Facile synthesis and antibacterial, antitubercular, and anticancer activities of novel 1,4-dihydropyridines

Article abstract of DOI:10.1002/ardp.200900243

A series of twenty new 4-substituted-2,6-dimethyl-3,5-bis-N-(heteroaryl)- carbamoyl-1,4-dihydropyridines have been prepared from a three-component one-pot condensation reaction of N-heteroaryl acetoacetamide, an aromatic/ heteroaromatic aldehyde, and ammonium acetate under four different experimental conditions. Except for the conventional method, all the experimental conditions were simple, eco-friendly, economical, and the reactions were rapid and high-yielding. The methods employed have been compared in terms of yields, cost, and simplicity. The synthesized compounds were characterized by different spectroscopic techniques and evaluated for their in-vitro anticancer, antibacterial, and antitubercular activities. Amongst the compounds tested, compound 25 exhibited the highest anticancer activity while compounds 14 and 18 exhibited significant antibacterial and antitubercular activities.

Full text of DOI:10.1002/ardp.200900243

342
Arch. Pharm. Chem. Life Sci. 2010, 343, 342–352
Full Paper
Facile Synthesis and Antibacterial, Antitubercular, and
Anticancer Activities of Novel 1,4-Dihydropyridines
Kalam Sirisha, Garlapati Achaiah, and Vanga Malla Reddy
Medicinal Chemistry Research Division, University College of Pharmaceutical Sciences, Kakatiya University,
Warangal, India
A series of twenty new 4-substituted-2,6-dimethyl-3,5-bis-N-(heteroaryl)-carbamoyl-1,4-dihydropyr-
idines have been prepared from a three-component one-pot condensation reaction of N-hetero-
aryl acetoacetamide, an aromatic/heteroaromatic aldehyde, and ammonium acetate under four
different experimental conditions. Except for the conventional method, all the experimental
conditions were simple, eco-friendly, economical, and the reactions were rapid and high-yield-
ing. The methods employed have been compared in terms of yields, cost, and simplicity. The syn-
thesized compounds were characterized by different spectroscopic techniques and evaluated for
their in-vitro anticancer, antibacterial, and antitubercular activities. Amongst the compounds
tested, compound 25 exhibited the highest anticancer activity while compounds 14 and 18
exhibited significant antibacterial and antitubercular activities.
Keywords: Anticancer activity / Antitubercular activity / 1,4-Dihydropyridines / N-Heteroaryl acetoacetamide / Micro-
wave irradiation /
Received: October 9, 2009; Accepted: December 31, 2009
DOI 10.1002/ardp.200900243
activities. 1,4-DHPs are also known to act as chemosensi-
Introduction
tizers in MDR tumor therapy [6]. The structure-activity
relationship studies of 1,4-DHPs with regard to calcium
channel modulatory activity revealed that changes in the
substitution pattern at C-3, C-4, and C-5 positions of the
1,4-DHP ring alter potency, tissue selectivity, and the
boat-shaped confirmation of the 1,4-DHP ring [7]. The pyr-
idyl substituent at C-3 and C-5 positions with a heterocy-
clic ring at C-4 proved to be effective [8]. A comparative
3D-QSAR study of dihydropyridines and dihydropyrimi-
dines with respect to their cytotoxicity revealed dihydro-
pyridines as the most potent candidates [9]. Likewise
CoMFA methodology, a 3D-QSAR technique, with some
novel 1,4-DHPs in respect of their antitubercular and
anticancer activities, also revealed the substituent
requirements at C-3, C-4, and C-5 positions [10].
In general, the classical Hantzsch method for the syn-
thesis of 1,4-DHPs requires long reaction times, yet, gain-
ing low yields. Considering the growing importance of
1,4-DHPs from a pharmaceutical, industrial, and syn-
thetic point of view, novel synthetic strategies [11] leading
to a drastic reduction of reaction times and a phenomenal
increase in yield havebeen developed.
Hantzsch 1,4-dihydropyridines (1,4-DHPs) and their deriv-
atives have gained great importance in the field of medic-
inal chemistry since they display a fascinating array of
pharmacological properties. 1,4-DHPs are well known as
calcium channel blockers, and have emerged as one of
the most important classes of drugs for the treatment of
several cardiovascular diseases, including angina pecto-
ris and hypertension. Interestingly, this heterocyclic sys-
tem has been found to be the structural feature of several
compounds belonging to different bio-active classes such
as vasodilator, bronchodilator, analgesic, anti-inflamma-
tory, antithrombotic, anticonvulsant, hepato-protective,
radioprotective, antiatherosclerotic, and antidiabetic
agents [1]. They were also reported to exhibit anticancer
[2], antitubercular [3], antibacterial [4], and antiviral [5]
Correspondence: Dr. V. M. Reddy, Medicinal Chemistry Research Divi-
sion, University College of Pharmaceutical Sciences, Kakatiya University,
Warangal 506 009, India.
E-mail: vangamallareddy@yahoo.co.in, vanga_mreddy@rediffmail.com
Fax: +91 870 245-3508
Abbreviation: 1,4-dihydropyridines (1,4-DHPs)
i 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Arch. Pharm. Chem. Life Sci. 2010, 343, 342–352
1,4-DHPs as Anticancer and Antitubercular agents
343
Table 1. Physical and analytical data of intermediates 3a–d.
Compound
Substituent
Ar
Mol. formula
(Mol. Wt)
M.p.
(8C)
Conventional
method
Microwave
method
Yield
Yield
(%)/(Period/h)
(%)/(Period/min)
3a
3b
C9H10N2O2
(178.19)
114–116
156–158
64 (0.5)
82 (0.5)
70 (3.0)
85 (3.0)
C9H9ClN2O2
(212.672)
3c
C10H12N2O2
(192.216)
102–104
156–158
52 (1.0)
55 (1.5)
62 (4.0)
60 (4.0)
3d
C13H13N3O3
(259.264)
Literature on 1,4-DHPs reveals an extensive work on potassium tert-butoxide in ethanol furnished the corre-
DHP ester derivatives. In contrary to this, the reports on sponding N-substituted acetoacetamides requiring
DHP carboxamide derivatives are meager [12]. However, refluxation for 0.5 to 1.5 h yielding 3a–d [24]. This reac-
recently, the synthesis and antitubercular activity of new tion was also carried out by microwave irradiation
N,N-diaryl-3,5-dicarbamoyl derivatives of 1,4-DHPs and method to afford these intermediates within 3–4 min.
1,4-DHPs containing different ester substitutes and The results are presented in Table 1. A three-component
diethyl carbamoyl groups have been reported [13]. It is condensation reaction of the N-substituted acetoacet-
also of interest to incorporate some biologically potent amides 3a–d with six different aldehydes (4a–f) and
heterocycles viz., pyridine [14], quinazolin-4(3H)-one [15], ammonium acetate 5 under four different experimental
imidazole [16], thiophene [17], furan [18], and pyrrole [19] conditions, viz.; conventional heating, barium nitrate-
into the DHP system along with the carboxamide func- catalyzed one-pot synthesis [11], microwave heating in
tionality with a regard to obtaining an increased biologi- solvent, and solvent-free microwave irradiation, led to
cal potency. Therefore, in continuation of our studies on the formation of various 4-substituted-2,6-dimethyl-3,5-
novel DHP carboxamides [20–24] and improved green bis-N-(heteroaryl)-carbamoyl-1,4-dihydropyridines 6–25
synthetic techniques [25], herein, we report the simpli- (Scheme 1). The results are shown in Table 2.
fied, rapid, and high-yielding syntheses of some new 4-
In the microwave procedure, synthesis of 1,4-DHPs 6–
substituted-2,6-dimethyl-3,5-bis-N-(heteroaryl)-carbamoyl- 25 was completed within 4–6 min as compared to 40–45
1,4-dihydropyridines 6–25, making use of specified he- h heating using the conventional method. The structures
terocycles along with their antibacterial, antitubercular, of the newly synthesized compounds were confirmed
and anticancer evaluation data.
from spectral (IR, 1H-NMR, Mass) and elemental analyses
data.
