Synthesis and Evaluation of Novel Spiro[oxindole-isoxazolidine] Derivatives as Potent Antioxidants

Article abstract of DOI:10.1002/jhet.2712

The antioxidant activity of isatin derivatives can be described with the presence of enolic hydroxyl group at the second position of the ring because of the keto-enol tautomerism between NH and C O groups of indolone moiety. The reducing ability of the tested compounds was evaluated by their interaction with the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) at various concentrations. Novel spiro[oxindole-isoxazolidine] derivatives (4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, 4i) have been synthesized by 1,3-dipolar cycloaddition reactions of variously substituted maleimides (1) with isatin ketonitrone (3) and tested for their in vitro antioxidant potency in the DPPH assay. All the synthesized compounds have been identified as potent in vitro antioxidants.

Full text of DOI:10.1002/jhet.2712

Month 2016
Synthesis and Evaluation of Novel Spiro[oxindole-isoxazolidine]
Derivatives as Potent Antioxidants
a
a
a
b
*
Manpreet Kaur, Baldev Singh, Baljit Singh, and Anania Arjuna
aDepartment of Chemistry, Punjabi University, Patiala 147002, India
bFaculty of Applied Medical Sciences, Lovely Professional University, Phagwara 144402, India
*
E-mail: manpreet21044@gmail.com
Received February 29, 2016
DOI 10.1002/jhet.2712
Published online 00 Month 2016 in Wiley Online Library (wileyonlinelibrary.com).
The antioxidant activity of isatin derivatives can be described with the presence of enolic hydroxyl
group at the second position of the ring because of the keto-enol tautomerism between NH and C¼O
groups of indolone moiety. The reducing ability of the tested compounds was evaluated by their
interaction with the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) at various concentrations.
Novel spiro[oxindole-isoxazolidine] derivatives (4a–i) have been synthesized by 1,3-dipolar cycloaddition
reactions of variously substituted maleimides (1) with isatin ketonitrone (3) and tested for their in vitro
antioxidant potency in the DPPH assay. All the synthesized compounds have been identified as potent
in vitro antioxidants.
J. Heterocyclic Chem., 00, 00 (2016).
INTRODUCTION
pharmacological activities and have been used in the
chemistry of natural products as more complex heterocy-
cles [3–5]. During our ongoing investigations on the
1,3-dipolar cycloaddition reactions using isatin derivatives,
it was found that trifluoroacetic acid can efficiently endorse
the condensation of isatin with N-arylhydroxylamine,
affording stable isatin ketonitrones in better yields under
mild conditions. Therefore, isatin ketonitrones were used
as substrates to prepare some novel spiro-isoxazolidines.
1,3-Dipoles such as nitrones, nitrile oxides, azomethine
ylides, and nitronates have been used as substrates in various
In general many methods have been developed to
synthesize isoxazolidines. Requisite ketonitrones were
prepared from isatin in analogy to our previous work where
aldonitrones have been synthesized via condensation of
an N-alkyl or N-arylhydroxylamine with an aldehyde.
Preparation of rarely stable ketonitrone remains a challenge
for chemists because of their low reactivity. Few synthetic
procedures have been reported so far for the synthesis of
ketonitrones [1,2]. Spiro compounds exhibited prominent
© 2016 Wiley Periodicals, Inc.

M. Kaur, B. Singh, B. Singh, and A. Arjuna
Vol 000
Table 1
1,3-dipolar cycloaddition reactions [6,7]. Azomethine N-
oxides are versatile synthetic intermediates in organic
synthesis to synthesize biologically interesting heterocycles
pyrrolo-isoxazolidines [8–10]. Michael et al. reported
isoxazolidine ring fused with ring D of steroidal moieties as
potential anti-inflammatory agents [11]. Isoxazolidine deriva-
tives also act as anti-HIV agents [12]. Hall et al. reported that
isoxazolidine derivatives demonstrated potent cytotoxicity
against the growth of Human HeLa S3 uterine carcinoma
and glioma tumor cell growth [13]. These derivatives were
also reported as Febrifugine alkaloids, which act as potent an-
timalarial agent [14]. Broad spectrum antibiotics Negamycin
and 3-Epinegamycin synthesized by introduction of asymme-
try through 1,3-dipolar cycloaddition with chiral nitrones
modified with carbohydrates also possess isoxazolidine moi-
ety [15]. Isoxazolidine derivatives are known to be selective
β-adrenergic agonist of brown adipose tissue and thermogen-
esis in the rat [16]. However, 4-isoxazolines, because of the
presence of a weak nitrogen–oxygen bond and the carbon–
carbon π system, undergo many types of rearrangements to
afford different heterocycles, such as 2-acylaziridine [17],
4-oxazoline [18], 1H-pyrrole-2,3-dione [19], and induline
[20]. A closely related structure mytragynine pseudoindoxyl,
which is a potent antiviral agent, also displayed promising
anticancer properties [21]. Therefore, these considerations
prompted us to establish an efficient route for novel synthesis
of a rare class of new spiro[oxindole-isoxazolidine] deriva-
tives generated from stable isatin ketonitrone and various
dipolarophiles, regioselectively and diastereoselectively by
1,3-dipolar cycloaddition reactions. Therefore, the present
study was designed to synthesize variously substituted spiro
[oxindole-isoxazolidine] derivatives, whichhave been evalu-
ated for their antioxidant activity.
