Synthesis and characterization of antitubercular triazine-chalcone hybrid molecules

Article abstract of DOI:10.14233/ajchem.2017.20832

A new series of 1,3,5-triazine-chalcone hybrid molecules have been synthesized and evaluated in vitro for Mycobacterium tuberculosis H37Rv inhibitory potency using Alamar blue assay and the activity expressed as the minimum inhibitory concentration (MIC)

Full text of DOI:10.14233/ajchem.2017.20832

Asian Journal of Chemistry; Vol. 29, No. 9 (2017), 2084-2090
ASIAN JOURNAL OF CHEMISTRY
https://doi.org/10.14233/ajchem.2017.20832
Synthesis and Characterization of Antitubercular Triazine-Chalcone Hybrid Molecules
*
AMAN RAWAT, ATINDER KAUR, SURJIT and HARPREET KAUR
Department of Chemistry, Lovely Professional University, Phagwara-144 411, India
*Corresponding author: E-mail: harpreet2.kaur@lpu.co.in
Received: 20 April 2017;
Accepted: 10 June 2017;
Published online: 15 July 2017;
AJC-18496
A new series of 1,3,5-triazine-chalcone hybrid molecules have been synthesized and evaluated in vitro for Mycobacterium tuberculosis
H37Rv inhibitory potency using Alamar blue assay and the activity expressed as the minimum inhibitory concentration (MIC) in µg/mL.
The antitubercular activity screening data revealed that the compounds 1 and 2B demonstrated comparatively the most potent inhibitory
activity, with MIC value 1.6 µg/mL. Most of the compounds displayed significantly promising activity.
Keywords: Heterocyclic chalcone, Mycobacterium tuberculosis, Antitubercular activity, Triazine-chalcone hybrid.
Tuberculosis is caused due to the several species of Mycobacteria
that are aerobic pathogens of higher vertebrates which are
actually intracellular, non-motile, Gram-positive and rod shaped
obligates. In the current therapy to cure anti-TB, it will require
almost nine months that is too long. Due to these factors the
therapy for the patient have become very difficult. The known
drawbacks of current existing drugs with the emergence of
MDR strains and the increasing occurrence of death due to
tuberculosis have arisen interest in the discovery and develop-
ment of new anti-tubercular drugs with novel mode of action.
So, there is an essential need to discover and develop the new
anti-TB drugs in order to overcome the drug resistance problem
[5].
INTRODUCTION
The concept of “molecular hybridization” is in current
demand as it can overcome the problem of drug resistance
and enhance the existing libraries of anti-infective agents. The
combination of two or more pharmacophores linked with each
other results in new molecules with the hope that they would
either give synergistic effect or additive pharmacological
activities [1].
A number of heterocyclic compounds have been reported
for their applications in the synthesis of biologically active
and medicinally important molecules. The compounds which
contain five membered rings having nitrogen and oxygen
like isoxazole and pyrazoles are found to possess biological
activities like antiviral, antitumor, anticonvulsant, analgesic,
antioxidant, antidepressant, herbicidal, insecticidal, fungicidal,
antibacterial, antimicrobial, cyclooxygenase inhibitory,
antimicrobial, etc. [2].A number of derivatives having s-triazine
moiety have been reported, which can be used as polymers
and drugs and also applicable as reactive dyes [3].
There are basically two classes of antitubercular agents:
The first line drugs which are given for six months are isoniazid
(INH), pyrazinamide (PZA), ethambutol (EMB), rifampin
(RIF) and streptomycin. If due to bacterial drug resistance the
treatment fails then second line drugs are used such as p-amino
salicylic acid (PAS), kanamycin, fluoroquinolones, capreo-
mycin, ethionamide and cycloserine are used. These drugs are
mostly less effective and have serious side effects. Therefore,
it is necessary to develop safe and cost-effective new antituber-
cular agents [6].
Mycobacterium tuberculosis (TB) is a serious public
health problem and in today’s world it is a leading infectious
cause of death. World Health Organization (WHO) has
launched a global project on antitubercular drug resistance in
order to measure the effect of drug resistance. According to
the data of global report on anti-tubercular drug resistance it
has been shown that it is still present worldwide. However, a
number of new chemical compounds having significant
antitubercular activity have been recently discovered, but no
new drug has entered the market from the last 55 years [4].
Chalcones are having wide range of biological activity
and are found to be effective as antibacterial, antifungal, anti-
inflammatory and anticancer etc. Chalcones are basically the
α,β-unsaturated carbonyl compounds in which it contain
ketoethylenic group. Chalcones have conjugated double bonds
and a totally delocalized π-electron framework on both benzene
rings.

Vol. 29, No. 9 (2017)
Synthesis and Characterization of Antitubercular Triazine-Chalcone Hybrid Molecules 2085
The nitrogen containing heterocycles which are proved
to be potent in the field of medicinal chemistry are the impor-
tant class of compounds [7]. Triazine known from a long period
of time as a class of six membered heterocyclic compound
containing nitrogen. In 1,3,5-triazine all the nitrogen atoms
are present symmetrically therefore it is also called as
symmetrical triazine or s-triazine [4]. Recently it has been
discovered that 2,4,6-trisubstituted-1,3,5-triazine scaffolds act
as a potent inhibitor of Mycobacterium tuberculosis (Mtb)
H37RV. The derivatives of s-triazine have also been found to
possess a wide range of biological activities [8].