The percentage yield of N-substituted acetoacetamides
3 has been improved considerably in the presence of a
base catalyst, potassium tert-butoxide. Among the four
sets of reaction conditions employed for the three-com-
Results and discussion
Chemistry
Condensation of ethyl acetoacetate 1 with various hetero- ponent cyclocondensation reaction to obtain DHPs, the
cyclic amines 2 in the presence of a trace of catalyst, microwave irradiation method on a solid support of
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344
K. Sirisha et al.
Arch. Pharm. Chem. Life Sci. 2010, 343, 342–352
Table 2. Physical and analytical data of 1,4-DHPs 6–25.
Compound
Ar
Ar9
Mol. formula M.p. (8C)
(Mol. wt)
Conventional Barium nitrate-
Microwave method &
method §
catalyzed
method #
Yield
Yield
Method I
Method II
Yield (%)
Methods I & II
(Period/min)
(%)/(Period/h) (%)/(Period/min) Yield (%)
6
2-Pyridyl
2-Pyridyl
2-Pyridyl
2-Pyridyl
2-Pyridyl
2-Pyridyl
2-Furyl
C23H21N5O3
415.448
C24H22N6O2
426.476
C23H21N5O2S
431.448
248–250
208–210
258–260
212–214
236–238
62 (42.0)
58 (45.0)
70 (45.0)
75 (38.0)
76 (42.0)
72 (45.0)
64 (38.0)
78 (36.0)
75 (34.0)
55 (40.0)
68 (40.0)
72 (40.0)
68 (45.0)
76 (43.0)
73 (42.0)
79 (44.0)
82 (40.0)
81 (40.0)
50 (45.0)
70 (40.0)
62 (35.0)
76 (40.0)
78 (30.0)
78 (40.0)
75 (45.0)
70 (35.0)
82 (30.0)
78 (30.0)
60 (45.0)
68 (40.0)
75 (35.0)
72 (45.0)
78 (40.0)
75 (40.0)
80 (45.0)
84 (40.0)
85 (35.0)
62 (45.0)
70
65
75
82
80
84
72
85
80
65
70
78
75
78
78
75
85
88
70
75
68
78
82
78
80
75
87
82
62
72
80
75
80
76
80
88
86
68
4.0
7
2-Pyridyl
2-Thienyl
4.0
8
4.5
9
2-Imidazolyl C22H21N7O2
415.458
4.0
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
2-Pyrrolyl
4Cl-C6H5
2-Pyridyl
2-Thienyl
2-Imidazolyl
2-Pyrrolyl
2-Furyl
C23H22N6O2
414.466
C25H22ClN5O2 238–240
459.976
C24H20Cl2N6O2 212–214
495.316
4.0
4.5
5-Chloro-
pyridin-2-yl
5-Chloro-
pyridin-2-yl
5-Chloro-
pyridin-2-yl
5-chloro-
pyridin-2-yl
5-Chloro-
pyridin-2-yl
5-Chloro-
pyridin-2-yl
6-Methyl-
pyridin-2-yl
6-Methyl-
pyridin-2-yl
6-Methyl-
pyridin-2-yl
6-Methyl-
pyridin-2-yl
6-Methyl-
pyridin-2-yl
6-Methyl-
pyridin-2-yl
2-Methyl-4-
oxo-3H-quinazo-
lin-3-yl
4.5
C
23H19Cl2N5O2 S 198–200
499.432
22H19Cl2N7O2 224–226
484.442
23H20Cl2N6O2 230–232
483.45
23H19Cl2N5O3 208–210
484.432
25H20Cl3N5O2 254–256
528.96
26H26N6O2
454.528
25H25N5O2S
459.5
5.0
C
5.0
C
5.5
C
5.0
4Cl-C6H5
2-Pyridyl
2-Thienyl
2-Furyl
C
5.5
C
234–236
260–262
252–254
242–244
234–236
4.0
C
4.5
C
25H25N5O3
4.0
443.5
2-Pyrrolyl
2-Imidazolyl
4Cl-C6H5
C
25H26N6O2
4.5
442.518
C
24H25N7O2
4.0
443.51
C27H26ClN5O2 258–260
488.028
4.0
2-Imidazolyl C30H27N9O4
577.556
260–262
6.0
25
2-Methyl-4-oxo-
3H-quinazolin-
3-yl
4Cl-C6H5
C33H28ClN7O4 272(d)
621.424
55 (45.0)
58 (45.0)
60
60
6.0
§ Reflux in ethanol for 40–45 h; # heating in the presence of Ba(NO3)2 for 30–45 min; & microwave irradiation in solvent (method I)
and solvent-free (method II).
silica gel or acidic alumina (solvent-free/dry-media) and synthesis of more analogs, probably due to steric hin-
the microwave heating in solvent have been found to be derance.
almost identical and offered the advantage of being eco-
friendly and simple in operation with greater reaction Biology
rates over the conventional method. The second in the Anticancer activity in human cancer cell lines
order of merit happens to be the barium nitrate-cata- The MTT microassay was used for the evaluation of in-
lyzed one-pot synthesis. Barium nitrate is a safe, commer- vitro anticancer activity of the synthetic compounds 6–
cially inexpensive reagent and the reaction in absence of 25. The compounds were evaluated for their growth-
organic solvents makes the process eco-friendly.
inhibitory effects against three human cancer cells lines
Reduced yield of 1,4-DHPs from N-(2-methyl-4-oxo-3H- including MCF-7 (breast), HT-29 (colorectal), and A431
quinazolin-3-yl)acetoacetamide 3d has handicapped the (skin) cells following the method described previously
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Arch. Pharm. Chem. Life Sci. 2010, 343, 342–352
1,4-DHPs as Anticancer and Antitubercular agents
345
Reagents and conditions: (i) EtOH, reflux, 40–45 h; (ii) 5 mol% Ba(No3)2, D, 30–45 min; (iii) MWI, EtOH/DMF, 4–6 min; (iv) silica gel
or acidic alumina, MWI, 4–6 min.
Scheme 1. Synthesis of compounds 6–25.
Table 3. In-vitro anticancer activity of 4-substituted-3,5-bis-N-
(heteroaryl)-carbamoyl-1,4-dihydropyridines 6–25 (IC50 values in
lg/mL)§.
[26]. Methotrexate was used as a reference drug for com-
parison. Assays were performed in triplicate for three
independent determinations. The anticancer activity was
expressed as IC50 (lg/mL), the concentration of the com-
pound that inhibit proliferation rate of the tumor cells
by 50% as compared to the control untreated cells. Com-
pounds with IC50 > 200 lg/mL were considered to be inac-
tive. The results of compounds which showed significant
anticancer activity against the cell lines tested are sum-
marized in Table 3.
The anticancer activity of the compounds against the
three cell lines indicates that compound 25 with a N-(2-
methyl-4-oxo-3H-quinazolin-3-yl) group at C-3, C-5 posi-
tions and a 4-chlorophenyl group at C-4 is equipotent
when compared with the standard methotrexate against
MCF-7 and HT-29 cell lines. Compound 19 with a N-(6-
methylpyridin-2-yl) group at C-3, C-5 positions and a 2-
thienyl group at C-4 is next in potency against MCF-7 and
HT-29 cell lines. However, it is more potent (IC50 = 6.97 €
1.3 lg/mL) than compound 25 (IC50 = 9.84 € 2.3 lg/mL)
against the A431 cell line. Thus, 2-thienyl and 4-chloro-
phenyl groups being at C-4 are found to contribute to the
anticancer activity in DHPs having 6-methylpyridin-2-yl
Compound
Cell line
HT-29
MCF-7
A431
7
8
NA
NA
125.7 € 2.0
NA
NA
173.2 € 1.3
90.2 € 2.0
159.4 € 1.5
200.1 € 2.6
53.4 € 2.3
122.2 € 1.5
6.97 € 1.3
NA
11
12
13
14
18
19
21
22
24
25
71.5 € 1.5
NA
NA
96.8 € 2.1
NA
47.2 € 1.2
86.9 € 2.1
70.95 € 0.9
10.8 € 1.5
NA
61.1 € 2.3
NA
8.86 € 2.2
NA
38.6 € 1.2
16.8 € 2.1
112.0 € 1.2
81.7 € 2.0
NA
NA
197.07 € 1.2
9.84 € 2.3
4.81 € 1.5
15.2 € 2.0
11.8 € 1.5
Methotrexate 8.1 € 1.1
§ Data are presented as means € S.D (n = 3). Compounds 6–25 or
methotrexate dissolved in DMSO were diluted with culture
medium containing 0.1% DMSO, respectively. The control cells
were treated with culture medium containing 0.1% DMSO.
Methotrexate was used as a positive control; NA – no activity (i.
e., their IC50 > 200 lg/mL).
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346
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Arch. Pharm. Chem. Life Sci. 2010, 343, 342–352
Table 4. Antibacterial activity of some 4-substituted-3,5-bis-N-(heteroaryl)-carbamoyl-1,4-diydropyridines 6–25*.
Compounds
Concentration
(lg/mL)
Diameter of zone of inhibition (mm)
Gram-positive
S. aureus
Gram-negative
P. vulgaris
B. subtilis
MRSA §
E. coli
11
13
14
18
21
24
12.5
25
50
9
12
15
17
–
–
–
–
9
7
9
11
12
–
10
12
–
11
14
–
1000
12.5
25
50
6
8
10
–
7
–
–
–
–
6
8
11
–
7
9
10
–
10
12
–
1000
12.5
25
50
–
8
12
–
7
9
10
–
–
–
–
8
10
15
21
–
9
14
22
–
1000
12.5
25
50
7
9
–
–
–
10
12
20
24
–
11
16
21
–
11
13
–
11
12
–
1000
12.5
25
50
–
6
8
–
7
9
11
–
–
–
–
–
10
12
14
–
8
11
13
–
1000
12.5
25
50
11
13
18
–
–
–
–
–
–
7
9
10
–
6
8
11
–
10
12
–
1000
Streptomycin
Tetracyclin
50
1000
22
–
21
–
–
18
23
–
26
–
50
1000
20
–
22
–
–
15
25
–
21
–
* The data of compounds showing significant zones of inhibition at the concentrations tested is shown. The rest of the molecules
are inactive at the concentrations tested; § MRSA – Methicillin-resistant Staphylococcus aureus.
and 2-methyl-4-oxo-3H-quinazolin-3-yl groups as N-sub- tested against methicillin-resistant Staphylococcus aureus
stituents at C-3 and C-5 positions.
(MRSA) at a concentration of 1 mg/mL (1000 lg/mL). Tet-
racyclin and streptomycin were used as standard drugs
and the solvent DMSO as control. Each compound was
Antibacterial activity in normal and resistant bacteria
The in-vitro antibacterial assay of compounds 6–25 was assessed in triplicate and the average of the results of the
performed by the disc diffusion method [27] in nutrient compounds which showed significant activity is pre-
agar medium (results in mm) at three different concen- sented in Table 4. All such compounds were also eval-
trations, viz., 12.5, 25, and 50 lg/mL using two Gram-pos- uated for antitubercular activity. Analysis of the data
itive bacterial strains: Bacillus subtilis (NCIM-2063, ATCC indicated that compound 18 with a 2-pyridyl group at
No. 6633) and Staphylococcus aureus (NCIM-2079, ATCC No. the C-4 position and a N-(6-methylpyridin-2-yl) group at
6538P) and two Gram-negative strains: Escherichia coli positions C-3 and C-5 was almost equipotent to strepto-
(NCIM-2068, ATCC No. 11105) and Proteus vulgaris (NCIM- mycin/tetracyclin against Gram-negative bacteria
2027, ATCC No. 13315). Compounds with significant anti- whereas compound 24 was more potent against B. subti-
bacterial activity (11, 13, 14, 18, 21, and 24) were then lis. Three other compounds (11, 14, and 18) were also
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Arch. Pharm. Chem. Life Sci. 2010, 343, 342–352
1,4-DHPs as Anticancer and Antitubercular agents
347
Table 5. Antitubercular activity of compounds 11, 13, 14, 18, 21,
and 24 against sensitive and resistant strains of Mycobacterium
tuberculosis.
3-yl) groups at positions,C-3 and C-5, and 2-thienyl and 4-
chlorophenyl groups at the C-4 position as in compounds
19 and 25 are effective against all the three cell lines
tested. Compound 19 having a N-(6-methylpyridin-2-yl)
group at C-3, C-5 positions (IC50 = 10.8 € 1.5 lg/mL; MCF-7)
was more active than the corresponding N-(pyridin-2-yl)
and N-(5-chloropyridin-2-yl) analogs i. e., compounds 8
(IC50 > 200 lg/mL) and 13 (IC50 = 47.2 € 1.2 lg/mL). Thus, it
can be concluded that the electron-donating methyl
group at position 6 of the 2-pyridyl system being at C-3, C-
5 positions of DHP was more favorable with regard to
anticancer activity.
Compounds
M. tuberculosis
M. tuberculosis
(H37Rv) MIC (lg/mL) (C110/09) MIC (lg/mL)
11
13
14
18
21
24
>25
>25
25
–
–
256
128
256
–
12.5
>25
>25
32
Pyrazinamide
128
Analyses of antibacterial and antitubercular activities
indicated that compounds 19 and 25, which showed
potent anticancer activity were devoid of antibacterial as
well as antitubercular activities. However, compound 24
containing a 2-imidazolyl ring at position C-4 and a N-(2-
methyl-4-oxo-3H-quinazolin-3-yl) group at C-3, C-5 posi-
tions, could exhibit potent antibacterial as well as antitu-
bercular activities. The heterocyclic substituents 2-pyr-
idyl at C-4 and 6-methylpyridin-2-yl on carbamoyl nitro-
gens at C-3 and C-5 positions of the DHPs were found to
contribute to a greater extent to the antitubercular and
antibacterial activity against Gram-negative bacteria.
found to exhibit significant inhibitory action against
MRSA (8–10 mm), at 1 mg/mL concentration.
Antitubercular activity in sensitive and resistant
Mycobacterium tuberculosis
The in-vitro antimycobacterial activity of the compounds
11, 13, 14, 18, 21, and 24 which exhibited significant anti-
bacterial activity (Table 4) was performed against Myco-
bacterium tuberculosis H37Rv (ATCC 27294, susceptible to
rifampicin, pyrazinamide, and isoniazid), at graded con-
centrations of 6.25, 12.5, 25, 50, and 100 lg/mL and also
against a clinical isolate of multidrug-resistant Mycobacte-
rium tuberculosis (MDR-T.B, C110/09) at concentrations of
64, 128, and 256 lg/mL using the LJ (Lowenstein-Jensen)
proportion method [28]. The activity is expressed as mini-
mum inhibitory concentration (MIC), i.e., the lowest con-
centration of compound that completely inhibited the
growth in culture. The results indicated that some of the
tested compounds were promising candidates with
uniquely good activity against both sensitive and resist-
ant strains of M. tuberculosis (H37Rv & C110/09). The results
of three independent determinations are given in Table
5. The data revealed compound 18 as more potent than
control with a maximum antibacterial activity against
the Gram-negative bacteria and also antitubercular activ-
ity (IC50 = 12.5 lg/mL). It was interesting to observe that
this compound was three-fold superior to the standard
pyrazinamide (IC50 = 32 lg/mL) against M. tuberculosis
H37Rv. Compound 14 was also found to exhibit good anti-
tubercular activity (IC50 = 25 lg/mL) and was almost equi-
potent to pyrazinamide. As observed in case of sensitive
strains, compound 14 showed almost 50% potency (MIC =
256 lg/mL) in comparison to compound 18.
Experimental
Chemistry
Melting points were determined in open capillaries using Tosh-
niwal electrical melting point apparatus (Toshniwal Instru-
ments, Amjer, India) and are uncorrected. IR spectra were
recorded on a Shimadzu FTIR-8700 spectrometer (Shimadzu,
Tokyo, Japan) in KBr discs. 1H-NMR spectra were recorded in
CDCl3 or DMSO-d6 with tetramethylsilane (TMS) as an internal
standard on a Bruker 80 MHz FT-NMR (300 MHz) spectrometer
(Bruker Bioscience, USA) and the chemical shifts are reported as
d (ppm). Mass spectra were recorded on a GC-MS QP-1100 Shi-
madzu instrument (70 eV; Shimadzu). Elemental analyses (C, H,
N) of the compounds were obtained from Perkin Elmer 240B
analyzer (Perkin Elmer, USA) and were within € 0.4 of the theo-
retical value. A domestic LG Little Chef microwave oven (LG,
India) was used for microwave irradiation. Reaction courses and
product mixtures were routinely monitored by thin-layer chro-
matography (TLC) on precoated silica gel 60 F254 aluminum
plates (Merck, Germany). Column chromatography was per-
formed on neutral aluminum oxide 90 (activity I–II, 70–230
mesh. ASTM, Merck).
General procedure for the synthesis of N-heteroaryl
acetoacetamides 3a–d
Conclusion
Conventional method: A mixture of ethyl acetoacetate (1, 1.3 g,
0.01 mol), an appropriate heterocyclic amine (2a–d, 0.01 mol)
and a catalytic amount of potassium tert-butoxide was taken
into a 250 mL RB flask and dissolved in 15 mL of ethanol (DMF
for 3d). The reaction mixture was heated under reflux for 0.5–
Structure-activity analysis of the title compounds for
anticancer activity infers that 1,4-DHPs containing N-(6-
methylpyridin-2-yl) and N-(2-methyl-4-oxo-3H-quinazolin-
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348
K. Sirisha et al.
Arch. Pharm. Chem. Life Sci. 2010, 343, 342–352
1.5 h. The solvent was removed from the reaction mixture to a
possible extent, under reduced pressure and the residue was
cooled and triturated with dry ether. The product was filtered
and washed with small portions of dry ether. Purification was
effected by recrystallization from aqueous ethanol to obtain a
colorless crystalline solid.
reaction by TLC. On completion of the reaction, the solvent was
removed to a possible extent by distillation under reduced pres-
sure and the residue was cooled. The product was filtered,
washed with small portions of ice-cold ethanol and dried. Fur-
ther purification was effected by column chromatography using
petrol ether/chloroform (3:1) as eluent.
Microwave method: A mixture of ethyl acetoacetate (1, 1.3 g,
0.01 mol), an appropriate heterocyclic amine (2a–d, 0.01 mol)
and a catalytic amount of potassium tert-butoxide was taken
into a 250 mL Pyrex beaker with an inverted glass funnel and
irradiated in a domestic microwave oven for 3–4 min with 30-s
pulses at 480 W (640 W for 3d) while monitoring the progress of
the reaction by TLC. On completion of the reaction, the reaction
mixture was cooled and triturated with ice-cold ether. The prod-
uct separated was filtered, washed with small portions of ice-
cold ether and dried. Purification by recrystallization from aque-
ous ethanol afforded a colorless crystalline solid.
Barium nitrate-catalyzed one-pot synthesis: A mixture of N-hetero-
aryl acetoacetamide (3a–d, 0.02 mol), an appropriate aldehyde
(4a–f, 0.01 mol) and ammonium acetate (5, 0.02 mol) in the pres-
ence of 5 mol% barium nitrate was heated on a hot water-bath
for 30–45 min while monitoring the reaction by TLC. On comple-
tion, the reaction mixture was poured into ice-cold water (25
mL) while stirring. The product was filtered, washed with small
portions of cold water and dried. It was purified by column chro-
matography using petrol ether/chloroform (3:1) as eluent.
In-solvent microwave irradiation (Method I): To a mixture of an N-
heteroaryl acetoacetamide (3a–d, 0.02 mol) and an appropriate
aldehyde (4a–f, 0.01 mol) in DMF (10 mL) in a Pyrex beaker (250
mL), ammonium acetate (5, 0.02 mol) was added and irradiated
in the microwave oven at 480 W (640 W for compounds 24, 25)
for 4–6 min, with pulses of 30 s to 1 min. After completion of the
reaction (as controlled by TLC), the reaction mixture was cooled
in a refrigerator and the product obtained was filtered, washed
with ice-cold water, and dried. Purification of the product was
effected by recrystallization from aqueous ethanol.
N-(Pyridin-2-yl)acetoacetamide 3a
IR (KBr) v (cm–1): 3236 (N-H str), 1660 (C=O str), 1154, 779, 705; 1H-
NMR (CDCl3) d (ppm): 2.27 (s, 3H, -CH3), 3.45 (s, 2H, -CH2), 7.53–
7.72 (m, 3H, H3, H4, & H5-pyridyl), 8.45 (d, J = 5 Hz, 1H, H6-pyr-
idyl), 9.54 (s, 1H, CO-NH); MS m/z (%): 178 (42) [M+], 163 (22), 135
(12), 121 (37), 106 (21), 93 (32). Anal. calcd. (%) for C9H10N2O2: C,
60.65; H, 5.65; N, 15.71. Found: C, 60.62; H, 5.61; N, 15.68.
Solvent-free microwave-irradiation method (Method II): N-Hetero-
aryl acetoacetamide (3a–d, 0.02 mol), an appropriate aldehyde
(4a–f, 0.01 mol), and ammonium acetate (5, 0.02 mol) were
mixed thoroughly with silica gel (l10 g) in a mortar. The reac-
tion mixture was transferred to a 250 mL Pyrex beaker and irra-
diated in a microwave oven at 480 W (640 W for compounds 24,
25) for 4–6 min. The progress of reaction was monitored by TLC,
and after completion, the reaction mixture was cooled and tritu-
rated with dichloromethane (3 6 50 mL). Silica gel was removed
by filtration, washed with small portions of dichloromethane,
and the washings were added to the filtrate. The dichlorome-
thane extracts were dried over anhydrous sodium sulphate, fil-
tered, and the solvent was removed by a rotary vacuum evapora-
tor under reduced pressure to obtain the product 6–25. Further
purification was effected by recrystallization from aqueous etha-
nol.
N-(5-Chloropyridin-2-yl)acetoacetamide 3b
IR (KBr) v (cm–1): 3232 (N-H str), 1668 (C=O str), 1159, 1111 (C-Cl
str), 1008, 922, 761; 1H-NMR (CDCl3) d (ppm): 2.33 (s, 3H, -CH3),
3.62 (s, 2H, -CH2), 7.62–7.70 (d, J = 7.5 Hz, 1H, H3-pyridyl), 8.10–
8.29 (m, 2H, H4 & H6-pyridyl), 9.48 (s, 1H, CO-NH); MS m/z (%): 212
(12) [M+], 169 (3), 155 (10), 128 (100), 112 (9), 101 (31), 85 (7). Anal.
calcd. (%) for C9H9ClN2O2: C, 50.82; H, 4.26; N, 13.16. Found: C,
50.79; H, 4.28; N, 13.15.
N-(6-Methylpyridin-2-yl)acetoacetamide 3c
IR (KBr) v (cm–1): 3239 (N-H str), 1662 (C=O str), 1152, 795, 738; 1H-
NMR (CDCl3) d (ppm): 2.30 (s, 3H, -CH3, pyridyl), 2.43 (s, 3H, CO-
CH3), 3.54 (s, 2H, -CH2), 7.09–7.15 (m, 1H, H5-pyridyl), 7.39–7.40
(m, 2H, H3 & H4-pyridyl), 9.32 (s, 1H, CO-NH); MS m/z (%): 192 (8)
[M+], 177 (10), 159 (2), 149 (7), 135 (12), 121 (5), 108 (67), 92 (32), 65
(37). Anal. calcd. (%) for C10H12N2O2: C, 62.48; H, 6.28; N, 14.57.
Found: C, 62.45; H, 6.25; N, 14.58.
4-(2-Furyl)-2,6-dimethyl-3,5-bis-N-(pyridin-2-yl)-
carbamoyl-1,4-dihydropyridine 6
IR (KBr) v (cm–1): 3355 (N-H str), 1645 (C=O str), 1525 (N-H bend,
amide), 1443, 1315 (C-N str), 742, 685; 1H-NMR (CDCl3) d (ppm):
2.42 (s, 6H, 2 -CH3), 5.11 (s, 1H, H4-DHP), 6.32 (d, J = 3.3 Hz, 1H,
H49-furyl), 6.83 (d, J = 3.3 Hz, 1H, H39-furyl), 7.19–7.52 (m, 9H, pyr-
idyl-H + H59-furyl), 7.63 (s, 1H, NH-DHP), 9.81 (s, 2H, 2 CO-NH); MS
m/z (%): 415 (100) [M+], 348 (24), 322 (10), 294 (38), 200 (55), 133
(21). Anal. calcd. (%) for C23H21N5O3: C, 66.48; H, 5.09; N, 16.86.
Found: C, 66.46; H, 5.05; N, 16.87.
N-(2-Methyl-4-oxo-3H-quinazolin-3-yl)acetoacetamide 3d
IR (KBr) v (cm–1): 3415 (N-H str), 1701 (C=O str), 1611 (N-H bend,
amide), 1322 (C-N str), 774, 694, 636; H-NMR (CDCl3) d (ppm):
2.36 (s, 3H, Ar-CH3), 2.55 (s, 3H, CO-CH3), 3.65 (s, 2H, -CH2), 7.40–
7.79 (m, 3H, Ar-H), 8.13–8.22 (m, 1H, H5, Ar-H), 9.70 (s, 1H, D2O
exchangeable, CO-NH); MS m/z (%): 260 (100) [M + H]+, 176 (8), 155
(20), 141 (60), 98 (10), 55 (50). Anal. calcd. (%) for C13H13N3O3: C,
60.22; H, 5.04; N, 16.18. Found: C, 60.19; H, 5.01; N, 16.15.
1
4-(2-Pyridyl)-2,6-dimethyl-3,5-bis-N-(pyridin-2-yl)-
General procedure for the synthesis of 4-substituted-2,6-
dimethyl-3,5-bis-N-(heteroaryl)-carbamoyl-1,4-
dihydropyridines 6–25
carbamoyl-1,4-dihydropyridine 7
IR (KBr) v (cm–1): 3327 (N-H str), 1667 (C=O str), 1540 (N-H bend,
1
amide), 1365, 1318 (C-N str), 771; H-NMR (CDCl3 + DMSO) d
Conventional method: A mixture of N-heteroaryl acetoacetamide
(3a–d, 0.02 mol), an appropriate aldehyde (4a–f, 0.01 mol) and
ammonium acetate (5, 0.02 mol) in ethanol (15 mL) was heated
under reflux on a water-bath for 40–45 h while monitoring the
(ppm): 2.67 (s, 6H, 2 -CH3), 5.15 (s, 1H, H4-DHP), 6.98–7.25 (m, 3H,
H39, H49, & H59-pyridyl), 7.67–7.71 (m, 4H, H4 & H5-pyridyl), 8.17
(s, 1H, NH-DHP), 8.2–8.29 (m, 5H, H3, H6, & H69-pyridyl), 10.51 (s,
2H, 2 CO-NH); MS m/z (%): 426 (8) [M+], 414 (2), 332 (48), 254 (25),
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Arch. Pharm. Chem. Life Sci. 2010, 343, 342–352
1,4-DHPs as Anticancer and Antitubercular agents
349
239 (7), 226 (11), 160 (18), 121 (40), 91 (27), 78(100). Anal. calcd.
(%) for C24H22N6O2: C, 67.58; H, 5.19; N, 19.70. Found: C, 67.55; H,
5.16; N, 19.66.
(100), 78(20). Anal. calcd. (%) for C24H20Cl2N6O2: C, 58.19; H, 4.04; N,
16.97. Found: C, 58.16;H, 4.01; N, 16.95.
4-(2-Thienyl)-2,6-dimethyl-3,5-bis-N-(5-chloropyridin-
4-(2-Thienyl)-2,6-dimethyl-3,5-bis-N-(pyridin-2-yl)-
carbamoyl-1,4-dihydropyridine 8
2-yl)-carbamoyl-1,4-dihydropyridine 13
IR (KBr) v (cm–1): 3290 (N-H str), 1673 (C=O str), 1374 (C-N str),
1232 (C-Cl str), 707; 1H-NMR (DMSO) d (ppm): 2.14 (s, 6H, 2 -CH3),
5.47 (s, 1H, H4-DHP), 6.72 (d, J = 7.8 Hz, 2H, H3-pyridyl), 7.21 (d, J =
3.6 Hz, 2H, H39 & H49-thienyl), 7.85 (d, J = 5.2 Hz, 1H, H59-thienyl),
8.11 (d, J = 7.8 Hz, 2H, H4-pyridyl), 8.36 (s, 2H, H6-pyridyl), 8.63 (s,
1H, NH-DHP), 10.36 (s, 2H, 2 CO-NH); MS m/z (%): 499 (7) [M+], 371
(10), 344 (100), 328 (5), 216 (52), 173 (11), 91 (9). Anal. calcd. (%)
for C23H19Cl2N5O2S: C, 55.19; H, 3.82; N, 13.99. Found: C, 55.14; H,
3.79; N, 13.96.
IR (KBr) v (cm–1): 3254 (N-H str), 1668 (C=O str), 1540 (N-H bend,
amide), 1433, 1303 (C-N str), 779; 1H-NMR (CDCl3 + DMSO) d
(ppm): 2.52 (s, 6H, 2 -CH3), 5.21 (s, 1H, H4-DHP), 6.79–6.95 (m, 4H,
H4-pyridyl & H39, H49-thienyl), 7.19 (d, J = 5 Hz, 1H, H59-thienyl),
7.53–7.72 (m, 2H, H5-pyridyl), 7.81 (s, 1H, NH-DHP), 7.95–8.16 (m,
4H, H3 & H6-pyridyl), 10.49 (s, 2H, 2 CO-NH); MS m/z (%): 431 (5)
[M+], 429 (4), 414 (33), 336 (12), 242 (65), 133 (46), 94 (28), 78 (100).
Anal. calcd. (%) for C23H21N5O2S: C, 64.02; H, 4.90; N, 16.23. Found:
C, 64.01; H, 4.86; N, 16.21.
4-(2-Imidazolyl)-2,6-dimethyl-3,5-bis-N-(5-chloropyridin-
2-yl)-carbamoyl-1,4-dihydropyridine 14
4-(2-Imidazolyl)-2,6-dimethyl-3,5-bis-N-(pyridin-2-yl)-
carbamoyl-1,4-dihydropyridine 9
IR (KBr) v (cm–1): 3383 (N-H str), 1678 (C=O str), 1524 (N-H bend,
1
amide), 1376 (C-N str), 1112 (C-Cl str), 745 (C-H bend); H-NMR
IR (KBr) v (cm–1): 3262 (N-H str), 1675 (C=O str), 1538 (N-H bend,
amide), 1322 (C-N str), 733; 1H-NMR (CDCl3 + DMSO) d (ppm): 2.11
(s, 6H, 2 -CH3), 4.98 (s, 1H, H4-DHP), 7.11 (d, J = 3 Hz, 2H, H49 & H59-
imidazolyl), 7.45 (d, J = 7.5 Hz, 4H, H4 & H5-pyridyl), 7.61 (s, 1H,
NH-DHP, D2O exchangeable), 7.89–7.95 (m, 5H, H3 & H6-pyridyl +
NH-imidazolyl), 10.89 (s, 2H, 2 CO-NH, D2O exchangeable); MS
m/z (%): 415 (14) [M+], 348 (5), 321 (66), 294 (21), 254 (32), 201
(100), 121 (19), 93 (20). Anal. calcd. (%) for C22H21N7O2: C, 63.59; H,
5.09; N, 23.06. Found: C, 63.55; H, 5.06; N, 23.04.
(CDCl3 + DMSO) d (ppm): 2.14 (s, 6H, 2 -CH3), 5.04 (s, 1H, H4-DHP),
6.79 (d, J = 7.8 Hz, 2H, H3-pyridyl), 7.53 (d, J = 3.2 Hz, 2H, H49 &
H59-imidazolyl), 7.76 (s, 1H, NH-DHP, D2O exchangeable), 8.06–
8.15 (m, 4H, H4 & H6-pyridyl), 10.89 (s, 3H, N-H imidazolyl + 2
CO-NH, D2O exchangeable); MS m/z (%): 483 (4) [M – H]+, 415 (2),
400 (35), 355 (87), 288 (36), 199 (100), 173 (56), 129 (33), 91 (18),
77 (24). Anal. calcd. (%) for C22H19Cl2N7O2: C, 54.58; H, 3.95; N,
20.24. Found: C, 54.60; H, 3.91; N, 20.27.
4-(2-Pyrrolyl)-2,6-dimethyl-3,5-bis-N-(5-chloropyridin-2-
yl)-carbamoyl-1,4-dihydropyridine 15
4-(2-Pyrrolyl)-2,6-dimethyl-3,5-bis-N-(pyridin-2-yl)-
carbamoyl-1,4-dihydropyridine 10
IR (KBr) v (cm–1): 3229 (N-H str), 1663 (C=O str), 1371 (C-N str),
1209 (C-Cl str), 711; 1H-NMR (DMSO) d (ppm): 2.44 (s, 6H, 2 -CH3),
5.22 (s, 1H, H4-DHP), 6.32–6.44 (m, 4H, H3-pyridyl + H39 & H49-pyr-
rolyl), 6.85 (s, 1H, NH-DHP), 6.97–7.01 (m, 5H, H4 & H6-pyridyl +
H59-pyrrolyl), 8.15 (d, J = 2.2 Hz, 1H, NH-pyrrolyl), 10.31 (s, 2H, 2
CO-NH); MS m/z (%): 483 (9) [M+], 356 (15), 328 (27), 201 (100), 173
(45), 155 (32), 91 (12). Anal. calcd. (%) for C23H20Cl2N6O2: C, 57.13;
H, 4.17; N, 17.38. Found: C, 57.10; H, 4.14; N, 17.35.
IR (KBr) v (cm–1): 3256 (N-H str), 1645 (C=O str), 1517 (N-H bend,
amide), 1312 (C-N str), 821; 1H-NMR (DMSO) d (ppm): 2.34 (s, 6H, 2
-CH3), 5.12 (s, 1H, H4-DHP), 6.07–6.22 (m, 6H, H4 & H5-pyridyl +
H39 & H49-pyrrolyl), 6.35 (s, 1H, NH-DHP), 6.47–6.68 (m, 5H, H3 &
H6-pyridyl + H59-pyrrolyl), 7.05 (d, J = 2.5 Hz, 1H, NH-pyrrolyl),
10.11 (s, 2H, 2 CO-NH); MS m/z (%): 414 (10) [M+], 348 (18), 321 (35),
293 (100), 172 (8), 94 (28). Anal. calcd. (%) for C23H22N6O2: C, 66.64;
H, 5.35; N, 20.28. Found: C, 66.62; H, 5.31; N, 20.25.
4-(2-Furyl)-2,6-dimethyl-3,5-bis-N-(5-chloropyridin-2-yl)-
carbamoyl-1,4-dihydropyridine 16
4-(4-Chlorophenyl)-2,6-dimethyl-3,5-bis-N-(pyridin-2-yl)-
carbamoyl-1,4-dihydropyridine 11
IR (KBr) v (cm–1): 3345 (N-H str), 1655 (C=O str), 1515 (N-H bend,
amide), 1315 (C-N str), 713; 1H-NMR (CDCl3 + DMSO) d (ppm): 2.52
(s, 6H, 2 -CH3), 5.21 (s, 1H, H4-DHP), 6.75 (d, J = 3.4 Hz, 1H, H49-
furyl & J = 7.6 Hz, 2H, H3-pyridyl ), 6.98 (d, J = 3.5 Hz, 1H, H39-
furyl), 7.29–7.62 (m, 5H, H4 & H6-pyridyl + H59-furyl), 7.83 (s, 1H,
NH-DHP), 10.81 (s, 2H, 2 CO-NH); MS m/z (%): 484 (8) [M+], 469 (12),
417 (5), 357 (51), 329 (100), 201 (15), 173 (21), 127 (9), 91 (12).
Anal. calcd. (%) for C23H19Cl2N5O3: C, 57.02; H, 3.95; N, 14.46.
Found: C, 57.05; H, 3.92; N, 14.43.
