Synthesis of 2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide-based azetidinone derivatives as potent antibacterial and antifungal agents

Article abstract of DOI:10.1007/s12039-012-0354-x

Twelve compounds belonging to series N-[3-chloro-2-oxo-4-(substituted) phenylazetidin-1-yl]-2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide (5a-l) were synthesized. These compounds were evaluated for their in vitro antibacterial against E. coli, S. aureus, K. pneumoniae, P. aeruginosa and antifungal activity against C. albicans, A. niger and A. flavus by cup-plate method. Structures of all the newly synthesized compounds were confirmed by their spectral data interpretation. Compound 5g having p-dimethylaminophenyl group on 4-position of azetidinone ring attached to N-atom of acetamido group on 1-position of 3-methyl-1H-quinoxaline-2-one, was found to be active against all the bacterial and fungal strains under investigation.

Full text of DOI:10.1007/s12039-012-0354-x

c
J. Chem. Sci. Vol. 125, No. 1, January 2013, pp. 129–139. ꢀ Indian Academy of Sciences.
Synthesis of 2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide-based
azetidinone derivatives as potent antibacterial and antifungal agents
SHIV KUMARa,∗, NITIN KUMARb, SUSHMA DRABUc and MD. AKRAM MINHAJa
aDivision of Pharmaceutical Chemistry, Department of Pharmacy, IEC College of Engineering and
Technology, Knowledge Park-I, Greater Noida 201 308, India
bDepartment of Pharmaceutical Technology, Meerut Institute of Engineering and Technology,
Meerut 250 005, India
cMaharaja Surajmal Institute of Pharmacy, Janak Puri, New Delhi 110 058, India
e-mail: shiv_hamdard@yahoo.co.in; shiv_hamdard@rediffmail.com
MS received 17 January 2012; revised 15 June 2012; accepted 28 June 2012
Abstract. Twelve compounds belonging to series N-[3-chloro-2-oxo-4-(substituted)phenylazetidin-1-yl]-2-
(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide (5a–l) were synthesized. These compounds were evaluated
for their in vitro antibacterial against E. coli, S. aureus, K. pneumoniae, P. aeruginosa and antifungal activity
against C. albicans, A. niger and A. flavus by cup-plate method. Structures of all the newly synthesized com-
pounds were confirmed by their spectral data interpretation. Compound 5g having p-dimethylaminophenyl
group on 4-position of azetidinone ring attached to N-atom of acetamido group on 1-position of 3-methyl-1H-
quinoxaline-2-one, was found to be active against all the bacterial and fungal strains under investigation.
Keywords. Quinoxaline; azetidinone; antibacterial; antifungal.
1. Introduction
Azetidin-2-one (β-lactam) ring is present in seve-
ral widely used families of antibiotics such as peni-
cillins, cephalosporins, carbapenems, and monocyclic
β-lactams (for example aztreonam, a potent inhibitor of
cephalosporinase). Recent discoveries have proved that
β-lactams can serve as mechanism based inhibitors of
serine protease.25,26 Subsequently 2-azetidinones were
highlighted as a potent mechanism based inhibitor
of several enzymes like human tryptase, chymase,
thrombin, leukocyte elastase, human cytomegalovirus
protease.27
Keeping the above facts in view, it was thought worth-
while to design the synthesis of compound series viz.
N-[3-chloro-2-oxo-4-(substituted)phenylazetidin-1-yl]-
2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide (5a–l)
wherein azetidinone ring has been attached to quinoxa-
line at 1- position with an intervening acetamido
amino linkage. All the synthesized compounds
have been screened for in vitro antibacterial acti-
vity against Gram positive bacteria Staphylococcus
aureus (ATCC2913), Gram negative bacteria Klebsiella
pneumoniae (ATCC700603), Pseudomonas aerugi-
nosa (ATCC27853), Escherichia coli (ATCC25922)
and antifungal activity against Candida albicans
(MTCC3017), Aspergillus niger (MTCC281) and
Nitrogen containing heterocyclic compounds are indis-
pensable structural units for both the chemists and bio-
chemists. Among the various classes of benzene fused
six-membered nitrogen containing heterocyclic com-
pounds, quinoxaline derivatives form an important class
of pharmacologically active compounds. Quinoxaline
ring is a part of various antibiotics such as hinomycin,
levomycin, and actinoleutin that are known to inhibit
growth of Gram positive bacteria and are active against
various transplantable tumours.1–7 Quinoxaline deriva-
tives have also been found to be associated with a wide
variety of biological activities including antifungal,8–10
antibacterial,10–14 antitubercular,8,9,15–18 antiinflamma-
tory agents.19 Further, hydrazinoquinoxalines and their
cyclic analogues have been reported as antimicrobial
agents.20 Similarly, four-member nitrogen containing
heterocyclic ring azetidinone has also been associated
with compounds possessing various pharmacological
activities viz. antibacterial,21,23,24 antiinflammatory,21
antifungal,22–24 antitubercular22 etc.
∗For correspondence
129

130
Shiv Kumar et al.

Synthesis of 2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide-based azetidinones as potent antimicrobial agents 131
O
O
CH2CH3
O
O
NHNH2
O
H
N
NH2
O
N
N
N
N
HO
O
O
+
NH2
CH3
N
CH3
CH3
CH3
O
N
N
H
O
N
N
CH3
O
Cl
O
N
N
H
O
N
N
CH3
Figure 1. Reaction scheme.
Aspergillus flavus (MTCC222) by using cup-plate 2.2 General procedure for the synthesis of titled
method (figure 1, table 1).
compounds
2.2a 3-Methyl-1H-quinoxaline-2-one (1): Pyruvic
acid (0.1 mol) and o-phenylenediamine (0.1 mol), in
20% HCl (100 mL), were mixed properly and heated
at 45◦C with continuous stirring for about 5 h. Product
was filtered, dried and washed with water, dried and
then purified by dissolving in 5% w/v NaOH (75 mL).
Then, liquid was filtered and cooled to temperature
below 5◦C and acidified with glacial acetic acid to pH
6. Buff coloured crystals appeared and then recrys-
tallized with dimethylformamide (DMF). Pale yellow
crystals, yield 60%, Rf (Ethyl acetate : Hexane = 7 : 3) 0.73, m.p.
230◦C, 1H-NMR (DMSO-d6, 300 MHz, δ ppm) : 7.62–
7.65 (d, 1H, quinoxaline ring protons, J = 8.1 Hz),
7.39–7.44 (t, 1H, quinoxaline ring protons, J = 5.4–
9.6 Hz), 7.18–7.25 (m, 2H, quinoxaline ring protons,
J = 2.7–7.5 Hz), 2.36 (s, 3H, CH3), 9.1 (s, 1H, NHCO);
IR (KBr, cm−1): 762 (ortho-disubstituted aromatic
ring), 1390 (C–N), 1500 (aromatic C=C), 1544 (-NH),
1688 (>C=O), 3314 (-NH).
2. Experimental
2.1 General
Melting points were determined in open capillary tubes
in a Hicon melting point apparatus and are uncor-
rected. All the Fourier Transform-Infra Red (FT-IR)
spectra were recorded in KBr pellets on Shimadzu-
1
8400S spectrometer. The H-NMR spectra were taken
on Bruker-Spectrospin DCX (300 MHz) NMR spec-
trometer. Chemical shifts (δ) are expressed in ppm rela-
tive to tetramethylsilane (TMS) as an internal stan-
dard. The ESI mass spectra of a few representative
compounds were recorded on a MICRO MASS QUAT-
TRO II triple quadrupole mass spectrometer. Elemen-
tal analysis was performed on Flash EA 1112 Thermo
Electron Corporation CHNS analyzer. The purity of
the compounds was checked by thin layer chromato-
graphy (TLC) on Merck Silica Gel 60F254 pre-coated
sheets. Iodine chamber and UV lamp were used for the 2.2b Ethyl-[3-methyl-2-oxo-quinoxaline-1-yl]acetate
visualization of TLC spots. (2): Compound (1) (0.0642 mol), ethylchloroacetate

132
Shiv Kumar et al.
