Synthesis and Evaluation of Novel 5-cyclohexyl-2-(4″-substitutedphenyl)-3-(2″-substitutedphenyl)4H-2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-dione Derivatives for Their In Vitro Antioxidant and Antibacterial Activities

Article abstract of DOI:10.1002/jhet.2543

1,3-Dipolar cycloaddition reactions of N-cyclohexyl maleimide (1) with azomethine N-oxide (2) have afforded novel isoxazolidine (3) in excellent yield. Their structures have been characterized from their IR,¹H-NMR,¹³C-NMR,¹H,¹H-COSY, MS(ESI), and elemental analysis techniques. In vitro antibacterial activity of the synthesized compounds were investigated against a representative panel of pathogenic strains specifically two Gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes) and two Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) using agar-well diffusion assay. Some of the compounds (3a, 3k, 3n, and 3o) exhibited promising antibacterial activities. All the synthesized compounds have also been screened for their antioxidant activities and were found to be significantly active.

Full text of DOI:10.1002/jhet.2543

Month 2015 Synthesis and Evaluation of Novel 5-cyclohexyl-2-(4″-substitutedphenyl)-
3-(2″-substitutedphenyl)4H-2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]
isoxazole-4,6-dione Derivatives for Their In Vitro Antioxidant
and Antibacterial Activities
*
Manpreet Kaur, Anjandeep Kaur, Baldev Singh, and Baljit Singh
Department of Chemistry, Punjabi University, Patiala 147002, India
*
E-mail: manpreet21044@gmail.com
Received June 4, 2015
DOI 10.1002/jhet.2543
Published online 00 Month 2015 in Wiley Online Library (wileyonlinelibrary.com).
1,3-Dipolar cycloaddition reactions of N-cyclohexyl maleimide (1) with azomethine N-oxide (2) have
afforded novel isoxazolidine (3) in excellent yield. Their structures have been characterized from their IR,
1H-NMR, 13C-NMR, 1H,1H-COSY, MS(ESI), and elemental analysis techniques. In vitro antibacterial
activity of the synthesized compounds were investigated against a representative panel of pathogenic strains
specifically two Gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes) and two
Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) using agar-well diffusion assay.
Some of the compounds (3a, 3 k, 3n, and 3o) exhibited promising antibacterial activities. All the synthesized
compounds have also been screened for their antioxidant activities and were found to be significantly active.
J. Heterocyclic Chem., 00, 00 (2015).
INTRODUCTION
excessive oxidative stress [2,3]. Their presence in the bio-
logical system is very harmful as these species are respon-
sible for the damage of biomolecules like nucleic acid,
proteins, lipids, DNA, and carbohydrates [4] and which
may cause many diseases such as cancer, atherosclerosis,
aging, hair loss, inflammation, immunosupresssion, dia-
betes, and neurodegenerated disorders (Alzheimer’s and
Parkinson’s diseases) [5–8]. The balance between the pro-
duction and elimination of ROS is normally controlled by
the body defence mechanism through the use of different
enzymes such as superoxide dismutase, catalase, and gluta-
thione peroxidase. However, when it is disturbed oxidative
stress is generated leading to oxidative damage to biomol-
ecules. Antioxidants are compounds which slow down the
oxidation of other molecules [9,10]. They interact with free
Free radicals are reactive oxygen and nitrogen species
with odd electron (ROS/RNS), which are continuously
produced in human body as a byproduct of cellular aerobic
respiration. Over production of ROS/RNS leads an expo-
sure to external oxidant substances, failure in the defence
mechanism or damage to biomolecules such as DNA,
lipids, or proteins [1]. Antioxidants are the agents capable
of effectively neutralizing these free radicals by interfering
with oxidative process, chelating catalytic metals, and also
by acting as oxygen scavengers. Reactive oxygen species
(ROS) such as hydroxyl radicals, superoxide radicals,
singlet oxygen, and hydrogen peroxide radical are con-
stantly formed as a result of normal organ functions or
© 2015 HeteroCorporation

M. Kaur, A. Kaur, B. Singh, and B. Singh
Vol 000
radicals and prevent the damage by ROS. Thus, the treat-
ment with antioxidants is potentially a way to overcome
the oxidative stress. Because of this, there is a great interest
in the discovery of natural and synthetic antioxidants,
which can serve as protective agents against these diseases.
Pyrrolo-isoxazolidine compounds are known for their
antimicrobial and antioxidant behavior. These act as free
radical scavengers, and their antioxidant potential depends
on the substituent present. Pyrrolo-isoxazolidine deriva-
tives have been reported as broad spectrum antibiotic as
they are highly active for many Gram-positive bacteria
(Staphylococcus aureus, Staphylococcus epidermidis,
and Enterococcus faecalis) and Gram-negative bacteria
(Escherchia coli and Pseudomonas aeruginosa) and have
also shown antifungal activity against Candida albican,
Candida galabrata, and Candida parapsilosis [11]. Amino-
substituted and chloro-substituted pyrrolo-isoxazolidines have
also been reported to be active against bacteria Vibrio
parahaemolyticus, Streptococcus pyogenes, Proteus vulgaris,
Shingella flexneri, Salmonella typhi, and Vibrio cholera [12].