Characterization data of 5′-aryl-2′-phenylspiro[3H-indol-3,3′(3′aH)-[2H]
pyrrolo[3,4-d]isoxazole]-2,4′,6′(1H,5′H,6′aH)-trione.
Compounds
X
Yielda (%)
Melting point (°C)
4a
4b
4c
4d
4e
4f
4g
4h
4i
H
85
75
72
64
65
75
69
70
65
185–187
210–212
200–202
180–182
204–206
201–203
197–198
188–189
205–207
4-Cl
4-Br
4-F
4-I
4-CH3
4-OCH3
4-OH
4-C2H5
aIsolated yield of the pure compound.
shoulder band at 1714 cmꢀ1 was assigned to the second
carbonyl group of succinimide ring. Absorption band at
3327 cmꢀ1 was assigned to the –NH stretch of oxindole
moiety.
1
In the H-NMR spectrum, compound 4a displayed two
doublets at δ 5.12 with J = 7.56Hz and δ 5.38 with
J = 8.92Hz, respectively, for protons C3a–H and C6a–H,
respectively, on coupling with C6a–H and C3a–H. The
C6a–H proton appeared downfield in comparison with the
C3a–H proton because of the electronegative oxygen atom
attached to C6a–H. Aromatic protons appeared as multi-
plets in the range of δ 6.96–7.35 (equivalent to 14H). It
displayed a singlet at δ 10.34 for –NH proton of indolone
moiety.
RESULTS AND DISCUSSION
Chemistry.
The 1,3-dipolar cycloaddition reaction of
In the 13C-NMR spectrum, compound 4a displayed the
characteristic signals at δ 174.35 and δ 173.82, which have
been assigned to two succinimide carbonyl carbons. A
signal at δ 171.90 has been assigned to carbonyl carbon
of oxindole moiety. The signals in the range of δ
138.33–114.03 have been assigned to aromatic carbons.
A signal at δ 78.47 has been assigned to spiro carbon
C-3. Another two signals at δ 70.32 and δ 54.91 have been
assigned to C6a and C3a carbon atoms, respectively. Each
of the succinimide carbonyl carbon exhibited a downfield
shift as compared with the carbonyl carbon of oxindole
moiety because of the more deshielding effect of the two
carbonyl groups present in the succinimide moiety as
compared with the one carbonyl carbon of oxindole moi-
ety. Only one isomer has been obtained in all cases as
evidenced by thin-layer chromatography (TLC) analysis
showing single spot in each case.
stable N-substituted maleimides 1 with isatin ketonitrone 3
resulted in the formation of a series of new spiro[oxindole-
isoxazolidine] derivatives 4a–i with high biological and
pharmacological importance in a highly regioselective
manner. The reaction was conducted in acetonitrile under
reflux, and yields of the products were moderately good
after 1.5 h (Table 1). These cycloadducts were characterized
through their melting point, elemental analysis, IR, 1H-
NMR, 13C-NMR, and mass spectral studies. All the
compounds have given satisfactory elemental analysis.
In the IR spectrum of 2′,5′-diphenylspiro[3H-indol-3,3′
(3′aH)-[2H]pyrrolo-[3,4-d]isoxazole]-2,4′,6′(1H,5′H,6′
aH)-trione (4a), the presence of carbonyl stretching intense
vibration band at 1778 cmꢀ1 as revealed because of the
emergence of carbonyl stretching bands of oxindole moiety
and one carbonyl group of succinimide ring, while a
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2016
Synthesis and Evaluation of Novel Spiro[oxindole-isoxazolidine] Derivatives as
Potent Antioxidants
In the 1H-NMR spectrum of compound 4a, protons
C3a–H and C6a–H appeared as doublets, and their corre-
sponding J values falling in the range of cis-orientation
confirmed that these two protons lie on one side.