(0.077 mol) and potassium carbonate (0.078 mol) were NHCO), 7.67–7.77 (m, 4H, quinoxaline ring protons,
taken in round bottom flask and refluxed in acetone J = 3–7.5 Hz), 7.41–7.53 (m, 5H, Ar–H, J = 2.7–
(100 mL) for 6 h. After completion of reaction, acetone 8.1 Hz), 5.42 (s, 2H, CH2), 5.03 (s, 1H, CH=N), 2.54
was removed by reduced pressure. The residue was (s, 3H, CH3); IR (KBr, cm−1): 723 (mono-substituted
added to ice cold water (300 mL), acidified with acetic aromatic ring), 769 (ortho-disubstituted aromatic ring),
acid, filtered, washed with cold water, dried and finally 854 (aromatic C=C), 964 (aromatic =C–H, bend),
recrystallized with ethyl acetate. Pale yellow crystals, 1199 (=C–N) 1388 (C–N), 1542 (-NH, bend), 1650
yield 45%, Rf (Ethyl acetate : Hexane = 7 : 3) 0.64, m.p. 112◦C, (CH=N), 1729 (>C=O), 2345 (N–N=), 3244 (-NH).
1H-NMR (DMSO-d6, 300 MHz, δ ppm) : 7.73–7.76 (d,
1H, quinoxaline ring protons, J = 8.1 Hz), 7.53–7.55
2.2f
Nꢁ -(4-chlorobenzylidene)-2-(3-methyl-2-
(t, 1H, quinoxaline ring protons, J = 3.9–4.2 Hz),
7.43–7.46 (d, 1H, quinoxaline ring protons, J = 3 Hz),
7.31–7.36 (t, 1H, quinoxaline ring protons, J = 6.6–
8.4 Hz), 4.11–4.18 (q, 2H, CH2OCO), 3.38 (s, 2H,
CH2CO), 2.39 (s, 3H, CH3), 1.14–1.19 (t, 3H, CH3); IR
(KBr, cm−1): 763 (ortho-disubstituted aromatic ring),
962 (aromatic =C–H, bend), 1199 (=C–N), 1285 (C–
O, coupled with H–C–H), 1380 (C–N), 1645 (CH=N),
1750 (>C=O), 2745 (C–C).
oxoquinoxalin-1(2H)-yl)acetohydrazide (4b): Light
yellow solid, yield 48%, Rf (Benzene : Acetone = 8 : 2) 0.72,
m.p. 230◦C, H-NMR (DMSO-d6, 300 MHz, δ ppm) :
1
8.03–8.06 (q, 4H, A2B2 pattern, Ar–H, J = 3.3–3.6 Hz),
8.18 (s, 1H, CONH), 7.57–7.76 (m, 4H, quinoxaline
ring protons, J = 2.7–8.1 Hz), 5.42 (s, 2H, CH2), 5.03
(s, 1H, CH=N), 2.35 (s, 3H, CH3); IR (KBr, cm−1):
765 (ortho-disubstituted aromatic ring), 823 (para-
disubstituted aromatic ring), 865 (aromatic C=C), 965
(aromatic =C–H, bend), 1129 (aryl C–Cl), 1203 (=C–
2.2c 3-Methyl-2-oxo-quinoxaline-1(2H)-acetohydra- N), 1385 (C–N), 1540 (-NH, bend), 1650 (CH=N),
zide (3): Compound 2 (0.02 mol) and hydrazine 1740 (>C=O), 2342 (N–N=), 3245 (-NH).
hydrate (0.03 mol) were dissolved in ethanol (50 mL)
and refluxed for 6 h. Reaction mixture was kept in
2.2g
Nꢁ -(4-hydroxybenzylidene)-2-(3-methyl-
deep freezer for overnight. Product was filtered, dried
and finally recrystallized with DMF. Biege coloured
solid, yield 50%, Rf (Toluene : Ethyl acetate ; Formic acid, TEF = 5 : 4 : 1)
0.9, m.p. 200◦C, 1H-NMR (DMSO-d6, 300 MHz,
δ ppm) : 7.72–7.75 (d, 1H, quinoxaline ring protons,
J = 7.8 Hz), 7.49–7.54 (t, 1H, quinoxaline ring pro-
tons, J = 6.3–9 Hz), 7.26–7.35 (q, 2H, quinoxaline ring
protons, J = 7.5–10.2 Hz), 4.84 (s, 2H, NHNH2), 4.28
(s, 2H, CH2CO), 2.43 (s, 3H, CH3); IR (KBr, cm−1):
760 (ortho-disubstituted aromatic ring), 963 (aromatic
=C–H, bend), 1198 (=C–N), 1385 (C–N), 1569 (-NH,
bend), 1645 (CH=N), 1749 (>C=O), 2320 (N–N),
3245 (-NH. str.).
2-oxoquinoxalin-1(2H)-yl)acetohydrazide (4c):
Greenish yellow solid, yield 45%, Rf (Benzene : Acetone = 8 : 2)
0.76, m.p. 254◦C, H-NMR (DMSO-d6, 300 MHz, δ
1
ppm) : 8.02–8.06 (q, 4H, A2B2 pattern, Ar–H, J =
3–3.6 Hz), 8.15 (s, 1H, CONH), 7.75–7.87 (m, 4H,
quinoxaline ring protons, 2.1–8.4 Hz), 5.32 (s, 2H,
CH2), 5.13 (s, 1H, CH=N), 2.48 (s, 1H, OH), 2.35 (s,
3H, CH3); IR (KBr, cm−1): 764 (ortho-disubstituted
aromatic ring), 825 (para-disubstituted aromatic ring),
863 (aromatic C=C), 960 (aromatic =C–H, bend),
1198 (=C–N), 1288 (C–O, coupled with H–C–H),
1382 (C–N), 1540 (-NH, bend), 1650 (CH=N),
1745 (>C=O), 2344 (N–N=), 3250 (-NH), 3675
(phenolic -OH).
2.2d 2-(3-Methyl-2-oxoquinoxalin-1(2H )-yl)-N ꢁ-
[(substituted)phenylmethylidene]aceto hydrazide (4a–
l): Equimolar quantities of compound 3 (0.0044 mol)
and aromatic aldehydes (0.0045 mol) were dissolved in
methanol (25 mL) and refluxed for 6 h. A solid appears
with vigorous bumping in each case. Solid was filtered,
washed with cold methanol, dried and recrystallized
with DMF.
2.2h 2-(3-Methyl-2-oxoquinoxalin-1(2H)-yl)-Nꢁ-(4-
nitrobenzylidene)acetohydrazide (4d): Grey solid,
yield 52%, Rf (Benzene : Acetone = 8 : 2) 0.70, m.p. 220◦C,
1H-NMR (DMSO-d6, 300 MHz, δ ppm) : 8.03–06 (q,
4H, A2B2 pattern, Ar–H, J = 3–3.3 Hz), 8.15 (s, 1H,
CONH), 7.77–7.87 (m, 4H, quinoxaline ring protons,
J = 2.4–7.5 Hz), 5.52 (s, 2H, CH2), 5.03 (s, 1H,
CH=N), 2.54 (s, 3H, CH3); IR (KBr, cm−1): 723
(ortho-disubstituted aromatic ring), 829 (para-
2.2e Nꢁ-benzylidene-2-(3-methyl-2-oxoquinoxalin-
1(2H)-yl)acetohydrazide (4a): Light yellow solid, disubstituted aromatic ring), 864 (aromatic C=C), 969
yield 54%, Rf (Benzene : Acetone = 8: 2) 0.85, m.p. 234◦C, (aromatic =C–H, bend), 1199 (=C–N), 1369 (aro-
1H-NMR (DMSO-d6, 300 MHz, δ ppm) : 8.06 (s, 1H, matic –NO2 sym., str.), 1385 (C–N), 1542 (-NH, bend),

Synthesis of 2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide-based azetidinones as potent antimicrobial agents 133
1551 (aromatic –NO2, asym., str.) 1648 (CH=N), 1748 Light yellow solid, yield 46%, Rf (Benzene : Acetone = 8 : 2)
1
(>C=O), 2341 (N–N=), 3247 (-NH).