Pyrrolo-isoxazolidine derivatives also exhibit a wide
array of biological activities like anti-HIV [13], antimicro-
bial [14], antistress [15], advanced glycation end product
formation inhibitory activity [16], antiamnestic [17], and
antioxidant [18–20]. The other isoxazole and isoxazolidine-
3,5-dione derivatives have been used as antidiabetic [21],
anticancer [22], and antitubercular agents [23] followed by
the synthesis of target compounds and their in vitro antioxi-
dant and antibacterial screening. Therefore, the present study
was designed to synthesize variously substituted pyrrolo-
isoxazolidines and to evaluate their antioxidant and antibac-
terial activities.
derivatives (3a–o) (Table 1), which have been characterized
through their melting point, elemental analysis, IR, 1H-
NMR, 13C-NMR, 1H,1H-COSY, and mass spectral studies.
All the compounds have given satisfactory results for their
elemental analysis. In the IR spectrum of 5-cyclohexyl-
2,3-diphenyl-4H-2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]
isoxazole-4,6-dione (3a), a strong absorption band in the region
of 1778cmꢀ1 and a shoulder band in the region of 1709cmꢀ1
have been assigned to the two carbonyl stretching vibrations
of succinimide moiety. Absorption band in the region of
1595cmꢀ1 has been assigned to aromatic carbon–carbon
double bond skeletal stretching vibrations.
In the 1H-NMR spectrum, compound 3a displayed
two doublets at δ 4.83 with J = 9.16Hz and δ 5.17 with
J = 7.76Hz, respectively, for protons C3-H and C6a-H on
coupling with proton C3a-H. Proton C6a-H appeared down-
field in comparasion to proton C3-H because of electroneg-
ative oxygen atom attached to C6a-H. Aromatic protons
appeared as multiplets in the range of δ 7.33–7.01 (equiv-
alent to 10H). A poorly resolved quartet appeared as triplet
at δ 3.93 (J =8.88 Hz and J = 8.00Hz) has been assigned to
proton C3a-H, and a multiplet in the range of δ 3.77–3.70
has been assigned to proton of cyclohexyl ring attached
to nitrogen atom because of coupling with ortho-protons.
While a multiplet in the range of δ 1.96–1.06 (equivalent
to 10H) has been assigned to aliphatic protons of
cyclohexyl moiety. In the 13C-NMR spectrum, compound
3a displayed the characteristic signals at δ 174.38 and δ
172.35, which have been assigned to two succinimide car-
bonyl carbons. The signals in the range of δ 147.13–119.07
has been assigned to aromatic carbons. Another two
signals at δ 76.43 and δ 69.60 have been assigned to C6a
and C3a carbon atoms, respectively. A signal at δ 53.72
has been assigned to C3 carbon. A signal at δ 50.91 has
been assigned to carbon of cyclohexyl ring directly at-
tached to nitrogen atom. The signals in the range of δ
28.41–24.64 have been assigned to five methylenic car-
bons of cyclohexyl moiety. Only one isomer has been
obtained in all cases as evidenced by thin layer chromatog-
raphy (TLC) analysis showing single spot in each case. In
RESULTS AND DISCUSSION
Chemistry.
The synthesis of variously substituted
pyrrolo-isoxazolidine have been carried out by 1,3-dipolar
cycloaddition reactions of N-cyclohexyl maleimide (1) and
azomethine N-oxide (2). The starting compounds, N-
cyclohexyl maleimide (1) (Scheme 1) and azomethine N-
oxide (2) (Scheme 2), were synthesized by following the
similar procedure as reported in literature. On refluxing, an
equimolar quantities of N-cyclohexyl maleimide (1) and
azomethine N-oxide (2) in sodium dried toluene provided 5-
cyclohexyl-2-(4″-substitutedphenyl)-3-(2″-substitutedphenyl)-
4H-2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-dione
1
the H,1H-COSY spectrum of 3a (Fig. 1), the presence of
off diagonal cross peaks from protons C3a-H/C3-H at δ
3.93/4.83 and C3a-H/C6a-H at δ 3.93/5.17 indicate the
“syn” geometry of all the three protons.
In these cycloaddition reactions the preferred orientation
of the azomethine N-oxide at the transition state seems to
Scheme 1. Schematic diagram describing the steps in the synthesis of N-cyclohexyl maleimide.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2015
Synthesis and Evaluation of Novel Pyrrolo-isoxazole-4,6-dione Derivatives for Their
In Vitro Antioxidant and Antibacterial Activities
Scheme 2. Schematic diagram describing the synthesis of 5-cyclohexyl-2-(4″-substitutedphenyl)-3-(2″-substitutedphenyl)-4H-2,3,3a,5,6,6a-
hexahydropyrrolo[3,4-d]isoxazole-4,6-dione derivatives.
Table 1
Characterization data of 5-cyclohexyl-2-(4″-substituted phenyl-3-(2″-
substituted phenyl)4H-2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-
4,6-dione derivatives (3a–o).
Melting point
(°C)
Compounds
X
Y
Yielda (%)
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
ꢀH
ꢀH
65
69
72
68
70
75
68
74
66
64
76
65
67
71
77
168–169
193–195
192–196
182–185
185–188
172–174
192–194
200–202
186–188
203–205
175–177
195–198
174–176
210–211
207–209
1
1
ꢀH
ꢀCl
Figure 1. The 400 MHz H, H-COSY spectrum of representative com-
pound 3a in DMSO-d6.
ꢀH
ꢀNO2
ꢀCH3
ꢀOCH3
ꢀH
ꢀH
ꢀH
ꢀCl
of imide nucleus come parallel to each other in addition
to the primary interaction leading to the π-electron overlap
of the reacting atoms of dipole and dipolarophile. It has
been found also from the study of dreiding models (Fig. 2)
that the cis-isomer is the most favored conformation as in
this case non-bonded-steric interactions are almost absent
as compared with the exo-transition state where no such
secondary interaction stabilization appears to occur, thus
showing only the formation of cis-isomer. This is further
ꢀCl
ꢀCl
ꢀCl
ꢀNO2
ꢀCH3
ꢀOCH3
-H
ꢀCl
ꢀCl
-CH3
ꢀCH3
ꢀCH3
ꢀCH3
ꢀCH3
ꢀCl
ꢀNO2
ꢀCH3
ꢀOCH3
aIsolated yield of the pure compound.
1
supported by the H-NMR data, where the protons C3-H,
C3a-H and C6a-H appear as doublet, poorly resolved quar-
tet, and doublet, respectively, and their corresponding J
values falling in the range of cis-orientation of the protons
confirming that all three protons lie on one side thus only
cis-isomer is formed.
be more thermodynamically stable “anti” one where steric
interactions are minimum (Fig. 2). As the dipole and
dipolarophile approach each other there occurs primary as
well as secondary interactions between the two substrates.
The more favored orientation of the azomethine N-oxide
results in the formation of the cis-isomer only, perhaps be-
cause of the steric requirements alone, where maximum
double bond accumulation occurs and the transition state
follows “endo addition rule.” In this transition state C-
phenyl nucleus of dipole and one of the carbonyl groups
Biological activities. Assay for DPPH radical scavenging
activity. In the present study, the antioxidant activity of
the synthesized compounds was assessed in vitro by the
1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging
assay [24–27]. The absorbance values were taken at
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Kaur, A. Kaur, B. Singh, and B. Singh
Vol 000
Figure 2. Possible transition states of synthesized derivatives (3a–o).
seven different concentrations (0.25, 0.54, 0.88, 1.37, 2.50,
5.00, and 7.50 μg/mL) of the tested compounds with DPPH
at 517nm. The ethanolic solution of DPPH was added to
the solution of the synthesized compounds in ethanol.
After 30-min incubation in dark the absorbance was
measured against ethanol as blank. Butylated hydroxyl
toluene (BHT) was used as reference. The DPPH has
an odd electron so it can accept an electron-free or
hydrogen-free radical. In the presence of antioxidant, this
odd electron becomes paired because of proton transfer
from antioxidant and hence DPPH absorbance decreases.
The antioxidant activity was calculated as follows:
the compound with p-CH3 substitution on this ring. Com-
pounds 3n, 3d, 3k, and 3b and 3e showed relatively high
antioxidant power while, compound 3j displayed least
antioxidant potency. Interestingly, in antioxidant activity,
highly efficient antioxidant members 3d, 3i, and 3n were
having methyl substitution on the C-phenyl ring.
In vitro antibacterial assay.
The antibacterial activity
[28] of the synthesized compounds (3a–o) were evaluated
(Table 3) using P. aeruginosa MTCC-424, Escherichia
coli MTCC-1687 (Gram-negative bacteria) and S. aureus
MTCC-96, S. pyogenes MTCC-442 (Gram-positive
bacteria) by well diffusion assay. An aliquot 0.1mL of
each bacterial strain was spread on nutrient agar. An agar-
well diffusion test was performed in each case. In these
tests, 6 mm wells were produced by using a sterile cork
borer and each well was then inoculated with 100 μL of
each key substance in DMF, resulting in a final
concentration of 1000 μg/mL. Nutrient agar plates were
incubated at 37°C for 24h. The zone of inhibition around
the well was determined. Ampicillin was used as the
reference antibacterial agent. In antibacterial activity, all
the synthesized compounds showed good zone of
inhibition against S. aureus. Compounds 3n, 3o, and 3a
showed significant activity against S. aureus, and
compound 3k exhibited maximum inhibitory potential
against P. aeruginosa.
%Activity ¼ ½ðAo ꢀ AiÞ=Aoꢁꢂ100
where Ao and Ai are the absorbances in the absence and
presence of tested compounds, respectively. The IC50
values were also determined for all the compounds by lin-
ear regression method. Figures 3 and 4 depict the percent-
age antioxidant activity at various concentrations and IC50
of the synthesized compounds (3a–o). All the samples
(3a–o) showed free radical scavenging ability. The data
from Table 2 revealed that all the synthesized compounds
exhibited good DPPH free radical scavenging activity
compared with standard antioxidant (BHT). These results
indicated the potential electron donating ability of the
samples.
