Sulfamic acid-catalyzed multicomponent one-pot synthesis of poly-substituted pyridines and their antimicrobial activity

Article abstract of DOI:10.1002/jhet.1564

A novel series of poly-substituted pyridines (7-(substituted aryl)-3,11-dimethoxy-5,6,8,9-tetrahydro-dibenzo[c,h]acridines) were synthesized via one-pot multicomponent approach using sulfamic acid as a catalyst and evaluated for their antimicrobial activity. The results indicate that the poly-substituted series (4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, 4i) showed weak to moderate antibacterial activity. However, compound (4c) had shown good antifungal activity against Candida rugosa with standard antifungal drug Amphotericin-B. Analogue (4c) was considered to be a lead compound for subsequent standard optimization.

Full text of DOI:10.1002/jhet.1564

Month 2013
Sulfamic Acid-Catalyzed Multicomponent One-Pot Synthesis of
Poly-Substituted Pyridines and Their Antimicrobial Activity
*
B. Janardhan, S. Vijayalaxmi, and B. Rajitha
Department of Chemistry, National Institute of Technology, Warangal 506004, India
*
E-mail: rajitabhargavi@yahoo.com
Received June 25, 2011
DOI 10.1002/jhet.1564
Published online 00 Month 2013 in Wiley Online Library (wileyonlinelibrary.com).
R
CHO
MeO
2
NH2SO3H
NH4OAc
H2O, 90-100oC, 1-2hrs
N
4(a-i)
R
O
1
3
2
MeO
OMe
A novel series of poly-substituted pyridines (7-(substituted aryl)-3,11-dimethoxy-5,6,8,9-tetrahydro-
dibenzo[c,h]acridines) were synthesized via one-pot multicomponent approach using sulfamic acid as a cat-
alyst and evaluated for their antimicrobial activity. The results indicate that the poly-substituted series (4a–i)
showed weak to moderate antibacterial activity. However, compound (4c) had shown good antifungal activ-
ity against Candida rugosa with standard antifungal drug Amphotericin-B. Analogue (4c) was considered to
be a lead compound for subsequent standard optimization.
J. Heterocyclic Chem., 00, 00 (2013).
INTRODUCTION
substituted pyridines in aqueous medium and screened for
antimicrobial activity (Tables 3 and 4). Among the series,
compounds (4e) and (4c) have shown good antibacterial
and antifungal activities against Klebsiella pneumoniae and
Candida rugosa, respectively.
Over a period, pyridine and its synthetic analogues are
widely spread as subunit in drugs, pharmaceuticals, and
natural products such as Indinavir (anti-HIV), Nexium,
Ogastro (anti-ulcer), Norvasc (hypertension), Omeprazole
(proton pump inhibitor) [1], and pyridine alkaloids [2].
These are also known to posses antimalarial, vasodilator,
anticonvulsant, antiepileptic, anthelmintic, antibacterial,
antifungal [3], antitumor [4], antiparasitic, antioxidant,
topoisomerase I and II inhibitors [5], calcium antagonist
activators [6,7], and agro chemicals such as fungicidal,
pesticidal, and herbicidal [8] activities. Poly-substituted
pyridines can be synthesized by Krohnke [9–16] and
Hantzsch [17] methods, and recently several new methods
have been developed containing solvent-free reactions
[10,11,18], microwave irradiation [7,20], acetic acid [21],
and L-proline [22] catalyzed reactions. Most of these
methods suffer from one or several drawbacks such as
low yield, long reaction time, tedious workup, use of toxic
solvents, and expensive reagents. Moreover from the past
few decades, multicomponent reactions have emerged as
a powerful tool in the synthesis of complex and important
biologically active molecules [17,19,23] from easily avail-
able starting materials. Therefore to overcome the afore-
mentioned problems and fulfill the criteria, we
investigated and successfully implemented the sulfamic
acid (SA) as the best and cheaper catalyst (which is a com-
mon sulfur-containing amino acid with mild acidity and
carries out many organic transformation under mild and
user-friendly conditions) for the preparation of poly-
RESULTS AND DISCUSSION
In continuation of our studies on the synthesis of biolog-
ically active heterocyclic compounds using SA as catalyst
[24], herein we report a simple and efficient procedure
for the synthesis of highly substituted pyridines by the
condensation of 6-methoxy-1-tetralone with different
aromatic aldehydes and ammonium acetate in aqueous
medium in presence of SA as catalyst furnished the target
compounds in excellent yields (Scheme 1). To know the
optimistic conditions (temperature, amount of SA) and ef-
fect of solvent on the reaction yield, a modal reaction
was performed with 6-methoxy-1-tetralone, benzaldehyde,
and ammonium acetate in different solvents (MeOH,
CH3CN, DMF, and H2O) at different temperatures, without
and with variant amount (5, 10, 15, 20 mol%) of SA, and
observations are as follows: at room temperature in ab-
sence of catalyst, no progress was observed; after adding
5 mol% of catalyst, only trace amount of compound was
formed; as the temperature increased to 90–100ꢀC, the
yield has drastically increased from 58 to 93% depending
on solvent and amount of SA; and as further increment of
temperature and amount of SA, there is no appreciable
change in the yields (Table 1). From these results, we de-
duce that 15 mol% SA in aqueous medium at 90–100ꢀC
© 2013 HeteroCorporation

B. Janardhan, S. Vijayalaxmi, and B. Rajitha
Vol 000
Scheme 1.