0.85, m.p. 238◦C, H-NMR (DMSO-d6, 300 MHz,
δ ppm) : 8.18 (s, 1H, CONH), 7.86–8.07 (m, 4H,
quinoxaline ring protons, J = 1.8–7.5 Hz), 8.13–8.17
(q, 4H, A2B2 pattern, Ar–H, J = 3–5.1 Hz), 5.32 (s,
2H, CH2), 5.13 (s, 1H, CH=N), 2.64 (s, 3H, CH3); IR
(KBr, cm−1): 768 (ortho-disubstituted aromatic ring),
845 (para-disubstituted aromatic ring), 869 (aromatic
C=C), 968 (aromatic =C–H, bend), 1199 (=C–N),
1288 (aryl C–F), 1385 (C–N), 1548 (-NH, bend), 1650
(CH=N), 1745 (>C=O), 2344 (N–N=), 3245 (-NH).
2.2i
Nꢁ-(4-methoxybenzylidene)-2-(3-methyl-2-
oxoquinoxalin-1(2H)-yl)acetohydrazide (4e): Light
yellow solid, yield 43%, Rf (Benzene : Acetone = 8 : 2) 0.80,
1
m.p. 218◦C, H-NMR (DMSO-d6, 300 MHz, δ ppm) :
8.02–8.05 (d, 4H, Ar–H, J = 9.6 Hz), 8.14 (s, 1H,
CONH), 7.57–7.67 (m, 4H, quinoxaline ring protons,
J = 2.4–7.5 Hz), 5.52 (s, 2H, CH2), 5.02 (s, 1H,
CH=N), 3.36 (s, 3H, OCH3), 2.35 (s, 3H, CH3); IR
(KBr, cm−1): 769 (ortho-disubstituted aromatic ring),
825 (para-disubstituted aromatic ring), 865 (aromatic
C=C), 964 (aromatic =C–H, bend), 1040 (C–O–C,
sym. str.), 1129 (aromatic C–O), 1198 (=C–N), 1240
(C–O–C, asym. str.), 1388 (C–N), 1540 (-NH, bend),
1648 (CH=N), 1745 (>C=O), 2344 (N–N=), 3250
(-NH).
2.2m Nꢁ-(2-hydroxybenzylidene)-2-(3-methyl-2-
oxoquinoxalin-1(2H)-yl)acetohydrazide (4i): Light
yellow solid, yield 48%, Rf (Benzene : Acetone = 8 : 2) 0.80,
m.p. 248◦C, H-NMR (DMSO-d6, 300 MHz, δ ppm) :
1
8.15 (s, 1H, CONH), 7.77–7.87 (m, 4H, quinoxaline
ring protons, J = 1.8–6.9 Hz), 7.52–7.53 (d, 1H, Ar–H,
J = 4.8 Hz), 7.33–7.35 (d, 1H, Ar–H, J = 7.8 Hz),
7.25–7.28 (t, 2H, Ar–H, J = 4.8–5.7 Hz), 5.52 (s, 2H,
CH2), 5.03 (s, 1H, CH=N), 2.48 (s, 1H, OH), 2.54 (s,
3H, CH3); IR (KBr, cm−1): 765 (ortho-disubstituted
aromatic ring), 868 (aromatic C=C), 969 (aromatic
=C–H, bend), 1198 (=C–N), 1258 (C–O, str.) 1385
(C–N), 1545 (-NH, bend), 1649 (CH=N), 1748
(>C=O), 2340 (N–N=), 3250 (-NH), 3365 (phenolic
-OH).
2.2j Nꢁ-(3,4-dimethoxybenzylidene)-2-(3-methyl-2-
oxoquinoxalin-1(2H)-yl)acetohydrazide (4f): Light
yellow solid, yield 40%, Rf (Benzene : Acetone = 8 : 2) 0.72,
1
m.p. 208◦C, H-NMR (DMSO-d6, 300 MHz, δ ppm) :
8.11 (s, 1H, CONH), 7.81–7.99 (m, 4H, quinoxaline
ring protons, J = 2.4–7.5 Hz), 7.77–7.79 (d, 1H, Ar–H,
J = 6.3 Hz), 7.67–7.69 (d, 1H, Ar–H, J = 6.6 Hz), 7.62
(s, 1H, Ar–H), 5.33 (s, 2H, CH2), 5.02 (s, 1H, CH=N),
3.62 (s, 6H, OCH3), 2.45 (s, 3H, CH3); IR (KBr, cm−1):
768 (ortho-disubstituted aromatic ring), 830 (para-
disubstituted aromatic ring), 863 (aromatic C=C), 965
(aromatic =C–H, bend), 1042 (C–O–C, sym. str.), 1132
(aromatic C–O), 1199 (=C–N), 1245 (C–O–C, asym.
str.), 1385 (C–N), 1545 (-NH, bend), 1650 (CH=N),
1745 (>C=O), 2344 (N–N=), 3245 (-NH).
2.2n
Nꢁ-(3-hydroxy-4-methoxybenzylidene)-2-(3-
methyl-2-oxoquinoxalin-1(2H)-yl)acetohydrazide (4j):
Yellow solid, yield 66%, Rf (Benzene : Acetone = 8 : 2) 0.87,
m.p. 188◦C, H-NMR (DMSO-d6, 300 MHz, δ ppm)
1
: 8.12 (s, 1H, CONH), 7.87–7.97 (m, 4H, quinoxaline
ring protons, J = 2.1–8.4 Hz), 7.63 (s, 1H, Ar–H), 7.77–
7.81 (t, 1H, Ar–H, J = 3–8.2 Hz), 7.82–7.84 (d, 1H,
Ar–H, J = 6.6 Hz), 5.22 (s, 2H, CH2), 5.12 (s, 1H,
CH=N), 2.48 (s, 1H, OH), 2.54 (s, 3H, CH3), 3.62 (s,
3H, OCH3); IR (KBr, cm−1): 769 (ortho-disubstituted
aromatic ring), 849 (para-disubstituted aromatic ring),
869 (aromatic C=C), 968 (aromatic =C–H, bend),
1045 (C–O–C, sym. str.), 1132 (aromatic C–O), 1199
(=C–N), 1245 (C–O–C, asym. str.), 1252 (C–O,
str.), 1384 (C–N), 1546 (-NH, bend), 1648 (CH=N),
1749 (>C=O), 2345 (N–N=), 3245 (-NH), 3352
(phenolic -OH).
2.2k Nꢁ-(4-(dimethylamino)benzylidene)-2-(3-methyl-
2-oxoquinoxalin-1(2H)-yl)acetohydrazide (4g): Yel-
low solid, yield 54%, Rf (Benzene : Acetone = 8 : 2) 0.86, m.p.
228◦C, 1H-NMR (DMSO-d6, 300 MHz, δ ppm) : 7.03–
7.08 (q, 4H, A2B2 pattern, Ar–H, J = 3–5.7 Hz), 7.81 (s,
1H, CONH), 7.55–7.67 (m, 4H, quinoxaline ring pro-
tons, J = 2.1–8.1 Hz), 5.22 (s, 2H, CH2), 5.01 (s, 1H,
CH=N), 2.35 (s, 3H, CH3), 1.83 (s, 6H, N–CH3); IR
(KBr, cm−1): 769 (ortho-disubstituted aromatic ring),
830 (para-disubstituted aromatic ring), 865 (aromatic
C=C), 968 (aromatic =C–H, bend), 1199 (=C–N),
1384 (C–N), 1550 (-NH, bend), 1648 (CH=N), 1750
(>C=O), 2344 (N–N=), 3124 (-CH3), 3245 (-NH).
2.2o
Nꢁ-(2-fluorobenzylidene)-2-(3-methyl-2-
oxoquinoxalin-1(2H)-yl)acetohydrazide (4k): Red
solid, yield 53%, Rf (Benzene : Acetone = 8 : 2) 0.85, m.p.