Among all the synthesized compounds the compounds
with p-CH3 substituent on the N-phenyl ring of the
succinimide moieties 3k, 3l, 3n, and 3o were found to be
exceedingly potent in comparison to the compound with
p-Cl substitution on these rings 3f, 3g, 3i, and 3j. Further-
more, among ꢀNO2 substituted compounds on the ortho-
position of C-phenyl ring of the succinimide moieties 3h
and 3m the compounds with p-Cl group on the N-phenyl
ring were comparatively more potent as compared with
CONCLUSION
A series of novel pyrrolo-isoxazole derivatives exhibited
significant antibacterial activity against Gram-positive bac-
terium S. aureus which can show innate resistance to many
antibiotics and disinfectants. In general, it was found that
the compounds 3n, 3o, and 3k displayed potent antioxidant
and antibacterial activities.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2015
Synthesis and Evaluation of Novel Pyrrolo-isoxazole-4,6-dione Derivatives for Their
In Vitro Antioxidant and Antibacterial Activities
Figure 3. Graphical presentation of in vitro DPPH radical scavenging activity of compounds (3a–o) relative to the standard antioxidant BHT.
[Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
Figure 4. Graphical presentation of the IC50 values in μg/mL for the antioxidant activity of the compounds (3a–o) measured at various concentrations.
[Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]
EXPERIMENTAL
thus obtained, was further cyclized to maleimides in acetic
anhydride in the presence of anhydrous sodium acetate
under reflux for 1.5h. The reaction mixture was then
poured in ice cold water and kept it for an overnight period
o afford the solid which was filtered and washed with water
to give the N-cyclohexyl maleimide (1) and subsequently
recrystallized from petroleum ether (Scheme 1).
General procedure for synthesis of N-phenylhydroxylamine.
A mixture of para-substituted nitrobenzene (0.04mol)
ammonium chloride (0.04mol) was placed in 500mL
beaker containing 100mL of water. Zinc dust (0.08mol)
was added in portions to the stirring mixture such that the
temperature of mixture does not rise above 60–70°C. The
stirring was continued further for a period of 15min until
the whole zinc dust was reduced. The reaction mixture was
filtered at the suction pump. The filtrate was extracted with
chloroform and used immediately for the next reaction.
All the melting points are uncorrected. IR spectra were
recorded on a Perkin Elmer RXIFT infrared spectropho-
tometer using KBr pellets. 1H-NMR and 1H,1H-COSY
spectra were recorded on 400 MHz Bruker avance spec-
trometer using TMS as internal standard. 13C-NMR spectra
were recorded on 100MHz Bruker avance spectrometer
using TMS as internal standard. MS (ESI) were recorded
on Waters Micromass Q-TOF of Micro (LC-MS) spectrom-
eter. TLC plates were coated with silica gel-G suspended in
methanol-chloroform. Elemental analysis was carried out
using Elementar vario MICRO cube CHN analyzer.
General procedure for synthesis of N-cyclohexyl maleimide
(1). Equimolar quantities of N-cyclohexylamine and maleic
anhydride were stirred in toluene at room temperature for 1h
to yield N-cyclohexyl maleanilic acid. The maleanilic acid,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Kaur, A. Kaur, B. Singh, and B. Singh
Vol 000
Table 2
Percentage of in vitro radical scavenging activity of synthesized compounds (3a–o).
Concentrations (μg/mL)
Compounds
0.25
0.54
0.88
1.37
2.50
5.00
7.50
IC50
3a
3b
3c
3d
3e
0.00
10.64
5.09
50.00
39.33
56.87
43.08
42.64
41.91
41.41
43.43
44.95
56.09
41.03
54.09
42.90
37.31
41.91
4.62
66.20
53.65
59.67
56.09
51.87
51.73
53.43
55.78
52.65
54.98
43.08
54.67
59.70
54.66
51.73
11.56
78.00
63.00
68.09
65.09
67.09
68.00
60.06
65.76
73.00
62.06
60.89
66.98
70.00
61.00
68.00
23.12
91.28
82.43
74.51
89.08
78.90
86.63
79.63
76.54
92.63
83.09
70.76
64.63
80.60
81.31
86.63
30.11
97.70
89.43
82.34
84.09
83.84
91.23
69.63
82.86
93.43
88.09
81.82
83.87
88.80
83.21
91.23
44.71
97.77
91.16
89.09
94.80
95.65
93.23
82.32
93.09
85.63
99.97
90.90
94.94
90.21
89.12
93.23
55.22
0.57
0.49
0.63
0.46
0.61
0.53
0.61
0.56
0.50
0.66
0.49
0.57
0.62
0.41
0.53
5.37
3.08
13.65
12.67
6.54
11.98
11.32
11.76
13.09
12.98
17.48
0.06
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
BHTa
12.67
-
No Activity
aButylated hydroxytoluene as standard substance.
Table 3
In vitro antibacterial activity (zone of inhibition in mm) of synthesized compounds (3a–o).