Antioxidant evaluation
IC50 values were also determined for all the compounds by
linear regression method. The RSA (%) for spiro[oxindole-
isoxazolidine] derivatives (4a–i) at seven different concen-
trations (0.25, 0.54, 0.88, 1.37, 2.50, 5.00, and 7.50μg/mL)
of the tested compounds with DPPH at 517nm has been
incorporated in Table 2. Figures 1 and 2 depict the percent-
age antioxidant activity at various concentrations and IC50
of the synthesized compounds 3a–d.
Assay for 1,1-diphenyl-2-picrylhydrazyl radical scavenging
activity.
The in vitro antioxidant activity of these
cycloadducts 4a–i was initially determined by the use of the
1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging
activity. The stable free radical DPPH was a useful reagent
to investigate the scavenger properties that proceed through
two different mechanisms: (a) the direct hydrogen atom
transfer and (b) the sequential proton loss electron transfer.
The antioxidant activity of the synthesized compounds
was measured in vitro by the DPPH radical scavenging as-
say [22–25]. A freshly prepared DPPH solution exhibited a
deep purple color with an absorption maximum at 517nm.
This purple color generally disappeared when an antioxi-
dant was present in the medium. The ethanolic solution
of DPPH was added to the solution of the synthesized com-
pounds in ethanol. After 30-min incubation in dark, the
absorbance was measured against ethanol as blank.
Butylated hydroxytoluene (BHT) was used as reference.
Thus, antioxidant molecules quenched DPPH free radicals
(by providing hydrogen atoms or by electron donation,
conceivably via a free-radical attack on the DPPH mole-
cule) and convert them to a colorless product. The DPPH
has an odd electron so it could accept an electron or
hydrogen free radical. In the presence of antioxidant, this
odd electron becomes paired because of the proton transfer
from antioxidant, and hence DPPH absorbance decreases.
The antioxidant activity was calculated as radical scav-
enging activity (RSA%) as follows:
In an attempt to establish some structure–activity rela-
tionship based on the presence of different substituents
on the phenyl ring of novel spiro[oxindole-isoxazolidine]
derivatives 4a–i and to understand the effect of different
functionalities on the antioxidant behavior, our findings in-
dicated that heterocyclic systems with oxindole nucleus
showed good antioxidant activity. It could be due to
keto-lactam ring present in the oxindole moiety. As per
chemical structural features, it was observed that electronic
characteristics of the substituents on the phenyl ring had a
remarkable effect on their antioxidant activity. Based on
the present study, it was indicated that the substituents on
RSA% ¼ ½ðAo–AiÞ=Aoꢁ100
where Ao and Ai are the DPPH absorbance in the absence
Figure 1. Graphical presentation of in vitro DPPH radical scavenging
activity of compounds 4a–i relative to the standard antioxidant BHT.
[Color figure can be viewed in the online issue, which is available at
wileyonlinelibrary.com.]
and presence of the tested compound, respectively. The
Table 2
Percentage of in vitro radical scavenging activity of synthesized compounds 4a–i.
Concentrations (μg/mL)
Compounds
0.25
12.05
17.08
15.07
15.05
9.04
11.05
6.05
11.04
0.56
0.54
0.88
1.37
2.50
5.00
7.50
IC50
4a
4b
4c
4d
4e
25.07
29.05
24.08
26.07
16.04
23.05
19.04
19.07
18.09
4.62
36.06
40.07
36.09
39.02
30.09
31.04
29.05
30.09
26.05
11.56
47.06
44.04
49.08
49.03
41.03
41.05
39.03
38.04
35.02
23.12
65.05
55.01
62.04
59.05
52.07
56.03
52.07
51.04
44.03
30.11
82.08
64.05
77.03
72.04
67.07
64.02
64.04
64.05
53.03
44.71
95.09
86.07
89.05
86.05
77.04
76.02
84.04
76.06
76.03
55.22
0.66
0.62
0.59
0.59
0.52
0.46
0.49
0.51
0.44
5.37
4f
4g
4h
4i
BHTa
—
aButylated hydroxytoluene as standard substance.
—, No Activity
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Kaur, B. Singh, B. Singh, and A. Arjuna
EXPERIMENTAL
Vol 000
All the melting points were uncorrected. IR spectra were
recorded on a Perkin Elmer RXIFT infrared spectropho-
tometer using KBr pellets. 1H-NMR spectra were recorded
on 400-MHz Bruker Avance spectrometer using TMS as
internal standard. 13C-NMR spectra were recorded on
100-MHz Bruker Avance spectrometer using TMS as
internal standard. MS (ESI) were recorded on Waters
Micromass Q-TOF of Micro (LC-MS) spectrometer.
Elemental analysis was carried out using Elementar vario
MICRO cube CHN analyzer. TLC analysis was carried
out on glass plates coated with silica gel-G suspended in
methanol–chloroform. Column chromatography was per-
formed using silica gel (100–200 mesh).
Figure 2. Graphical presentation of the IC50 values in μg/mL for the an-
tioxidant activity of compounds 4a–i measured at various concentrations.
[Color figure can be viewed in the online issue, which is available at
wileyonlinelibrary.com.]
General
procedure
for
the
synthesis
of
the phenyl ring directly influenced the antioxidant potency
of the molecule. Antioxidant behavior of the synthesized
compounds 4a–i followed this sequence: –C2H5 >–
CH3 > –OCH3 > –OH > –I >–Br =–F >–Cl >–H. Com-
pound with no substituents on the phenyl ring exhibited
least activity. Introduction of electron-withdrawing halo-
gen groups decreased the activity. For halogenated deriva-
tives, the activity depended on the halo atom on the phenyl
ring. All other halogen derivatives exhibited better antiox-
idant activity than chlorinated ones. Incorporation of
hydroxyl and methoxy groups was beneficial to the activ-
ity. With a further analysis it was observed that there was
a clear odd–even effect in this activity. The activity of
spiro[oxindole-isoxazolidine] derivative with ethyl group
on the phenyl ring having even carbon atoms was more
potent than that of the derivative with odd carbon atom cor-
responding to compound 4f having one carbon atom of the
methyl group. Further investigation of synthesized com-
pounds 4a–i revealed that presence of ethyl, methyl, and
methoxy groups at para position in the aromatic ring, hav-
ing high electron-donating properties (positive mesomeric
effect was higher than negative inductive effect) activated
the aromatic ring. Halogen groups that deactivated the
aromatic ring showed least activity. Among those synthe-
sized compounds 4a–i, the highest scavenging activity of
compound 4i was probably due to the presence of the
electron-donating ethyl group at the para position in the
aromatic ring. The moderate activity of compounds 4g and
4f was due to the presence of the methoxy and methyl
groups, present at the para position in the aromatic ring,
whereas the para halogenated derivatives showed decrease
in antioxidant activity. The least activity was observed in
compounds 4h, 4b, 4c, 4d, and 4e because of the presence
of the hydroxyl group and the electron-withdrawing chloro,
bromo, fluoro, and iodo groups in the para position,
respectively. Compound 4a exhibited the weakest antioxidant
activity among all tested compounds. This could be explained
by their structural difference from the rest of the synthesized
compounds, mainly by having no aromatic substitution.
N-substituted maleimide (1a–i). Maleic anhydride (1.96g;
20 mmol) and diethyl ether (25mL) were placed in a 100-
mL three-necked flask provided with a stirrer, a reflux
condenser, and a dropping funnel. The maleic anhydride
dissolved upon stirring, and a solution of 1 equiv. (20 mmol)
of the appropriate aniline in 5mL of diethyl ether was run
through the dropping funnel. The resulting thick suspension
was stirred at room temperature for 1.5h and was then
cooled in an ice bath. The N-substituted maleanilic acid was
recovered by filtration, dried, and subsequently added to a
flask containing a solution of anhydrous sodium acetate
(0.65g, 8mmol) in acetic anhydride (6.7 mL) under reflux
for 1.5h. The reaction mixture was then poured in ice-cold
water and kept it for an overnight period that afforded the
solid product. The precipitated product was recovered by
filtration, washed three times with 30-mL portions of ice-
cold water, and dried. The crude N-substituted maleimide
was recrystallized from ethanol/water to afford the desired
product 1a–i (Scheme 1).
General procedure for the synthesis of isatin imine (2).
All these compounds were prepared by reacting equimolar
quantities of corresponding isatin (0.005mol) and aniline
(0.005 mol) in 30mL of absolute ethanol containing two
to three drops of glacial acetic acid in a 100-mL round
bottomed flask. The reaction mixture was refluxed for half
an hour. On usual workup, the reaction mixture provided
Scheme 1. Schematic diagram describing the steps in the synthesis of N-aryl
maleimide.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2016
Synthesis and Evaluation of Novel Spiro[oxindole-isoxazolidine] Derivatives as
Potent Antioxidants
the crude product, which on recrystallization from
chloroform gave the desired product (2; Scheme 2).
10.34 (s, 1H); 13C-NMR (100MHz, DMSO-d6): δ 54.91,
70.32, 78.47, 114.03, 117.47, 124.35, 125.78, 126.26,
126.75, 127.54, 128.00, 128.47, 128.83, 129.40, 130.93,
135.15, 138.33, 171.90, 173.82, 174.35; MS: m/z: 411 [M+].
Anal. Calcd for C24H17N3O4: C, 70.07; H, 4.13; N, 10.21.
Found: C, 70.10; H, 4.19; N, 10.22.
General
procedure
for
the
synthesis
of
N-phenylhydroxylamine.
A mixture of nitrobenzene
(0.04mol) and ammonium chloride (0.04 mol) were
placed in 500mL beaker containing 100 mL of water.
Zinc dust (0.08mol) was added in portions to the stirring
mixture such that the temperature of mixture remained
60–70°C. The stirring was continued until the whole zinc
dust became reduced. The reaction mixture was filtered at
the suction pump. The filtrate was extracted with
chloroform and used immediately for the next reaction.
General procedure for the synthesis of isatin ketonitrone (3).
N-Phenylhydroxylamine (18.30mmol) was dissolved in
50mL chloroform. After stirring, isatin imine (2;
18mmol) was added to the reaction mixture. The reaction
mixture was warmed at 60°C for a few minutes. After
completion of the reaction (indicated by TLC), the orange
colored crystals of isatin ketonitrone were obtained. The
crude product that separated was filtered and washed with
cold ethanol (m.p. 217–219°C; (Scheme 3).
5′-(4-Chlorophenyl)-2′-phenylspiro[3H-indol-3,3′(3′aH)-
[2H]pyrrolo[3,4-d]isoxazole]-2,4′,6′(1H,5′H,6′aH)-trione
(4b).
Compound obtained as a white solid (yield
75%), m.p. 210–212°C; IR (KBr pellets, νmax/cmꢀ1):
1708, 1777 (C¼O), 3465 (N–H) cmꢀ1
;
1H-NMR
(400 MHz, CDCl3): δH 4.98 (d, 1H, J = 7.65 Hz), 5.10
(d, 1H, J = 7.76 Hz), 6.38–7.89 (m, 13H), 10.04 (s,
1H); 13C-NMR (100 MHz, CDCl3): δ 52.70, 72.42,
76.44, 110.02, 116.40, 125.15, 125.88, 126.66, 127.75,
128.54, 129.08, 129.47, 129.83, 129.90, 133.99, 137.65,
140.45, 171.00, 174.62, 174.85; MS: m/z: 445 [M+], 447
[M+ +2]. Anal. Calcd for C24H16N3O4Cl: C, 64.71; H, 3.59;
N, 9.43. Found: C, 64.72; H, 3.50; N, 9.50.
5′-(4-Bromophenyl)-2′-phenylspiro[3H>-indol-3,3′(3′aH)-
[2H]pyrrolo[3,4-d]isoxazole]-2,4′,6′(1H,5′H,6′aH)-trione
General procedure the for synthesis of cycloadducts
(4a–i). An oven-dried flask was cooled under a stream
of nitrogen and charged with N-substituted maleimide
(1; 1.5mmol) and isatin ketonitrone (3; 1mmol) in 5 mL
acetonitrile. The contents in the flask were refluxed for
1–1.5h until the substrates were consumed as indicated by
TLC. On completion of the reaction, the reaction mixture
was cooled under the tap water, the solvent was removed
under high vacuum, and the crude product was purified by
column chromatography using hexane–ethyl acetate (9:1)
and was recrystallized from ethanol to give white crystals
of cycloadduct (4; Scheme 4).
(4c).