248◦C, H-NMR (DMSO-d6, 300 MHz, δ ppm) : 8.14
1
2.2l 2-(3-Methyl-2-oxoquinoxalin-1(2H)-yl)-Nꢁ-(4-
(s, 1H, CONH), 7.88–7.98 (m, 4H, quinoxaline ring
(trifluoromethyl)benzylidene) acetohydrazide (4h): protons, J = 1.8–7.5 Hz), 7.62–7.65 (d, 1H, Ar–H,

134
Shiv Kumar et al.
J = 8.4 Hz), 7.43–7.46 (d, 1H, Ar–H, J = 7.5 Hz), 2.3b N-[3-chloro-2-(4-chlorophenyl)-4-oxoazetidin-1-yl]-
7.55–7.59 (t, 2H, Ar–H, J = 2.4–5.1 Hz), 5.13 (s, 2H, 2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide (5b):
CH2), 5.23 (s, 1H, CH=N), 2.55 (s, 3H, CH3); IR (KBr, Orange solid, yield 78%, Rf (TEF) 0.84, m.p. 224◦C,
cm−1): 769 (ortho-disubstituted aromatic ring), 864 1H-NMR (DMSO-d6, 300 MHz, δ ppm) : 8.17 (s, 1H,
(aromatic C=C), 968 (aromatic =C–H, bend), 1199 NHCO), 7.65–7.75 (m, 4H, quinoxaline ring protons,
(=C–N), 1285 (aryl C–F), 1387 (C–N), 1548 (-NH, J = 1.2–7.9 Hz), 7.03–7.07 (q, 4H, A2B2 pattern, Ar–
bend), 1650 (CH=N), 1745 (>C=O), 2345 (N–N=), H, J = 2.7–5.7 Hz), 5.43 (s, 2H, CH2), 2.54 (s, 3H,
3248 (-NH).
CH3), 3.09 (s, 1H, CH–Cl), 4.14 (s, 1H, CH–Ar); IR
(KBr, cm−1): 765 (ortho-disubstituted aromatic ring),
824 (para-disubstituted aromatic ring), 854 (aromatic
C=C), 961 (aromatic =C–H, bend), 1195 (=C–N),
1284 (CH–Cl, str.), 1388 (C–N), 1285 (CH–Cl, str.),
1665 (-NCO, str.), 1545 (-NH, bend), 1677 (-NCO,
str.), 1730 (>C=O), 3244 (-NH); MS (ESI, m/z, M+):
430.7; Elemental Analysis [Found (Calculated)]: C
55.81 (55.70), H 3.65 (3.74), Cl 16.48 (16.44), N 13.02
(12.99), O 11.04 (11.13).
2.2p
Nꢁ-(2-chlorobenzylidene)-2-(3-methyl-2-
oxoquinoxalin-1(2H)-yl)acetohydrazide (4l): Light
yellow solid, yield 43%, Rf (Benzene : Acetone = 8 : 2) 0.80,
m.p. 218◦C, H-NMR (DMSO-d6, 300 MHz, δ ppm) :
1
8.13 (s, 1H, CONH), 7.78–7.88 (m, 4H, quinoxaline
ring protons, J = 1.8–7.8 Hz), 7.52–7.55 (d, 1H, Ar–H,
J = 9.9 Hz), 7.33–7.36 (d, 1H, Ar–H, J = 7.8 Hz), 7.45–
7.49 (t, 2H, Ar–H, J = 6.6 Hz), 5.03 (s, 2H, CH2), 5.13
(s, 1H, CH=N), 2.54 (s, 3H, CH3); IR (KBr, cm−1):
768 (ortho-disubstituted aromatic ring), 865 (aromatic
C=C), 968 (aromatic =C–H, bend), 1106 (aryl C–Cl),
1198 (=C–N), 1385 (C–N), 1545 (-NH, bend), 1648
(CH=N), 1752 (>C=O), 2346 (N–N=), 3245 (-NH).
2.3c N-[3-chloro-2-(4-hydroxyphenyl)-4-oxoazetidin-1-yl]-
2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide (5c):
Biege solid, yield 78%, Rf (TEF) 0.82, m.p. 234◦C,
1H-NMR (DMSO-d6, 300 MHz, δ ppm) : 8.17 (s, 1H,
NHCO), 7.65–7.75 (m, 4H, quinoxaline ring protons,
J = 1.5–7.5 Hz), 7.33–7.37 (q, 4H, A2B2 pattern, Ar–
H, J = 1.8–6 Hz), 5.435 (s, 2H, CH2), 2.54 (s, 3H,
CH3), 3.10 (s, 1H, CH–Cl), 4.16 (s, 1H, CH–Ar), 3.16
(s, 1H, phenolic -OH); IR (KBr, cm−1): 762 (ortho-
disubstituted aromatic ring), 828 (para-disubstituted
aromatic ring), 851 (aromatic C=C), 962 (aromatic
=C–H, bend), 1199 (=C–N), 1285 (CH–Cl, str.), 1385
(C–N), 1288 (C–O, str., coupled with H–C–H), 1664
(-NCO, str.), 1545 (-NH, bend), 1678 (-NCO, str.),
1729 (>C=O), 3245 (-NH), 3564 (phenolic –OH, str.);
MS (ESI, m/z, M+): 412.5; Elemental Analysis [Found
(Calculated)]: C 58.22 (58.19), H 4.20 (4.15), Cl 8.55
(8.59), N 13.58 (13.57), O 15.45 (15.50).
2.3 N-[3-chloro-2-oxo-4-(substituted)phenylazetidin-
1-yl]-2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide
(5a–l)
Equimolar quantities of compounds (4a–l),
chloroacetylchloride and triethylamine were dissolved
in dry benzene (20 mL) and then stirred continuously
at 0◦C for about 6 h. Product was filtered, dried and
recrystallized with DMF.
2.3a N-(3-chloro-2-oxo-4-phenylazetidin-1-yl)-2-
(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide (5a): 2.3d N-[3-chloro-2-(4-nitrophenyl)-4-oxoazetidin-1-
Light orange solid, yield 74%, Rf (TEF) 0.82, m.p. yl]-2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide
1
214◦C, H-NMR (DMSO-d6, 300 MHz, δ ppm): 8.17 (5d): Light brown solid, yield 72%, Rf (TEF) 0.85,
1
(s, 1H, NHCO), 7.77–7.87 (m, 4H, quinoxaline ring m.p. 184◦C, H-NMR (DMSO-d6, 300 MHz, δ ppm) :
protons, J = 1.5–7.8 Hz), 7.52–7.58 (m, 5H, Ar–H, 8.22 (s, 1H, NHCO), 7.75–7.85 (m, 4H, quinoxaline
J = 1.2–7.8 Hz), 5.42 (s, 2H, CH2), 2.556 (s, 3H, ring protons, J = 1.8–8.1 Hz), 7.53–7.57 (q, 4H, A2B2
CH3), 3.16 (s, 1H, CH–Cl), 4.10 (s, 1H, CH–Ar); IR pattern, Ar–H, J = 1.5–5.7 Hz), 5.44 (s, 2H, CH2),
(KBr, cm−1): 726 (mono-substituted aromatic ring), 2.53 (s, 3H, CH3), 3.12 (s, 1H, CH–Cl), 4.16 (s, 1H,
765 (ortho-disubstituted aromatic ring), 854 (aromatic CH–Ar),; IR (KBr, cm−1): 763 (ortho-disubstituted
C=C), 961 (aromatic =C–H, bend), 1195 (=C–N), aromatic ring), 832 (para-disubstituted aromatic ring),
1388 (C–N), 1285 (CH–Cl, str.), 1665 (-NCO, str.), 849 (aromatic C=C), 959 (aromatic =C–H, bend),
1545 (-NH, bend), 1730 (>C=O), 3244 (-NH); MS 1197 (=C–N), 1285 (CH–Cl, str.), 1368 (aromatic
(ESI, m/z, M+): 396.8; Elemental Analysis [Found NO2, sym. str.), 1384 (C–N), 1666 (-NCO, str.), 1549
(Calculated)]: C 60.87 (60.53), H 4.16 (4.32), Cl 9.1 (-NH, bend), 1560 (aromatic NO2, asym. str.), 1679
(8.93), N 14.11 (14.12), O 11.76 (12.10).