Spectral data for compound 3: The IR of compound 3
exhibited ν(N-H) = 3500-3300 cm–1 (N-H str. due to 2° amines),
ν(C=C)=1633.76 cm–1 (-C=C- str. in aromatic ring), ν(C-O-C)
stretching = 1222.91 cm–1 (C-O-C in ether), ν(C-N)stretching
= 802.41 cm–1, ν(C-H)(sp2) stretching = 3150-2950; 1H NMR
(400 MHz, DMSO-d6) δ ppm: 3.33 (s, 6H, -2OCH3), 6.5 (s,
1H (C-H), pyrimidine ring), 7.38-7.42 (m, 10H, Ar-H).
Synthesis of compound 7: 4-Aminoacetophenone (1.35 g,
0.01 mol) and 2-chloro-4,6-dimethoxy-1,3,5-triazine (1.75 g,
0.01 mol) were taken in round bottom flask and dissolved in
dry acetone (50 mL). The reaction mixture was refluxed for 8
h. The reaction mixture was poured into ice water. After
neutralization, the solid was filtered, washed and dried.
Synthesis of 1-[4-(4,6-dimethoxy-1,3,5-triazin-2-
ylamino)phenyl]-3-(3-methoxyphenyl)prop-2-en-1-one
(1A-1E): Compound 7 (2.74 g, 0.01 mol) was dissolved in
methanol (40 mL) in a 250 mL round bottom flask and to this
4-methoxy benzaldehyde (0.01 mol) was added. The solution
was kept on stirring for 30 min at room temperature. To the
reaction mixture sodium hydroxide solution (20 % w/v) was
added. After checking the completion of the reaction by TLC,
crushed ice was added in the reaction mixture and neutrali-
zation was done. The product was filtered and washed, dried
and recrystallized from ethanol. Synthesis of 1B, 1C, 1D and
1E was done by same method.
The pyrimidines and their derivatives have found to
possess diverse pharmacological properties and a wide range
of biological activities against unrelated DNA and RNA,
viruses including polio herps viruses, diuretic, antitumor, anti
HIV, cardiovascular and so on [7].
In the present work, the triazine-pyrimidine hybrids were
synthesized by using different schemes and were evaluated
for their in vitro antitubercular activity.
EXPERIMENTAL
Condenser, round bottom flask (250 mL), magnetic stirrer,
beakers (500 mL), tripod stand, thermometer, guard tube,
separating funnel, magnetic bead, measuring cylinder, test
tubes, TLC plate, U.V. chamber.
p-Nitroacetophenone, Fe-powder, ethanol, methanol,
ethylacetate, 2-chloro-4,6-dimethoxy-1,3,5-triazine, sodium
hydroxide pellets, potassium hydroxide, conc. HCl, dry acetone,
sodium carbonate, guanidine hydrochloride, 1,3-diphenyl
propane-2-one, chloroform, ethyl acetate, butanol, hexane,
distilled water, anisaldehyde, benzaldehyde, p-benzaloxy
benzaldehyde, p-chloro benzaldehyde, p-cyano benzaldehyde.
All the chemicals were purchased from Loba Chemical Ltd.
Synthesis of 4,6-diphenylpyrimidin-2-amine (2): 1,3-
Diphenyl propen-2-one (0.01mol) (1) were taken in a 250 mL
round bottom flask and dissolved in ethanol (25 mL). To this
guanidine chloride (0.01 mol) and ethanolic KOH (5 mL of
40 %) were added. The reaction mixture was refluxed for 10 h.
The mixture was then poured into water (ice-cold) and
neutralized with dil. HCl. After neutralization, the solid was
filtered, washed with excess of water, dried and recrystallized
from ethanol from ethanol to give pure product.
Spectral data for compound 1A: The IR of compound
1A exhibited ν(N-H) = 3330 cm–1 (N-H str. in 2° amine), ν(C-H)
= 2843 cm–1 (C-H str. in aromatic ring), ν(C=O) stretching =
1640 cm–1, ν(C=C)= 1632 cm–1 (-C=C- str. in aromatic ring),
ν(C-O-C) stretching = 1220 cm–1 (C-O-C in ether); ν(C-N)
stretching = 807 cm–1 (C-N- str. in s-triazine); 1H NMR (400
MHz, DMSO-d6) δ ppm: 3.33(s, 6H, -2OCH3), 3.82 (s, 3H,
P-OCH3), 7.10-7.90 (m, 8H,Ar-H), 7.98 (d, 1H of –CO-CH=),
8.18 (d, 1H of Ar-CH=), 10.47(s, 1H, -NH) [10].
Spectral data for compound 1B: ν(N-H) = 3223.16 cm–1
(N-H str. in 2° amine), ν(C-H)stretching = 2887.53 cm–1 (C-H
str. in aromatic ring), ν(C=O)stretching =1770.71 cm–1, ν(C=C)
= 1653-1618 cm–1 (-C=C- str. in aromatic ring),, ν(C=C)= 1548
cm–1 (-C=C- str. due to unsaturation with carbonyl), ν(C-O-C)
stretching = 1271.13 cm–1 (C-O-C in ether); ν(C-N)stretching
1
= 958 cm–1 (C-N- str. in s-triazine); H NMR (400 MHz,
DMSO-d6, δ, ppm): 7.13-7.74 (m, 9H, Ar-H), 7.78 (d, 1H,
HC=CH (H-α)), 8.01 (d, 1H, HC=CH (H-β)), 9.74 (s, 1H,
NH), 3.33 (s, 6H, -2OCH3) [5].
Spectral data for compound 2: The IR of compound
2 exhibited ν(C=C) stretching = 1537-1494 cm–1, ν(N-H)
(1° amine) stretching = 3302 cm–1 and 3475 cm–1, ν(C-N)
stretching = 1220.98 cm–1, ν(C-H)(Sp2) stretching = 3180.72
Spectral data for compound 1C: ν(N-H) = 3495.13 cm–1
(N-H str. in 2° amine), ν(C-H)stretching = 2924.18 cm–1 (C-H str.
in aromatic ring), ν(C=O) stretching =1678.13 cm–1, ν(C=C) =
1601.12 cm–1 (-C=C- str. in aromatic ring),, ν(C=C)= 1556.61
cm–1 (-C=C- str. due to unsaturation with carbonyl), ν(C-O-C)
stretching = 1269.2 cm–1 (C-O-C in ether); ν(C-N)stretching =
837.13 cm–1 (C-N- str. in s-triazine); 1H NMR (400 MHz, DMSO-
d6) δ ppm: 5.18 (s, 2H, -OCH2-Ar), 3.33 (s, 6H, -2OCH3), 7.0-
7.90 (m, 13H, Ar-H), 7.96 (d, 1H of –CO-CH=CH), 8.18 (d, 1H
of Ar-CH=CH-), 10.12 (s, 1H, NH-) [10].
Spectral data for compound 1D: ν(N-H) = 3489 cm–1
(N-H str. in 2° amine), ν(C-H)stretching = 3057.27 cm–1 (C-H
str. in aromatic ring), ν(C=O) stretching =1670-1620 cm–1,
ν(C=C)= 1552.75 cm–1 (-C=C- str. in aromatic ring), ν(C=C)
1
cm–1. H NMR (400 MHz, DMSO-d6) δ ppm: 3.43 (s, 3H,
-OCH3), 5.1 (s, 2H, -NH2), 7.0 to 8.0 (m, 20H, Ar-H and
NH) [9]. The yield, melting point and Rf has been shown in
Table-1.
Synthesis of compound 3: 4,6-Diphenylpyrimidin-2-
amine (0.01 mol) and 2-chloro-4,6- dimethoxy-1,3,5-triazine
(0.01 mol) were taken in round bottom flask and dissolved in
dry acetone (50 mL). The reaction mixture was refluxed for
8 h. After checking the TLC, the reaction mixture was poured
into ice-cold water. Neutralization of HCl was done by sodium
carbonate solution (0.005 N, 10 mL water). The solid was
filtered, washed and dried.

2086 Rawat et al.
Asian J. Chem.
= 1446.66 cm–1 (-C=C- str. due to unsaturation with carbonyl),
Spectral data for compound 2E: The IR of compound
2D exhibited ν(N-H) = 3504.77 cm–1 (Broad N-H str. due to 1°
and 2° amine), ν(C=C)= 1683.91 cm–1 (-C=C- str. in aromatic
ring), ν(C-O-C) stretching = 1273.06 cm–1 (C-O-C in ether),
ν(C-N)stretching = 837.13 cm–1; 1H NMR (400 MHz, DMSO-
d6) δ ppm: 3.32 (s, 3H, -OCH3), 7.0 to 8.0 (m, 20H, Ar-H and
NH) [11].
ν(C-O-C) stretching = 1269.2 cm–1 (C-O-C in ether); ν(C-N)
1
stretching = 835.21 cm–1 (C-N- str. in s-triazine); H NMR
(400 MHz, DMSO d6, δ, ppm): 7.61 (d, J = 15.2 Hz, 1H,
HC=CH (H-α)), 7.67-7.82 (m, 8H, Ar-H), 7.87 (d, J = 15.2
Hz, 1H, HC=CH (H-β)), 9.63 (s, 1H, NH), 3.33 (s, 6H, -
2OCH3) [5].
Spectral data for compound 1E: ν(N-H) = 3504.77 cm–1
(N-H str. in 2° amine), ν(C-H) stretching = 3032.20 cm–1 (C-H
str. in aromatic ring), ν(C=O)stretching =1683.91 cm–1, ν(C=C)
= 1543.10 cm–1 (-C=C- str. in aromatic ring),, ν(C=C)=1456.30-
1417.73 cm–1 (-C=C- str. due to unsaturation with carbonyl),
ν(C-O-C)stretching = cm–1 (C-O-C in ether); ν(C-N)stretching
= 837.13 cm–1 (C-N- str. in s-triazine).