Gram-negative bacteria
Pseudomonas aeruginosa
Gram-positive bacteria
Compounds
Escherichia coli
Staphylococcus aureus
Streptococcus pyogenes
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
2
0
5
5
11
1
4
0
2
10
21
11
6
12
13
14
5
5
6
6
6
6
7
5
7
6
7
6
7
12
5
20
21
14
12
12
12
15
14
11
13
17
10
12
19
24
23
12
8
7
6
6
8
6
2
6
7
8
9
7
6
9
7
15
Ampicillin
General procedure for synthesis of azomethine N-oxide (2).
To the above para-substituted N-phenylhydroxylamine
(0.01 mol), the mixture was added ortho-substituted
benzaldehyde (0.01 mol) and the reaction mixture was
stirred for about 1h with mechanical stirrer. The color of
reaction mixture changed from light yellow to mustard
yellow indicating the completion of reaction. Crude
solid precipitated out, which was filtered, dried, and
recrystallized from ethanol. The synthesis of product was
confirmed by TLC, and melting points of the nitrones (2)
obtained (Scheme 2).
General procedure for cycloadditions (3a–o). An oven-
dried flask was cooled under a stream of nitrogen and
charged with variously substituted N-cyclohexyl
maleimides (1) (1.79g, 0.01mol) and azomethine N-oxide
(2) in sodium dried toluene (25mL). The contents in the
flask were refluxed for 4–4.5h until the substrates were
consumed as judged by TLC. On completion of reaction
the reaction mixture was cooled under the tap water. The
crude product that separated was filtered and recrystallized
from toluene–petroleum ether (1:1) to give cycloadduct (3)
(Scheme 2).
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2015
Synthesis and Evaluation of Novel Pyrrolo-isoxazole-4,6-dione Derivatives for Their
In Vitro Antioxidant and Antibacterial Activities
1H-NMR (400MHz, DMSO-d6) δ 5.18 (d, J=7.76 Hz), 4.86
(d, J=9.12 Hz), 3.94 (t, 1H, J=8.32Hz and J=8.60Hz),
7.34–7.01 (m, 9H), 3.74–3.68 (m, 1H), 2.10–1.20 (m, 10H),
3.68 (s, 3H); 13C-NMR (100MHz, DMSO-d6), δ 175.00,
173.79, 154.28, 149.42, 128.64, 128.59, 126.86, 125.37,
121.58, 118.83, 115.02, 113.35, 77.22, 70.20, 63.93, 54.59,
51.10, 27.40, 27.06, 25.10, 24.61, 23.50; MS(ESI): m/z =407
[M + H]+. Anal. % Calcd for C24H26N2O4: C: 70.93, H: 6.16,
5-Cyclohexyl-2,3-diphenyl-4H-2,3,3a,5,6,6a-hexahydropyrrolo
[3,4-d]isoxazole-4,6-dione (3a). Compound obtained as white
solid, yield 65%; mp 168–169°C. IR (KBr pellets, ʋmax
/
cmꢀ1): 1709, 1778 (C¼O), 1595cmꢀ1 (C¼C); H-NMR
(400MHz, DMSO-d6): δ 5.17 (d, J=7.76Hz), 4.83 (d,
J=9.16Hz), 3.93 (t, J=8.88Hz and J=8.00Hz), 7.33–7.01
(m, 10H), 3.77–3.70(m, 1H), 1.96–1.06 (m, 10H); 13C-
NMR (100MHz, DMSO-d6), δ 174.38, 172.35, 147.13,
134.03, 132.85, 129.22, 128.48, 128.21, 124.53, 119.07,
76.43, 69.60, 53.72, 50.91, 28.41, 27.80, 25.27, 24.64; MS
(ESI): m/z= 377 [M+H]+. Anal. % Calcd for C23H24N2O3:
1
N: 6.9. Found: C: 70.99, H: 6.12, N: 6.93.
2-(4′-Chlorophenyl)-5-cyclohexyl-3-phenyl-4H-2,3,3a,5,6,6a-
hexahydropyrrolo[3,4-d]isoxazole-4,6-dione (3f). Compound
C: 73.60, H: 6.13, N: 7.46. Found: C: 73.59, H: 6.11, N: 7.48.
3-(2″-Chlorophenyl)-5-cyclohexyl-2-phenyl-4H-2,3,3a,5,6,6a-
hexahydropyrrolo[3,4-d]isoxazole-4,6-dione (3b). Compound
obtained as white solid, yield 75%; mp 172–174°C. IR
(KBr pellets,
ʋ
max/cmꢀ1): 1707, 1781cm-1 (C¼O);
1
1575cm-1 (C¼C); H-NMR (400MHz, CDCl3), δ 5.41 (d,
1H, J=7.74Hz), 4.88 (d, 1H, J=9.12Hz), 3.87 (t, 1H,
J=8.70Hz and J=8.44Hz), 7.91–6.82 (m, 9H), 3.71 (m,
1H), 2.00–1.09 (m, 9H); 13C-NMR (100MHz, CDCl3), δ
174.32, 173.42, 148.56, 148.16, 141.08, 132.75, 130.60,
129.35, 121.82, 114.11, 77.23, 68.75, 56.76, 52.54, 27.83,
27.68, 25.55, 25.34, 24.28; MS(ESI): m/z=411 [M+H]+.
Anal. % Calcd for C23H23ClN2O3: C: 67.48, H: 5.62, N:
obtained as white solid, yield 69%; mp 193–195°C. IR (KBr
1
pellets, ʋmax/cmꢀ1): 1708, 1782 (C¼O), 1565 (C¼C); H-
NMR (400MHz, CDCl3): δ 5.13 (d, J=7.76Hz), 4.79 (d,
J=9.04Hz), 3.93 (t, J=8.78Hz and 8.40Hz), 7.82–7.03
(m, 9H), 3.84–3.78 (m, 1H), 2.15–1.14 (m, 10H); 13C-
NMR (100MHz, CDCl3), δ 170.42, 170.10, 149.32,
148.43, 124.82, 123.55, 121.91, 121.34, 118.54, 116.46,
114.22, 112.28, 68.43, 64.24, 54.20, 52.05, 24.63, 24.25,
20.21, 20.08; MS(ESI): m/z=411 [M+H]+. Anal. % Calcd
for C23H23ClN2O3: C: 67.32, H: 5.36, N: 6.83. Found: C:
67.39, H: 5.32, N: 6.80.
6.84. Found: C: 67.50, H: 5.63, N: 6.83.
2-(4′-Chlorophenyl)-3-(2″-chlorophenyl)-5-cyclohexyl-4H-
2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-dione
(3g). Compound obtained as white solid, yield 68%; mp
5-Cyclohexyl-3-(2″-nitrophenyl)-2-phenyl-4H-2,3,3a,5,6,6a-
192–194°C. IR (KBr pellets, ʋmax/cmꢀ1): 1703, 1782
1
hexahydropyrrolo[3,4-d]isoxazole-4,6-dione (3c).
Compound
(C¼O); 1586 (C¼C); H-NMR (400MHz, CDCl3), δ 5.02
obtained as yellow solid, yield 72%; mp 192–196°C. IR
(KBr pellets, ʋmax/cmꢀ1): 1700, 1778 (C¼O), 1572 (C¼C);
1H-NMR (400MHz, DMSO-d6) δ 5.15 (d, J=7.72Hz), 4.90
(d, J=9.12Hz), 3.98 (t, J=8.70Hz and 8.38Hz), 8.31–7.02
(m, 9H), 3.82–3.77 (m, 1H), 2.24–1.10 (m, 10H); 13C-NMR
(100MHz, DMSO-d6), δ 174.34, 172.13, 147.36, 134.81,
128.31, 128.10, 127.97, 127.42, 124.24, 118.76, 112.62,
110.08, 76.34, 70.66, 53.76, 50.96, 28.37, 27.74, 25.26,
24.57, 23.20; MS(ESI): m/z =422 [M +H]+. Anal. % Calcd
for C23H23N3O5: C: 65.71, H: 5.24, N: 10.00. Found: C:
65.69, H: 5.20, N: 9.89.
(d, 1H, J=7.60Hz), 4.75 (d, 1H, J= 9.15 Hz), 3.92 (t, 1H,
J=8.62Hz and J=8.34Hz), 7.99–7.14 (m, 8H), 3.93 (m,
1H), 2.01–1.07 (m, 10H); 13C-NMR (100MHz, CDCl3), δ
170.52, 170.10, 149.32, 148.44, 124.86, 123.45, 121.79,
121.23, 118.85, 116.94, 112.82, 111.20, 68.35, 64.24,
54.00, 52.30, 24.36, 24.12, 20.82, 20.70; MS(ESI): m/z =445
[M+ H]+. Anal. % Calcd for C23H22Cl2N2O3: C: 62.16, H:
4.95, N: 6.30. Found: C: 62.12, H: 4.94, N: 6.28.
2-(4′-Chlorophenyl)-5-cyclohexyl-3-(2″-nitrophenyl)-4H-
2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-dione (3h).
Compound obtained as white solid, Yield 74%; mp 200–
5-Cyclohexyl-3-(2″-methylphenyl)-2-phenyl-4H-2,3,3a,5,6,6a-
202°C. IR (KBr pellets, ʋmax/cm-1): 1708, 1779 (C=O);
1
hexahydropyrrolo[3,4-d]isoxazole-4,6-dione (3d).
