 (s, 3H, CH3); C-NMR (100 MHz, DMSO-d6): 165.5,
160.6, 158.1, 151.6, 149.1, 131.5, 129.4, 124.5, 115.6, 97.2, 50.7, 48.6, 17.8; EIMS m/z (% rel.
abund.): 264 (M+, 12), 249 (68), 169 (100), 137 (80); HREI-MS Calcd for C13H13FO3N2: m/z =
264.0910, Found 264.0905.
Methyl 6-methyl-2-oxo-4-(4ʹ-(trifluoromethyl) phenyl)-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (32)
Yield: 82%; M.P.: 188-190 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.30 (s, 1H, NH), 7.83 (s, 1H,
NH), 7.70 (d, J3',2/5',6' = 8.0 Hz, 2H, H-3', 5'), 7.45 (d, J2',3'/6',5' = 8.0 Hz, 2H, H-2', 6'), 5.22 (d, J4,NH
= 3.2 Hz, 1H, H-4), 3.52 (s, 3H, OCH3), 2.25 (s, 3H, CH3); 13C-NMR (100 MHz, DMSO-d6):
165.6, 151.9, 149.3, 149.1, 127.0, 127.0, 125.5, 125.5, 125.5, 125.4, 98.3, 53.6, 50.8, 17.9; EIMS
m/z (% rel. abund.): 314 (M+, 26), 255 (48), 169 (100), 137 (36); HREI-MS Calcd for
C14H13F3O3N2: m/z = 314.0878, Found 314.0897.
Methyl 6-methyl-4-(4ʹ-nitrophenyl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (33)
Yield: 80%; M.P.: 235-237 ºC; 1H-NMR (300 MHz, DMSO-d6) δ 9.37 (s, 1H, NH), 8.21 (d, J3',2'
= J5',6' = 8.7 Hz, 2H, H-3', 5'), 7.90 (s, 1H, NH), 7.50 (d, J2',3'/6',5' = 8.7 Hz, 2H, H-2', 6'), 5.26 (d,
J4,NH = 3.3 Hz, 1H, H-4), 3.52 (s, 3H, OCH3), 2.25 (s, 3H, CH3); 13C-NMR (100 MHz, DMSO-
d6): 165.5, 151.8, 151.8, 149.6, 146.7, 127.6, 127.6, 123.8, 123.8, 98.0, 53.5, 50.9, 17.9; EIMS
m/z (% rel. abund.): 291 (M+, 5), 169 (100), 137 (62); HREI-MS Calcd for C13H13O5N3: m/z =
291.0855, Found 291.0840.
Methyl 4-(4ʹ-isopropylphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate
(34)
Yield: 80%; M.P.: 200-202 ºC; 1H-NMR (300 MHz, DMSO-d6) δ 9.18 (s, 1H, NH), 7.69 (s, 1H,
NH), 7.19 (m, 4H, H-2', 3', 5', 6'), 5.09 (d, J4,NH = 3.0 Hz, 1H, H-4), 3.52 (s, 3H, OCH3), 2.87 (m,
13
1H, CH(CH3)2, 2.23 (s, 3H, CH3), 1.17 (d, J = 6.9 Hz, 6H, CH(CH3)2); C-NMR (75 MHz,
DMSO-d6): 165.8, 152.2, 148.4, 147.3, 142.1, 126.2, 126.2, 126.0, 126.0, 99.1, 53.4, 50.7, 33.0,
23.8, 23.8, 17.7; EIMS m/z (% rel. abund.): 288 (M+, 47), 229 (81), 169 (100); HREI-MS Calcd
for C16H20O3N2: m/z = 288.1474, Found 288.1464.
27

Methyl 4-(4ʹ-(dimethyl amino) phenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (35)
Yield: 82%; M.P.: 238-240 ºC; 1H-NMR (300 MHz, DMSO-d6) δ 9.17 (s, 1H, NH), 7.68 (s, 1H,
NH), 6.88 (m, 2H, H-3', 5'), 6.84 (d, J2',3' = 6.0 Hz, 1H, H-2'), 6.71 (d, J6',5' = 9.0 Hz, 1H, H-6'),
5.09 (d, J4,NH = 3.0 Hz, 1H, H-4), 3.70 (s, 6H, N(CH3)2), 3.53 (s, 3H, OCH3), 2.24 (s, 3H, CH3);
13C-NMR (75 MHz, DMSO-d6): 165.9, 152.2, 149.7, 147.8, 132.4, 126.7, 126.7, 112.2, 112.2,
99.5, 53.1, 53.1, 50.6, 50.6, 17.7; EIMS m/z (% rel. abund.): 289 (M+ 100), 230 (96), 169 (30),
120 (96); HREI-MS Calcd for C15H19O3N3: m/z = 289.1426, Found 289.1420.
Methyl
4-(3ʹ-(benzyloxy)
phenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (36)
Yield: 80%; M.P.: 173-175 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.18 (s, 1H, NH), 7.71 (s, 1H,
NH), 7.42 (m, 5H, H-2'', 3'', 4'', 5'', 6''), 7.24 (t, J5'(4',6') = 7.6 Hz, 1H, H-5'), 6.90 (m, 3H, H-2', 4',
13
6'), 5.10 (s, 1H, H-4), 5.04 (s, 2H, OCH2Ph), 3.51 (s, 3H, OCH3), 2.23 (s, 3H, CH3); C-NMR
(100 MHz, DMSO-d6): 165.7, 158.3, 152.1, 148.7, 146.1, 136.9, 129.5, 128.3, 128.3, 127.7,
127.7, 127.7, 127.7, 118.4, 113.0, 98.7, 69.1, 53.5, 50.7, 17.7; EIMS m/z (% rel. abund.): 352
(M+, 29), 293 (15), 261 (72), 169 (78), 91 (100); HREI-MS Calcd for C20H20O4N2: m/z =
352.1423, Found 352.1422.
Methyl
4-(2ʹ-(benzyloxy)
phenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-
carboxylate (37)
Yield: 80%; M.P.: 205-207 ºC; 1H-NMR (400 MHz, DMSO-d6) δ 9.13 (s, 1H, NH), 7.51 (d, J2''/3''
= 7.2 Hz, 1H, H-2''), 7.40 (t, J3''(2'',6'') = J5''(4'',6'') = 6.8 Hz, 2H, H-3'', 5''), 7.32 (t, J4''(3'',5'') = 6.8 Hz,
1H, H-4''), 7.32 (t, J6'',5'' = 7.2 Hz, 1H, H-6''), 7.22 (s, 1H, NH), 7.19 (t, J4'(3',5') = 7.6, 1H, H-4'),
7.09 (d, J6',5' = 7.6 Hz, 1H, H-6'), 7.01 (d, J3',4' = 8.4 Hz, 1H, H-3'), 6.88 (t, J5'(4',6') = 7.6 Hz, 1H,
H-5'), 5.60 (s, 1H, H-4), 5.17 (s, 2H, OCH2Ph), 3.43 (s, 3H, OCH3), 2.26 (s, 3H, CH3); 13C-NMR
(100 MHz, DMSO-d6): 165.8, 155.2, 152.1, 149.0, 137.4, 132.0, 128.6, 128.4, 128.4, 127.6,
127.2, 127.2, 127.2, 120.5, 112.5, 97.6, 69.3, 50.7, 48.7, 17.8; EIMS m/z (% rel. abund.): 352
(M+, 30), 169 (5), 91 (100); HREI-MS Calcd for C20H20O4N2: m/z = 352.1423, Found 352.1408.
28

Acknowledgements: The authors are thankful to the Higher Education Commission (HEC) for
their financial support to Project No. 20-1910.
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