IR (KBr) v (cm–1): 3243 (N-H str), 1633 (C=O str), 1525 (N-H bend,
amide), 1326 (C-N str), 802; 1H-NMR (CDCl3 + DMSO) d (ppm): 2.56
(s, 6H, 2 -CH3), 5.32 (s, 1H, H4-DHP), 6.87–7.01 (m, 4H, H4 & H5-
pyridyl), 7.11–7.23 (m, 6H, H3 & H6-pyridyl + H29 & H69-phenyl),
7.32–7.41 (m, 2H, H39 & H59-phenyl), 7.67 (s, 1H, NH-DHP), 9.31 (s,
2H, 2 CO-NH); MS m/z (%): 459 (8) [M+], 366 (27), 338 (40), 217 (12),
116 (7), 121 (100), 91 (15). Anal. calcd. (%) for C25H22ClN5O2: C,
65.27; H, 4.82; N, 15.20. Found: C, 65.25; H, 4.79; N, 15.16.
4-(2-Pyridyl)-2,6-dimethyl-3,5-bis-N-(5-chloropyridin-2-
4-(4-Chlorophenyl)-2,6-dimethyl-3,5-bis-N-(5-
yl)-carbamoyl-1,4-dihydropyridine 12
chloropyridin-2-yl)-carbamoyl-1,4-dihydropyridine 17
IR (KBr) v (cm–1): 3319 (N-H str), 1671 (C=O str), 1552 (N-H bend,
amide), 1342 (C-N str), 722; 1H-NMR (CDCl3 + DMSO) d (ppm): 2.76
(s, 6H, 2 -CH3), 5.44 (s, 1H, H4-DHP), 6.95–6.99 (m, 2H, H3-pyridyl),
7.21–7.27 (m, 6H, H4 & H6-pyridyl + H29 & H69-phenyl), 7.52–7.61
(m, 2H, H39 & H59-phenyl), 7.87 (s, 1H, NH-DHP), 10.31 (s, 2H, 2
CO-NH); MS m/z (%): 528 (6) [M+], 401 (12), 373 (34), 246 (100), 218
IR (KBr) v (cm–1): 3277 (N-H str), 1665 (C=O str), 1376 (C-N str), 1225
(C-Cl str), 722; 1H-NMR (CDCl3 + DMSO) d (ppm): 2.85 (s, 6H, 2 -CH3),
5.23 (s, 1H, H4-DHP), 7.11–7.18 (m, 3H, H39, H49, & H59-pyridyl),
7.82–7.91 (m, 2H, H3-pyridyl), 8.22 (s, 1H, NH, DHP), 8.31–8.36 (m,
5H, H69-pyridyl + H4 & H6-pyridyl), 10.77 (s, 2H, 2 CO-NH); MS m/z
(%): 494 (10) [M – H]+, 367 (26), 339 (35), 240 (9), 212 (15), 121 (42), 94
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K. Sirisha et al.
Arch. Pharm. Chem. Life Sci. 2010, 343, 342–352
(55), 186 (7), 155 (17), 91 (18). Anal. calcd. (%) for C25H20Cl3N5O2: C,
56.76; H, 3.81; N, 13.24. Found: C, 56.72; H, 3.80; N, 13.20.
calcd. (%) for C24H25N7O2: C, 64.99; H, 5.68; N, 22.11. Found: C,
64.96; H, 5.69; N, 22.07.
4-(4-Chlorophenyl)-2,6-dimethyl-3,5-bis-N-(6-
4-(2-Pyridyl)-2,6-dimethyl-3,5-bis-N-(6-methylpyridin-2-
methylpyridin-2-yl)-carbamoyl-1,4-dihydropyridine 23
IR (KBr) v (cm–1): 3242 (N-H str), 1670 (C=O str), 1510 (N-H bend,
amide), 1362 (C-N str), 714; 1H-NMR (CDCl3 + DMSO) d (ppm): 2.49
(s, 6H, 2 -CH3, DHP), 2.54 (s, 6H, 2 -CH3, pyridyl), 5.17 (s, 1H, H4-
DHP), 5.22 (s, 1H, NH-DHP), 6.57–6.82 (m, 4H, H4 & H5-pyridyl),
7.21–7.33 (m, 4H, H3-pyridyl + H29 & H69-phenyl), 7.52–7.81 (m,
2H, H39 & H59-phenyl), 9.98 (s, 2H, 2 CO-NH); MS m/z (%): 488 (5)
[M+], 353 (33), 246 (12), 230 (9), 218 (100), 183 (21), 136 (15). Anal.
calcd. (%) for C27H26ClN5O2: C, 66.44; H, 5.37; N, 14.35. Found: C,
66.42; H, 5.35; N, 14.31.
yl)-carbamoyl-1,4-dihydropyridine 18
IR (KBr) v (cm–1): 3267 (N-H str), 1648 (C=O str), 1515 (N-H bend,
amide), 1320 (C-N str), 776; 1H-NMR (CDCl3) d (ppm): 2.37 (s, 6H, 2
-CH3, DHP), 2.44 (s, 6H, 2 -CH3, pyridyl), 5.05 (s, 1H, H4-DHP), 5.73
(s, 1H, NH-DHP), 6.81 (m, 2H, H5-pyridyl), 7.21–7.24 (m, 3H, H39,
H49 & H59-pyridyl), 7.5–7.54 (m, 4H, H3 & H4-pyridyl), 7.95 (m, 1H,
H69-pyridyl), 9.93 (s, 2H, 2 CO-NH); MS m/z (%): 454 (55) [M+], 346
(60), 319 (22), 243 (10), 185 (24), 109 (72). Anal. calcd. (%) for
C26H26N6O2: C, 68.69; H, 5.76; N, 18.49. Found: C, 68.67; H, 5.74;
N, 18.46.
4-(2-Thienyl)-2,6-dimethyl-3,5-bis-N-(6-methylpyridin-2-
4-(2-Imidazolyl)-2,6-dimethyl-3,5-bis-N-(2-methyl-4-oxo-
yl)-carbamoyl-1,4-dihydropyridine 19
3H-quinazolin-3-yl)-carbamoyl-1,4-dihydropyridine 24
IR (KBr) v (cm–1): 3404 (N-H str), 1609 (C=O str), 1474, 1267 (C-N
str), 771; 1H-NMR (DMSO) d (ppm): 2.27 (s, 6H, 2 -CH3, quinazo-
linyl), 2.49 (s, 6H, 2 -CH3, DHP), 5.28 (s, 1H, H4-DHP), 6.94 (s, 1H,
NH-DHP), 7.48–7.68 (m, 6H, Ar-H, quinazolinyl), 7.78–7.9 (m, 2H,
Ar-H, H5-quinazolinyl), 8.05–8.15 (d, J = 4 Hz, 2H, H49 & H59-imida-
zolyl), 8.67–8.9 (d, J = 2.5 Hz, 1H, NH-imidazolyl), 11.4 (s, 2H, 2
CO-NH); MS m/z (%): 578 (100) [M + H]+, 511 (20), 403 (15), 375 (20),
228 (24), 175 (14), 161 (20). Anal. calcd. (%) for C30H27N9O4: C,
62.37; H, 4.71; N, 21.82. Found: C, 62.40; H, 4.68; N, 21.85.
IR (KBr) v (cm–1): 3236 (N-H str), 1675 (C=O str), 1545 (N-H bend,
amide), 1313 (C-N str), 773; 1H-NMR (CDCl3) d (ppm): 2.22 (s, 6H, 2
-CH3, DHP), 2.34 (s, 6H, 2 -CH3, pyridyl), 5.11 (s, 1H, H4-DHP), 5.54
(s, 1H, NH-DHP), 6.85–7.01 (m, 4H, H5-pyridyl & H39, H49-thienyl),
7.11 (d, J = 5 Hz, 1H, H59-thienyl), 7.25–7.31 (m, 4H, H3 & H4-pyr-
idyl), 10.13 (s, 2H, 2 CO-NH); MS m/z (%): 459 (24) [M+], 352 (13),
334 (37), 250 (9), 143 (51), 135 (40), 107 (15). Anal. calcd. (%) for
C25H25N5O2S: C, 65.34; H, 5.48; N, 15.24. Found: C, 65.31; H, 5.44;
N, 15.25.
4-(2-Furyl)-2,6-dimethyl-3,5-bis-N-(6-methylpyridin-2-yl)-
carbamoyl-1,4-dihydropyridine 20
4-(4-Chlorophenyl)-2,6-dimethyl-3,5-bis-N-(2-methyl-4-
oxo-3H-quinazolin-3-yl)-carbamoyl-1,4-dihydropyridine
25
IR (KBr) v (cm–1): 3351 (N-H str), 1650 (C=O str), 1556 (N-H bend,
amide), 1320 (C-N str), 734; 1H-NMR (CDCl3 + DMSO) d (ppm): 2.31
(s, 6H, 2 -CH3, DHP), 2.44 (s, 6H, 2 -CH3, pyridyl), 5.08 (s, 1H, H4-
DHP), 5.24 (s, 1H, NH-DHP), 6.23 (d, J = 3.6 Hz, 1H, H49-furyl), 6.55
(d, J = 3.6 Hz, 1H, H39-furyl), 7.11 (d, J = 8 Hz, 2H, H5-pyridyl),
7.19–7.28 (m, 5H, H3 & H4-pyridyl + H59-furyl), 9.65 (s, 2H, 2 CO-
NH); MS m/z (%): 443 (14) [M+], 352 (45), 266 (19), 160 (55), 132
(100), 107 (24). Anal. calcd. (%) for C25H25N5O3: C, 67.70; H, 5.68; N,
15.79. Found: C, 67.68; H, 5.66; N, 15.76.
IR (KBr) v (cm–1): 3388 (N-H str), 3031 (C-H str, aromatic), 2922 (C-
H, aliphatic), 1693 (C=O, quinazolinyl), 1607 (C=N, aromatic); 1H-
NMR (CDCl3 + DMSO) d (ppm): 2.42 (s, 6H, 2 -CH3, quinazolinyl),
2.59 (s, 6H, 2 -CH3, DHP), 5.39 (s, 1H, H4-DHP), 7.04 (s, 1H, NH-
DHP), 7.82–7.95 (m, 6H, Ar-H, quinazolinyl), 8.18–8.19 (m, 2H,
Ar-H, H5-quinazolinyl), 8.25–8.33 (m, 2H, H29 & H69-phenyl),
8.87–8.94 (m, 2H, H39 & H59-phenyl), 11.55 (s, 2H, 2 CO-NH); MS
m/z (%): 622 (14) [M + H]+, 521 (36), 346 (25), 318 (19), 305 (42), 256
(7), 176 (12). Anal. calcd. (%) for C33H28ClN7O4: C, 63.70; H, 4.53; N,
15.76. Found: C, 63.68; H, 4.50; N, 15.73.
4-(2-Pyrrolyl)-2,6-dimethyl-3,5-bis-N-(6-methylpyridin-2-
yl)-carbamoyl-1,4-dihydropyridine 21
IR (KBr) v (cm–1): 3304 (N-H str), 1675 (C=O str), 1515 (N-H bend,
amide), 1325 (C-N str), 715; 1H-NMR (CDCl3 + DMSO) d (ppm): 2.21
(s, 6H, 2 -CH3, DHP), 2.34 (s, 6H, 2 -CH3, pyridyl), 5.10 (s, 1H, H4-
DHP), 5.21 (s, 1H, NH-DHP), 6.37–6.42 (m, 4H, H5-pyridyl + H39 &
H49-pyrrolyl), 6.81–6.86 (m, 5H, H3 & H4-pyridyl + H59-pyrrolyl),
7.85 (d, J =2.3 Hz, 1H, NH-pyrrolyl), 10.11 (s, 2H, 2 CO-NH); MS m/z
(%): 442 (9) [M+], 376 (12), 269 (44), 240 (62), 225 (6), 106 (19). Anal.
calcd. (%) for C25H26N6O2: C, 67.85; H, 5.92; N, 18.99. Found: C,
67.83; H, 5.91; N, 18.97.
Biological evaluation
Anticancer activity
Three different human cancer cell lines viz., MCF-7 (breast can-
cer), HT-29 (colorectal cancer), A431 (skin cancer) were used in
the in-vitro assay. These cell lines were obtained from the
National Center for Cell Science (NCCS), Pune, India and main-
tained in the Cell Culture Collection of the Indian Institute of
Chemical Technology (IICT), Hyderabad, India. MTT [3-(4,5-dime-
thylthiazol-2-yl)-2,5-diphenyltetrazolium bromide], Trypsin,
EDTA were purchased from Sigma Chemicals (St. Louis, MO,
USA).
4-(2-Imidazolyl)-2,6-dimethyl-3,5-bis-N-(6-methylpyridin-
2-yl)-carbamoyl-1,4-dihydropyridine 22
Twenty-four hours before addition of the test agents, the cells
were plated in 96-well plates (Sarstedt, USA) at a density of 104
cells per well. All cell lines were maintained in the MEM media
supplemented with 10% fetal bovine serum (Gibco, USA), 100
lg/mL penicillin, 200 lg/mL streptomycin (Himedia, India),
2 mM Glutamine (Gibco, USA). The cells were incubated at 378C
in the humid atmosphere saturated with 5% CO2. Stock solu-
tions of compounds 6–25 were prepared in DMSO (10 mg/mL)
IR (KBr) v (cm–1): 3344 (N-H str), 1672 (C=O str), 1525 (N-H bend,
amide), 1323 (C-N str), 745; 1H-NMR (CDCl3 + DMSO) d (ppm): 2.09
(s, 6H, 2 -CH3, DHP), 2.24 (s, 6H, 2 -CH3, pyridyl), 4.87 (s, 1H, H4-
DHP), 5.22 (s, 1H, NH-DHP), 6.32 (d, J = 8.2 Hz, 2H, H5-pyridyl),
7.23 (d, J = 3.4 Hz, 2H, H49 & H59-imidazolyl), 7.79–7.87 (m, 5H, H3
& H4-pyridyl + NH-imidazolyl), 10.32 (s, 2H, 2 CO-NH); MS m/z (%):
443 (10) [M+], 336 (36), 201 (13), 185 (44), 143 (67), 107 (22). Anal.
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Arch. Pharm. Chem. Life Sci. 2010, 343, 342–352
1,4-DHPs as Anticancer and Antitubercular agents
351
and from them various dilutions were made with sterile water
to get the final drug concentrations of 10, 50, 100, and 200
lg/mL. The solvent (DMSO) used to prepare the solution of the
test compounds did not show any cytotoxic activity. Methotrex-
ate was employed as a reference drug. The cytotoxicity (MTT)
assay was performed after 72 h exposure of the cultured cells at
concentrations ranging from 10 to 200 lg/mL of the test com-
pounds by the method described in the literature [26].
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