Compound
1592 (C=C); H-NMR(400 MHz, DMSO-d6), δ 5.15 (d,
obtained as white solid, yield 68%; mp 182–185°C. IR (KBr
1H, J= 7.74Hz); 4.92 (d, 1H, J= 9.00Hz); 3.83 (t, 1H,
J=8.72Hz and J= 8.36Hz); 7.87–6.73 (m, 8H), 3.75 (m,
1H), 2.20–1.02 (m, 10H); 13C-NMR (100 MHz, DMSO-d6),
δ 169.82, 169.32, 146.68, 129.42, 125.54, 124.48, 123.78,
123.54, 121.24, 121.10, 113.27, 110.68, 70.44, 68.76,
52.64, 51.41, 28.36, 28.22, 24.44, 24.30; MS(ESI): m/z=456
[M+H]+. Anal. % Calcd for C23H22ClN3O5: C: 60.65, H:
1
pellets, ʋmax/cmꢀ1): 1704, 1779 (C¼O), 1575 (C¼C); H-
NMR (400 MHz, DMSO-d6) δ 5.14 (d, J=7.80Hz), 4.98 (d,
J=9.02Hz), 3.78 (t, J=8.62Hz and J=8.42Hz), 7.98–7.71
(m, 9H), 3.70–3.62 (m, 1H), 2.11–1.20 (m, 10H), 2.53 (s,
3H); 13C-NMR (100MHz, DMSO-d6), δ 174.37, 173.15,
148.62, 148.13, 141.09, 132.75, 130.01, 129.34, 123.17,
123.15, 121.80, 114.17, 76.72, 68.71, 56.74, 52.50, 27.88,
27.69, 25.51, 25.49, 24.82, 24.20; MS(ESI): m/z =391 [M
+H]+. Anal. % Calcd for C24H26N2O3: C: 73.85, H: 6.41,
4.84, N: 9.23. Found: C: 66.64, H: 4.82, N: 9.25.
2-(4′-Chlorophenyl)-5-cyclohexyl-3-(2″-methylphenyl)-4H-
2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-dione (3i).
Compound obtained as white solid, yield 66%, mp 186–188°C.
IR (KBr pellets, ʋmax/cmꢀ1): 1702, 1779 (C¼O); 1583
N: 7.18. Found: C: 73.87, H: 6.42, N: 7.10.
5-Cyclohexyl-3-(2″-methoxyphenyl)-2-phenyl-4H-2,3,3a,5,6,6a-
hexahydropyrrolo[3,4-d]isoxazole-4,6-dione (3e). Compound
1
(C¼C); H-NMR (400MHz, DMSO-d6), δ 5.32 (d, 1H,
J= 7.75 Hz); 4.90 (d, 1H, J=9.15Hz); 3.86 (t, 1H,
J=8.88Hz and J= 8.44 Hz); 7.99–7.12 (m, 8H); 3.82 (m,
obtained as white solid, yield 70%; mp 185–188°C. IR (KBr
pellets, ʋmax/cmꢀ1): 1706, 1780 (C¼O), 1574 (C¼C);
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Kaur, A. Kaur, B. Singh, and B. Singh
Vol 000
1H); 2.20–1.20 (m, 10H); 2.52 (s, 3H); 13C-NMR
(100MHz, DMSO-d6), δ 174.02, 172.86, 151.24, 135.57,
128.22, 127.48, 126.59, 126.34, 120.26, 120.42, 112.58,
110.22, 70.00, 66.62, 52.47, 51.26, 28.28, 27.89, 25.44,
24.32, 24.20, 23.27; MS(ESI): m/z =425 [M+H]+. Anal. %
Calcd for C24H25ClN2O3: C: 67.92, H: 5.90, N: 6.60.
J=8.76Hz and J=8.32Hz); 8.04–7.02 (m, 8H); 3.82 (m,
1H); 1.94–1.04 (m, 10H); 9.34 (s, 1H); 2.54 (s, 3H); 13C-
NMR (100 MHz, DMSO-d6), δ 170.74, 170.42, 149.80,
143.24, 128.81, 128.26, 125.06, 125.20, 123.42, 122.88,
112.82, 111.81, 72.00, 70.08, 56.44, 52.64, 25.08, 25.45,
23.54, 23.27, 20.59, 19.82; MS(ESI): m/z=436 [M+H]+.
Anal. % Calcd for C24H25N3O5: C: 66.21, H: 5.75, N:
Found: C: 67.90, H: 5.88, N: 6.61.
2-(4′-Chlorophenyl)-5-cyclohexyl-3-(2″-methoxyphenyl)-4H-
2,3,3a,5,6,6a- hexahydropyrrolo[3,4-d]isoxazole-4,6-dione (3j).
9.66. Found: C: 66.25, H: 5.76, N: 9.70.
5-Cyclohexyl-2-(4′-methylphenyl)-3-(2″-methylphenyl)-4H-
2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-dione (3n).
Compound obtained as white solid, yield 64%; mp 203–
205°C. IR (KBr pellets, ʋmax/cmꢀ1): 1699, 1775 (C¼O);
Compound obtained as white solid, yield 71%; mp 210–
1
1577 (C¼C); H-NMR (400MHz, DMSO-d6), δ 4.98 (d,
211°C. IR (KBr pellets, ʋmax/cmꢀ1): 1704, 1775 (C¼O);
1
1575 (C¼C); H-NMR (400MHz, DMSO-d6), δ 5.19 (d,
1H, J= 7.72 Hz); 4.42 (d, 1H, J= 9.12 Hz); 3.89 (t, 1H,
J=8.72Hz and J=8.34Hz); 7.89–6.82 (m, 8H); 3.87 (m,
1H); 2.00–1.06 (m, 10H); 3.68 (s, 3H); 13C-NMR
(100MHz, DMSO-d6), δ 175.00, 173.38, 1544.2, 149.34,
128.76, 128.45, 126.78, 125.43, 121.55, 118.68, 115.00,
112.29, 74.43, 70.56, 63.92, 54.45, 51.21, 23.54, 23.32,
20.44, 20.43; MS(ESI): m/z=441 [M+H]+. Anal. % Calcd
for C24H25ClN2O4: C: 65.45, H: 5.68, N: 6.36. Found: C:
65.47, H: 5.66, N: 6.34.