Synthesis of N-(4-(4-(2,6-dimethoxypyrimidin-4-
ylamino)phenyl)-6-(4-methoxyphenyl)pyrimidin-2-yl)-4,6-
dimethoxy-1,3,5-triazin-2-amine (3A-3E): Compound 3A
(0.01 mol) and 2-chloro-4,6-dimethoxy-1,3,5-triazine (6) (1.75
g, 0.01 mol) were taken in a 250 mL round bottom flask and
dissolved in dry acetone (50 mL). The reaction mixture was
refluxed for 8 h. Completion of reaction was confirmed by
TLC. The reaction mixture was poured into ice water. After
neutralization, the solid was filtered, washed with excess of
water and dried. Purification of compound was done by ethyl
acetate and hexane.
Synthesis of N-[4-(2-amino-6-(4-methoxyphenyl)
pyrimidin-4-yl) phenyl]-2,6-dimethoxypyrimidin-4-amine
(2A-2E): Compound 1A (0.01 mol) was dissolved in 25 mL
ethanol in a 250 mL round bottom flask. To the solution
guanidine hydrochloride (0.01 mol) and KOH (5 mL of 40 %)
were added. Reflux the reaction mixture for 10 h. Completion
of the reaction was confirmed with the help of TLC. After
completion of reaction, the reaction mixture was cooled,
poured into crushed ice, washed and dried to give the product.
The synthesis of 2B, 2C, 2D and 2E was carried out in
the similar manner.
Spectral data for compound 3A: The IR of compound
3A exhibited ν(N-H) = 3608-3533 cm–1 (Broad N-H str. due
to 2° amines), ν(C=C)= 1649.19 cm–1 (-C=C- str. in aromatic
ring), ν(C-O-C) stretching = 1263.42 cm–1 (C-O-C in ether),
ν(C-N) stretching = 802.41 cm–1, ν(C-H)(sp3) stretching =
2966.62 cm–1. 1H NMR (400 MHz, DMSO-d6) δ ppm: 3.37 (s,
15H, -OCH3), 7.06 (d, 2H,Ar-H), 7.94 (s, 1H (C-H), pyrimidine
ring), 7.84 (d, 2H, Ar-H). The yield, melting point and Rf has
been shown in Table-1.
Spectral data for compound 2A: The IR of compound
2A exhibited ν(N-H) = 3479.7 cm–1 (Broad N-H str. due to 1°
and 2° amine), ν(C=C)= 1653.05 cm–1 (-C=C- str. in aromatic
ring), ν(C-O-C) stretching = 1344.43 cm–1 (C-O-C in ether),
ν(C-N) stretching = 806.27; 1H NMR (400 MHz, DMSO-d6)
δ ppm: 3.43 (s, 3H, -OCH3), 5.1 (s, 2H, -NH2), 7.0 to 8.0 (m,
20H, Ar-H and NH) [11]. The yield, melting point and Rf has
been shown in Table-1.
Spectral data for compound 3B: The IR of compound
3B exhibited ν(N-H) = 3282.95 cm–1 (Broad N-H str. due to
2° amines), ν(C=C) = 1543.10 cm–1 (-C=C- str. in aromatic
ring), ν(C-O-C) stretching = 1089.82 cm–1 (C-O-C in ether),
ν(C-N) stretching = 800.49 cm–1, ν(C-H)(sp2) stretching =
3026.69 cm–1. 1H NMR (400 MHz, DMSO-d6) δ ppm: 3.32 (s,
12H, -OCH3), 6.78 (s, 1H (C-H), pyrimidine ring), 7.85 (d,
2H, Ar-H), 8.22 (s, 4H, Ar-H), 7.91(d, 2H, Ar-H).
Spectral data for compound 2B: The IR of compound
2B exhibited ν(N-H) = 3238-3450 cm–1 (Broad N-H str. due
to 1° and 2° amine), ν(C=C)= 1678-1618 cm–1 (-C=C- str. in
aromatic ring), ν(C-O-C) stretching = 1089.82 cm–1 (C-O-C
in ether), ν(C-N) stretching = 956 cm–1; 1H NMR (400 MHz,
DMSO-d6) δ ppm: 3.43 (s, 3H, -OCH3), 5.1 (s, 2H, -NH2), 7.0
to 8.0 (m, 20H, Ar-H and NH) [11]. The yield, melting point
and Rf has been shown in Table-1.
Spectral data for compound 3C: The IR of compound
3C exhibited ν(N-H) = 3504.77 cm–1 (Broad N-H str. due to
2° amines), ν(C=C) = 1670.41 cm–1 (-C=C- str. in aromatic
ring), ν(C-O-C) stretching = 1263.42 cm–1 (C-O-C in ether),
ν(C-N) stretching = 800.49 cm–1, ν(C-H)(sp2) stretching =
3059.20 cm–1.
Spectral data for compound 2C: The IR of compound
2C exhibited ν(N-H) = 3440-3500 cm–1 (Broad N-H str. due
to 1° and 2° amine), ν(C=C)= 1640-1680 cm–1 (-C=C- str. in
aromatic ring), ν(C-O-C) stretching = 1273.06 cm–1 (C-O-C
in ether), ν(C-N)stretching = 835.21 cm–1; 1H NMR (400 MHz,
DMSO-d6) δ ppm: 3.9 (s, 3H, -OCH3), 5.1 (s, 2H, -NH2), 7.0
to 8.0 (m, 20H, Ar-H and NH) [11]. The yield, melting point
and Rf has been shown in Table-1.
Spectral data for compound 3D: The IR of compound
3D exhibited ν(N-H) = 3471.98 cm–1 (Broad N-H str. due to
2° amines), ν(C=C) = 1585.54 cm–1 (-C=C- str. in aromatic
ring), ν(C-O-C) stretching = 1267.27 cm–1 (C-O-C in ether),
ν(C-N) stretching = 1055.1 cm–1, ν(C-H)(sp2) stretching =
2926.11 cm–1. 1H NMR (400 MHz, DMSO-d6) δ ppm: 3.60 (s,
12H, -OCH3), 6.78 (s, 1H (C-H), pyrimidine ring), 7.19 (d,
2H, Ar-H), 7.55 (m, 4H, Ar-H), 7.87(d, 2H, Ar-H).
Spectral data for compound 3E: ν(N-H) = 3354.77 cm–1
(Broad N-H str. due to 2° amines), ν(C=C) = 1678.13 cm–1
(-C=C- str. in aromatic ring), ν(C-O-C) stretching = 1269.20
cm–1 (C-O-C in ether), ν(C-N) stretching = 798.56 cm–1,
ν(C-H)Sp stretching = 2893.92 cm–1.
Spectral data for compound 2D: The IR of compound
2D exhibited ν(N-H) = 3450-3300 cm–1 (Broad N-H str. due
to 1° and 2° amine), ν(C=C) = 1627.97 cm–1 (-C=C- str. in
aromatic ring), ν(C-O-C) stretching = 1361.19 cm–1 (C-O-C in
ether), ν(C-N)stretching = 871.85 cm–1; 1H NMR (400 MHz,
DMSO-d6) δ ppm: 3.9 (s, 3H, -OCH3), 5.1 (s, 2H, -NH2), 7.0
to 8.0 (m, 20H, Ar-H and NH). 1H NMR (400 MHz, DMSO-
d6) δ ppm: 3.33 (s, 12H, -OCH3), 6.72 (s, 1H (C-H), pyrimidine
ring), 7.23 (m, 8H, Ar-H) [11].
Anti-TB activity using alamar blue dye: The anti-
tubercular activity of the synthesized compounds was checked
against H37RV M. tuberculosis using alamar blue assay. 200
µL of sterile water was added each well of 96 well plates. 100

Vol. 29, No. 9 (2017)
Synthesis and Characterization of Antitubercular Triazine-Chalcone Hybrid Molecules 2087
TABLE-1
ANTITUBERCULAR ACTIVITY OF COMPOUNDS 1-3A-E
Samples
TRZ
1
100 µg/mL
50 µg/mL
25 µg/mL
12.5 µg/mL
6.25 µg/mL
3.12 µg/mL
1.6 µg/mL
0.8 µg/mL
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
R
S
S
S
R
S
S
R
S
S
S
S
R
S
R
S
R
S
R
S
R
S
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
S
R
R
R
R
R
S
R
R
R
R
R
S
R
R
R
R
R
R
R
S
2
1-A
1-B
1-C
1- D
1-E
2-A
2-B
2-C
2-D
2-E
3-A
3-B
3-C
3-D
3-E
S
R
S
R
S
R
S
S
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
µL of the Middlebrook 7H9 broth was added in each well,
serial dilutions were made directly. Drug concentration was
checked for 100-0.2 µg/mL. Plates were incubated for five
days at 37 °C. After 5 days 25 µL of 1:1 mixture of almar blue
reagent and 10 % Tween 80 was added and the plates were
further incubated for 24 h. A blue coloration shows bacterial
growth inhibition and pink colour indicates bacterial cell
growth. Pyrazinamide and streptomycin were used as standards
for analysis [12].
Compound 3 was characterized by IR, 1H NMR and 13C
NMR spectroscopy. It gave a single characteristic peaks at
3500-3300 cm–1 (2° amine) and the peaks of N-H stretching
1
(1° amine) vanished. H NMR done in DMSO-d6 showing
singlet at δ = 3.33 ppm for 6H (2-OCH3) and at 6.5 ppm for
1H (C-H) of pyrimidine ring, multiplet at 7.38-7.42 ppm for
10H of aromatic ring were observed. The structure of compound
3 was confirmed to be N-(4,6-diphenylpyrimidin-2-yl)-4,6-
dimethoxy-1,3,5-triazin-2-amine.
In Scheme-II, compound 5 was synthesized by the reaction
of p-amino acetophenone with s-triazine in dry acetone. This
was further reacted with substituted aromatic aldehyde to form
compounds 1A-1E. Compound 5 gave characteristic peak at
3300-3250 cm–1 for N-H stretching (2° amine) and for carbonyl
stretching peak at 1670-1660 cm–1 was observed [5]. This con-
firmed the structure of compound 5 to be 1-[4-(4,6-dimethoxy-
1,3,5-triazin-2-ylamino)phenyl]ethanone.
RESULTS AND DISCUSSION
Two schemes were followed for the synthesis of compounds.
Compounds 2 and 3 were synthesized using Scheme-I and
compounds 1A-3E were synthesized using Scheme-II.
Compound 2 was synthesized by reaction of un-substituted
to form pyrimidine ring (Scheme-I). Compound 2 gave charac-
teristic peaks at 3400-3200 cm–1 showing the presence of NH2
group. The data was correlated with those present in literature
[7].
Compounds 1A-1E were synthesized by subsequent
condensation of compound 5 with various aromatic aldehydes
(A-E) in basic medium (40 % NaOH) using methanol as
OCH3
N
N
NH2
OCH3
N
NH
a
N
N
b
N
N
O
Chalcone (1)
4,6-Diphenylpyrimidin-2-amine (2)
N-(4,6-Diphenylpyrimidin-2-yl)-4,6-
dimethoxy-1,3,5-triazin-2-amine (3)
Reagents and conditions: (a) Guanidine HCl, 40 % KOH, ethanol, reflux 10 h, (b) 2-chloro-4,6-dimethoxy-1,3,5-triazine, dry acetone, reflux 8 h
Scheme-I: Representation of synthesis of compound 1-3

2088 Rawat et al.
Asian J. Chem.
NO2
NH2
c
2FeCl3
2H2O
6HCl
2Fe
+
+
+
H3C
O
H3C
O
4
5
NH2
O
N
O
Cl
O
N
N
d
H
N
N
N
+
O
N
O
7
6
H3C
O
5
O
N
O
N
N
CHO
O
N
O
N
N
NH
O
R
e
H
N
+
R
1A-1E
O
OCH3
7
N
N
f
NH2
N
OCH3
OCH3
N
N
g
R
OCH3
N
N
Cl
N
R
N
N
N
N
N
H
H3CO
2A-2E
N
N
H
N
H3CO
O
O
3A-3E
R
A = 4-OCH3
B = H
C = 4-OCH2-C6H5
D = 4-Cl
E = 4-CN
Reagents and conditions: (c) ethanol, reflux 6 h, 60 °C, (d) dry acetone, reflux 8 h, (3) methanol,
40 % NaOH, reflux 16 h, (f) guanidine HCl, 40 % KOH, ethanol, reflux 10 h, (g) dry acetone, reflux 8 h
Scheme-II: Representation of synthesis of compound 1A-3E
solvent medium. Compound B gave characteristic peak at
3350-3200 cm–1 due to N-H stretching (2°amine) and at 1650-
1600 cm–1 due to carbonyl stretching (C=O) group. The data
was confirmed with those present in literature [5] and the
structure of compound 1A was confirmed to be 1-[4-(4,6-
dimethoxy-1,3,5-triazin-2-ylamino)phenyl]-3-(3-methoxy-
phenyl)prop-2-en-1-one.
Compound 1B gave characteristic peak at 3250-3200 cm–1
due to N-H stretching (2° amine) and at 1680-1580 cm–1 due
to carbonyl (C=O) group. The data was confirmed with those
present in literature [5] and the structure of compound 1B was
confirmed to be 1-[4-(4,6-dimethoxy-1,3,5-triazin-2-ylamino)-
phenyl]-3-phenylprop-2-en-1-one.
Compound 1C gave characteristic peak at 3500-3400 cm–1
due to N-H stretching (2°amine) and at 1700-1650 cm–1 due
to carbonyl (C=O) group. The data was confirmed with those
present in literature [5] and the structure of compound 1C
was confirmed to be 3-(3-(benzyloxy)phenyl)-1-[4-(4,6-
dimethoxy-1,3,5-triazin-2-ylamino)phenyl]prop-2-en-1-one.
Compound 1D gave characteristic peak at 3500-3450 cm–1
due to N-H stretching (2°amine) and at 1700-1600 cm–1 due
to carbonyl (C=O) group. The data was confirmed with those

Vol. 29, No. 9 (2017)
Synthesis and Characterization of Antitubercular Triazine-Chalcone Hybrid Molecules 2089
present in literature [5] and the structure of compound 1D
was confirmed to be (E)-3-(4-chlorophenyl)-1-(4-(2,6-dimethoxy-
pyrimidin-4-ylamino)phenyl)prop-2-en-1-one.
structure of the compound was confirmed to be 4-(2-amino-
6-(4-(2,6-dimethoxypyrimidin-4-ylamino)phenyl)pyrimidin-
4-yl)benzonitrile.
Compound 1E gave characteristic peak at 3500-3550 cm–1
due to N-H stretching (2°amine) and at 1700-1600 cm–1 due
to carbonyl (C=O) group. The structure of compound 1E was
confirmed to be 3-(3-(4-(4,6-dimethoxy-1,3,5-triazin-2-ylamino)-
phenyl)-3-oxoprop-1-enyl)benzonitrile.
Compounds 3A-3E were synthesized by further reaction
of compound 2A-2E with s-triazine in dry acetone at 60 °C.
The structure of the compounds was assigned with the help of
IR, 1H NMR and 13C NMR.
The 1H NMR was done at 400 MHz in DMSO-d6, showing
characteristic peaks at δ =3.5-4.0 ppm for -OCH3 proton and
at 6.5-7.0 ppm for 1H (C-H) of pyrimidine ring. Two doublets
at 7.10-7.60 ppm and a multiplet at 7.50-7.90 ppm for aromatic
proton were also observed.
Compounds 2A-2E were synthesized by the reaction of
compounds 1A-1E with guanidine hydrochloride in basic
medium (40 % KOH) to form pyrimidine ring. The structure
of the synthesized compounds was assigned on the basis of
IR, 1H NMR. The proton NMR was done at 400 MHz in DMSO-
d6. The characteristic peaks at δ 3.5-4.0 ppm (singlet) for -OCH3
group and at 5.0-5.3 ppm (singlet) for -NH2 protons were
observed. A multiplet at 7.0 to 7.5 ppm for aromatic proton
were also observed.
Compound 3A gave a single characteristic peaks at 3600-
3500 cm–1 of 2° amine and the peaks of N-H stretching (1° amine)
was removed. The structure of compound 3A was confirmed
to be N-(4-(4-(2,6-dimethoxypyrimidin-4-ylamino)phenyl)-6-
(4-methoxyphenyl)pyrimidin-2-yl)-4,6-dimethoxy-1,3,5-
triazin-2-amine.
Compound 2A gave two characteristic peaks at 3500-3300
cm–1 showing the presence of N-H stretching (1° amine) and
the characteristic peak of α,β-unsaturation carbonyl group
(1650-1600 cm–1) was absent showing the condensation of
guanidine hydrochloride with that group and a characteristic
peak of C=N stretching was observed at 1530 cm–1. The struc-
ture of the compound was confirmed to be N-[4-(2-amino-6-
(4-methoxyphenyl)pyrimidin-4-yl)phenyl]-2,6-dimethoxy-
pyrimidin-4-amine.
Compound 3B gave a single characteristic peaks at 3300-
3250 cm–1 of 2° amine and the peaks of N-H stretching (1° amine)
was removed. The structure of compound 3A was confirmed
to be N-(4-(4-(2,6-dimethoxypyrimidin-4-ylamino)phenyl)-6-
phenylpyrimidin-2-yl)-4,6-dimethoxy-1,3,5-triazin-2-amine.
Compound 3C gave a single characteristic peaks at 3504 cm–1
of 2° amine and the peaks of N-H stretching (1° amine) was
removed. The structure of compound 3A was confirmed to be
N-(4-(4-(benzyloxy)phenyl)-6-(4-(2,6-dimethoxypyrimidin-
4-ylamino)phenyl)pyrimidin-2-yl)-4,6-dimethoxy-1,3,5-
triazin-2-amine.
Compound 2B gave two characteristic peaks at 3450-3250
cm–1 showing the presence of N-H stretching (1° amine) and
the characteristic peak of α,β-unsaturation carbonyl group
(1680-1580 cm–1) was absent showing the condensation of
guanidine hydrochloride with that group and a characteristic
peak of C=N stretching was observed at 1440 cm–1. The structure
of the compound was confirmed to be N-[4-(2-amino-6-phenyl-
pyrimidin-4-yl)phenyl]-2,6-dimethoxypyrimidin-4-amine.
Compound 2C gave two characteristic peaks at 3440-3500
cm–1 showing the presence of N-H stretching (1° amine) and
the characteristic peak of α,β-unsaturation carbonyl group
(1700-1650 cm–1) was absent showing the condensation of
guanidine hydrochloride with that group and a characteristic
peak of C=N stretching was observed at 1540-1480 cm–1. The
structure of the compound was confirmed to be N-(4-(2-amino-
6-(4-(benzyloxy)phenyl)pyrimidin-4-yl)phenyl)-2,6-dime-
thoxypyrimidin-4-amine.
Compound 3D gave a single characteristic peaks at 3500-
3400 cm–1 of 2° amine and the peaks of N-H stretching (1° amine)
was removed. The structure of compound 3A was confirmed to be
N-(4-(4-chlorophenyl)-6-(4-(2,6-dimethoxypyrimidin-4-ylamino)-
phenyl)pyrimidin-2-yl)-4,6-dimethoxy-1,3,5-triazin-2-amine.
Compound 3E gave a single characteristic peaks at 3450-
3300 cm–1 of 2° amine and the peaks of 1° NH2 were vanished.
The structure of compound 3A was confirmed to be 4-(2-(4,
6-dimethoxy-1,3,5-triazin-2-ylamino)-6-(4-(2,6-dimethoxy-
pyrimidin-4-ylamino)phenyl) pyrimidin-4-yl)-benzonitrile.
Furthermore, the compounds 1-3 (A-E) were evaluated
for their in vitro antitubercular activity using H37RV Mycobac-
terium tuberculosis by alamar blue assay (Fig. 1). The MIC
(minimum inhibitory concentration) is expressed in minimum
in µg/mL. From the results, it is revealed that the compounds 1
and 2B are showing the maximum inhibition of bacterium, with
MIC value of 1.6 µg/mL. The compound 1E showed promising
activity, with MIC values 3.12 µg/mL. Some of compounds like
1D and 2C showed activity at 12.5 µg/mL (Table-1) [12].
Compound 2D gave two characteristic peaks at 3450-3300
cm–1 showing the presence of N-H stretching (1° amine) and
the characteristic peak of α,β-unsaturation carbonyl group
(1700-1600 cm–1) was absent showing the condensation of
guanidine hydrochloride with that group and a characteristic
peak of C=N stretching was observed at 1600-1450 cm–1. The
structure of the compound was confirmed to be N-(4-(2-amino-
6-(4-chlorophenyl)pyrimidin-4-yl)phenyl)-2,6-dimethoxy-
pyrimidin-4-amine.
Conclusions
In order to explore the novel concept of developing hybrid
molecules for tuberculosis and in view of the excellent anti-
TB activity exhibited by triazine, chalcone and pyrimidine
moieties. A series of eighteen triazine-chalcone and triazine-
chalcone-pyrimidine hybrids were synthesized and evaluated
for their ant-TB activity.
Compound 2E gave two characteristic peaks at 3500-3450
cm–1 showing the presence of N-H stretching (1° amine) and
the characteristic peak of α,β-unsaturation carbonyl group
(1700-1600 cm–1) was absent showing the condensation of
guanidine hydrochloride with that group and a characteristic
peak of C=N stretching was observed at 1550-1450 cm–1. The
In the present study, it is found that Compound 1 and 2B
are very potent against tuberculosis at a concentration of 1.6

2090 Rawat et al.
Asian J. Chem.
100
60
26
12.5
6.25
3.12
1.6
0.8
A number of lead compounds have been synthesized.
Further work could be undertaken to develop quite potent drug
against one of the World’s most deadly disease.
TRZ
1-A
1-C
The third series containing triazine-chalcone-pyrimidine
is reported for the first time. Further work could be on the
third series to find out its medicinal importance.
1-D
1-E
2-B
REFERENCES
1-B
2-A
2-C
3-D
2-D
2
1. V.R.Avupati and R.P.Yejella, World J. Pharm Pharm. Sci., 3, 278 (2014).
2. R. Ghosh and A. Das, World J. Pharm. Pharm. Sci., 3, 578 (2014).
3. A. Solanki and R. Patel, Indian J. Chem., 53B, 1448 (2014).
4. M.R. Gajula and Y.V.R. Reddy, Eur. J. Chem., 5, 374 (2014);
https://doi.org/10.5155/eurjchem.5.2.374-379.1027.
5. S.R. Dwarampudi, G.S. Dannana, V.R. Avupati and V.S.M. Bendi, Eur.
J. Chem., 5, 570 (2014);
https://doi.org/10.5155/eurjchem.5.4.570-576.1098.
6. R. Saha, M.M. Alam and M. Akhter, RSC Adv., 5, 12807 (2015);
https://doi.org/10.1039/C4RA14440F.
1
3-B
3-E
7. V. Sharma and K.V. Sharma, Rasayan J. Chem., 4, 17 (2011).
8. F.G. Khan, M.V.Yadav, S.R. Khapate andA.D. Sagar, Indo-Am. J. Pharm.
Res., 5, 1447 (2015).
2-E
3-A
3-B
9. S. Syam, S.I.Abdelwahab, M.A.Al-Mamary and S. Mohan, Molecules,
17, 6179 (2012);
https://doi.org/10.3390/molecules17066179.
Fig. 3. Anti-TB results of the synthesized compounds
10. A. Solankee, K. Patel and R. Patel, E-J. Chem., 9, 1897 (2012);
https://doi.org/10.1155/2012/638452.
11. A. Solankee and Y. Prajapati, Rasayan J. Chem., 2, 9 (2009).
12. M.C.S. Lourenço, M.V.N. de Souza, A.C. Pinheiro, M. de L. Ferreira,
R.S.B. Gonçalves, T.C.M. Nogueira and M.A. Peralta, Arkivoc, 181
(2007);
µg/mL, whereas compound 1E is efficacious at a concentration
of 3.12 µg/mL. Compounds like 1D and 2C are effective at
12.5 µg/mL whereas all others are sensitive at a concentration
of 25 µg/mL.
https://doi.org/10.3998/ark.5550190.0008.f18.