(-NCO, str.), 1732 (>C=O), 3232 (-NH); MS (ESI,

Synthesis of 2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide-based azetidinones as potent antimicrobial agents 135
m/z, M+): 441.7; Elemental Analysis [Found (Calcu- (m, 4H, quinoxaline ring protons, J = 1.8–6.9 Hz),
lated)]: C 54.42 (54.37), H 3.62 (3.65), Cl 7.99 (8.02), 7.32–7.37 (q, 4H, A2B2 pattern, Ar–H, J = 1.8–6.9 Hz),
N 15.90 (15.85), O 18.07 (18.11).
5.40 (s, 2H, CH2), 2.518 (s, 3H, CH3), 3.10 (s, 1H, CH–
Cl), 4.12 (s, 1H, CH–Ar), 2.31 (s, 6H, N(CH3)2); IR
(KBr, cm−1): 762 (ortho-disubstituted aromatic ring),
832 (para-disubstituted aromatic ring), 849 (aromatic
C=C), 964 (aromatic =C–H, bend), 1199 (=C–N),
1285 (CH–Cl, str.), 1384 (C–N), 1548 (-NH, bend),
1648 (-NCO, str.), 1680 (-NCO, str.), 1752 (>C=O),
3236 (-NH); MS (ESI, m/z, M+): 439.3; Elemental
Analysis [Found (Calculated)]: C 60.11 (60.07), H
4.99 (5.04), Cl 8.05 (8.06), N 15.99 (15.92), O 10.86
(10.91).
2.3e N-[3-chloro-2-(4-methoxyphenyl)-4-oxoazetidin-
1-yl]-2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide
(5e): Light yellow solid, yield 78%, Rf (TEF) 0.74, m.p.
1
154◦C, H-NMR (DMSO-d6, 300 MHz, δ ppm) : 8.10
(s, 1H, NHCO), 7.73–7.81 (m, 4H, quinoxaline ring
protons, J = 1.2–7.8 Hz), 7.43–7.47 (q, 4H, A2B2 pat-
tern, Ar–H, J = 1.5–5.7 Hz), 5.41 (s, 2H, CH2), 2.52 (s,
3H, CH3), 3.11 (s, 1H, CH–Cl), 4.13 (s, 1H, CH–Ar),
2.51 (s, 3H, OCH3); IR (KBr, cm−1): 763 (ortho-
disubstituted aromatic ring), 829 (para-disubstituted
aromatic ring), 852 (aromatic C=C), 955 (aromatic
=C–H, bend), 1093 (C–O–C, sym. str.), 1129 (aromatic
C–O, str.), 1199 (=C–N), 1225 (C–O–C, asym. str.),
1284 (CH–Cl, str.), 1385 (C–N), 1549 (-NH, bend),
1649 (-NCO, str.), 1681 (-NCO, str.), 1749 (>C=O),
3245 (-NH); MS (ESI, m/z, M+): 426.3; Elemental
Analysis [Found (Calculated)]: C 59.11 (59.09), H
4.45 (4.49), Cl 8.32 (8.31), N 13.16 (13.13), O 14.96
(14.99).
2.3h N-{3-chloro-2-oxo-4-[4-(trifluoromethyl)phenyl]
azetidin-1-yl}-2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)
acetamide (5h): Dark brown solid, yield 72%, Rf (TEF)
1
0.78, m.p. 195◦C, H-NMR (DMSO-d6, 300 MHz, δ
ppm) : 8.31 (s, 1H, NHCO), 7.72–7.81 (m, 4H, quinox-
aline ring protons, J = 1.8–7.2 Hz), 7.33–7.38 (q, 4H,
A2B2 pattern, Ar–H, J = 2.7–6.6 Hz), 5.41 (s, 2H,
CH2), 2.52 (s, 3H, CH3), 3.12 (s, 1H, CH–Cl), 4.22 (s,
1H, CH–Ar); IR (KBr, cm−1): 761 (ortho-disubstituted
aromatic ring), 835 (para-disubstituted aromatic ring),
852 (aromatic C=C), 965 (aromatic =C–H, bend),
1198 (=C–N), 1272 (CH–Cl, str.),1288 (aryl C-F, str.),
1386 (C–N), 1548 (-NH, bend), 1649 (-NCO, str.),
1685 (-NCO, str.), 1755 (>C=O), 3245 (-NH); MS
(ESI, m/z, M+): 464.5; Elemental Analysis [Found
(Calculated)]: C 54.28 (54.26), H 3.50 (3.47), Cl 7.60
(7.63), F 12.25 (12.26), N 11.99 (12.05), O 10.38
(10.33).
2.3f N-[3-chloro-2-(3,4-dimethoxyphenyl)-4-oxoazetidin-
1-yl]-2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide
(5f): Grey solid, yield 79%, Rf (TEF) 0.72, m.p. 144◦C,
1H-NMR (DMSO-d6, 300 MHz, δ ppm) : 7.99 (s, 1H,
NHCO), 7.71–7.79 (m, 4H, quinoxaline ring protons,
J = 1.8–7.2 Hz), 7.32 (s, 1H, Ar–H), 7.52–7.57 (t,
1H, Ar–H, J = 1.8–7.5 Hz), 7.42–7.45 (d, 1H, Ar–H,
J = 9.3 Hz), 5.40 (s, 2H, CH2), 2.51 (s, 3H, CH3),
3.12 (s, 1H, CH–Cl), 4.12 (s, 1H, CH–Ar), 2.56 (s,
6H, OCH3); IR (KBr, cm−1): 765 (ortho-disubstituted
aromatic ring), 832 (para-disubstituted aromatic ring),
855 (aromatic C=C), 952 (aromatic =C–H, bend),
1094 (C–O–C, sym. str.), 1135 (aromatic C–O, str.),
1198 (=C–N), 1232 (C–O–C, asym., str.), 1285 (CH–
Cl, str.), 1381 (C–N), 1551 (-NH, bend), 1639 (-NCO,
str.), 1681 (-NCO, str.), 1752 (>C=O), 3241 (-NH);
MS (ESI, m/z, M+): 456.2; Elemental Analysis [Found
(Calculated)]: C 57.85 (57.83), H 4.62 (4.63), Cl 7.80
(7.76), N 12.25 (12.26), O 17.48 (17.51).
2.3i N-[3-chloro-2-(2-hydroxyphenyl)-4-oxoazetidin-1-
yl]-2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide
(5i): Light brown solid, yield 80%, Rf (TEF) 0.81, m.p.
1
175◦C, H-NMR (DMSO-d6, 300 MHz, δ ppm) : 8.11
(s, 1H, NHCO), 7.71–7.80 (m, 4H, quinoxaline ring
protons, J = 1.8–6.9 Hz), 7.31–7.34 (dd, 2H, Ar–H),
7.41–7.44 (d, 1H, Ar–H, J = 8.4 Hz), 7.37–7.40 (t, 1H,
Ar–H, J = 1.5–6 Hz), 5.41 (s, 2H, CH2), 2.52 (s, 3H,
CH3), 3.12 (s, 1H, CH–Cl), 4.22 (s, 1H, CH–Ar), 2.82
(s, 1H, phenolic -OH); IR (KBr, cm−1): 762 (ortho-
disubstituted aromatic ring), 848 (aromatic C=C), 964
(aromatic =C–H, bend), 1198 (=C–N), 1275 (CH–Cl,
str.), 1384 (C–N), 1549 (-NH, bend), 1650 (-NCO,
str.), 1685 (-NCO, str.), 1752 (>C=O), 3248 (-NH),
3564 (phenolic –OH, str.); MS (ESI, m/z, M+): 412.8;
Elemental Analysis [Found (Calculated)]: C 58.20
(58.19), H 4.18 (4.15), Cl 8.55 (8.59), N 13.58 (13.57),
O 15.49 (15.50).