1H, J= 7.76 Hz); 4.85 (d, 1H, J=9.16Hz); 3.86 (t, 1H,
J=8.8Hz); 7.88–7.02 (m, 8H); 3.78 (m, 1H); 1.92–1.04
(m, 10H); 9.32 (s, 1H); 2.53 (s, 3H); 13C-NMR (100MHz,
DMSO-d6), δ 174.00, 173.62, 154.04, 149.08, 127.61,
127.38, 126.22, 125.86, 121.20, 119.02, 114.08, 110.82,
72.35, 70.36, 52.76, 50.32, 25.38, 25.20, 24.33, 24.06,
21.42, 21.33, 19.18; MS(ESI): m/z=405 [M+H]+. Anal.
% Calcd for C25H28N2O3: C: 74.26, H: 6.93, N: 6.93.
Found: C: 74.22, H: 6.90, N: 6.91.
5-Cyclohexyl-3-(2″-methoxyphenyl)-2-(4′-methylphenyl)-
4H-2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-dione (3o).
5-Cyclohexyl-2-(4′-methylphenyl)-3-phenyl-4H-2,3,3a,5,6,6a-
hexahydropyrrolo[3,4-d]isoxazole-4,6-dione (3k).
Compound
obtained as white solid, Yield 76%; mp 175–177°C. IR
(KBr pellets, ʋmax/cmꢀ1): 1709, 1780 (C¼O); 1565 (C¼C);
1H-NMR (400 MHz, DMSO-d6), δ 5.00 (d, 1H, J=7.72Hz);
4.72 (d, 1H, J= 9.12Hz); 3.86 (t, 1H, J=8.66Hz and
J= 8.32Hz); 8.22–7.06 (m, 9H); 3.86 (m, 1H); 1.97–1.02 (m,
9H); 9.32 (s, 1H); 2.58 (s, 3H); 13C-NMR (100MHz,
DMSO-d6), δ 172.60, 172.14, 158.26, 146.54, 141.56,
128.96, 126.27, 123.21, 120.44, 118.64, 74.23, 70.62, 55.28,
49.88, 24.46, 24.36, 24.26, 22.44, 22.21; MS(ESI): m/z=391
[M+ H]+. Anal. % Calcd for C24H26N2O3: C: 74.04, H: 6.68,
Compound obtained as white solid, yield 77%; mp 207–
209°C. IR (KBr pellets, ʋmax/cmꢀ1): 1695, 1772 (C¼O);
1
1577 (C¼C); H-NMR (400MHz, DMSO-d6), δ 5.18 (d,
1H, J= 7.76 Hz); 4.77 (d, 1H, J= 9.16 Hz); 3.88 (t, 1H,
J=8.76Hz and J= 8.42 Hz); 8.04–7.04 (m, 8H); 3.77 (m,
1H); 1.93–1.02 (m, 10H); 9.35 (s, 1H); 2.52 (s, 3H); 13C-
NMR (100MHz, DMSO-d6), δ 172.03, 171.82, 156.21,
150.38, 128.61, 128.42, 127.25, 126.87, 120.58, 117.86,
114.03, 112.52, 74.09, 70.84, 63.33, 54.85, 50.12, 24.48,
24.00, 23.78, 20.41, 20.06, 19.70; MS(ESI): m/z=421 [M
+H]+. Anal. % Calcd for C25H28N2O4: C: 71.43, H: 6.67,
N: 6.67. Found: C: 71.39, H: 6.66, N: 6.65.
N: 7.20. Found: C: 74.00, H: 6.67, N: 7.18.
3-(2″-Chlorophenyl)-5-cyclohexyl-2-(4′-methylphenyl)-4H-
2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-dione (3l).
Compound obtained as white solid, yield 65%; mp 195–
198°C. IR (KBr pellets, ʋmax/cmꢀ1): 1700, 1782 (C¼O);
1575 (C¼C); 1H-NMR (400 MHz, DMSO-d6), δ 5.21
(d, 1H, J = 7.76 Hz); 4.84 (d, 1H, J = 9.16 Hz); 3.91 (t,
1H, J = 8.80 Hz and J = 8.42 Hz); 8.02–7.20 (m, 8H);
3.79 (m, 1H); 1.92–1.06 (m, 10H); 9.34 (s, 1H); 2.54 (s,
Acknowledgments. The authors are thankful to the University
Grant Commission, New Delhi, for financial assistance and
the Sophisticated Analytical Instrumentation Facility, Panjab
University, Chandigarh, for spectral analysis.
3H); 13C-NMR (100 MHz, DMSO-d6),
δ 170.68,
170.42, 147.72, 135.86, 125.66, 124.25, 120.68, 120.33,
118.84, 114.32, 113.88, 112.02, 68.78, 64.32, 54.45,
51.76, 24.63, 24.38, 24.03, 20.66, 20.34, 19.60; MS
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet