Synthesis of potential antitubercular and antimicrobial s-triazine-based scaffolds via Suzuki cross-coupling reaction

Article abstract of DOI:10.1007/s00044-012-0041-y

Two series of bis(3,5-dimethylpiperidinyl)-1,3,5-triazinyl)-N-(phenyl/ benzothiazolyl)-acetamides were synthesized so as to investigate their antimicrobial and antimycobacterial actions. Intermediate 4-(4,6-bis(3,5- dimethylpiperidin-1-yl)-1,3,5-triazin-2-yl)aniline was synthesized by palladium-catalyzed Suzuki cross-coupling reaction to furnish C-C bond formation to s-triazine ring. Pharmacological screening against eight bacteria (S. aureus, B. cereus, E. coli, P. aeruginosa, K. pneumoniae, S. typhi, P. vulgaris, and S. flexneri), four fungi (A. niger, A. fumigatus, A. clavatus, and C. albicans), and Mycobacterium tuberculosis H37Rv was examined and the effects of various substituents on biological profiles (MIC, 1.56-50 μg/mL) of final analogues were investigated. Four (8c, 8i, 9d, 9j) of the final analogues displayed antimycobacterial activity (3.12-6.25 μg/mL) equipotent to standard drugs.

Full text of DOI:10.1007/s00044-012-0041-y

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2013) 22:367–381
DOI 10.1007/s00044-012-0041-y
ORIGINAL RESEARCH
Synthesis of potential antitubercular and antimicrobial
s-triazine-based scaffolds via Suzuki cross-coupling reaction
•
Amit B. Patel Rahul V. Patel Premlata Kumari
•
•
•
Dhanji P. Rajani Kishor H. Chikhalia
Received: 1 February 2012 / Accepted: 24 March 2012 / Published online: 5 April 2012
Ó Springer Science+Business Media, LLC 2012
Abstract Two series of bis(3,5-dimethylpiperidinyl)-1,3,
5-triazinyl)-N-(phenyl/benzothiazolyl)-acetamides were
Introduction
synthesized so as to investigate their antimicrobial and
antimycobacterial actions. Intermediate 4-(4,6-bis(3,5-
dimethylpiperidin-1-yl)-1,3,5-triazin-2-yl)aniline was syn-
thesized by palladium-catalyzed Suzuki cross-coupling
reaction to furnish C–C bond formation to s-triazine ring.
Pharmacological screening against eight bacteria (S. aur-
eus, B. cereus, E. coli, P. aeruginosa, K. pneumoniae,
S. typhi, P. vulgaris, and S. flexneri), four fungi (A. niger,
A. fumigatus, A. clavatus, and C. albicans), and Myco-
bacterium tuberculosis H37Rv was examined and the
effects of various substituents on biological profiles (MIC,
1.56–50 lg/mL) of final analogues were investigated. Four
(8c, 8i, 9d, 9j) of the final analogues displayed antimyco-
bacterial activity (3.12–6.25 lg/mL) equipotent to standard
drugs.
Infectious microbial disease remains a pressing problem
worldwide, because microbes have resisted prophylaxis or
therapy longer than any other form of life. In spite of a
large number of antibiotics and chemotherapeutics avail-
able for medical use, at the same time, the emergence of
old and new antibiotic resistances created, in the past few
decades, a substantial medical need for new classes of
antibacterial agents. A potential approach to overcome the
resistance problem is to design innovative agents with a
different mode of action so that no cross-resistance with the
present therapeuticals can occur (Vicini et al., 2006;
McDonald, 2006). It was observed that mycobacterium
species have developed drug resistance against developed
drugs; so we feel the necessity of the scope of developing
new drugs which would show some significant effect.
Tuberculosis, or TB, is an infectious bacterial disease
caused by Mycobacterium tuberculosis, which most com-
monly affects the lungs. It is a leading infectious cause of
death worldwide. According to the World Health Organi-
zation (WHO), there were 9.4 million new TB cases
(including 3.3 million women) in 2009, including 1.1
million cases among people with HIV. 1.7 Million people
died from TB (including 380,000 women) in 2009,
including 380,000 people with HIV, equal to 4,700 deaths a
day. The estimated global incidence rate fell to 137 cases
per 100,000 populations in 2009, after peaking in 2004 at
142 cases per 100,000. The rate is still falling but too
slowly (Khoshneviszadeh et al., 2009; WHO report, 2010).
Because of the concern of the resistance to most of the
commonly used drugs displayed by the considered myco-
bacteria, most efforts have been carried out to introduce
new anti-tubercular agents. A literature survey reveals that
piperazine-substituted s-triazine derivatives are known as
Keywords 2,4,6-Trichloro-1,3,5-triazine: piperidine ꢀ
Suzuki coupling: antimicrobial activity ꢀ
Antimycobacterial activity
A. B. Patel ꢀ R. V. Patel ꢀ P. Kumari
Department of Applied Chemistry, S. V. National Institute
of Technology, Surat 395007, India
D. P. Rajani
Microcare Laboratory, Surat 395 001, Gujarat, India
K. H. Chikhalia (&)
Department of Chemistry, School of Science,
Gujarat University, Ahmedabad 380 009, India
e-mail: chikhalia_kh@yahoo.com
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Med Chem Res (2013) 22:367–381
promising antimicrobial agents. s-Triazine ring is an
important pharmacophore, and its coupling with other rings
could furnish new biologically active compounds. These
derivatives exhibit various types of biological properties,
such as anti HIV, anti tuberculosis, anticancer, antimyco-
bacterial, antifungal, and antibacterial (Solankee et al.,
2010; Xiong et al., 2008; Sunduru et al., 2010; Kaswala
et al., 2009).
from 4-bromo aniline under nitrogen atmosphere using
n-BuLi (in 1.6 M of hexane) and trimethylsilyl chloride
1
(TMSCl) in tetrahydrofuran solvent at 0 °C. In H NMR
spectra of 4a, all the 18 hydrogen atoms were found to
reveal corresponding singlet at 0.39 ppm, whereas the
corresponding carbon atoms appeared at 1.24 ppm in 13C
NMR spectra. The prepared trimethylsilyl-protected
4-bromo aniline 4a was then converted into 4-amin-
ophneylboronic acid pinacol ester 4b using n-BuLi, pinacol
and triisopropyl borate in dry tetrahydrofuran solvent under
N2 atmosphere. In 1H NMR spectra of 4b, an –NH2 proton
were found to resonate at 8.53 ppm, whereas 12 methyl
protons were resonated at 1.23 ppm in the form of singlet.
13C NMR spectra of 4b displayed a peak at 83.11 ppm,
which was due to the two carbon atoms, both bearing a
couple of methyl functional groups (Scheme 1).
Our research group has been largely involved in the
synthesis of 2,4,6-trisubstituted s-triazine derivatives.
Recently, we have concluded that 3,5-dimethylpiperidine-
substituted s-triazine derivatives exhibited excellent
antibacterial, antifungal, antituberculosis, and anticancer
activities (Patel et al., 2011a). In continuation of the study on
some novel s-triazine derivatives (Patel et al., 2011b, c, d),
we, herein, report the synthesis of N-(4-substituted)phenyl-
acetamide and N-(6-substituted thiazol-2-yl)acetamide
derivatives of s-triazine using Suzuki-coupling reaction and
their in vitro anti-tubercular and antimicrobial activities. The
Suzuki coupling offers several advantages, such as mild
reaction conditions, comparative stability, and low toxicity
(Giroux, 2003; McKenna et al., 2001). Aiming at studying
mild strategies to design novel 1,3,5-triazine derivatives, we
focused on a general method for the synthesis of arylboronic
ester usable to palladium-catalyzed reaction with one of the
chlorine atom of 2,4,6-trichlorotriazine to give some bio-
logically active compounds.
Simultaneously, a two-step reaction was carried out, in
which two reactive chlorine atoms of s-triazine ring were
replaced by the equimolecular amount of 3,5,-dimethyl
piperidine at 0–5 °C and room temperature, respectively to
afford intermediate 6. Further, the intermediate 6was reacted
with the previously synthesized 4-aminophneylboronic acid
pinacol ester 4b in the presence of a catalytic amount of
tetrakis-(triphenylphosphine)palladium in basic media to
obtain final intermediate 7 to which various phenyl(benzo-
thiazolyl)acetamides were condensed. The 1H NMR spectra
of compound 7 revealed two doublet of doublets at 3.73 ppm
and 3.56 ppm, and amultiplet at 1.75 ppm and in the range of
0.89–0.83 ppm corresponding to the protons belongs to 3.5-
dimethyl piperidine moiety. The 13C NMR spectra of com-
pound 7 displayed peaks in the range nearby of 48–53,
35–40, and 28–32 ppm corresponding to the piperidine
carbon atoms.
Results and discussion
Chemistry
2-Chloro-N-(substituted)aryl acetamides 1a–k, 2-amino-6-
substituted benzothiazoles 2a–k and N-(benzo[d]thiazol-2-
yl)-2-chloroacetamides 3a–k were synthesized according to
the reported literature. Chloroacetyl chloride was reacted
with para-(substituted) aryl amines to give the correspond-
ing 2-chloro-N-(substituted)aryl acetamides 1a–k (Baraldi
et al., 2007; Zhaowen et al., 2007). The 2-amino-6-substi-
tuted benzothiazoles 2a–k were synthesized by reacting aryl
amines with potassium thiocyanate in satisfactory yields by a
known preparation method and were converted to the
Above mentioned acetamide derivatives 1a–k and
3a–k were then condensed to the intermediate 7 in acetone
solvent at reflux temperature furnished 8a–k and 9a–k. All
the IR, 1H NMR, and 13C NMR spectral data of compounds
8a–k and 9a–k were in accordance with assumed struc-
tures. The purity of the synthesized compounds was
respective
N–(benzo[d]thiazol-2-yl)-2-chloroacetamides
3a–k using chloroacetyl chloride in benzene solvent as
described in literature (Rana et al., 2008; Sawhney and
Boykin, 1979; Zitouni et al., 2003).
The present study deals with the Suzuki cross-coupling
reaction to facilitate the C–C bond formation between the
carbon atom of s-triazine ring and a phenyl ring with ani-
line-functionality. The overall procedure includes two
chemical steps, in which a first step comprises the forma-
tion of trimethylsilyl-protected 4-bromo aniline 4a entity
Scheme 1 Synthesis of 4-aminophenylboronic acid pinacol ester.
Reagents and conditions: (i) n-BuLi, TMS-Cl, THF, 0 °C; (ii) n-BuLi,
B(Oi-Pr)3, pinacol, AcOH (pH 5), THF, -78 to 25 °C
123

Med Chem Res (2013) 22:367–381
369
monitored by TLC and ascertained by elemental analysis
(Scheme 2).
N-benzothiazolyl acetamide moiety appeared with poten-
tial inhibitory efficacy against S. aureus at 1.56 lg/mL of
MIC with 25 and 26 mm of inhibition zone, respectively.
These two derivatives were found equipotent to the stan-
dard drug ciprofloxacin against S. aureus in terms of MIC.
In the case of N-phenyl acetamides, compound 8c with
bromo substituent was found most active at 3.12 lg/mL
MIC against S. aureus. This activity increases to 1.56 lg/mL
in 9c when N-phenyl acetamide moiety was replaced by
N-benzothiazolyl acetamide moiety. Similarly in com-
pounds 8i and 8j along with methoxy and ethoxy substit-
uents, activity was found to be increased from 50 lg/mL to
In vitro antimicrobial activity
Some of the compounds showed moderate-to-good activi-
ties against some of the tested bacteria. From the bioassay,
it can be stated that the final analogues with the substitu-
tions of N-benzothiazolyl acetamides were, in most of the
cases, more active against all the pathogenic strains studied
than N-phenyl acetamides. Final derivatives 9c and 9i
with bromo and methoxy functional groups to the
Scheme 2 Synthesis of final s-triazine derivatives. Reagents and
conditions: (i) 3,5-dimethylpiperidine, acetone, K2CO3, 0 °C; (ii) 3,5-
dimethylpiperidine, acetone, K2CO3, R.T; (iii) 4-aminophenylboronic
acid pinacol ester, Pd(PPh3)4, Na2CO3, DME, 90 °C; and (iv) K2CO3,
acetone, reflux
123

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Med Chem Res (2013) 22:367–381
1.56 lg/mL in 9i and 25 lg/mL to 6.25 lg/mL in 9j,
respectively against S. aureus. 9c has also displayed
potential inhibitory efficacy toward S. typhi at 6.25 lg/mL
of MIC with 24 mm of inhibition zone. Compounds 8b and
8d with chloro and fluoro substituents were found to be
active against Gram-negative bacteria S. flexneri at
12.5 lg/mL MIC. In the case of N-benzothiazolyl acet-
amide analogues, this value was also increased in 9b and
9d to be at 6.25 lg/mL. Compounds 8c and 8d with bromo
and fluoro substituents have shown moderate-to-good
activity at 12.5 lg/mL MIC level with 27 mm zone of
inhibition against P. aeruginosa. This value slightly
decreases in the case of N-benzothiazolyl acetamide
derivatives. 8g bearing cyano (C:N) substituent at
N-phenyl acetamide moiety was active against S. aureus
and K. Pneumoniae at 12.5 lg/mL, while similar com-
pound with N-benzothiazolyl acetamide moiety was found
to be active against S. aureus at 6.25 lg/mL MIC. Sur-
prisingly, the most inactive analogues 8k and 9k with
acetamido linkage to the N-phenyl acetamide and N-ben-
zothiazolyl acetamide moieties have shown moderate-to-
good activity against Gram-negative P. vulgaris with
6.25 lg/mL of MIC (27 and 26 mm zone of inhibition,
respectively). Compound 9d with strong electronegative
fluorine substituent at N-benzothiazolyl acetamide moiety
showed good inhibitory efficacy against both S. aureus and
B. cereus at 3.12 lg/mL of MIC with 25 and 28 mm of
inhibition zone, respectively.
The results indicated that both N-phenyl acetamide and
N-benzothiazolyl acetamide-based analogues were active
against mycobacteria. Preliminary antituberculosis screen-
ing results using BACTEC MGIT method revealed that final
N-phenyl acetamide-based 8c and 8i as well as N-benzo-
thiazolyl acetamide-based 9d and 9j analogues displayed the
highest inhibition (99 %) at a constant concentration level
(6.25 lg/mL) against M. tuberculosis H37Rv. The second-
ary biological screening was performed using Lowenstein–
Jensen MIC method, and it is worthwhile to note that 8c with
N-4-bromophenyl acetamide substituent and 9d with N-(6-
fluorobenzo[d]thiazol-2-yl)acetamide substituent were the
only compounds displaying inhibition of M. tuberculosis
H37Rv completely (99 %) at the MIC of 3.12 lg/mL. This
compound was considered to display even better efficacy,
than the standard drug, pyrazinamide, while the MIC levels
of compounds 8i and 9j were same as BACTEC method
results (6.25 lg/mL), i.e., equipotent to the standard drug
pyrazinamide (Table 3).
Conclusion
In conclusion, this study demonstrates the synthesis, and in
vitro activity evaluation of new s-triazine-based congeners
against a wide range of human pathogenic microorganisms.
In general, the results of the in vitro pharmacological
activities are moderate to good, as out of two series tested,
compounds with N-benzothiazolyl acetamide exhibited
promising potential to act as leads for further drug dis-
covery. From the bioassay results, it was also possible to
make a number of correlations regarding the relationship
between the structure of the newer scaffolds and their
antimicrobial activities. Both, N-phenyl acetamides as well
as N-benzothiazoly acetamides analogues with alkoxy,
acetamido, and halogen substituents were mixedly active
against S. aureus as well as against M. tuberculosis H37Rv
strain. Analogues with cyano substituent were active
against E. coli and K. pneumoniae, whereas, analogue with
nitro functional group was found to be active against
A. clavatus. All the most potent analogues against all the
fungi were belonging to N-benzothiazolyl acetamides ser-
ies. N-benzothiazolyl acetamides analogues with alkoxy
substituent were active against P. vulgaris bacteria and
C. albicans fungi.
In vitro antifungal activity data of synthesized com-
pounds indicate that in the case of N-phenyl acetamide
analogues, the most inactive compound 8k with acetamido
group was found to be most active against A. niger fungi at
12.5 lg/mL of MIC with 22 mm on zone of inhibition. It
suffices to mention here that the final analogue with acet-
amido functional group linkage bearing N-benzothiazolyl
acetamide moiety 9k indicated strong growth inhibitory
potency against A. niger fungi at 6.25 lg/mL of MIC with
24 mm on zone of inhibition. The latter compound 9d
was also found to contribute promising activity against
A. fumigatus fungi at 25 lg/mL of MIC with 25 mm of zone
of inhibition. Analogue with the nitro substituent linked to
N-benzothiazolyl acetamide moiety 9f displayed remarkable
activity against A. clavatus fungi at 25 lg/mL of MIC with
28 mm of inhibition zone, whereas final similar series of
analogues 9i and 9j with alkoxy substituent (methoxy and
ethoxy) showed potential inhibitory efficacy against
C. albicans fungi at 12.5 lg/mL of MIC and 25 mm of zone
of inhibition (Tables 1, 2).
Experimental
In vitro antimycobacterial activity
2,4,6-Trichloro-1,3,5-triazine, TMSCl, n-butyllithium
(2.5 M) in hexane, and tetrakis(triphenylphosphine)palla-
dium(0) (Pd(PPh3)4) were purchased from Sigma Aldrich
Chemicals Pvt. Ltd., Mumbai, India. Triisopropyl borate,
In vitro tuberculosis activities of compounds 8a–k
and 9a–k were assessed against M. tuberculosis H37Rv.
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Med Chem Res (2013) 22:367–381
371
Table 1 In vitro antimicrobial activity
H3
C
N
CH3
H3
C
CH3
N
N
N
N
N
N
N
N
H3C
H3
C
N
NH
N
H
N
N
H
CH3
O
S
N
H
CH3
O
R
8a-k
9a-k
R
Entry
R
MIC in lg/mL (zone of inhibition in mm)
S.a B.c E.c
P.a
K.p
S.t
P.v
S.f
8a
8b
8c
H
50 (11)
50 (12)
50 (\10)
50 (19)
25 (26)
12.5 (27)
12.5 (27)
25 (24)
50 (20)
50 (21)
50 (17)
50 (22)
50 (16)
50 (19)
50 (16)
25 (26)
25 (25)
25 (25)
50 (16)
50 (18)
50 (18)
50 (15)
50 (20)
12.5 (23)
50 (19)
0.78 (33)
–
50 (\10)
50 (21)
25 (24)
50 (21)
50 (23)
50 (12)
12.5 (28)
50 (\10)
50 (\10)
50 (\10)
50 (\10)
50 (\10)
50 (23)
50 (11)
25 (25)
50 (12)
50 (18)
25 (27)
50 (16)
50 (23)
50 (24)
50 (21)
0.78 (33)
–
50 (\10)
50 (18)
25 (20)
25 (21)
50 (17)
50 (15)
50 (20)
50 (18)
25 (20)
25 (21)
50 (\10)
50 (12)
25 (22)
6.25 (24)
12.5 (23)
50 (17)
50 (19)
50 (18)
50 (\10)
50 (20)
50 (19)
50 (17)
0.39 (30)
–
50 (14)
50 (21)
50 (13)
50 (16)
25 (23)
50 (13)
50 (19)
50 (16)
25 (22)
12.5 (25)
6.25 (27)
50 (18)
50 (20)
25 (23)
25 (25)
12.5 (26)
50 (19)
25 (22)
50 (20)
6.25 (27)
12.5 (26)
6.25 (26)
0.39 (31)
–
50 (\10)
12.5 (24)
12.5 (22)
12.5 (25)
50 (20)
50 (17)
50 (15)
50 (11)
50 (19)
25 (22)
50 (16)
50 (\10)
6.25 (26)
12.5 (25)
6.25 (26)
25 (23)
50 (21)
50 (22)
50 (12)
12.5 (25)
50 (17)
50 (13)
1.56 (32)
–
Cl
25 (18)
3.12 (24)
12.5 (20)
50 (17)
50 (13)
6.25 (27)
25 (22)
50 (16)
50 (16)
50 (19)
50 (14)
25 (23)
50 (20)
50 (12)
50 (14)
6.25 (27)
6.25 (26)
3.12 (28)
25 (24)
12.5 (26)
50 (22)
50 (19)
12.5 (25)
25 (24)
50 (17)
0.39 (31)
–
50 (12)
25 (19)
25 (20)
50 (\10)
50 (13)
25 (20)
50 (13)
50 (19)
12.5 (24)
50 (20)
50 (14)
25 (21)
12.5 (23)
25 (20)
50 (18)
50 (18)
6.25 (25)
50 (16)
25 (20)
12.5 (23)
50 (19)
1.56 (32)
–
Br
8d
8e
F
I
8f
NO2
CN
CH3
OCH3
OC2H5
12.5 (20)
12.5 (19)
50 (\10)
50 (16)
8g
8h
8i
8j
25 (19)
8k
9a
9b
9c
NHCOCH3
50 (\10)
50 (16)
H
Cl
6.25 (22)
1.56 (25)
3.12 (25)
12.5 (21)
12.5 (22)
6.25 (24)
50 (15)
Br
9d
9e
F
I
9f
NO2
CN
9g
9h
9i
CH3
OCH3
OC2H5
NHCOCH3
1.56 (26)
6.25 (23)
50 (19)
9j
9k
Cip.
DMSO
1.56 (30)
–
Cip., ciprofloxacin; S.a, Staphylococcus aureus; B.c, Bacillus cereus; E.c, Escherichia coli; P.a, Pseudomonas aeruginosa; K.p, Klebsiella
pneumoniae; S.t, Salmonella typhi; P.v, Proteus vulgaris; S.f, Shigella flexneria
chloroacetyl chloride different aniline derivatives were
purchased from Spectrochem Pvt. Ltd., Mumbai, India.
3,5-Dimethylpiperidine was purchased from Thermo Fisher
Scientific India Pvt. Ltd. Mumbai, India. THF, acetone, and
potassium carbonate were purchased from Rankem, Surat,
India. The TLC plates (silica gel 60 F254) were obtained
from Merck, Germany. Melting points were determined in
open capillaries on a Veego electronic apparatus VMP-D
(Veego Instrument Corporation, Mumbai, India) and are
uncorrected. IR spectra (4,000–400 cm-1) of synthesized
compounds were recorded on a Shimadzu 8400-S FT-IR
spectrophotometer (Shimadzu India Pvt. Ltd., Mumbai,
India) using KBr pellets. Thin-layer chromatography was
performed on object glass slides (2 9 7.5 cm) coated with
silica gel-G, and spots were visualized under UV irradia-
1
tion. H NMR and 13C NMR spectra were recorded on a
Varian 400 MHz model spectrometer (Varian India Pvt.
Ltd., Mumbai, India) using DMSO as a solvent and TMS as
1
internal standard with H resonant frequency of 400 MHz
and 13C resonant frequency of 100 MHz. The 1H NMR and
13C NMR chemical shifts were reported as parts per million
(ppm) downfield from TMS (Me4Si) and CFCl3 and were
123

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Med Chem Res (2013) 22:367–381
Table 2 In vitro antifungal activity
H3
C
N
CH3
H3
C
CH3
N
N
N
N
N
N
N
N
H3C
H3
C
N
NH
N
H
N
N
H
CH3
O
S
N
H
CH3
O
R
8a-k
9a-k
R
Entry
R
MIC in lg/mL (Zone of inhibition in mm)
A.n A.f
A.c
C.a
8a
8b
8c
H
Cl
Br
F
50 (\10)
50 (\10)
[50 (\10)
[50 (\10)
50 (25)
[50 (\10)
[50 (\10)
50 (13)
50 (\10)
50 (12)
50 (18)
50 (\10)
50 (18)
50 (\10)
50 (\10)
50 (14)
25 (19)
12.5 (22)
50 (\10)
50 (17)
50 (19)
12.5 (22)
50 (\10)
12.5 (23)
25 (19)
50 (\10)
25 (19)
25 (20)
6.25 (24)
1.56 (30)
–
50 (14)
50 (23)
8d
8e
50 (22)
50 (13)
50 (15)
I
50 (16)
[50 (\10)
50 (24)
[50 (\10)
50 (13)
8f
NO2
50 (18)
8g
8h
8i
CN
50 (11)
[50 (\10)
[50 (\10)
[50 (\10)
50 (14)
[50 (\10)
50 (11)
CH3
[50 (\10)
[50 (\10)
[50 (\10)
50 (12)
OCH3
OC2H5
25 (21)
8j
25 (24)
8k
9a
9b
9c
NHCOCH3
50 (19)
50 (17)
H
[50 (\10)
[50 (\10)
50 (19)
[50 (\10)
[50 (\10)
50 (26)
[50 (\10)
50 (12)
Cl
Br
50 (18)
9d
9e
F
25 (25)
50 (25)
50 (23)
I
[50 (\10)
50 (22)
50 (11)
50 (20)
9f
NO2
CN
25 (28)
50 (16)
9g
9h
9i
50 (22)
50 (16)
[50 (\10)
50 (13)
CH3
[50 (\10)
[50 (\10)
50 (16)
[50 (\10)
50 (23)
OCH3
OC2H5
NHCOCH3
12.5 (25)
12.5 (25)
25 (22)
9j
50 (16)
9k
Kit.
DMSO
[50 (\10)
0.78 (29)
–
50 (24)
0.78 (31)
–
1.56 (33)
–
Kit, ketoconazole; A.n, Aspergillus niger; A.f, Aspergillus fumigates; A.c, Aspergillus clavatus; C.a, Candida albicans
performed at The Centre for Excellence, Vapi, India. The
splitting patterns are designated as follows: s, singlet; br s,
broad singlet; d, doublet; and m, multiplet. Elemental
analyses (C, H, and N) were performed using a Heraeus
Carlo Erba 1180 CHN analyzer (Hanau, Germany).
(Staphylococcus aureus MTCC 96, Bacillus cereus MTCC
430, Escherichia coli MTCC 739, Pseudomonas aerugin-
osa MTCC 741, Klebsiella pneumoniae MTCC 109,
Salmonella typhi MTCC 733, Proteus vulgaris MTCC 1771,
Shigella flexneri MTCC 1457), fungi (Aspergillus niger
MTCC 282, Aspergillus fumigatus MTCC 343, Aspergillus
clavatus MTCC 1323, and Candida albicans MTCC 183)
using paper disk diffusion technique (Gillespie, 1994) and
agar streak dilution method. The Mueller–Hinton agar media
were sterilized (autoclaved at 120 °C for 30 min), poured at
uniform depth of 5 mmand allowed to solidify. The microbial
Agar diffusion method for in vitro antimicrobial
activity
The synthesized derivatives (8a–k, 9a–k) were exam-
ined for antimicrobial activity against several bacteria
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Med Chem Res (2013) 22:367–381
373
Table 3 In vitro antimycobacterial activity
H3
C
N
CH3
H3
C
CH3
N
N
N
N
N
N
N
N
H3C
H3
C
N
NH
N
H
N
N
H
CH3
O
S
N
H
CH3
O
R
8a-k
9a-k
R
Entry
R
BACTEC MGIT methoda
L. J. MIC methoda
MIC (lg/mL)
% Inhibition
MIC (lg/mL)
% Inhibition
8a
8b
8c
8d
8e
8f
H
[6.25
[6.25
6.25
–
–
250
25
95
98
99
97
95
94
96
95
99
98
95
94
97
99
99
96
98
95
97
98
99
98
Cl
Br
–
3.12
25
F
[6.25
[6.25
[6.25
[6.25
[6.25
6.25
–
I
–
250
100
62.5
250
6.25
25
NO2
CN
CH3
OCH3
–
8g
8h
8i
–
–
99
–
8j
OC2H5
NHCOCH3
H
[6.25
[6.25
[6.25
[6.25
[6.25
6.25
8k
9a
9b
9c
9d
9e
9f
–
62.5
500
62.5
12.5
3.12
200
50
–
Cl
–
Br
–
F
–
I
[6.25
[6.25
[6.25
[6.25
[6.25
6.25
–
NO2
–
9g
9h
9i
CN
–
100
250
12.5
6.25
50
CH3
–
OCH3
OC2H5
NHCOCH3
Isoniazid
Rifampicin
Ethambutol
–
9j
–
9k
[6.25
0.20
–
99
99
99
99
0.25
3.12
Pyrazinamide
6.25
a
Each value is the mean of three independent experiments
suspension (105 CFU/mL) (0.5 McFarland Nephelometery
Standards) was streaked over the surface of media using
a sterile cotton swab to ensure even growth of the organisms.
The tested compounds were dissolved in dimethylsulfoxide
(DMSO) to give solutions of 3.12–50 lg/mL. Sterile filter
paper disks measuring 6.25 mm in diameter (Whatman no. 1
filter paper), previously soaked in a known concentration of
the respective test compound in DMSO were placed on the
solidified nutrient agar medium that had been inoculated with
the respective microorganism and the plates were incu-
bated for 24 h at (37 1) °C. A control disk impregnated
with an equivalent amount of DMSO without any sample
was also used and did not produce any inhibition. Ciproflox-
acin and ketoconazole (100 lg/disk) were used as con-
trol drugs for antibacterial and antifungal activity,
respectively.
MIC of the compound was determined by agar streak
dilution method (Hawkey and Lewis, 1994). A stock
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Med Chem Res (2013) 22:367–381
solution of the synthesized compound (100 lg/mL) in
DMSO was prepared and graded quantities of the test
compounds were incorporated in a specified quantity of
molten sterile agar, i.e., nutrient agar for evaluation of
antibacterial activity and sabouraud dextrose agar for
antifungal activity, respectively. The medium containing
the test compound was poured into a petri dish at a depth of
4–5 mm and allowed to solidify under aseptic conditions.
A suspension of the respective microorganism of approx-
imately 105 CFU/mL was prepared and applied to plates
with serially diluted compounds with concentrations in the
range of 3.12–50 lg/mL in DMSO and incubated at
(37 1) °C for 24 h (bacteria) or 48 h (fungi). The lowest
concentration of the substance that prevents the develop-
ment of visible growth is considered to be the MIC value.
adopting L. J. (conventional Lowenstein and Jensen) agar
dilution method (Anargyros et al., 1990) for the measure-
ment of MIC, and is defined as the lowest concentration of
drug, which inhibits C99 % of bacterial population present
at the beginning of the assay. Stock solutions of 100, 62.5,
50, 25, 12.5, 6.25, 3.12, and 1.56 lg/mL dilutions of each
test compound in DMSO were added in the liquid L.
J. Medium, and then media were sterilized by inspissation
method. A culture of M. tuberculosis H37Rv growing on L.
J. Medium was harvested in 0.85 % saline in bijou bottles.
These tubes were then incubated at 37 °C for 24 h fol-
lowed by streaking of M. tuberculosis H37Rv (5 9 104
bacilli per tube). These tubes were then incubated at 37 °C.
Growth of bacilli was seen after 12 days, 22 days, and
finally at 28th day of incubation. Tubes having the com-
pounds were compared with control tubes where medium
alone was incubated with M. tuberculosis H37Rv. The
concentration at which no development of colonies
occurred or \20 colonies was taken as MIC concentration
of test compound. The standard strain M. tuberculosis
H37Rv was tested with known drugs Isoniazid, Rifampicin,
Ethambutol and Pyrazinamide.
Methods of in vitro evaluation of antitubercular activity
BACTEC MGIT method
The Mycobacteria Growth Indicator Tubes (MGIT) con-
taining 4 mL of modified Middle brook 7H9 Broth Base
were numbered as per the title compounds to be tasted for
antituberculosis efficacy by means of various concentrations
prepared. The suspension was allowed to sit for 20 min, and
the tubes were centrifuged at 3,000 rpm for 15 min. After
that 104 to 107 CFU/mL of H37RV M. tuberculosis strain
suspension prepared was added in the medium to be incu-
bated and 0.1 mL of egg-based medium (L. J.) was also
added. The MGIT tubes were then tightly recapped, mixed
well, and incubated into BACTEC MGIT instrument at
37 °C until positivity is observed. The readings were mea-
sured daily starting from the second day of incubation.
Positive cultures were usually detected within 10 days. For
reading the actual results, the MGIT tubes were removed
from incubator and placed on the UV light next to a Positive
Control tube and an uninoculated tube. Bright fluorescence
detected by the corresponding MGIT tube was noticed in the
form of bright orange color in the bottom of the tube and also
an orange reflection on the meniscus (Isenberg, 1992). The
primary screening was conducted at concentration of
6.25 lg/mL against M. tuberculosis H37Rv in BACTEC
MGIT system. Compounds demonstrating 99 % inhibition
in the primary screen were described as most potent com-
pounds. All the other compounds to be tasted were
re-examined for their actual MIC by adopting conventional
L. J. agar dilution method. The MIC was defined as the
lowest concentration inhibiting 99 % of the inoculum.
Synthetic part
4-Bromo-N,N-bis(trimethylsilyl)aniline (4a)
To a stirred solution of 4-bromoaniline 4 (10.0 g,
0.06 mol) in dry tetrahydrofuran (THF) (200 mL),
(81.3 mL, 0.13 mol) of n-butyllithium in 1.6 M of hexane
was added dropwise by using additional funnel over 2.5 h
at 0 °C under nitrogen purging system. Then (16.8 mL,
0.13 mol) of TMSCl was added to the flask using a syringe
and syringe pump over 1.5 h. The reaction flask was
warmed to room temperature and stirred overnight under
nitrogen. The solvent was removed via vacuum evapora-
tion, and the thick black residue was vacuum distilled in
four different cuts. The last two colorless fractions were
used as 4a (Das et al., 2003). Colorless liquid, Yield: 49 %,
1
bp 300–303 °C. H NMR (400 MHz, DMSO-d6): 7.21 (d,
J = 7.3 Hz, 2H), 6.75 (t, J = 8.1 1H), 0.39 (s, 19H, CH3).
13C NMR (100 MHz, DMSO-d6): 143.27 (1C, Car–Nsi),
131.27, 124.10, 120.18, 116.73, 115.10 (5C, Ar–C), 1.24
(6C, CH3).
4-Aminophenylboronic acid pinacol ester {4-(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)aniline} (4b)
2-(4-Bromo-phenyl)-1,1,1,3,3,3-hexamethyl-disilazane 4a
(10.0 g, 0.032 mol) in dry THF (200 mL) cooled to -78 °C
was added n-Butyllithium (2.5 M) (15.2 mL, 0.038 mol)
under nitrogen atmosphere. After 1 h of stirring at same
temperature, triisopropyl borate (8.6 mL, 0.038 mol) was
Conventional or Lowenstein and Jensen method
The preliminary antitubercular screening for test com-
pounds was obtained for M. Tuberculosis H37Rv, by
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Med Chem Res (2013) 22:367–381
375
added into the reaction mass. The reaction mass was stirred
for 3 h at same temperature. The mixture was then warmed to
25 °C over 1 h. After an additional stirring for 30 min at
same temperature, a solution of pinacol (1.08 g, 9.16 mmol)
in THF (10 mL) was added and after 5 min, glacial acetic
acid was added until the pH reached 5. After 45 min of
stirring at room temperature, the mixture was diluted with
ether, filtered, and concentrated. The ethereal solution was
washed with a saturated aqueous solution of NaHCO3. The
organic layer was dried over Na2SO4 and concentrated to
obtain (4b) (Primas et al., 2009). Pale greenish solid, Yield:
79 %, mp 162–165 °C. 1H NMR (400 MHz, DMSO-d6): d
8.53 (s, 2H, NH2), 7.59 (d, J = 7.6 Hz, 2H), 6.81 (d,
J = 7.3 Hz, 2H), 1.23 (s, 12H, CH3). 13C NMR (100 MHz,
DMSO-d6): 156.92 (1C, C-NH2), 150.35 (1C, Car–B),
141.94, 123.29 (4C, Ar–C), 83.11 (2C, O–C (CH3)2), 23.92
(4C, CH3).
(400 MHz, DMSO-d6): 3.69 (dd, J = 12.1, 7.8 Hz, 4H,
H-20, H-60), 3.52 (dd, J = 11.8, 7.5 Hz, 4H, H-200, H-600),
1.80 (m, 4H, H-30, 300, H-50, 500), 1.21 (d, J = 6.8 Hz, 6H,
2CH3), 0.99 (d, J = 5.7 Hz, 6H, 2CH3), 0.81–0.76 (m, 4H,
H-40, 400). 13C NMR (100 MHz, DMSO-d6): 169.31 (2C,
C-2, 6, Ctri–Npip), 164.09 (1C, C-4, Ctri–Cl), 52.19, 50.27
(4C, C-20, 200, 60, 600, piperidine), 43.21, 37.99 (2C, C-40, 400,
piperidine), 33.67, 29.15 (4C, C-30, 300, 50, 500, piperidine),
20.90 (2C, 2CH3), 23.67 (2C, 2CH3).
4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)aniline (7)
A mixture of 2-chloro-4,6-bis(3,5-dimethylpiperidin-1-yl)-
1,3,5-triazine (20.0 g, 0.06 mol), a catalytic amount
of tetrakis-(triphenylphosphine)palladium(0) (0.87 mg,
0.00075 mol), sodium carbonate solution 2 M (50 mL),
4-aminophneylboronic acid pinacol ester (19.7 g,
0.09 mmol), and DME (300 mL) was refluxed for 24 h. The
solvent was evaporated, and the residue was dissolved in
methylene dichloride and filtered. The filtrate was washed
with water (2 9 500 mL), dried over Na2SO4, concentrated,
and purified by column chromatography eluting with ethyl
acetate : hexanes (1:1) to give of 4-(4,6-bis(3,5-dim-
ethylpiperidin-1-yl)-1,3,5-triazin-2-yl)aniline 7 (Venkate-
san et al., 2010). Amorphous white solid, Yield: 81 %, mp
255–259 °C. IR (KBr, cm-1): 3385, 3359 (–NHs), 841 (s
triazine C–N str.). 1H NMR (400 MHz, DMSO-d6): 8.63 (s,
2H, –NH2), 7.57 (d, J = 7.7 Hz, 2H, Ar–H), 6.74 (d,
J = 7.3 Hz, 2H, Ar–H), 3.73 (dd, J = 12.2, 7.7 Hz, 4H,
H-20, 60), 3.56 (dd, J = 11.9, 7.3 Hz, 4H, H-200, 600), 1.75 (m,
4H, H-30, 300, H-50, 500), 1.27 (d, J = 6.6 Hz, 6H, 2CH3), 0.92
(d, J = 5.9 Hz, 6H, 2CH3), 0.89–0.83 (m, 4H, H-40, 400). 13C
NMR (100 MHz, DMSO-d6): d 171.68 (2C, C-2 and C-6,
Ctri–Npip), 164.29 (1C, C-4, Ctri–Cph), 149.13 (1C, C-10, C–
NH2), 143.10–124.80 (5C, Ar–C), 51.27, 49.12 (4C, C-20, 200,
60, 600, piperidine), 40.76, 36.98 (2C, C-40, 400, piperidine),
31.3, 28.64 (4C, C-30, 300, 50, 500, piperidine), 19.93 (2C,
2CH3), 22.73 (2C, 2CH3).
2,4-Dichloro-6-(3,5-dimethylpiperidin-1-yl)-1,3,5-triazine
(5)
3,5-Dimethylpiperidine (12.8 g, 0.1 mol) was slowly
added into the mixture of cyanuric chloride (18.5 g,
0.1 mol) and base potassium carbonate (1.21 g, 0.012 mol)
in acetone (100 mL) with constant stirring for 6 h at
0–5 °C. Progress of the reaction was monitored by TLC
using toluene:acetone (9:1) as eluent. Finally, the contents
were poured into crushed ice (500 g). The solid separated,
was filtered, washed with water, dried, and recrystallized
from ethanol to obtained compound 5. White solid, Yield:
1
87 %, mp 260–265 °C. H NMR (400 MHz, DMSO-d6):
3.91 (dd, J = 12.5, 7.4 Hz, 4H, H-20, H-60), 1.62 (m, 2H,
H-30, H-50), 0.97 (d, J = 6.8 Hz, 6H, 2CH3), 0.79 (m, 2H,
H-40). 13C NMR (100 MHz, DMSO-d6): d 171.68 (1C, C-6,
Ctri–Npip), 165.37 (2C, Ctri–Cl), 53.19 (2C, C-20, 60,
piperidine), 38.76 (1C, C-40, piperidine), 30.55 (2C, C-30,
50, piperidine), 18.94 (2C, 2CH3).
2-Chloro-4,6-bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazine
(6)
Synthesis of N-phenylacetamide-substituted final
compounds (8a–k)
3,5-Dimethylpiperidine (8.67 g, 0.077 mol) was slowly
added to the stirred solution of 2,4-dichloro-6-(3,5-dim-
ethylpiperidin-1-yl)-1,3,5-triazine (5) (20.0 g, 0.077 mol)
and base potassium carbonate (12.66 g, 0.092 mol) in
acetone (200 mL) at 0–5 °C. Then temperature was raised
to 45 °C and same temperature was continued for 15 h.
Progress of the reaction was monitored by TLC using
toluene:acetone (9:1) as eluent. Finally, the reaction mass
was poured into 500 g crushed ice. The solid separated,
was filtered, washed with water, dried, and recrystallized
from ethanol to give compound 6 (Patel et al., 2011a).
White solid, Yield: 85 %, mp 245–247 °C. 1H NMR
Mixture of 4-(4,6-bis(3,5-dimethylpiperidin-1-yl)-1,3,5-
triazin-2-yl)aniline 7 (0.05 mol), different acetamides
1a–k (0.05 mol) and K2CO3 (0.052 mol) was refluxed in
acetone (50 mL) for 8–15 h. After the completion of
reaction, the reaction mass was poured in crushed ice
(200 g), and the resulting precipitates were filtered, washed
with water, dried, and crystallized with suitable solvent to
obtained 8a–k (Amir et al., 2011). The progress of the
reaction was monitored by Thin Layer Chromatography
using n-hexane:ethyl acetate (8:2) solvent system.
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Med Chem Res (2013) 22:367–381
H-30, 300, 50, 500), 1.28 (d, J = 6.6 Hz, 6H, 2CH3), 0.99 (d,
J = 5.9 Hz, 6H, 2CH3), 0.87–0.80 (m, 4H, H-40, 400). 13C
NMR (100 MHz, DMSO-d6): d 170.11 (2C, C-2 and C-6,
Ctri–Npip), 169.19 (1C, C-15, C=O), 164.11 (1C, C-4,
Ctri–Cph), 151.32 (1C, C-10, C–NH), 144.11–117.25 (11C,
Ar–C), 53.12, 48.15 (4C, C-20, 200, 60, 600, piperidine), 46.19
(1C, C-14, NHCH2CO), 39.42, 35.55 (2C, C-40, 400,
piperidine), 33.65, 27.25 (4C, C-30, 300, 50, 500, piperidine),
18.98 (2C, 2CH3), 21.47 (2C, 2CH3). Anal. Calcd for
C31H40BrN7O: C, 61.38; H, 6.65; N, 16.16; Found: C,
61.54; H, 6.50; N, 16.24.
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-phenylacetamide (8a)
Light brown solid, Yield: 80 %, mp 289–290 °C. IR (KBr,
cm-1): 3286, 3280 (–NHs), 834 (s triazine C–N str.), 1680
1
(C=O). H NMR (400 MHz, DMSO-d6): d 9.41 (s, 1H,
H-16, –NH), 7.78–7.07 (m, 9H, Ar–H), 4.89 (s, 1H, H-13,
–NH), 4.13 (s, 2H, H-14, –NHCOCH2NH), 3.73 (dd,
J = 12.2, 7.7 Hz, 4H, H-20, 60), 3.56 (dd, J = 11.9, 7.3 Hz,
4H, H-200, 600), 1.73 (m, 4H, H-30, 300, 50, 500), 1.27 (d,
J = 6.6 Hz, 6H, 2CH3), 0.92 (d, J = 5.9 Hz, 6H, 2CH3),
0.89–0.83 (m, 4H, H-40, 400). 13C NMR (100 MHz, DMSO-
d6): d 168.68 (2C, C-2 and C-6, Ctri–Npip), 169.40 (1C,
C-15, C=O), 163.89 (1C, C-4, Ctri–Cph), 150.97 (1C, C-10,
C–NH), 147.37–115.29 (11C, Ar–C), 54.76, 47.92 (4C,
C-20, 200, 60, 600, piperidine), 47.15 (1C, C-14, NHCH2CO),
38.39, 37.12 (2C, C-40, 400, piperidine), 33.29, 28.98 (4C,
C-30, 300, 50, 500, piperidine),18.75 (2C, 2CH3), 23.62 (2C,
2CH3). Anal. Calcd for C31H41N7O: C, 70.56; H, 7.83; N,
18.58; Found: C, 70.74; H, 7.59; N, 18.42.
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(4-fluorophenyl)acetamide (8d)
Light brown solid, Yield: 76 %, mp 279–280 °C. IR (KBr,
cm-1): 3295, 3277 (–NHs), 825 (s triazine C–N str.), 1684
1
(C=O). H NMR (400 MHz, DMSO-d6): d 9.56 (s, 1H,
H-16, –NH), 7.89 (dd, J = 7.5, 1.7 Hz, 1H), 7.82–7.18 (m,
5H, Ar–H), 7.11 (t, J = 7.4 Hz, 2H), 4.86 (s, 1H, H-13,
–NH), 4.15 (s, 2H, H-14, –NHCOCH2NH), 3.73 (dd,
J = 12.2, 7.7 Hz, 4H, H-20, 60), 3.71 (dd, J = 11.9, 7.3 Hz,
4H, H-200, 600), 1.88 (m, 4H, H-30, 300, 50, 500), 1.21 (d,
J = 6.6 Hz, 6H, 2CH3), 0.93 (d, J = 5.9 Hz, 6H, 2CH3),
0.90–0.84 (m, 4H, H-40, 400). 13C NMR (100 MHz, DMSO-
d6): d 172.23 (2C, C-2 and C-6, Ctri–Npip), 169.03 (1C,
C-15, C=O), 164.89 (1C, C-4, Ctri-Cph), 151.71 (1C, C-10,
C–NH), 145.04–119.23 (11C, Ar–C), 54.06, 47.95 (4C,
C-20, 200, 60, 600, piperidine), 45.97 (1C, C-14, NHCH2CO),
38.11, 36.87 (2C, C-40, 400, piperidine), 32.47, 28.11 (4C,
C-30, 300, 50, 500, piperidine), 19.15 (2C, 2CH3), 22.85 (2C,
2CH3). Anal. Calcd for C31H40FN7O: C, 68.23; H, 7.39; N,
17.97; Found: C, 68.37; H, 7.25; N, 18.04.
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(4-chlorophenyl)acetamide (8b)
Light brown solid, Yield: 75 %, mp 295–297 °C. IR (KBr,
cm-1): 3301, 3292 (–NHs), 842 (s triazine C–N str.), 1669
1
(C=O). H NMR (400 MHz, DMSO-d6): d 9.29 (s, 1H,
H-16, –NH), 7.87 (dd, J = 7.6, 1.5 Hz, 1H), 7.71–6.89 (m,
8 h, Ar–H), 4.84 (s, 1H, H-13, –NH), 4.09 (s, 2H, H-14,
–NHCOCH2NH), 3.81 (dd, J = 12.2, 7.7 Hz, 4H, H-20, 60),
3.69 (dd, J = 11.9, 7.3 Hz, 4H, H-200, 600), 1.79 (m, 4H,
H-30, 300, 50, 500), 1.19 (d, J = 6.6 Hz, 6H, 2CH3), 0.92 (d,
J = 5.9 Hz, 6H, 2CH3), 0.91–0.85 (m, 4H, H-40, 400). 13C
NMR (100 MHz, DMSO-d6): d 173.47 (2C, C-2 and C-6,
Ctri–Npip), 168.72 (1C, C-15, C=O), 165.09 (1C, C-4,
Ctri–Cph), 154.29 (1C, C-10, C–NH), 143.89–120.17 (11C,
Ar–C), 50.91, 49.71 (4C, C-20, 200, 60, 600, piperidine), 45.71
(1C, C-14, NHCH2CO), 39.21, 36.55 (2C, C-40, 400,
piperidine), 31.79, 27.19 (4C, C-30, 300, 50, 500, piperidine),
19.21 (2C, 2CH3), 22.13 (2C, 2CH3). Anal. Calcd for
C31H40ClN7O: C, 66.23; H, 7.17; N, 17.44; Found: C,
66.02; H, 7.09; N, 17.59.
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(4-iodophenyl)acetamide (8e)
Light brown solid, Yield: 79 %, mp 298–299 °C. IR (KBr,
cm-1): 3300, 3291 (–NHs), 842 (s triazine C–N str.), 1682
1
(C=O). H NMR (400 MHz, DMSO-d6): d 9.23 (s, 1H,
H-16, –NH), 7.83–7.25 (m, 6H, Ar–H), 7.13 (d,
J = 8.0 Hz, 2H), 4.99 (s, 1H, H-13, –NH), 4.23 (s, 2H,
H-14, –NHCOCH2NH), 3.83 (dd, J = 12.2, 7.7 Hz, 4H,
H-20, 60), 3.59 (dd, J = 11.9, 7.3 Hz, 4H, H-200, 600), 1.76
(m, 4H, H-30, 300, 50, 500), 1.26 (d, J = 6.6 Hz, 6H, 2CH3),
0.97 (d, J = 5.9 Hz, 6H, 2CH3), 0.87–0.82 (m, 4H, H-40,
400). 13C NMR (100 MHz, DMSO-d6): d 168.97 (2C, C-2
and C-6, Ctri–Npip), 169.17 (1C, C-15, C=O), 163.93 (1C,
C-4, Ctri–Cph), 152.47 (1C, C-10, C–NH), 145.82–118.27
(11C, Ar–C), 52.25, 48.03 (4C, C-20, 200, 60, 600, piperidine),
47.02 (1C, C-14, NHCH2CO), 39.85, 36.12 (2C, C-40, 400,
piperidine), 32.69, 27.88 (4C, C-30, 300, 50, 500, piperidine),
19.87 (2C, 2CH3), 23.11 (2C, 2CH3). Anal. Calcd for
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(4-bromophenyl)acetamide (8c)
Light yellow solid, Yield: 81 %, mp 301–304 °C. IR (KBr,
cm-1): 3298, 3287 (–NHs), 831 (s triazine C–N str.), 1674
1
(C=O). H NMR (400 MHz, DMSO-d6): d 9.35 (s, 1H,
H-16, –NH), 7.91 (dd, J = 7.6, 1.8 Hz, 1H), 7.71–6.97 (m,
8 h, Ar–H), 5.01 (s, 1H, H-13, –NH), 4.25 (s, 2H, H-14,
–NHCOCH2NH), 3.87 (dd, J = 12.2, 7.7 Hz, 4H, H-20, 60),
3.71 (dd, J = 11.9, 7.3 Hz, 4H, H-200, 600), 1.69 (m, 4H,
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1
C31H40IN7O: C, 56.97; H, 6.17; N, 15.00; Found: C, 56.83;
H, 6.31; N, 14.93.
(C=O). H NMR (400 MHz, DMSO-d6): d 9.51 (s, 1H,
H-16, –NH), 7.59–7.01 (m, 9H, Ar–H), 4.97 (s, 1H, H-13,
–NH), 4.15 (s, 2H, H-14, –NHCOCH2NH), 3.75 (dd,
J = 12.2, 7.7 Hz, 4H, H-20, 60), 3.68 (dd, J = 11.9, 7.3 Hz,
4H, H-200, 600), 1.61 (m, 4H, H-30, 300, 50, 500), 1.17 (d,
J = 6.6 Hz, 6H, 2CH3), 0.97 (d, J = 5.9 Hz, 6H, 2CH3),
0.87–0.81 (m, 4H, H-40, 400), 1.26 (s, 3H, CH3). 13C NMR
(100 MHz, DMSO-d6): d 168.43 (2C, C-2 and C-6, Ctri–
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(4-nitrophenyl)acetamide (8f)
Yellow solid, Yield: 72 %, mp 292–294 °C. IR (KBr,
cm-1): 3290, 3279 (–NHs), 830 (s triazine C–N str.), 1679
1
(C=O). H NMR (400 MHz, DMSO-d6): d 9.41 (s, 1H,
Npip), 169.23 (1C, C-15, C=O), 164.12 (1C, C-4, Ctri–Cph),
H-16, –NH), 7.80 (d, J = 7.7 Hz, 2H), 7.73–7.07 (m, 6H,
Ar–H), 4.89 (s, 1H, H-13, –NH), 4.13 (s, 2H, H-14,
–NHCOCH2NH), 3.73 (dd, J = 12.2, 7.7 Hz, 4H, H-20, 60),
3.56 (dd, J = 11.9, 7.3 Hz, 4H, H-200, 600), 1.73 (m, 4H,
H-30, 300, 50, 500), 1.27 (d, J = 6.6 Hz, 6H, 2CH3), 0.93 (d,
J = 5.9 Hz, 6H, 2CH3), 0.84–0.90 (m, 4H, H-40, 400). 13C
NMR (100 MHz, DMSO-d6): d 170.59 (2C, C-2 and C-6,
Ctri–Npip), 168.83 (1C, C-15, C=O), 164.73 (1C, C-4, Ctri–
Cph), 153.11 (1C, C-10, C–NH), 146.42–119.12 (11C, Ar–
C), 52.89, 47.97 (4C, C-20, 200, 60, 600, piperidine), 45.68
(1C, C-14, NHCH2CO), 40.06, 36.52 (2C, C-40, 400,
piperidine), 33.22, 28.95 (4C, C-30, 300, 50, 500, piperidine),
18.91 (2C, 2CH3), 23.16 (2C, 2CH3). Anal. Calcd for
C31H40N8O3: C, 65.01; H, 7.04; N, 19.57; Found: C, 64.89;
H, 7.16; N, 19.65.
15.02 (1C, C-10, C–NH), 144.56–120.03 (11C, Ar–C),
53.37, 49.22 (4C, C-20, 200, 60, 600, piperidine), 46.12 (1C,
C-14, NHCH2CO), 40.71, 35.89 (2C, C-40, 400, piperidine),
31.45, 28.02 (4C, C-30, 300, 50, 500, piperidine), 19.47 (2C,
2CH3), 23.01 (2C, 2CH3), 19.80 (1C, CH3). Anal. Calcd for
C32H43N7O: C, 70.95; H, 8.00; N, 18.10; Found: C, 71.09;
H, 8.18; N, 17.95.
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(4-methoxyphenyl)acetamide (8i)
Light brown solid, Yield: 82 %, mp 243–246 °C. IR (KBr,
cm-1): 3327, 3301 (–NHs), 841 (s triazine C–N str.), 1683
1
(C=O). H NMR (400 MHz, DMSO-d6): d 9.29 (s, 1H,
H-16, –NH), 7.80 (d, J = 7.3 Hz, 2H), 7.59–7.22 (m, 4H,
Ar–H), 6.85 (d, J = 7.7 Hz, 2H), 5.03 (s, 1H, H-13, –NH),
4.26 (s, 2H, H-14, –NHCOCH2NH), 3.86 (s, 3H, –OCH3),
3.80 (dd, J = 12.2, 7.7 Hz, 4H, H-20, 60), 3.64 (dd,
J = 11.9, 7.3 Hz, 4H, H-200, 600), 1.85 (m, 4H, H-30, 300, 50,
500), 1.22 (d, J = 6.6 Hz, 6H, 2CH3), 0.91 (d, J = 5.9 Hz,
6H, 2CH3), 0.91–0.84 (m, 4H, H-40, 400). 13C NMR
(100 MHz, DMSO-d6): d 171.55 (2C, C-2 and C-6, Ctri–
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(4-cyanophenyl)acetamide (8g)
Light brown solid, Yield: 72 %, mp 272–274 °C. IR (KBr,
cm-1): 3292, 3275 (–NHs), 839 (s triazine C–N str.), 1671
1
(C=O). H NMR (400 MHz, DMSO-d6): d 9.61 (s, 1H,
H-16, –NH), 7.84 (d, J = 7.5 Hz, 2H), 7.76 (d,
J = 7.5 Hz, 2H), 7.63–7.22 (m, 4H, Ar–H), 4.89 (s, 1H,
H-13, –NH), 4.17 (s, 2H, H-14, –NHCOCH2NH), 3.89 (dd,
J = 12.2, 7.7 Hz, 4H, H-20, H-60), 3.69 (dd, J = 11.9,
7.3 Hz, 4H, H-200, 600), 1.83 (m, 4H, H-30, 300, 50, 500), 1.27
(d, J = 6.6 Hz, 6H, 2CH3), 0.94 (d, J = 5.9 Hz, 6H,
2CH3), 0.92–0.86 (m, 4H, H-40, 400). 13C NMR (100 MHz,
DMSO-d6): d 171.22 (2C, C-2 and C-6, Ctri–Npip), 168.99
(1C, C-15, C=O), 165.01 (1C, C-4, Ctri–Cph), 150.99 (1C,
C-10, C–NH), 147.11–117.85 (10C, Ar–C), 106.08 (1C,
C:N), 97.29 (1C, –C–C:N), 51.43, 48.82 (4C, C-20, 200,
60, 600, piperidine), 46.76 (1C, C-14, NHCH2CO), 39.49,
37.02 (2C, C-40, 400, piperidine), 32.92, 27.45 (4C, C-30, 300,
50, 500, piperidine), 18.79 (2C, 2CH3), 22.02 (2C, 2CH3).
Anal. Calcd for C32H40N8O: C, 69.54; H, 7.29; N, 20.27;
Found: C, 69.40; H, 7.43; N, 20.20.
Npip), 168.79 (1C, C-15, C=O), 163.97 (1C, C-4, Ctri–Cph),
154.19 (1C, C-10, C–NH), 143.99–116.22 (11C, Ar–C),
57.55 (1C, OCH3), 51.34, 48.08 (4C, C-20, 200, 60, 600,
piperidine), 46.99 (1C, C-14, NHCH2CO), 38.22, 36.39
(2C, C-40, 400, piperidine), 33.01, 27.21 (4C, C-30, 300, 50, 500,
piperidine), 18.77 (2C, 2CH3), 23.22 (2C, 2CH3). Anal.
Calcd for C32H43N7O2: C, 68.91; H, 7.77; N, 17.58; Found:
C, 68.76; H, 7.83; N, 17.39.
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(4-ethoxyphenyl)acetamide (8j)
Light green solid, Yield: 80 %, mp 243–246 °C. IR (KBr,
cm-1): 3294, 3280 (–NHs), 835 (s triazine C–N str.), 1677
(C=O). 1H NMR (400 MHz, DMSO-d6): d 9.57 (s, 1H, H-16,
–NH), 7.91 (d, J = 7.5 Hz, 2H), 7.67–7.29 (m, 4H, Ar–H),
6.85 (d, J = 7.4 Hz, 2H), 4.84 (s, 1H, H-13, –NH), 4.11 (s,
2H, H-14, –NHCOCH2NH), 3.88 (q, J = 6.8 Hz, 2H, –O–
CH2–), 3.81 (dd, J = 12.2, 7.7 Hz, 4H, H-20, 60), 3.71 (dd,
J = 11.9, 7.3 Hz, 4H, H-200, 600), 1.81 (m, 4H, H-30, 300, 50,
500), 1.24 (t, 3H, CH3), 1.17 (d, J = 6.6 Hz, 6H, 2CH3), 0.96
(d, J = 5.9 Hz, 6H, 2CH3), 0.86–0.81 (m, 4H, H-40, 400). 13C
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(p-tolyl)acetamide (8h)
Light brown solid, Yield: 74 %, mp 287–288 °C. IR (KBr,
cm-1): 3315, 3299 (–NHs), 827 (s triazine C–N str.), 1676
123

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1
(C=O), 1652 (C=N, benzothiazole). H NMR (400 MHz,
NMR (100 MHz, DMSO-d6): d 168.87 (2C, C-2 and C-6,
Ctri–Npip), 169.01 (1C, C-15, C=O), 165.03 (1C, C-4, Ctri–
Cph), 153.89 (1C, C-10, C–NH), 145.67–117.42 (11C, Ar–
C), 66.90 (1C, OCH2CH3), 52.99, 48.69 (4C, C-20, 200, 60, 600,
piperidine), 47.48 (1C, C-14, NHCH2CO), 39.85, 37.01 (2C,
C-40, 400, piperidine), 31.88, 27.67 (4C, C-30, 300, 50, 500,
piperidine), 19.25 (2C, 2CH3), 22.82 (2C, 2CH3), 21.79 (1C,
OCH2CH3). Anal. Calcd for C33H45N7O2: C, 69.32; H, 7.93;
N, 17.15; Found: C, 69.19; H, 8.03; N, 17.26.
DMSO-d6): d 9.57 (s, 1H, H-16, –NH), 7.61–6.96 (m, 9 h,
Ar–H), 4.93 (s, 1H, H-13, –NH), 4.16 (s, 2H, H-14,
–NHCOCH2NH), 3.89 (dd, J = 12.2, 7.7 Hz, 4H, H-20, 60),
3.58 (dd, J = 11.9, 7.3 Hz, 4H, H-200, 600), 1.62 (m, 4H,
H-30, 300, 50, 500), 1.24 (d, J = 6.6 Hz, 6H, 2CH3), 0.91 (d,
J = 5.9 Hz, 6H, 2CH3), 0.90–0.83 (m, 4H, H-40, 400). 13C
NMR (100 MHz, DMSO-d6): d 170.29 (2C, C-2 and C-6,
Ctri–Npip), 169.11 (1C, C-15, C=O), 164.83 (1C, C-4, Ctri–
Cph), 157.98 (1C, C-2, benzothiazole), 153.64 (1C, C-10,
C–NH), 145.32–117.13 (11C, Ar–C), 52.33, 49.47 (4C,
C-20, 200, 60, 600, piperidine), 47.32 (1C, C-14, NHCH2CO),
39.63, 36.87 (2C, C-40, 400, piperidine), 31.92, 27.33 (4C,
C-30, 300, 50, 500, piperidine), 19.27 (2C, 2CH3), 23.78 (2C,
2CH3). Anal. Calcd for C32H40N8OS: C, 65.72; H, 6.89; N,
19.16; Found: C, 65.60; H, 7.03; N, 19.27.
N-(4-Acetamidophenyl)-2-((4-(4,6-bis(3,5-
dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)acetamide (8k)
Light pink solid, Yield: 77 %, mp 294–295 °C. IR (KBr,
cm-1): 3317, 3299 (–NHs), 829 (s triazine C–N str.), 1681
(C=O). 1H NMR (400 MHz, DMSO-d6): d 9.55 (s, 1H, H-16,
–NH), 8.52 (s, 1H, –NH), 7.77 (d, J = 7.6 Hz, 2H),
7.67–7.04 (m, 9H, Ar–H), 4.99 (s, 1H, H-13, –NH), 4.21 (s,
2H, H-14, –NHCOCH2NH), 3.87 (dd, J = 12.2, 7.7 Hz, 4H,
H-20, 60), 3.68 (dd, J = 11.9, 7.3 Hz, 4H, H-200, 600), 1.91 (s,
3H, –CH3), 1.87 (m, 4H, H-30, H-300, 50, 500), 1.19 (d,
J = 6.6 Hz, 6H, 2CH3), 0.92 (d, J = 5.9 Hz, 6H, 2CH3),
0.91–0.84 (m, 4H, H-40, 400). 13C NMR (100 MHz, DMSO-
d6): d 170.39 (2C, C-2 and C-6, Ctri–Npip), 168.93, 167.10
(2C, C=O), 164.22 (1C, C-4, Ctri–Cph), 153.79 (1C, C-10,
C–NH), 147.25–116.89 (11C, Ar–C), 53.52, 47.32 (4C, C-20,
200, 60, 600, piperidine), 46.14 (1C, C-14, NHCH2CO), 38.51,
35.62 (2C, C-40, 400, piperidine), 32.45, 28.62 (4C, C-30, 300,
50, 500, piperidine), 19.82 (2C, 2CH3), 23.55 (2C, 2CH3),
19.56 (1C, CH3). Anal. Calcd for C33H44N8O2: C, 67.78; H,
7.58; N, 19.16; Found: C, 67.62; H, 7.71; N, 19.04.
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(6-chlorobenzo[d]thiazol-2-
yl)acetamide (9b)
Light green solid, Yield: 73 %, mp 271–272 °C. IR (KBr,
cm-1): 3315, 3291 (–NHs), 825 (s triazine C–N str.), 1671
1
(C=O). 1665 (C=N, benzothiazole). H NMR (400 MHz,
DMSO-d6): d 9.64 (s, 1H, H-16, –NH), 7.76 (d,
J = 1.8 Hz, 1H), 7.63 (d, J = 7.5 Hz, 1H), 7.53 (dd,
J = 7.6, 1.4 Hz, 1H), 7.45–7.25 (m, 4H, Ar–H), 4.92 (s,
1H, H-13, –NH), 4.28 (s, 2H, H-14, –NHCOCH2NH), 3.74
(dd, J = 12.2, 7.7 Hz, 4H, H-20, 60), 3.69 (dd, J = 11.9,
7.3 Hz, 4H, H-200, 600), 1.87 (m, 4H, H-30, 300, 50, 500), 1.22
(d, J = 6.6 Hz, 6H, 2CH3), 0.98 (d, J = 5.9 Hz, 6H,
2CH3), 0.91–0.85 (m, 4H, H-40, 400). 13C NMR (100 MHz,
DMSO-d6): d 168.74 (2C, C-2 and C-6, Ctri–Npip), 169.39
(1C, C-15, C=O), 163.94 (1C, C-4, Ctri–Cph), 159.02 (1C,
C-2, benzothiazole), 154.09 (1C, C-10, C–NH),
144.55–120.11 (11C, Ar–C), 53.01, 49.01 (4C, C-20, 200, 60,
600, piperidine), 46.19 (1C, C-14, NHCH2CO), 38.32, 37.08
(2C, C-40, 400, piperidine), 33.07, 28.47 (4C, C-30, 300, 50, 500,
piperidine), 18.92 (2C, 2CH3), 22.32 (2C, 2CH3). Anal.
Calcd for C32H39ClN8OS: C, 62.07; H, 6.35; N, 18.10;
Found: C, 62.18; H, 6.21; N, 18.26.
Synthesis of N-benzothiazolyl acetamide-substituted
final compounds (9a–k)
Mixture of 4-(4,6-bis(3,5-dimethylpiperidin-1-yl)-1,3,5-tria-
zin-2-yl)aniline 7 (0.05 mol), different 2-chloro-N-(6-sub-
stituted-benzothiazol-2-yl)-acetamide 3a–k (0.05 mol) and
K2CO3 (0.052 mol) was refluxed for 6–12 h in acetone
(50 mL). After the completion of reaction, the reaction mass
waspouredincrushed ice(200 g), andtheresulting precipitates
were filtered, washed with water, dried, and crystallized with
suitable solvent to obtained 9a–k (Akhtar et al., 2008). The
progress of the reaction was monitored by Thin Layer Chro-
matography using n-hexane:ethyl acetate (8:2) solvent system.
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(6-bromobenzo[d]thiazol-2-
yl)acetamide (9c)
Light yellow solid, Yield: 78 %, mp 264–265 °C. IR (KBr,
N-(Benzo[d]thiazol-2-yl)-2-((4-(4,6-bis(3,5-
dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)acetamide (9a)
cm-1): 3299, 3280 (–NHs), 833 (s triazine C–N str.), 1667
1
(C=O), 1661 (C=N, benzothiazole). H NMR (400 MHz,
DMSO-d6): d 9.45 (s, 1H, H-16, –NH), 7.79 (d,
J = 1.8 Hz, 1H), 7.59–7.18 (m, 6H, Ar–H), 5.01 (s, 1H,
H-13, –NH), 4.10 (s, 2H, H-14, –NHCOCH2NH), 3.86 (dd,
J = 12.2, 7.7 Hz, 4H, H-20, 60), 3.57 (dd, J = 11.9, 7.3 Hz,
Light pink solid, Yield: 81 %, mp 261–263 °C. IR (KBr,
cm-1): 3321, 3302 (–NHs), 828 (s triazine C–N str.), 1684
123

Med Chem Res (2013) 22:367–381
379
4H, H-200, 600), 1.61 (m, 4H, H-30, 300, 50, 500), 1.28 (d,
J = 6.6 Hz, 6H, 2CH3), 0.95 (d, J = 5.9 Hz, 6H, 2CH3),
0.89–0.82 (m, 4H, H-40, 400). 13C NMR (100 MHz, DMSO-
d6): d 168.88 (2C, C-2 and C-6, Ctri–Npip), 169.07 (1C,
C-15, C=O), 165.01 (1C, C-4, Ctri-Cph), 157.24 (1C, C-2,
benzothiazole), 153.22 (1C, C-10, C–NH), 145.71–119.87
(11C, Ar–C), 54.71, 48.92 (4C, C-20, 200, 60, 600, piperidine),
45.98 (1C, C-14, NHCH2CO), 39.39, 35.47 (2C, C-40, 400,
piperidine), 32.61, 28.92 (4C, C-30, 300, 50, 500, piperidine),
19.23 (2C, 2CH3), 22.57 (2C, 2CH3). Anal. Calcd for
C32H39BrN8OS: C, 57.91; H, 5.92; N, 16.88; Found: C,
57.80; H, 5.78; N, 17.05.
C-6, Ctri–Npip), 168.84 (1C, C-15, C=O), 164.97 (1C, C-4,
Ctri–Cph), 155.87 (1C, C-2, benzothiazole), 154.15 (1C,
C-10, C–NH), 146.73–117.67 (11C, Ar–C), 51.32, 48.11
(4C, C-20, 200, 60, 600, piperidine), 46.33 (1C, C-14,
NHCH2CO), 40.15, 37.11 (2C, C-40, 400, piperidine), 32.25,
28.42 (4C, C-30, 300, 50, 500, piperidine), 18.97 (2C, 2CH3),
22.35 (2C, 2CH3). Anal. Calcd for C32H39IN8OS: C, 54.08;
H, 5.53; N, 15.77; Found: C, 54.19; H, 5.39; N, 15.83.
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(6-nitrobenzo[d]thiazol-2-
yl)acetamide (9f)
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(6-fluorobenzo[d]thiazol-2-
yl)acetamide (9d)
Light yellow solid, Yield: 69 %, mp 279–280 °C. IR (KBr,
cm-1): 3299, 3282 (–NHs), 829 (s triazine C–N str.), 1679
1
(C=O), 1657 (C=N, benzothiazole). H NMR (400 MHz,
DMSO-d6): d 9.53 (s, 1H, H-16, –NH), 7.89 (d, J = 1.8 Hz,
1H), 7.77 (dd, J = 7.3, 2.2 Hz, 1H), 7.64 (d, J = 7.6 Hz,
1H), 7.46 (dd, J = 7.4, 1.7 Hz, 2H), 7.39–7.26 (m, 2H, Ar–
H), 4.97 (s, 1H, H-13, –NH), 4.09 (s, 2H, H-14,
–NHCOCH2NH), 3.91 (dd, J = 12.2, 7.7 Hz, 4H, H-20,
H-60), 3.52 (dd, J = 11.9, 7.3 Hz, 4H, H-200, 600), 1.63 (m,
4H, H-30, 300, 50, 500), 1.27 (d, J = 6.6 Hz, 6H, 2CH3), 0.92 (d,
J = 5.9 Hz, 6H, 2CH3), 0.91–0.86 (m, 4H, H-40, 400). 13C
NMR (100 MHz, DMSO-d6): d 171.03 (2C, C-2 and C-6,
Ctri–Npip), 169.33 (1C, C-15, C=O), 164.42 (1C, C-4, Ctri–
Cph), 155.48 (1C, C-2, benzothiazole), 151.03 (1C, C-10, C–
NH), 144.87–116.62 (11C, Ar–C), 52.67, 48.32 (4C, C-20,
200, 60, 600, piperidine), 46.67 (1C, C-14, NHCH2CO), 39.42,
36.49 (2C, C-40, 400, piperidine), 33.27, 27.37 (4C, C-30, 300,
50, 500, piperidine), 19.49 (2C, 2CH3), 22.07 (2C, 2CH3).
Anal. Calcd for C32H39N9O3S: C, 61.03; H, 6.24; N, 20.02;
Found: C, 61.19; H, 6.13; N, 19.86.
Light yellow solid, Yield: 72 %, mp 271–273 °C. IR (KBr,
cm-1): 3312, 3292 (–NHs), 842 (s triazine C–N str.), 1680
1
(C=O), 1659 (C=N, benzothiazole). H NMR (400 MHz,
DMSO-d6): d 9.51 (s, 1H, H-16, –NH), 7.84 (dd, J = 8.0,
1.7 Hz, 1H), 7.70 (dd, J = 1.9, 8.4 Hz, 1H), 7.58 (dd,
J = 5.3, 8.4 Hz, 1H), 7.49–7.26 (m, 4H, Ar–H), 4.94 (s,
1H, H-13, –NH), 4.27 (s, 2H, H-14, –NHCOCH2NH), 3.81
(dd, J = 12.2, 7.7 Hz, 4H, H-20, 60), 3.68 (dd, J = 11.9,
7.3 Hz, 4H, H-200, 600), 1.87 (m, 4H, H-30, 300, 50, 500), 1.19
(d, J = 6.6 Hz, 6H, 2CH3), 0.97 (d, J = 5.9 Hz, 6H,
2CH3), 0.87–0.82 (m, 4H, H-40, 400). 13C NMR (100 MHz,
DMSO-d6): d 171.42 (2C, C-2 and C-6, Ctri–Npip), 168.97
(1C, C-15, C=O), 164.63 (1C, C-4, Ctri–Cph), 156.56 (1C,
C-2, benzothiazole), 153.87 (1C, C-10, C–NH),
147.27–116.33 (11C, Ar–C), 52.07, 47.99 (4C, C-20, 200, 60,
600, piperidine), 46.67 (1C, C-14, NHCH2CO), 38.73, 36.33
(2C, C-40, 400, piperidine), 31.82, 27.19 (4C, C-30, 300, 50, 500,
piperidine), 19.86 (2C, 2CH3), 21.99 (2C, 2CH3). Anal.
Calcd for C32H39FN8OS: C, 63.76; H, 6.52; N, 18.59;
Found: C, 63.64; H, 6.68; N, 18.48.
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(6-cyanobenzo[d]thiazol-2-
yl)acetamide (9g)
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(6-iodobenzo[d]thiazol-2-
yl)acetamide (9e)
Light yellow solid, Yield: 71 %, mp 277–278 °C. IR (KBr,
cm-1): 3313, 3295 (–NHs), 833 (s triazine C–N str.), 1676
1
(C=O), 1653 (C=N, benzothiazole). H NMR (400 MHz,
DMSO-d6): d 9.38 (s, 1H, H-16, –NH), 7.87 (d,
J = 1.5 Hz, 1H), 7.69 (d, J = 7.6 Hz, 1H), 7.50 (dd,
J = 8.8, 1.5 Hz, 1H), 7.43–7.18 (m, 4H, Ar–H), 5.03 (s,
1H, H-13, –NH), 4.29 (s, 2H, H-14, –NHCOCH2NH), 3.75
(dd, J = 12.2, 7.7 Hz, 4H, H-20, 60), 3.57 (dd, J = 11.9,
7.3 Hz, 4H, H-200, 600), 1.69 (m, 4H, H-30, 300, 50, 500), 1.25
(d, J = 6.6 Hz, 6H, 2CH3), 0.94 (d, J = 5.9 Hz, 6H,
2CH3), 0.86–0.82 (m, 4H, H-40, H-400). 13C NMR
(100 MHz, DMSO-d6): d 170.19 (2C, C-2 and C-6, Ctri–
Light yellow solid, Yield: 79 %, mp 266–267 °C. IR (KBr,
cm-1): 3307, 3289 (–NHs), 839 (s triazine C–N str.), 1685
1
(C=O), 1655 (C=N, benzothiazole). H NMR (400 MHz,
DMSO-d6): d 9.61 (s, 1H, H-16, –NH), 7.73 (d, J = 2.4 Hz,
1H), 7.61 (d, J = 7.5 Hz, 1H), 7.54 (dd, J = 8.7, 1.3 Hz,
1H), 7.46–7.22 (m, 4H, Ar–H), 4.88 (s, 1H, H-13, –NH), 4.22
(s, 2H, H-14, –NHCOCH2NH), 3.77 (dd, J = 12.2, 7.7 Hz,
4H, H-20, 60), 3.71 (dd, J = 11.9, 7.3 Hz, 4H, H-200, 600), 1.63
(m, 4H, H-30, 300, 50, 500), 1.23 (d, J = 6.6 Hz, 6H, 2CH3),
0.94 (d, J = 5.9 Hz, 6H, 2CH3), 0.92–0.86 (m, 4H, H-40, 400).
13C NMR (100 MHz, DMSO-d6): d 170.53 (2C, C-2 and
Npip), 169.09 (1C, C-15, C=O), 163.89 (1C, C-4, Ctri–Cph),
158.19 (1C, C-2, benzothiazole), 151.47 (1C, C-10, C–
NH), 145.27–115.73 (10C, Ar–C), 104.93 (1C, C:N),
123

380
Med Chem Res (2013) 22:367–381
98.51 (1C, –C–C:N), 51.74, 49.25 (4C, C-20, 200, 60, 600,
piperidine), 47.17 (1C, C-14, NHCH2CO), 40.62, 35.89
(2C, C-40, 400, piperidine), 32.17, 28.98 (4C, C-30, 300, 50, 500,
piperidine), 20.02 (2C, 2CH3), 23.52 (2C, 2CH3). Anal.
Calcd for C33H39N9OS: C, 65.00; H, 6.45; N, 20.67;
Found: C, 64.87; H, 6.58; N, 20.52.
piperidine), 18.99 (2C, 2CH3), 21.17 (2C, 2CH3). Anal.
Calcd for C33H42N8O2S: C, 64.47; H, 6.89; N, 18.23;
Found: C, 64.58; H, 6.93; N, 18.06.
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(6-ethoxybenzo[d]thiazol-2-
yl)acetamide (9j)
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(6-methylbenzo[d]thiazol-2-
yl)acetamide (9h)
Light yellow solid, Yield: 80 %, mp 282–283 °C. IR (KBr,
cm-1): 3321, 3305 (–NHs), 841 (s triazine C–N str.), 1675
1
(C=O), 1660 (C=N, benzothiazole). H NMR (400 MHz,
Light yellow solid, Yield: 75 %, mp 272–273 °C. IR (KBr,
DMSO-d6): d 9.61 (s, 1H, H-16, –NH), 7.73–7.61 (m, 2H),
7.51 (dd, J = 8.6, 1.7 Hz, 1H), 7.44–7.29 (m, 4H,
Ar–H), 5.03 (s, 1H, H-13, –NH), 4.25 (s, 2H, H-14,
–NHCOCH2NH), 4.10 (q, J = 6.9 Hz, 2H, OCH2CH3),
3.80 (dd, J = 12.2, 7.7 Hz, 4H, H-20, 60), 3.52 (dd,
J = 11.9, 7.3 Hz, 4H, H-200, 600), 2.29 (t, J = 6.5 Hz, 3H,
CH2CH3), 1.61 (m, 4H, H-30, 300, 50, 500), 1.28 (d,
J = 6.6 Hz, 6H, 2CH3), 0.95 (d, J = 5.9 Hz, 6H, 2CH3),
0.90–0.86 (m, 4H, H-40, 400). 13C NMR (100 MHz, DMSO-
d6): d 168.69 (2C, C-2 and C-6, Ctri–Npip), 168.77 (1C,
C-15, C=O), 163.94 (1C, C-4, Ctri–Cph), 156.10 (1C, C-2,
benzothiazole), 153.59 (1C, C-10, C–NH), 144.87–119.25
(11C, Ar–C), 65.29 (1C, OCH2CH3), 53.78, 48.62 (4C,
C-20, 200, 60, 600, piperidine), 46.57 (1C, C-14, NHCH2CO),
40.45, 36.82 (2C, C-40, 400, piperidine), 32.56, 28.62 (4C,
C-30, 300, 50, 500, piperidine), 20.09 (2C, 2CH3), 23.42 (2C,
2CH3), 21.33 (1C, OCH2CH3). Anal. Calcd for
C34H44N8O2S: C, 64.94; H, 7.05; N, 17.82; Found: C,
64.83; H, 6.94; N, 17.89.
cm-1): 3300, 3281 (–NHs), 825 (s triazine C–N str.), 1671
1
(C=O), 1659 (C=N, benzothiazole). H NMR (400 MHz,
DMSO-d6): d 9.28 (s, 1H, H-16, –NH), 7.71 (d,
J = 7.4 Hz, 1H), 7.64–7.29 (m, 6H, Ar–H), 4.88 (s, 1H,
H-13, –NH), 4.26 (s, 2H, H-14, –NHCOCH2NH), 3.79 (dd,
J = 12.2, 7.7 Hz, 4H, H-20, 60), 3.63 (dd, J = 11.9, 7.3 Hz,
4H, H-200, 600), 1.66 (m, 4H, H-30, 300, 50, 500), 1.41 (s, 3H,
CH3), 1.20 (d, J = 6.6 Hz, 6H, 2CH3), 0.97 (d,
J = 5.9 Hz, 6H, 2CH3), 0.87–0.84 (m, 4H, H-40, H-400).
13C NMR (100 MHz, DMSO-d6): d 171.89 (2C, C-2 and
C-6, Ctri–Npip), 168.86 (1C, C-15, C=O), 164.68 (1C, C-4,
Ctri–Cph), 157.04 (1C, C-2, benzothiazole), 152.53 (1C,
C-10, C–NH), 145.43–115.42 (11C, Ar–C), 53.41, 48.87
(4C, C-20, 200, 60, 600, piperidine), 45.99 (1C, C-14,
NHCH2CO), 38.98, 35.52 (2C, C-40, 400, piperidine), 31.95,
27.61 (4C, C-30, 300, 50, 500, piperidine), 19.88 (2C, 2CH3),
22.62 (2C, 2CH3), 19.83 (1C, CH3). Anal. Calcd for
C33H42N8OS: C, 66.19; H, 7.07; N, 18.71; Found: C,
66.32; H, 7.23; N, 18.61.
N-(6-Acetamidobenzo[d]thiazol-2-yl)-2-((4-(4,6-bis(3,5-
dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)acetamide (9k)
2-((4-(4,6-Bis(3,5-dimethylpiperidin-1-yl)-1,3,5-triazin-2-
yl)phenyl)amino)-N-(6-methoxybenzo[d]thiazol-2-
yl)acetamide (9i)
Light yellow solid, Yield: 72 %, mp 289–291 °C. IR (KBr,
Light yellow solid, Yield: 70 %, mp 265–267 °C. IR (KBr,
cm-1): 3295, 3280 (–NHs), 830 (s triazine C–N str.), 1682
1
cm-1): 3327, 3301 (–NHs), 834 (s triazine C–N str.), 1669
(C=O), 1654 (C=N, benzothiazole). H NMR (400 MHz,
1
(C=O), 1663 (C=N, benzothiazole). H NMR (400 MHz,
DMSO-d6): d 9.60 (s, 1H, H-16, –NH), 8.59 (s, 1H, –NH),
7.81 (d, J = 1.8 Hz, 2H), 7.72 (dd, J = 7.6, 2.0 Hz, 2H),
7.49 (dd, J = 8.4, 1.5 Hz, 1H), 7.41–7.26 (m, 2H, Ar–H),
4.88 (s, 1H, H-13, –NH), 4.17 (s, 2H, H-14,
–NHCOCH2NH), 3.94 (dd, J = 12.2, 7.7 Hz, 4H, H-20, 60),
3.65 (dd, J = 11.9, 7.3 Hz, 4H, H-200, 600), 2.20 (s, 3H,
CH3), 1.82 (m, 4H, H-30, 300, 50, 500), 1.20 (d, J = 6.6 Hz,
6H, 2CH3), 0.97 (d, J = 5.9 Hz, 6H, 2CH3), 0.89–0.83 (m,
4H, H-40, 400). 13C NMR (100 MHz, DMSO-d6): d 168.91
(2C, C-2 and C-6, Ctri–Npip), 169.06, 167.89 (2C, C=O),
164.78 (1C, C-4, Ctri–Cph), 159.23 (1C, C-2, benzothia-
zole), 154.07 (1C, C-10, C–NH), 146.01–116.42 (11C, Ar–
C), 54.06, 49.09 (4C, C-20, 200, 60, 600, piperidine), 46.89
(1C, C-14, NHCH2CO), 39.87, 35.55 (2C, C-40, 400,
piperidine), 33.11, 27.75 (4C, C-30, 300, 50, 500, piperidine),
DMSO-d6): d 9.22 (s, 1H, H-16, –NH), 7.86–7.77 (m, 2H),
7.57 (dd, J = 8.6, 1.5 Hz, 1H), 7.49–7.26 (m, 4H,
Ar–H), 4.99 (s, 1H, H-13, –NH), 4.09 (s, 2H, H-14,
–NHCOCH2NH), 3.91 (dd, J = 12.2, 7.7 Hz, 4H, H-20, 60),
3.79 (s, 3H, OCH3), 3.70 (dd, J = 11.9, 7.3 Hz, 4H, H-200,
600), 1.88 (m, 4H, H-30, 300, 50, 500), 1.21 (d, J = 6.6 Hz, 6H,
2CH3), 0.99 (d, J = 5.9 Hz, 6H, 2CH3), 0.91–0.84 (m, 4H,
H-40, 400). 13C NMR (100 MHz, DMSO-d6): d 170.23 (2C,
C-2 and C-6, Ctri–Npip), 169.29 (1C, C-15, C=O), 165.03
(1C, C-4, Ctri–Cph), 154.90 (1C, C-2, benzothiazole),
151.87 (1C, C-10, C–NH), 147.09–120.07 (11C, Ar–C),
56.98 (1C, OCH3), 52.59, 49.66 (4C, C-20, 200, 60, 600,
piperidine), 47.41 (1C, C-14, NHCH2CO), 39.67, 36.18
(2C, C-40, 400, piperidine), 32.47, 28.15 (4C, C-30, 300, 50, 500,
123

Med Chem Res (2013) 22:367–381
381
Patel RV, Kumari P, Rajani DP, Chikhalia KH (2011a) Synthesis and
studies of novel 2-(4-cyano-3-trifluoromethylphenyl amino)-4-
(quinoline-4-yloxy)-6 (piperazinyl/piperidinyl)-s-triazines as
potential antimicrobial, antimycobacterial and anticancer agents.
Eur J Med Chem 46(9):4354–4365
19.97 (2C, 2CH3), 23.69 (2C, 2CH3), 20.11 (1C, CH3).
Anal. Calcd for C34H43N9O2S: C, 63.62; H, 6.75; N, 19.64;
Found: C, 63.52; H, 6.84; N, 19.53.
Acknowledgments The authors are thankful to the Applied Chem-
istry Department of S. V. National Institute of Technology, Surat for
the scholarship, encouragement and facilities. The authors wish to
offer their deep gratitude to the Microcare Laboratory, Surat, India for
carrying out the biological screenings. The authors are also thankful
Patel RV, Kumari P, Rajani DP, Chikhalia KH (2011b) Synthesis,
characterization and pharmacological activities of 2-[4-cyano-(3-
trifluoromethyl)phenyl amino)]-4-(4-quinoline/coumarin-4-yloxy)-
6-(fluoropiperazinyl)-s-triazines. J Fluorine Chem 132(9):617–627
Patel RV, Kumari P, Rajani DP, Chikhalia KH (2011c) Discovery of
2-(4-cyano-3-trifluoromethylphenyl amino)-4-(4-quinazolinyl-
oxy)-6-piperazinyl(piperidinyl)-s-triazines as potential antibac-
terial agents. Med Chem Res. doi:10.1007/s00044-011-9950-4O
Patel RV, Kumari P, Rajani DP, Chikhalia KH (2011d) A new class of
2-(4-cyanophenyl amino)-4-(6-bromo-4-quinolinyloxy)-6-piper-
azinyl (piperidinyl)-1,3,5-triazine analogues with antimicrobial/
antimycobacterial activity. J Enzym Inhib Med Chem. doi:
10.3109/14756366.2011.592491
PrimasN, BouillonA, LancelotJC, KashefHE, RaultS (2009)Synthesis
of 5-arylthiazoles. Comparative study between Suzuki cross-
coupling reaction and direct arylation. Tetrahedron 65(29–30):
5739–5746
Rana A, Siddiqui N, Khan SA, Haque SE, Bhat MA (2008) N-{[(6-
Substituted-1,3-benzothiazole-2-yl)amino]carbonothioyl}-2/4-
substituted benzamides: synthesis and pharmacological
evaluation. Eur J Med Chem 43(5):1114–1122
1
to the Centre for Excellence, Vapi, India for carrying out FT-IR, H
NMR, and 13C NMR analyses.
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