R
CHO
MeO
2
NH2SO3H
NH4OAc
H2O, 90-100oC, 1-2hrs
R
N
O
1
3
2
MeO
OMe
4(a-i)
Compound
R
4a
4b
4c
4d
4e
4f
4g
4h
4i
-C6H5
4-F-C6H4
4-Cl-C6H4
4-OCH3-C6H4
4-CH3-C6H4
4-OH-C6H4
3-NO2-C6H4
3-OCH3-4-OH-C6H3
2-OH-3-OCH3-C6H3
Plausible Mechanism:
H
H
HO
R
N
R
H
O
O
SA
-H3O+ MeO
OMe
..
R
H
H
R
H
NH2
NH
OMe
O
H
MeO
R
R
R
N
H
..
..
NH
2O
-H3O+
MeO
N
H
OH
MeO
OMe
H
H
MeO
OMe
OMe
-H+
R
N
MeO
OMe
R = Aryl
is the optimistic condition for obtaining the excellent yield.
In these optimistic conditions, we performed a reaction us-
ing different aromatic aldehydes and the results are postu-
lated in Table 2. The catalyst was recovered by
evaporating the water and washed with diethyl ether, dried,
and reused after activation with only a gradual decrease in
activity observed. For example, the reaction of 6-methoxy-1-
tetralone, benzaldehyde, and ammonium acetate gave the
corresponding highly substituted pyridine (4a) in 93%, 91%,
and 88% yields over three cycles.
1560–1620 cmÀ1(C═N stretching) and molecular ion peak
from mass spectrum confirm the formation of the substi-
tuted pyridine moiety.
A plausible mechanism for the synthesis of highly substi-
tuted pyridine catalyzed by SA has been proposed. The
aldehydic carbonyl oxygen becomes activated by the acid
part of SA through intermolecular H-bonding and subse-
quent condensation with 6-methoxy-1-tetralone followed
by dehydration and rearrangement afforded the final product.
Biological activities. All the newly synthesized compounds
were tested for in vitro antibacterial and antifungal activities
(Department of Biology, Indian Institute of Chemical
Technology, Hyderabad) against Bacillus subtilis,
Staphylococcus aureus, Staphylococcus epidermidis (Gram-
All the synthesized compounds were characterized by
IR, NMR, and mass spectral data. The disappearance of
IR band at 1650–1780 cmÀ1(C═O stretching) and peak at
~186 ppm (13C NMR) and the presence of IR band at
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2013
Synthesis of Poly-Substituted Pyridines and Their Antimicrobial Activity
Table 1
Multicomponent reaction of 6-methoxy-1-tetralone, benzaldehyde, and ammonium acetate in different solvents at different temperature and different mol
% of catalyst (SA).
Entry
Catalyst (mol%)
Solvent
Temperature (ꢀC)
Time (h)
Yield (%)a
1
2
3
4
5
6
7
8
—
—
—
—
5
5
5
5
5
CH3OH
CH3CN
DMF
RT
RT
RT
RT
RT
RT
RT
RT
90–100
90–100
90–100
90–100
90–100
90–100
90–100
90–100
90–100
90–100
90–100
90–100
110–120
90–100
24
24
24
24
24
24
24
24
6
6
6
6
4
4
4
4
2
2
2
2
2
—
—
—
H2O
—
CH3OH
CH3CN
DMF
Trace
Trace
Trace
Trace
58
56
60
65
66
61
72
79
84
80
88
93
93
H2O
9
CH3OH
CH3CN
DMF
10
11
12
13
14
15
16
17
18
19
20
21
22
5
5
5
H2O
10
10
10
10
15
15
15
15
15
20
CH3OH
CH3CN
DMF
H2O
CH3OH
CH3CN
DMF
H2O
H2O
H2O
2
93
aYields refer to isolated products.
Table 2
Synthesis of highly substituted pyridine at 90–100 ꢀC in aqueous medium using 15 mol% of catalyst (SA).
Analogue
Aldehyde
Time (min)
Yield (%)a
4a
4b
4c
4d
4e
4f
4g
4h
4i
Benzaldehyde
4-Fluorobenzaldehyde
4-Chlorobenzaldehyde
4-Methoxybenzaldehyde
4-Methylbenzaldehyde
4-Hydroxybenzaldehyde
3-Nitrobenzaldehyde
3-Methoxy-4-hydroxybenzaldehyde
2-hydroxy-3-methoxybenzaldehyde
110
90
65
80
85
120
95
75
93
91
96
90
91
90
94
96
92
80
aYields refer to isolated products. All the compounds were characterized by spectral data (IR, NMR, and mass).
positive), Escherichia coli, Pseudomonas aeruginosa, and
K. pneumoniae (Gram-negative) bacterial strains with
respect to penicillin and streptomycin as the positive
control drugs and Aspergillus flavus, Saccharomyces
cerevisiae, C. rugosa, and Candida albicans fungal strains
by taking Amphotericin-B as the positive control drug.
Antibacterial activity. The minimum inhibitory concentration
(MIC) values for analogues and the positive control drugs
penicillin and streptomycin were determined against the
six bacterial strains through the use of the liquid dilution
method [25,26]. Different concentrations of analogues
and positive control drugs were prepared in chloroform.
Inocula of the bacterial cultures were also prepared.
Inoculum (0.2 mL) and sterile water (3.8 mL) were added
to a series of test tubes each containing 1 mL of test
solution at different concentrations. The tubes were
incubated for 24 h at 37ꢀC and carefully observed for the
presence of turbidity. The minimum concentration at
which no growth was observed was taken as the MIC
value (Table 3).
Compound (4e) has shown good activity against K.
pneumoniae Gram-negative bacteria, and the remaining
compounds showed moderate activity.
Antifungal activity. Zone of inhibition (ZOI; in mm)
values for analogues and positive control drug
Amphotericin-B was determined against four different
fungal strains by agar diffusion method. All the compounds
were dissolved in chloroform. The fungal strains were
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

B. Janardhan, S. Vijayalaxmi, and B. Rajitha
Vol 000
Table 3
Minimum inhibitory concentration (MIC) values for 7-(substituted aryl)-3,11-dimethoxy-5,6,8,9-tetrahydro-dibenzo[c,h]acridines (4a–i) and positive
control drugs against different bacterial strains.
Minimum inhibitory concentration (mg/mL)
Gram-positive bacteria
Gram-negative bacteria
Analogue
B. subtilis
S. aureus
S. epidermidis
E. coli
P. aeruginosa
K. pneumoniae
4a
4b
4c
4d
4e
4f
4g
4h
150
150
150
150
150
150
150
150
150
1.562
6.25
150
150
150
150
150
150
150
150
150
1.562
6.25
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
12.5
6.25
150
150
150
150
150
150
150
150
150
12.5
1.562
37.5
75
75
37.5
18.75
75
75
37.5
37.5
6.25
3.125
4i
Penicillin
Streptomycin
3.125
3.125
Table 4
Zone of inhibition data for 7-(substituted aryl)-3,11-dimethoxy-5,6,8,9-tetrahydro-dibenzo[c,h]acridines (4a–i) against different fungal strains at 100 and
150 mg/mL concentrations.
Zone of inhibition (in mm)
Analogue
A. flavus
S. cerevisiae
C. rugosa
C. albicans
100 mg
150 mg
100 mg
150 mg
100 mg
150 mg
100 mg
150 mg
4a
4b
4c
4d
4e
4f
4g
4h
9
11
11
—
8
12
16
15
—
11
10
—
—
11
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
15
—
—
—
—
—
—
—
—
22
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
7
—
—
7
4i
AMP-B
25
25
22
23.5
AMP-B, Amphotericin-B.
grown and maintained on Sabouraud glucose agar plates.
The plates were incubated at 26ꢀC for 48 h, and resulting
ZOIs were measured. Antifungal screening for analogues
and positive control was performed at a concentration of
100 and 150 mg/mL, and the results are illustrated in Table 4.
Compound (4c) has shown high ZOI against C. rugosa
and, compounds (4b) and (4c) have shown moderate zone
of inhibition against A. flavus fungal strain.
the antibacterial activity against K. pneumoniae bacterial
strain whereas introduction of chlorine has shown marked
antifungal activity against C. rugosa fungal strain.
EXPERIMENTAL
The melting points were determined in open capillaries and are
uncorrected. The progress of the reaction was monitored by TLC
and visualized with UV light and iodine vapors. IR spectra were
recorded on Thermo Nicolet Nexus 670 spectrometer (Waltham,
MA) using KBr pellet, and values are expressed in cmÀ1. The
C, H, and N analysis of the compounds was performed on a Carlo
Erba model EA1108 (Lakewood, NJ), NMR spectra were
recorded on Bruker 300-MHz spectrometer (Billerica, MA)
using TMS as an internal standard, and chemical shifts are
expressed in ppm. Mass spectra were recorded on a Jeol
JMSD-300 spectrometer (Tokyo, Japan).
CONCLUSION
In conclusion, we have described an efficient, facile, and
flexible multicomponent synthesis of highly substituted
pyridine in aqueous medium using inexpensive SA as
catalyst with excellent yields. The antimicrobial screening
results reveal that electron-releasing methyl group enhanced
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2013
Synthesis of Poly-Substituted Pyridines and Their Antimicrobial Activity
General procedure for the synthesis of (4a–j). To a mixture
of 6-methoxy-1-tetralone (2 mmol), appropriate aromatic
aldehyde (1 mmol), and ammonium acetate (2 mmol) in 10 mL
of distilled water, SA (15 mol %) was added and heated at
90–100ꢀC for 1–2 h. After completion of the reaction indicated
by TLC, the solid obtained was filtered, washed with water, and
recrystallized from ethanol-furnished pure product with excellent
yields. The recovered catalyst was washed with diethyl ether,
dried, and reused for subsequent runs.
4-(3,11-Dimethoxy-5,6,8,9-tetrahydro-dibenzo[c,h]acridin-7-
yl)-phenol (4f). A white solid, mp 208–210ꢀC; IR (KBr) υmax
(cmÀ1): 3390, 2954, 2838, 1611, 1549, 1518, 1452,1133; 1H
NMR (300 MHz, CDCl3): d 2.90 (t, 4H), 3.04–3.09 (m, 4H),
3.88 (s, 6H), 6.72 (d, 1H), 6.88–6.92 (m, 2H), 7.39 (d,
4H), 7.79 (s, 1H), 8.13 (d, 2H), 9.15 (s, 1H); 13C NMR
(75 MHz, CDCl3): 160.1, 158.9, 149.7, 146.5, 139.5, 129.9,
130.5, 128.6, 127.2, 126.7, 115.8, 112.4, 111.1,. 56.0, 55.2,
28.6, 25.7; MS(ESI), 70 eV, m/z: 436 (M + H); Anal. Calcd. for
C29H25NO3: C, 79.98; H, 5.79; N, 3.22; Found: C, 79.94; H,
5.81; N, 3.21.
3,11-Dimethoxy-7-phenyl-5,6,8,9-tetrahydro-dibenzo[c,h]
acridine (4a). A white solid, mp 162–164ꢀC; IR (KBr) υmax
7-(3-Nitro-phenyl)-3,11-dimethoxy-5,6,8,9-tetrahydro-
dibenzo[c,h]acridine (4g). Pale yellow solid, mp 138–140ꢀC;
IR (KBr) υmax (cmÀ1): 2942, 2836, 1612, 1552, 1516, 1465,
1
(cmÀ1): 2940, 2835, 1610, 1548, 1510, 1465, 1074; H NMR
(300 MHz, CDCl3): 2.91 (t, 4H), 3.04–3.09 (m, 4H), 3.86 (s,
6H), 6.70 (d, 1H), 6.86–6.90 (m, 2H), 7.34–7.37 (m, 5H), 7.75
(s, 1H), 8.10 (d, 2H); 13C NMR (75 MHz, CDCl3): 160.0,
149.8, 146.5, 139.5, 137.8, 129.9, 128.9, 127.3, 127.2, 126.7,
112.4, 111.3,. 56.1, 55.2, 28.7, 25.8; MS(ESI), m/z: 420
(M + H); Anal. Calcd. for C29H25NO2: C, 83.03; H, 6.01; N,
3.34; Found: C, 83.01; H, 6.04; N, 3.32.
1
1057; H NMR (300 MHz, CDCl3): d 2.98 (t, 4H), 3.06–3.11
(m, 4H), 3.89 (s, 6H), 6.75 (d, 1H), 6.89–6.98 (m, 2H), 7.34–
7.39 (m, 4H), 7.78 (s, 1H), 8.15 (d, 2H); 13C NMR (75 MHz,
CDCl3): 160.0, 149.9, 148.6, 146.4, 139.6, 138.7, 133.3,
130.0, 129.9, 127.2, 126.7, 121.9, 121.2, 112.4, 111.2,. 56.1,
55.1, 28.7, 25.6; MS(ESI), 70 eV, m/z: 465 (M + H); Anal.
Calcd. for C29H24N2O4: C, 74.98; H, 5.21; N, 6.03; Found: C,
74.95; H, 5.23; N, 6.06.
7-(4-Fluoro-phenyl)-3,11-dimethoxy-5,6,8,9-tetrahydro-
dibenzo[c,h]acridine (4b). A white solid, mp 112–114ꢀC; IR
(KBr) υmax (cmÀ1): 2945, 2838, 1608, 1492, 1055, 1020; 1H
NMR (300 MHz, CDCl3): d 2.93 (t, 4H), 3.06–3.09 (m, 4H),
3.89 (s, 6H), 6.74 (d, 1H), 6.88–7.02 (m, 2H), 7.39 (d, 4H),
7.77 (s, 1H), 8.15 (d, 2H); 13C NMR (75 MHz, CDCl3): 162.2,
160.3, 149.9, 146.4, 139.6, 129.8, 128.7, 128.5, 127.2, 126.7,
115.4, 112.4, 111.2,. 56.0, 55.2, 28.6, 25.7; MS(ESI): 70 eV,
m/z: 438 (M + H); Anal. Calcd. for C29H24F NO2: C, 79.61; H,
5.53; N, 3.20; Found: C, 79.64; H, 5.51; N, 3.26.
4-(3,11-Dimethoxy-5,6,8,9-tetrahydro-dibenzo[c,h]acridin-7-
yl)-2-methoxy-phenol 4(h). White crystals, mp 202–204ꢀC; IR
(KBr) υmax (cmÀ1): 3384, 2940, 2837, 1607, 1548, 1508, 1459,
1
1157; H NMR (300 MHz, CDCl3): d 2.58–2.64 (m, 4H), 2.77
(t, 4H), 3.76 (s, 3H), 3.80 (s, 6H), 6.64–6.66 (m, 1H), 6.80–
6.96 (m, 6H), 8.31 (d, 2H), 9.17 (s, 1H); 13C NMR (75 MHz,
CDCl3): 160.0, 149.9, 147.1, 146.5, 144.9, 139.5, 129.9, 128.5,
127.2, 126.7, 121.6, 114.4, 112.5, 112.4, 111.1,. 56.0, 55.2,
28.6, 25.7; MS(ESI), 70 eV, m/z: 466 (M + H); Anal. Calcd. for
C30H27NO4: C, 77.40; H, 5.85; N, 3.01; Found: C, 77.38; H,
5.88; N, 3.04.
7-(4-Chloro-phenyl)-3,11-dimethoxy-5,6,8,9-tetrahydro-
dibenzo[c,h]acridine (4c). White crystals, mp 121–123ꢀC; IR
(KBr) υmax (cmÀ1): 2932, 2840, 1595, 1458, 1084, 835; 1H
NMR (300 MHz, CDCl3): d 2.92 (t, 4H), 3.05–3.09 (m, 4H),
3.87 (s, 6H), 6.71 (d, 1H), 6.87–6.90 (m, 2H), 7.37 (d, 4H), 7.76
(s, 1H), 8.12 (d, 2H); 13C NMR (75MHz, CDCl3): 160.2, 149.7,
146.6, 139.7, 135.7, 134.4, 129.8, 129.1, 128.5, 127.2, 126.7,
112.3, 111.3,. 56.5, 55.3, 28.8, 25.8; MS(ESI), 70 eV, m/z: 454
(M + H); Anal. Calcd. for C29H24Cl NO2: C, 76.73; H, 5.33; N,
3.09; Found: C, 76.75; H, 5.30; N, 3.11.
2-(3,11-Dimethoxy-5,6,8,9-tetrahydro-dibenzo[c,h]acridin-7-
yl)-6-methoxy-phenol (4i). A white solid, mp 254–256ꢀC; IR
(KBr) υmax (cmÀ1): 3385, 2945, 2836, 1618, 1549, 1512, 1463,
1
1153; H NMR (300 MHz, CDCl3): d 2.58–2.65 (m, 4H), 2.79
(t, 4H), 3.76 (s, 3H), 3.81 (s, 6H), 6.64–6.67 (m, 1H), 6.82–
6.98 (m, 6H), 8.35 (d, 2H), 9.15 (s, 1H); 13C NMR (75 MHz,
CDCl3): 160.3, 151.7, 149.8, 146.5, 142.1, 139.5, 129.8, 129.5,
127.3, 126.7, 122.9, 121.1, 116.0, 112.4, 111.1,. 56.1, 55.6,
55.2, 28.5, 25.6; MS(ESI), 70 eV, m/z: 466 (M + H); Anal.
Calcd. for C30H27NO4: C, 77.40; H, 5.85; N, 3.01; Found: C,
77.38; H, 5.88; N, 3.02.
7-(4-Methoxy-phenyl)-3,11-dimethoxy-5,6,8,9-tetrahydro-
dibenzo[c,h]acridine (4d). A white solid, mp 196–198ꢀC; IR
(KBr) υmax (cmÀ1): 2936, 2842, 1607, 1550, 1508, 1465,
1062; 1H NMR (300 MHz, CDCl3): d 2.90 (t, 4H), 3.05–3.08
(m, 4H), 3.75 (s, 3H), 3.82 (s, 6H), 6.70 (d, 1H), 6.82–6.90
(m, 2H), 7.36 (d, 4H), 7.74 (s, 1H), 8.11 (d, 2H); 13C NMR
(75 MHz, CDCl3): 161.0, 159.9, 149.8, 146.5, 139.6, 129.9,
129.7, 128.3, 127.2, 126.7, 114.6, 112.5, 111.2,. 56.2, 55.3,
28.8, 25.6; MS(ESI), 70 eV, m/z: 450 (M + H); Anal. Calcd. for
C30H27NO3: C, 80.15; H, 6.05; N, 3.12; Found: C, 80.12; H,
6.08; N, 3.15.
7-(4-Methyl-phenyl)-3,11-dimethoxy-5,6,8,9-tetrahydro-
dibenzo[c,h]acridine (4e). A white solid, mp 140–142ꢀC; IR
(KBr) υmax (cmÀ1): 2951, 2846, 1615, 1548, 1508, 1455,
1075; 1H NMR (300MHz, CDCl3): d2.37 (s, 3H), 2.91 (t,
4H), 3.04–3.08 (m, 4H), 3.86 (s, 6H), 6.72 (d, 1H), 6.87–6.91
(m, 2H), 7.35 (d, 4H), 7.75 (s, 1H), 8.10 (d, 2H); 13C NMR
(75 MHz, CDCl3): 160.2, 149.9, 146.5, 139.5, 138.7, 134.6,
129.8, 129.4, 127.3, 127.2, 126.7, 112.4, 111.1,. 56.0, 55.2,
28.6, 26.3, 25.7; MS(ESI), 70eV, m/z: 434 (M+ H); Anal.
Calcd. for C30H27NO2: C, 83.11; H, 6.28; N, 3.23; Found: C,
83.15; H, 6.26; N, 3.20.
Acknowledgments. The authors wish to thanks Dr. U. S. N.
Murthy, Head, Biology division, Indian Institute of Chemical
Technology, Hyderabad, for screening the antimicrobial
activity of the synthesized compounds. The authors B.J. and
S.V. thank the Ministry of Human Resource Development
for the financial assistance.
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Journal of Heterocyclic Chemistry
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