2.3g N -[3-chloro-2-(4-dimethylaminophenyl)-4-
oxoazetidin-1-yl]-2-(3-methyl-2-oxoquinoxalin-1(2H)-
yl)acetamide (5g): Light greenish solid, yield 65%,
Rf (TEF) 0.78, m.p. 164◦C, 1H-NMR (DMSO-d6,
300 MHz, δ ppm) : 8.21 (s, 1H, NHCO), 7.72–7.80

136
Shiv Kumar et al.
2.3j N-[3-chloro-2-(3-hydroxy-4-methoxyphenyl)-4-
bend), 1685 (-NCO, str.), 1750 (>C=O), 3229 (-NH);
oxoazetidin-1-yl]-2-(3-methyl-2-oxoquinoxalin-1(2H)- MS (ESI, m/z, M+): 430.7; Elemental Analysis [Found
yl)acetamide (5j): Grey solid, yield 78%, Rf (TEF) (Calculated)]: C 55.72 (55.70), H 3.72 (3.74), Cl 16.45
1
0.77, m.p. 215◦C, H-NMR (DMSO-d6, 300 MHz, δ (16.44), N 13.04 (12.99), O 11.09 (11.13).
ppm) : 8.12 (s, 1H, NHCO), 7.71–7.79 (m, 4H, quinox-
aline ring protons, J = 1.5–7.2 Hz), 7.31–7.34 (d, 1H,
2.4 Antibacterial and antifungal activity
Ar–H, J = 9 Hz), 7.41–7.44 (d, 1H, Ar–H, J = 9 Hz),
7.37–7.40 (t, 1H, Ar–H, J = 1.5–7.2 Hz), 5.39 (s, 2H,
All the synthesized compounds have been screened
in vitro for antibacterial activity against Gram posi-
CH2), 2.53 (s, 3H, CH3), 3.12 (s, 1H, CH–Cl), 4.19
(s, 1H, CH–Ar), 2.81 (s, 1H, phenolic -OH), 3.21 (s,
tive bacteria S. aureus (ATCC2913), Gram negative
3H, -OCH3); IR (KBr, cm−1): 762 (ortho-disubstituted
bacteria K. pneumonia (ATCC700603), P. aeruginosa
aromatic ring), 835 (para-disubstituted aromatic ring),
(ATCC27853), E. coli (ATCC25922) and antifungal
849 (aromatic C=C), 966 (aromatic =C–H, bend),
activity against C. albicans (MTCC3017), A. niger
1192 (=C–N), 1285 (CH–Cl, str.), 1285 (C–O, str.,
(MTCC281) and A. flavus (MTCC277) by using cup-
plate method.
The growth media (Nutrient Agar media for bacte-
rial growth and Sabouraud Dextrose Agar media for
coupled with H–C–H), 1385 (C–N), 1552 (-NH, bend),
1654 (-NCO, str.), 1685 (-NCO, str.), 1754 (>C=O),
3249 (-NH), 3532 (phenolic –OH, str.); MS (ESI, m/z,
M+): 442.9; Elemental Analysis [Found (Calculated)]:
fungal growth) were prepared and sterilized in auto-
C 57.01 (56.95), H 4.33 (4.32), Cl 7.98 (8.01), N 12.69
clave at 15 psig for 15 min. These media were poured
(12.65), O 17.99 (18.06).
into petri-plates under standard conditions and allowed
to solidify. On the surface of media, test microorga-
2.3k N-[3-chloro-2-(2-fluorophenyl)-4-oxoazetidin-1-yl]-
2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide (5k):
Dark brown solid, yield 68%, Rf (TEF) 0.82, m.p. 198◦C,
1H-NMR (DMSO-d6, 300 MHz, δ ppm) : 8.22 (s, 1H,
NHCO), 7.74–7.82 (m, 4H, quinoxaline ring protons,
J = 1.2–6.9 Hz), 7.36–7.39 (dd, 2H, Ar–H), 7.45–7.48
(d, 1H, Ar–H, J = 10.5 Hz), 7.41–7.43 (t, 1H, Ar–H,
J = 1.2–7.8 Hz), 5.45 (s, 2H, CH2), 2.52 (s, 3H, CH3),
3.22 (s, 1H, CH–Cl), 4.26 (s, 1H, CH–Ar); IR (KBr,
cm−1): 766 (ortho-disubstituted aromatic ring), 852
(aromatic C=C), 962 (aromatic =C–H, bend), 1199
(=C–N), 1272 (CH–Cl, str.), 1285 (aryl C-F, str.),1385
(C–N), 1549 (-NH, bend), 1686 (-NCO, str.), 1752
(>C=O), 3250 (-NH); MS (ESI, m/z, M+): 414.2; Ele-
mental Analysis [Found (Calculated)]: C 57.93 (57.91),
H 3.92 (3.89), Cl 8.51 (8.55), F 4.60 (4.58), N 13.54
(13.51), O 11.50 (11.57).
nisms were inoculated with sterilized nickel loop wire.
Cups were made by boring on the surface of growth
media with previously sterilized borer. Four cups were
made on each petri-plate. These cups were filled with
different concentrations (50 μg/mL and 100 μg/mL
in DMSO) of the test compounds, third with control
(DMSO) and fourth one with standard drug. The plates
were kept in cold for 1 h to allow the diffusion of test
compounds and then incubated at 35◦C for 48 h (for
antifungal activity) and at 37◦C for 24 h (for antibacte-
rial activity). The zones of inhibition formed around the
cups after respective incubation were measured.
3. Results and discussion
3.1 Chemistry
Equimolar quantities of pyruvic acid and ortho-
phenylenediamine were dissolved in 20% HCl and
heated with continuous stirring at 45◦C for 5 h to give
2.3l N-[3-chloro-2-(2-chlorophenyl)-4-oxoazetidin-
1-yl]-2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide
(5l): Yellow solid, yield 78%, Rf (TEF) 0.85, m.p. 3-methyl-1H-quinoxaline-2-one (1). The solid residue,
1
228◦C, H-NMR (DMSO-d6, 300 MHz, δ ppm) : 8.21 thus obtained was purified by treatment with 5% w/v
(s, 1H, NHCO), 7.72–7.81 (m, 4H, quinoxaline ring NaOH. Compound (1) on refluxing with equimo-
protons, J = 1.8–7.5 Hz), 7.34–7.38 (dd, 2H, Ar–H), lar quantities of ethylchloroacetate and potassium
7.44–7.47 (d, 1H, Ar–H, J = 8.1 Hz), 7.40–7.43 (t, 1H, carbonate in acetone yielded ethyl-[3-methyl-2-oxo-
Ar–H, J = 1.5–6.9 Hz), 5.41 (s, 2H, CH2), 2.52 (s, 3H, quinoxaline-1-yl]acetate (2). Compound (2) on reflux-
CH3), 3.21 (s, 1H, CH–Cl), 4.25 (s, 1H, CH–Ar); IR ing with hydrazine hydrate in ethanol yielded 3-
(KBr, cm−1): 764 (ortho-disubstituted aromatic ring), Methyl-2-oxo-quinoxaline-1(2H)-acetohydrazide (3).
846 (aromatic C=C), 965 (aromatic =C–H, bend), Compound (3) on refluxing with equimolar quanti-
1106 (aryl C-Cl, str.), 1199 (=C–N), 1278 (CH–Cl, ties of appropriate aromatic aldehyde in methanol
str.), 1288 (aryl C-F, str.),1385 (C–N), 1548 (-NH, furnished corresponding Schiff’s bases viz. 2-

Synthesis of 2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide-based azetidinones as potent antimicrobial agents 137
(3-methyl-2-oxoquinoxalin-1(2H)-yl)-Nꢁ-[(substituted) (J = 7.5–10.2 Hz) confirmed another two protons at
phenylmethylidene]aceto hydrazide (4a–l). Equimo- C-6 and C-7 of quinoxaline ring. A singlet at 4.84 ppm
lar quantities of compound (4a–l), triethylamine and belonged to two protons of hydrazine group attached
chloroacetylchloride were dissolved in dry benzene and with CH2CO at N-1 of quinoxaline ring. This anoma-
stirred continuously at 0◦–5◦C for 6 h to yield N-[3- lous behaviour may due to proton exchange. A sing-
chloro-2-oxo-4-(substituted)phenylazetidin-1-yl]-2-(3-
let at 4.28 ppm belonged to two protons of CH2CO at
methyl-2-oxoquinoxalin-1(2H)-yl)acetamide (5a–l). N-1 of quinoxaline ring. A singlet at 2.432 ppm con-
Structures of all the newly synthesized compounds firmed three protons of methyl group at C-3 of quinox-
were confirmed by their spectral data interpretation.
aline ring. FT-IR spectrum of compound (3) showed
1H-NMR spectra of 3-methyl-1H-quinoxaline-2-one prominent peaks at 760 cm−1, 963 cm−1, 1198 cm−1,
(1) showed a doublet at 7.62–7.65 ppm (J = 8.1 Hz) 1385 cm−1, 1569 cm−1, 1645 cm−1, 1749 cm−1,
belonging to one proton at C-5 of quinoxaline ring. A 2320 cm−1, 3245 cm−1 confirming ortho-disubstituted
triplet in at 7.39–7.44 ppm with J value 5.4–9.6 Hz aromatic ring, aromatic =C–H, bend, =C–N, C–
also confirmed another one proton at C-8 of quinoxa- N, -NH (bend), CH=N, >C=O, N–N, -NH (str.),
1
line ring. A multiplet in region 7.18–7.25 ppm (J = respectively. H-NMR spectrum of Nꢁ-benzylidene-2-
2.7–7.5) confirmed another two protons at C-6 and C-7 (3-methyl-2-oxoquinoxalin-1(2H)-yl)acetohydrazide
of quinoxaline ring. A singlet at 2.36 ppm belonged to (4a) showed a singlet at 8.06 ppm belonging to pro-
three protons of methyl group at C-3 of quinoxaline ton of amide linkage. A multiplet at 7.67–7.77 ppm
ring. A singlet at 9.1 ppm confirmed cyclic amide (J = 3–7.5 Hz) confirmed four quinoxaline protons at
proton. FT-IR spectrum of compound (1) showed C-5, C-6, C-7 and C-8. A multiplet at 7.41–7.53 ppm
prominent peaks at 762 cm−1, 1390 cm−1, 1500 cm−1, (J = 2.7–8.1 Hz) confirmed five aromatic protons of
1544 cm−1, 1688 cm−1, 3314 cm−1 belonging to ortho- phenyl group attached to imine linkage. A singlet at
disubstituted aromatic ring, C–N, aromatic C=C, (-NH 5.42 ppm confirmed two protons of CH2CO at N-1
(bend)), >C=O, -NH (str.), respectively. 1H-NMR of quinoxaline ring. A singlet at 5.03 ppm confirmed
spectrum of ethyl-[3-methyl-2-oxo-quinoxaline-1- proton of imine linkage with CH2CO group. A sing-
yl]acetate (2) showed a doublet at 7.73–7.76 ppm (J = let at 2.54 ppm confirmed three protons of methyl
8.1 Hz) belonging to proton at C-5 of quinoxaline group attached to C-3 of quinoxaline ring. FT-IR spec-
ring. A triplet at 7.53–7.55 ppm (J = 3.9–4.2 Hz) trum of compound (4a) showed prominent peaks−a1t
belonged to one proton at C-6 of quinoxaline ring. 723 cm−1, 769 cm−1, 854 cm−1, 964 cm−1, 1199 cm ,
A doublet at 7.43–7.46 ppm (J = 3 Hz) confirmed 1388 cm−1, 1542 cm−1, 1650 cm−1, 1729 cm−1,
another proton at C-8 of quinoxaline ring. A triplet at 2345 cm−1, 3244 cm−1 confirming mono-substituted
7.31–7.36 ppm (J = 6.6–8.4) also confirmed another aromatic ring, ortho-disubstituted aromatic ring, aro-
proton at C-7 of quinoxaline ring. A quartlet at 4.11– matic C=C, aromatic =C–H (bend), =C–N, C–N, -NH
4.18 ppm confirmed two protons of methylene group (bend), CH=N, CH=N, >C=O, N–N=, -NH (str.),
of ethoxy group attached to ester linkage at N-1 of respectively. 1H-NMR spectrum of N-(3-chloro-2-oxo-
quinoxaline ring. A singlet at 3.38 ppm confirmed two 4-phenylazetidin-1-yl)-2-(3-methyl-2-oxoquinoxalin-
methylene protons of CH2CO group attached at N-1 1(2H)-yl)acetamide (5a) showed a singlet at 8.17 ppm
of quinoxaline ring. A singlet at 2.39 ppm confirmed belonging to amide group. A multiplet at 7.77–
three protons of methyl group at C-3 of quinoxaline 7.87 ppm (J = 1.5–7.8 Hz) confirmed four quinoxaline
ring. A triplet at 1.14–1.19 ppm confirmed three methyl protons at C-5, C-6, C-7 and C-8. A multiplet at 7.52–
protons of ethoxy group attached to CH2CO at N-1 7.58 ppm belonged to five aromatic protons of phenyl
of quinoxaline ring. FT-IR spectrum of compou−n1d group attached to C-4 of azetidinone ring. A singlet at
(2) showed prominent peaks at 763 cm−1, 962 cm , 5.42 ppm belonged to two protons of CH2CO attached
1199 cm−1, 1285 cm−1, 1380 cm−1, 1645 cm−1, to N-1 of quinoxaline ring. A singlet at 2.55 ppm
1750 cm−1, 2745 cm−1 belonging to ortho-disubstituted belonged to three protons of CH3 at C-3 of quinoxaline
aromatic ring, aromatic =C–H (bend), (=C–N, C–O ring. A singlet at 3.16 ppm confirmed one proton at C-3
(coupled with H–C–H)), C–N, CH=N, >C=O, C–C of azetidinone ring, while another singlet at 4.10 ppm
1
bond respectively. H-NMR spectrum of 3-methyl-2- confirmed one proton at C-4 of azetidinone ring. FT-IR
oxo-quinoxaline-1(2H)-acetohydrazide (3) showed a spectrum of compound (5a) showed prominent peaks at
doublet at 7.72–7.75 ppm (J = 7.8 Hz) belonging to 726 cm−1, 765 cm−1, 854 cm−1, 961 cm−1, 1195 cm−1,
one proton at C-5 of quinoxaline ring. A triplet at 7.49– 1388 cm−1, 1285 cm−1, 1665 cm−1, 1545 cm−1,
7.54 ppm (J = 6.3–9 Hz) belonged to another proton at 1730 cm−1, 3244 cm−1 confirming mono-substituted
C-8 of quinoxaline ring. A quartlet at 7.26–7.35 ppm aromatic ring, ortho-disubstituted aromatic ring,

138
Shiv Kumar et al.
aromatic C=C, aromatic =C–H (bend), =C–N, C–N, compounds 5g and 5j having 4-N(CH3)2-C6H4 and
CH–Cl (str.), -NCO (str.), -NH (bend), >C=O, -NH 3-OH-4-OCH3-C6H3 groups on 4-position of azetidi-
(str.), respectively. ESI-MS of compound (5a) showed none ring exhibited better activity. Azetidinone deriva-
M∗+ at m/z 396.8. Similarly, structures of all the newly tives with 4-N(CH3)2-C6H4 (5g) and 4-CF3-C6H4 (5h)
synthesized were confirmed.
on 4-position of azetidinone ring showed better activity
while compounds 5i, 5k and 5l having 2-OH-C6H4, 2-
F-C6H4 and 2-Cl-C6H4, respectively exhibited minimal
activity.
3.2 Biological activity
Compounds 5b, 5d, 5g and 5h having 4-Cl, 4-
NO2, 4-N(CH3)2 and 4-CF3, respectively on phenyl ring
attached to 4-position of azetidinone ring attached to
N-atom of acetamido group on 1-position of 3-methyl-
2-oxo-quinoxaline-1(2H)-acetamide were found to be
more active against all the bacterial strains under inves-
tigation. Compound 5g was also found to be more
active against all bacterial and fungal strains under
investigation.
All the newly synthesized compounds have been eval-
uated for their antibacterial activity against E. coli, S.
aureus, K. pneumoniae, P. aeruginosa and antifungal
activity against C. albicans, A. niger and A. flavus.
In the present communication, we have concentrated
on ‘the effect of various substituents on phenyl ring
attached at 4-position of azetidinone nucleus attached
to N-atom of acetamido functionality on 1-position of
3-methyl-2-oxo-quinoxaline-1(2H)-acetamide’.
Against E.coli, compounds with 4-Cl (5b), 4-NO2
(5d), 4-N(CH3)2 (5g), 4-CF3 (5h), 3-OH-4-OCH3 (5j)
on phenyl ring attached to 4-position of azetidinone
ring on the above said position have shown better
activity, while compounds with functionalities unsub-
stituted phenyl ring (5a), 4-OH (5c), 4-OCH3 (5e),
3,4-(OCH3)2 (5f), 2-OH (5i), 2-F (5k) on the phenyl
ring attached to azetidinone ring have exhibited mode-
rate activity. Among azetidinone derivatives, com-
pounds with 4-Cl (5b), 4-OH (5c), 4-NO2 (5d), 4-
N(CH3)2 (5g), 4-CF3 (5h), 3-OH-4-OCH3 (5j) on the
phenyl ring attached at above mentioned position have
shown better activity against S. aureus. While, com-
pounds with 4-OCH3 (5e), 3,4- (OCH3)2 (5f), 2-OH
(5i), 2-F (5k), 2-Cl (5l) exhibited intermediate acti-
vity against S. aureus. Against K. pneumoniae, com-
pounds with functional groups 4-Cl (5b), 4-OH (5c),
4-NO2 (5d), 4-N(CH3)2 (5g), 4-CF3 (5h) on phenyl
ring attached to 4-position of azetidinone ring exhi-
bited better activity. Compounds 5i having 2-OH-C6H4
on 4-position of azetidinone ring has shown minimal
activity against K. pneumoniae. Most of newly synthe-
sized compounds have shown good antibacterial acti-
vity against P. aeruginosa. Compounds having 4-Cl
(5b), 4-OH (5c), 4-NO2 (5d), 4-N(CH3)2 (5g), 4-CF3
(5h), and 3-OH-4-OCH3 (5j) on phenyl ring attached
to above mentioned positions at azetidinone ring exhi-
bited better activity. Against fungal strains C. albicans,
A. niger, A. flavus, most of the newly synthesized com-
pound exhibited moderate activity. Azetidinone deriva-
tives with 4-OH (5c), 4-N(CH3)2 (5g), 4-CF3 (5h) and
3-OH-4-OCH3 (5j) groups on phenyl ring have been
found to be more active, while, compound 5l having
2-Cl-C6H4 group on respective position on azetidinone
nucleus exhibited minimal activity. Against, A. niger,
4. Conclusion
All the synthesized compounds were evaluated for
their antibacterial activity against E. coli, S. aureus,
P. aeruginosa, K. pneumoniae and antifungal activity
against C. albicans, A. niger and A. flavus using cup-
plate method. 2-(3-Methyl-2-oxoquinoxalin-1(2H)-
yl)acetamide-based azetidinone derivatives having
aromatic phenyl ring substituted with 4-Cl, 4-NO2, 4-
N(CH3)2 and 4-CF3 exhibited better activity against all
the bacterial strains under investigation. 2-(3-Methyl-2-
oxoquinoxalin-1(2H)-yl)acetamide-based azetidinone
derivatives having aromatic phenyl ring substituted
with 4-N(CH3)2 (5g) was found to be most active
against all bacteria and fungi under investigation. These
compounds may act as lead for future investigation.
References
1. Grande F, Aiello F, Grazia O D, Brizzi A, Garofalo A
and Neamati N 2007 Bioorg. Med. Chem. 15 288
2. Amin K M, Ismail M M F, Noaman E, Soliman D H and
Ammar Y A 2006 Bioorg. Med. Chem. 14 6917
3. Zarranz B, Jaso A, Aldana I and Monge A 2004 Bioorg.
Med. Chem. 12 3711
4. Lee H, Cho S, Namgoong K, Jung JK and Yang S 2004
Bioorg. Med. Chem. Lett. 14 235
5. Diana P, Martorana A, Barraja P and Montalbaro A 2008
J. Med. Chem. 51 2387
6. Chung H J, Jung O J, Chae M J, Hong S Y, Chung K H
and Lee SK 2005 Bioorg. Med. Chem. Lett. 15 3380
7. Katsuyuki A, Obata T, Yamazaki Y, Mori Y, Hirokawa
H, Koseki J, Hattori T, Niitsu K, Takeda S, Aburada M
and Miyamoto K 2007 Chem. Pharm. Bull. 55 255
8. Carta A, Loriga M, Paglietti G, Mattana A, Fiori PL,
Mollicotti P, Sechi L and Zanetti S 2004 Eur. J. Med.
Chem. 39 195

Synthesis of 2-(3-methyl-2-oxoquinoxalin-1(2H)-yl)acetamide-based azetidinones as potent antimicrobial agents 139
9. Carta A, Paglietti G, Nikookar M E R, Sanna P, Sechi L 18. Seitz L E, Suling W J and Reynolds R C 2002 J. Med.
and Zanetti S 2002 Eur. J. Med. Chem. 37 355
Chem. 45 5604
10. Tandon V K, Yadav D B, Maurya H K, Chaturvedi 19. Burguete A, Pontiki E, Litina D H, Villar R, Vicente
A K and Shukla P K 2006 Bioorg. Med. Chem. 14
6120
E, Solano B, Ancizu S, Aldana I and Monge A 2007
Bioorg. Med. Chem. Lett. 17 6439
11. Kotharkar S A and Shinde D B 2006 Bioorg. Med. 20. El-Bendary E R, Goda F E, Maaronf A R and Badria F
Chem. Lett. 16 6181 A 2004 Sci. Pharm. 72 175
12. Mashevskaya I V, Makhmudov R R, Aleksandrova G A, 21. Ceric´ H, Šindler-Kulyk M, Kovacˇevic´ M, Peric´ M and
Golovnira O V, Duvalov A V and Maslivets A N 2001
Pharm. Chem. J. 35 196
13. Mashevskaya I V, Tolmacheva I A, Voronova E V,
Odegova T F, Alkeksandrova G A, Goleneva A F,
Kot’tsova S V and Maslivets A N 2002 Pharm. Chem. J.
36 86
14. Vyas D A, Chauhan N A and Parikh A R 2007 Indian J.
Chem. 46B 1699
15. Jaso A, Zarranz B, Aldana I and Monge A 2003 Eur. J.
Med. Chem. 38 791
16. Zarranz B, Jaso A, Aldana I and Monge A 2003 Bioorg.
Med. Chem. 11 2149
17. Jaso A, Zarranz B, Aldana I and Monge A 2005 J. Med.
Chem. 48 2019
Živkovic´ A 2010 Bioorg. Med. Chem. 18 3053
22. Patel J A, Mistry B D and Desai K R 2008 Indian J.
Chem. 47B 1695
23. Kumar S, Khan S A, Alam O, Azim R, Khurana A,
Shaquiquzzaman M, Siddiqui N and Ahsan W 2011
Bull. Korean Chem. Soc. 32 2260
24. Zarei M and Mohamadzadeh M 2011 Tetrahedron 67
5832
25. Abell A D and Oldham M D 1999 Bioorg. Med. Chem.
Lett. 9 497
26. Annunziata R, Benaglia M, Cinquini M, Cozzi F and
Puglisi A 2002 Bioorg. Med. Chem. 10 1813
27. Mehta P D, Sengar N P S and Pathak A K 2010 Eur. J.
Med. Chem. 45 5541