Compound obtained as a white solid (yield
72%), m.p. 200–202°C; IR (KBr pellets, νmax/cmꢀ1):
1714, 1782 (C¼O), 3410 (N–H) cmꢀ1
,
1H-NMR
(400 MHz, CDCl3): δH 4.88 (d, 1H, J = 7.66 Hz), 5.18
(d, 1H, J=8.72Hz), 6.65–7.85 (m, 13H), 10.44 (s, 1H);
13C-NMR (100MHz, CDCl3): δ 53.11, 72.12, 77.77,
112.03, 116.44, 118.9, 125.98, 126.22, 126.85, 127.44,
128.08, 128.87, 129.33, 129.70, 133.03, 136.25,
140.32, 171.70, 174.62, 175.00; MS: m/z: 490 [M+],
492 [M+ + 2], 494 [M+ + 4]. Anal. Calcd for
C24H16N3O4Br: C, 58.77; H, 3.26; N, 8.57. Found: C,
58.71; H, 3.29; N, 8.50.
2′,5′-Diphenylspiro[3H-indol-3,3′(3′aH)-[2H]pyrrolo-[3,4-
d]isoxazole]-2,4′,6′(1H,5′H,6′aH)-trione (4a). Compound
obtained as a white solid (yield 85%), m.p. 185–187°C;
IR (KBr pellets, νmax/cmꢀ1): 1714, 1778 (C¼O), 3327
(N–H); 1H-NMR (400 MHz, CDCl3): δH 5.12 (d, 1H,
J= 7.56 Hz), 5.38 (d, 1H, J=8.92Hz), 6.96–7.35 (m, 14H),
5′-(4-Flourophenyl)-2′-phenylspiro[3H-indol-3,3′(3′aH)-
[2H]pyrrolo[3,4-d]isoxazole]-2,4′,6′(1H,5′H,6′aH)-trione
(4d). Compound obtained as a white solid (yield 64%),
m.p. 180–182°C; IR (KBr pellets, νmax/cmꢀ1): 1718,
1790 (C¼O), 3455 (N–H) cmꢀ1
;
1H-NMR (400MHz,
DMSO-d6): δH 4.11 (d, 1H, J =7.07Hz), 4.88 (d, 1H,
J = 7.02 Hz), 6.46–7.75 (m, 13H), 9.98 (s, 1H);
13C-NMR (100 MHz, DMSO-d6):
δ 54.91, 70.32,
Scheme 2. Schematic diagram describing the synthesis of isatin imine from
78.47, 114.03, 119.27, 125.88, 126.16, 127.77, 128.34,
128.65, 128.88, 129.93, 130.50, 132.63, 135.00,
140.34, 155.56, 170.20, 173.00, 173.30; MS: m/z: 429
[M+]. Anal. Calcd for C24H16N3O4F: C, 67.13; H, 3.72;
N, 9.79. Found: C, 67.11; H, 3.69; N, 9.80.
isatin and aniline.
5′-(4-Iodophenyl)-2′-phenylspiro[3H-indol-3,3′(3′aH)-[2H]
pyrrolo[3,4-d]isoxazole]-2,4′,6′(1H,5′H,6′aH)-trione (4e).
Compound obtained as a white solid (yield 65%), m.p. 204–
206°C; IR (KBr pellets, νmax/cmꢀ1): 1706, 1784 (C¼O),
Scheme 3. Schematic diagram describing the synthesis of isatin ketonitrone
from isatin imine and phenyl hydroxylamine.
3375 (N–H) cmꢀ1 1H-NMR (400 MHz, DMSO-d6): δH
;
4.42 (d, 1H, J= 7.86 Hz), 4.98 (d, 1H, J= 7.86 Hz), 6.58–
7.92 (m, 13H), 10.04 (s, 1H); 13C-NMR (100MHz,
DMSO-d6): δ 64.92, 71.30, 77.67, 95.78, 111.01, 115.27,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Kaur, B. Singh, B. Singh, and A. Arjuna
Vol 000
Scheme 4. Schematic diagram describing the synthesis of spiro[oxindole-isoxazolidine].
125.55, 126.16, 126.85, 127.55, 128.06, 128.37, 128.88,
129.20, 130.33, 134.25, 139.23, 172.80, 174.92, 175.20;
MS: m/z: 537 [M+]. Anal. Calcd for C24H16N3O4I: C, 53.63;
H, 2.97; N, 7.82. Found: C, 53.61; H, 2.99; N, 7.85.
5′-(Methylphenyl)-2′-phenylspiro[3H-indol-3,3′(3′aH)-[2H]
pyrrolo[3,4-d]isoxazole]-2,4′,6′(1H,5′H,6′aH)-trione (4f).
Compound obtained as a white solid (yield 75%), m.p.
201–203°C; IR (KBr pellets, νmax/cmꢀ1): 1709, 1775
125.35, 125.98, 126.77, 127.88, 128.08, 128.87, 129.99,
130.40, 133.32, 136.19, 138.56, 140.88, 171.60, 174.89,
175.05; MS: m/z: 427 [M+]. Anal. Calcd for C24H17N3O5: C,
67.44; H, 3.98; N, 9.83. Found: C, 67.17; H, 3.79; N, 9.80.
5′-(Ethylphenyl)-2′-phenylspiro[3H-indol-3,3′(3′aH)-[2H]pyrrolo
[3,4-d]isoxazole]-2,4′,6′(1H,5′H,6′aH)-trione (4i).
Compound
obtained as a white solid (yield 65%), m.p. 205–207°C;
IR (KBr pellets, νmax/cmꢀ1): 1712, 1788 (C¼O), 3432
(C¼O), 3369 (N–H) cmꢀ1
;
1H-NMR (400 MHz,
(N–H) cmꢀ1 1H-NMR (400 MHz, CDCl3): δH 1.23
;
CDCl3): δH 2.32 (s, 3H), 5.10 (d, 1H, J = 7.86 Hz), 5.58
(d, 1H, J = 8.20 Hz), 6.56–7.58 (m, 13H), 10.43 (s, 1H);
13C-NMR (100 MHz, CDCl3): δ 23.44, 58.90, 72.12,
76.47, 111.07, 115.27, 124.75, 125.88, 126.66, 126.78,
127.94, 128.35, 128.66, 128.88, 129.90, 131.99, 135.15,
139.73, 172.90, 175.25, 175.85; MS: m/z: 425 [M+].
Anal. Calcd for C25H19N3O4: C, 70.59; H, 4.47; N, 9.88.
Found: C, 70.55; H, 4.50; N, 9.80.
(t, 3H), 2.45 (q, 2H), 4.82 (d, 1H, J = 7.77Hz), 5.15
(d, 1H, J= 7.42 Hz), 6.88–7.82 (m, 13H), 10.24 (s, 1H);
13C-NMR (100MHz, CDCl3): δ 15.55, 36.20, 54.82,
72.42, 76.45, 114.83, 117.67, 123.85, 125.02, 126.76,
127.78, 128.10, 128.66, 128.94, 129.35, 132.46, 135.78,
139.83, 140.43, 172.96, 174.92, 175.55; MS: m/z: 439
[M+]. Anal. Calcd for C26H21N3O4: C, 71.07; H, 4.78; N,
9.56. Found: C, 70.91; H, 4.10; N, 10.01.
5′-(Methoxyphenyl)-2′-phenylspiro[3H-indol-3,3′(3′aH)-[2H]
pyrrolo[3,4-d]isoxazole]-2,4′,6′(1H,5′H,6′aH)-trione (4g).
Compound obtained as a white solid (yield 69%), m.p.
197–198°C; IR (KBr pellets, νmax/cmꢀ1): 1705, 1776
CONCLUSION
The aforementioned results help us to promote the
synthesis of novel spiro[oxindole-isoxazolidine] deriva-
tives synthesized from isatin ketonitrone that are found to
be interesting lead molecules as antioxidants. It can be
concluded that spiro[oxindole-isoxazolidine] derivatives
containing isatin moiety certainly shows significant
antioxidant activity.
(C¼O), 3270 (N–H) cmꢀ1
,
1H-NMR (400MHz,
DMSO-d6): δH 3.60 (s, 3H), 4.82 (d, 1H, J=7.76Hz),
5.14 (d, 1H, J=7.82Hz), 6.26–7.75 (m, 13H), 10.02
(s, 1H); 13C-NMR (100MHz, DMSO-d6): δ 59.99, 63.32,
72.52, 79.67, 111.72, 114.53, 124.45, 125.98, 126.46,
126.85, 127.84, 128.20, 128.44, 128.88, 129.80, 132.13,
135.75, 142.38, 171.04, 174.88, 175.05; MS: m/z: 441
[M+]. Anal. Calcd for C25H19N3O5: C, 68.02; H, 4.30; N,
9.52. Found: C, 68.80; H, 4.29; N, 9.60.
Acknowledgments. The authors are thankful to the University Grant
Commission (UGC), New Delhi, for financial assistance and the
Sophisticated Analytical Instrumentation Facility (SAIF), Panjab
University, Chandigarh for spectral analysis.
5′-(Hydroxyphenyl)-2′-phenylspiro[3H-indol-3,3′(3′aH)-[2H]
pyrrolo[3,4-d]isoxazole]-2,4′,6′(1H,5′H,6′aH)-trione (4h).
Compound obtained as a white solid (yield 70%), m.p.
188–189°C; IR (KBr pellets, νmax/cmꢀ1): 1710, 1780
1
(C¼O), 3410 (N–H) cmꢀ1; H-NMR (400MHz, CDCl3):
REFERENCES AND NOTES
δH 4.88 (d, 1H, J=7.96Hz), 5.28 (d, 1H, J=8.02Hz),
6.46–7.75 (m, 13H), 9.32 (s, 1H), 10.32 (s, 1H); 13C-NMR
(100MHz, CDCl3): δ 49.91, 69.22, 74.44, 117.63, 119.48,
[1] Tacconi, G.; Righetti, P. P.; Desimoni, G. J Prakt Chem 1980,
322, 679.
[2] Aurich, H. G.; Weiss, W. Tetrahedron 1976, 32, 159.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2016
Synthesis and Evaluation of Novel Spiro[oxindole-isoxazolidine] Derivatives as
Potent Antioxidants
[3] Kobayashi, J.; Tsuda, M.; Agemi, K.; Shigemori, H.; Ishibashi,
[16] Howe, R.; Rao, B. S.; Holloway, B. R.; Stribling, D. J Med
Chem 1992, 35, 1759.
[17] Lai, L. S.; Chou, S. T.; Chao, W. W. J Agric Food Chem 2001,
49, 963.
[18] Gao, J.; Igarashi, K.; Nukina, M. Chem Pharm Bull 2000, 48,
1075.
M.; Sasaki, T.; Mikami, Y. Tetrahedron 1991, 47, 6617.
[4] James, D. M.; Kunze, H. B.; Faulkner, D. J. J Nat Prod 1991,
54, 1137.
[5] Longeon, A.; Guyot, M.; Vacelet, J. Experentia 1990, 46, 548.
[6] Tufariello, J. J. In 1,3-Dipolar Cycloaddition ChemistryPadwa,
A. Ed.; Wiley: New York, 1984.
[19] Blois, M. S. Nature 1958, 26, 1199.
[7] Torssell, K. B. G. Nitrile Oxides, Nitrones and Nitronates in
Organic Synthesis; New York: VCH, 1988.
[20] Burits, M.; Bucar, F. Phytother Res 2000, 14, 323.
[21] Baldwin, J. E.; Pudussery, R. G.; Qureshi, A. K.; Sklarz, B. J
Am Chem Soc 1968, 90, 5325.
[22] Damavandy, J. A.; Jones, R. A. Y. J Chem Soc Perkin Trans
1981, 1, 712.
[23] Huisgen, R.; Seidl, H.; Bruning, I. Chem Ber 1969, 102, 1102.
[24] Tomioka, Y.; Nagahiro, C.; Nomura, Y.; Maruoka, H. J
Heterocyclic Chem 2003, 40, 121.
[25] a Takayama, H.; Hurihara, M.; Subhadhisakul, S.; Kitajima,
M.; Aimi, N.; Sakai, S. I. Heterocycles 1996, 42, 87; b Takayama, H.;
Ishikawa, H.; Kurihara, M.; Kitajima, M.; Aimi, N.; Ponglux, D.;
Koyama, F.; Matsumoto, K.; Moriyama, T.; Yamamoto, L. T.; Watanabe, K.
J Med Chem 2002, 45, 1949.
[8] Black, D. S. C.; Crozier, R. F.; Davis, V. C. Synthesis 1975, 4, 205.
[9] Banerji, A.; Sahu, A. J Scient Indus Res 1986, 45, 355.
[10] Banerji, A.; Basu, S. Tetrahedron 1992, 48, 3335.
[11] Green, M. J.; Tiberi, R. L.; Friary, R.; Lutsky, B. N.;
Berkenkoph, J.; Monahan, M. J Med Chem 1982, 25, 1492.
[12] Loh, B.; Vozzolo, L.; Mok, B. J.; Lee, C. C.; Fitzmaurice, R.
J.; Caddick, S.; Fassati, A. Chem Biol Drug Des 2010, 75, 461.
[13] Hall, J. H.; Izydore, R. A.; Daniels, D. L.; Woodard, T.;
Debnath, M. L.; Tse, E.; Muhammad, R. A. Arch Pharm 1997, 330, 67.
[14] Pellissier, H. Tetrahedron 2007, 63, 3235.
[15] Kasahara, K.; Iida, H.; Kibayashi, C. J Org Chem 1989, 54, 2225.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet