Chitosan-encapsulated manganese ferrite particles bearing sulfonic acid group catalyzed efficient synthesis of spiro indenoquinoxalines

Article abstract of DOI:10.1039/d0ra04925e

A simple, highly versatile and efficient synthesis of 5-phenyl-spiro[diindenopyridine-indenoquinoxaline]-diones is achieved through a four-component one pot reaction of ninhydrin, 1,2-diaminobenzene, 1,3-indandione and aniline. This reaction was catalyzed by MnFe₂O₄?CS-Bu-SO₃H MNPs as a very efficient, recyclable heterogeneous catalyst in acetonitrile under reflux conditions. The catalyst can be recovered from the subsequent reaction mixture and reused for at least five cycles without any appreciable loss in its efficiency. The core-shell structure and composition of the produced magnetic nanocatalyst were analyzed using FT-IR, XRD, VSM, SEM, EDX and TGA techniques.

Full text of DOI:10.1039/d0ra04925e

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PAPER
Chitosan-encapsulated manganese ferrite particles
bearing sulfonic acid group catalyzed efficient
synthesis of spiro indenoquinoxalines†
Cite this: RSC Adv., 2020, 10, 33334
*
Sepideh Lahouti and Hossein Naeimi
A simple, highly versatile and efficient synthesis of 5-phenyl-spiro[diindenopyridine-indenoquinoxaline]-
diones is achieved through a four-component one pot reaction of ninhydrin, 1,2-diaminobenzene, 1,3-
indandione and aniline. This reaction was catalyzed by MnFe2O4@CS-Bu-SO3H MNPs as a very efficient,
recyclable heterogeneous catalyst in acetonitrile under reflux conditions. The catalyst can be recovered
from the subsequent reaction mixture and reused for at least five cycles without any appreciable loss in
its efficiency. The core–shell structure and composition of the produced magnetic nanocatalyst were
analyzed using FT-IR, XRD, VSM, SEM, EDX and TGA techniques.
Received 4th June 2020
Accepted 20th August 2020
DOI: 10.1039/d0ra04925e
rsc.li/rsc-advances
Chitosan is a natural attractive due to the presence of amine
and hydroxyl groups.13–16 These groups serve as adsorption sites
1. Introduction
for many adsorbates. Therefore, it is an appropriate polymer for
use to modify MnFe2O4 NPs. Many investigations have been
performed on chitosan-modied magnetic NPs for biomedical
applications.17
Spirocycles, structures that have two or more rings joined at
a single carbon, remain a challenging design for synthetic chem-
ists. Some of the most important spirocycles are spirooxindole and
spiroindoline alkaloids isolated from natural sources.1–3 Spiropyr-
ans and spiroquinoxalines, in particular, have possible applica-
tions as photochromic materials in data recording, storage, and
transfer and in other industrial elds.4 The indole nucleus is
perhaps the most well-known heterocycle, a common and impor-
tant feature of a variety of natural products and medicinal agents.5
The spirooxindole ring system is a broadly dispersed structural
framework present in a number of natural and pharmaceutical
products. Indenoquinoxaline derivatives are an important class of
nitrogen-containing heterocycles which are useful intermediates
in organic synthesis.6,7
Heterogeneous catalysis has been studied for many years and
has become vital for efficient and eco-friendly organic trans-
formations over the past few decades.8–10 Magnetite is an ideal
oxide support and easy to make, with a very effective surface for
adsorptions or immobilization of metals and ligands, which can
be separated by magnetic separation.11 Magnetite nanoparticles
are not very resistant under ambient conditions and are easily
oxidized to magnetite or dissolved in an acidic medium.12
Chitosan (CS) has various favorable properties, such as,
biocompatibility, low toxicity, good lm making, high
mechanical strength and high hydrophilicity, and has therefore
been an important material for the preparation of magnetic
carriers.
Multicomponent reactions (MCRs) enjoy an outstanding
reputation in organic and medicinal chemistry for their high
degree of atomic economy and application in the diversity
oriented convergent synthesis of complex organic molecules
from simple and readily available layers in a single vessel; they
full some of the objectives of perfect synthesis because
complex products are formed in a single step and diversity can
be obtained simply by varying the reaction components.18–24
In continuation of our previously reported work on catalytic
reactions,25,26 herein we report the preparation of MnFe2O4@CS-
n-Bu-SO3H MNPs and their use as an efficient nanocatalyst for
the
synthesis
of
5-phenyl-spiro[diindenopyridine-
indenoquinoxaline]-dione derivatives through the condensa-
tion of ninhydrin, 1,2-diamino-benzene, 1,3-indandione and
various anilines under thermal conditions (Scheme 1).
2. Results and discussion
2.1. Preparation and characterization of MnFe2O4@CS-Bu-
SO3H MNPs
The manganese ferrite nanoparticles were prepared by co-
precipitation of Fe(III) and Mn(II) at a molar ratio of 2 : 1
which was dropped slowly into NaOH solution at a temperature
of 97 ꢀC. Then, the synthesized magnetic nanoparticles were
modied with chitosan as a natural polymer. To prepare the
modied MnFe2O4–chitosan nanoparticles, MnFe2O4 nano-
particles were dispersed in distilled water under ultrasound
irradiation and chitosan in acetic acid solution was slowly
Department of Organic Chemistry, Faculty of Chemistry, University of Kashan, Kashan,
Iran. E-mail: naeimi@kashanu.ac.ir; Fax: +98 591 2397; Tel: +98 591 2388
† Electronic supplementary information (ESI) available. See DOI:
10.1039/d0ra04925e
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Scheme 1 Synthesis of 5-phenyl-spiro[diindenopyridine-indenoquinoxaline]-dione using MnFe2O4@CS-Bu-SO3H MNPs.
added under vigorous stirring for 1 h. The magnetically microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX),
heterogeneous organocatalyst MnFe2O4@CS-Bu-SO3H MNPs vibrating sample magnetometry (VSM), thermal gravimetric
were characterized by X-ray diffraction (XRD), scanning electron analysis (TGA) and Fourier transform infrared (FT-IR)
spectroscopy.
2.1.1 FT-IR analysis. The FT-IR spectra (Fig. 1) of (a) chi-
tosan, (b) MnFe2O4, (c) MnFe2O4@CS NPs and (d) MnFe2O4@-
CS-Bu-SO3H MNPs are instructive. The O–H stretching vibration
was detected at 3428 and 3433 cmꢁ1 in the peaks of Fig. 1a–d.
The FT-IR spectrum of chitosan was characterized by the
following absorption bands: the (NH) of the polymer backbone
at 3435 and 1630 cmꢁ1, the (C–O) of the primary alcoholic group
at 1382 cmꢁ1, and (C–H) at 2940 cmꢁ1 (Fig. 1a). The FT-IR
spectrum of MnFe2O4 showed characteristic peaks at
3427 cmꢁ1 and 1630 cmꢁ1 which were assigned to the vibration
of hydroxyl groups; in addition, an obvious peak at 584 cmꢁ1
was attributed to the Fe–O bond vibration (Fig. 1b). Compared
with curve b, curve c shows the most signicant band shi of
Fe–O stretching (from 584 to 657 cmꢁ1), indicating that iron
ions bind to the NH2 group of chitosan. Electrostatic interaction
between the negatively charged MnFe2O4 nanoparticle surface
and the positively charged protonated chitosan also contributes
to the IR change. The peak at 3412 cmꢁ1 was probably the
amino group of chitosan, which is overlapped by the O–H
stretching vibration of MnFe2O4 nanoparticles (Fig. 1c). The FT-
IR spectrum of MnFe2O4@CS-Bu-SO3H MNPs shows the
stretching and out-of-plane bending of acidic O–H groups as
two broad bands at 2800–3500 cmꢁ1. Also, the S]O stretching
bands of the –SO3H group appeared at 1000–1200 cmꢁ1
(Fig. 1d).
Fig. 1 IR spectra of (a) chitosan (CS), (b) MnFe2O4, (c) MnFe2O4@CS
NPs and (d) MnFe2O4@CS-Bu-SO3H MNPs.
Fig.
2 XRD patterns of (a) chitosan (CS), (b) MnFe2O4, and (c)
Fig. 3 Magnetization versus applied field for MnFe2O4 and MnFe2-
MnFe2O4@CS-Bu-SO3H MNPs.
O4@CS-Bu-SO3H MNPs.
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Fig. 4 The thermal gravimetric analysis (TGA) of MnFe2O4@CS-Bu-
Fig. 6 The energy dispersive X-ray (EDX) spectrum of MnFe2O4@CS-
SO3H NPs.
Bu-SO3H MNPs.
2.1.2 X-ray diffraction (XRD) analysis. The crystal structures
of chitosan and MnFe2O4@CS-n-Bu-SO3H MNPs are shown in
Fig. 2. The sharp peaks in the XRD patterns conrm the good
crystallinity of the prepared samples. There are six diffraction
peaks at 2q values of about 29.94ꢀ, 35.24ꢀ, 42.75ꢀ, 52.94ꢀ, 56.42ꢀ
and 61.86ꢀ, corresponding to the (220), (311), (400), (422), (511),
and (440) planes in the MnFe2O4@CS-n-Bu-SO3H MNPs, which is
the standard pattern for crystalline magnetite with cubic structure
(JCPDS card no. 01-1111). The small and weak broad bands in the
range of 12–20ꢀ show the existence of amorphous chitosan. The
average crystal sizes of pure MnFe2O4 and chitosan-coated
MnFe2O4 nanoparticles are 19 and 25, respectively.
2.1.3 Magnetic properties. The magnetization curves for
MnFe2O4 nanoparticles and MnFe2O4@CS-Bu-SO3H MNPs
nanoparticles are shown in Fig. 3. Room temperature specic
magnetization versus applied magnetic eld curve measure-
ments of the MnFe2O4@CS-Bu-SO3H MNPs indicate a satura-
tion magnetization value of 10.27 emu gꢁ1, lower than that of
the pristine MnFe2O4 nanoparticles (12.69 emu gꢁ1) due to the
coated shell.
2.1.5 Scanning electron microscopy (SEM). Fig. 5 exhibits
the morphology and particle size of MnFe2O4@CS-Bu-SO3H
MNPs. It indicates that the chitosan polymeric matrix uniformly
covers the surface of MnFe2O4 (Fig. 5). The SEM image shows
that the structural size of MnFe2O4@CS-Bu-SO3H MNPs is
bigger. The SEM of MnFe2O4@CS-Bu-SO3H MNPs clearly reveals
the structure of the CS-coated magnetite nanoparticles.
2.1.6 Energy dispersive X-ray (EDX) spectroscopy. The
elemental compositions are calculated from the energy disper-
sive X-ray (EDX) spectrum. The elemental composition of
MnFe2O4@CS-Bu-SO3H MNPs is 3.01%, 11.56%, 6.83%,
29.73%, 30.74% and 18.12% for N, C, S, O, Fe and Mn,
respectively. This implies that the chitosan polymer was coated
on the surface of the MnFe2O4 NPs (Fig. 6).
Moreover, in accordance with the SEM image of the
MnFe2O4@CS-Bu-SO3H nanoparticles, the particle size distri-
bution histogram is shown in Fig. 7. As can be observed, the
dispersed nanoparticles formed with a uniform size and the
mean value and standard deviation could be estimated as 27 ꢂ
3 nm from this size distribution histogram.
2.1.4 Thermal gravimetric analysis (TGA). In order to
obtain information on the thermal stability, TGA experiments
were carried out by heating MnFe2O4@CS-Bu-SO3H MNPs up to
800 ꢀC (Fig. 4). The weight loss of MnFe2O4@CS-Bu-SO3H MNPs
nanoparticles is about 40% in the range 250–420 ꢀC, corre-
sponding to the thermal decomposition of the chitosan chains
over MnFe2O4 nanoparticles.
2.2. Investigation of catalyst activity in organic reactions
In the present work, we investigated the model reaction of
ninhydrin, 1,2-diamino benzene, 1,3-indandione and anilines
Fig. 5 SEM image of MnFe2O4@CS-Bu-SO3H MNPs.
33336 | RSC Adv., 2020, 10, 33334–33343
Fig. 7 Particle size distribution histogram of the catalyst.
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Table
1 The reaction in the presence of different solvents and
derivatives under the above-mentioned conditions. The high-
MnFe2O4@CS-Bu-SO3H MNPsa
est
yields
of
5-phenyl-spiro[diindenopyridine-
indenoquinoxaline]-dione derivatives were obtained using the
electron-releasing para-methyl group as a substituent for
aromatic amines.
Entry
Solvent
Time (h)
Yieldb (%)
1
2
3
4
H2O
18
15
3
38
43
97
31
EtOH
CH3CN
CHCl3
Furthermore, comparison of the reactions in the presence of
p-TSA catalyst, as previously reported,6 with the present work
was carried out on production of 5a, 5j and 5k. The results are
listed in Table 4. As shown, the product yields using the present
method were higher than those from the previously reported
method and the reaction times were shorter than those ob-
tained in the reported work (Table 4, entries 2, 4, 6 vs. 1, 3, 5).
The proposed reaction mechanism for the synthesis of spiro
indenoquinoxalines catalyzed by MnFe2O4@CS-n-Bu-SO3H
MNPs is depicted in Scheme 2. As shown in Scheme 2,
compound 5 could be synthesized via sequential iminization–
aromatization, condensation, addition, enamination and cycli-
zation. Initially, the MnFe2O4@CS-n-Bu-SO3H MNPs catalyst
protonates the carbonyl group of ninhydrin (1); this step is
regarded as a fast iminization–aromatization reaction in which
the ninhydrin (1) rst reacts with 1,2-diamino benzene (2) to
afford 11H indeno[2,1-b]quinoxalin-11-one (A) in the presence
of MnFe2O4@CS-Bu-SO3H MNPs in acetonitrile. Then, the
catalyst protonates the carbonyl group of compound A and
compound A is condensed with 1,3-indenedione (3) to afford
compound B. This step is regarded as a fast Knoevenagel
condensation reaction. Then, compound B is attacked by
another 1,3-indene dione (3) in a Michael-type addition to
produce intermediate C. Finally, compound C reacted with
aniline (4) to produce compound D, followed by intramolecular
cyclization and tautomerization to afford the product (5).
Reusability is one of the signicant properties of this cata-
lyst. The reusability of MnFe2O4@CS-Bu-SO3H MNPs was
studied for the reaction of ninhydrin, 1,2-diamino benzene, 1,3-
indandione and anilines. Aer completion of the reaction, the
nanocatalyst was easily separated using an external magnet.
The recovered magnetite nanoparticles were washed several
times with acetone and then dried at room temperature (Fig. 8).
The results of ve consecutive runs (98%, 98%, 97%, 96% and
96%) indicated that the yields remained similar with no
detectable loss of yield or catalytic activity.
24
a
Reaction conditions: ninhydrin 1.0 mmol, 1,2-diamino benzene
1.0 mmol, 1,3-indandione 2.0 mmol and anilines 1.0 mmol under
heat. b Isolated yields.
in the presence of MnFe2O4@CS-Bu-SO3H MNPs under heat
condition. In this research, the effects of different solvents and
various amounts of catalyst on the model reaction were exam-
ined. First, several organic solvents, such as H2O, CH3CN, EtOH
and CHCl3, were examined (Table 1). According to the data
given in Table 1, entry 3, CH3CN was the most efficient solvent
for this reaction.
Furthermore, various catalysts and different amounts of
catalyst were used in the sample reaction (Table 2). No reaction
was observed in the absence of catalyst without heat (Table 2,
entry 1). When the reaction was performed at room temperature
in the presence of MnFe2O4@CS-Bu-SO3H MNPs, the product
was obtained in lower yield and with longer reaction time (Table
2, entry 6), while heat and MnFe2O4@CS-n-butyl SO3H NPs gave
the best yield in the shortest time. An excellent yield of 97% was
obtained with 20 mol% catalyst (Table 2, entry 8) and was not
improved by increasing to 30 mol% (Table 2, entry 9).
We also applied MnFe2O4@CS-Bu-SO3H MNPs catalyst for
the
synthesis
of
5-phenyl-spiro[diindenopyridine-
indenoquinoxaline]-dione derivatives from various aromatic
amines under similar conditions, as seen in Table 3. The results
indicate that excellent yields were achieved in the reaction in
the presence of MnFe2O4@CS-Bu-SO3H MNPs (20 mol%) under
reux conditions. The inuence of electron-withdrawing and
electron-donating substituents on the aromatic ring of amines
upon the reaction yields was investigated. Electron-releasing
substituents on aromatic amines gave good to excellent yields
of 5-phenyl-spiro[diindenopyridine-indenoquinoxaline]-dione
Table 2 Optimization of the various amounts and types of catalystsa
Entry
Condition
Catalyst (mol%)
Time (h)
Yieldb (%)
1
2
3
4
5
6
7
8
9
R.T.
—
Et3N
p-TSA
Nano Fe3O4
48
24
16
20
18
48
3
—
10
70
43
48
10
76
97
97
Heat
Heat
Heat
Heat
R.T.
Heat
Heat
Heat
Nano MnFe2O4
MnFe2O4@CS-Bu-SO3H NPs (10)
MnFe2O4@CS-Bu-SO3H NPs (10)
MnFe2O4@CS-Bu-SO3H NPs (20)
MnFe2O4@CS-Bu-SO3H NPs (30)
3
3
a
b
Reaction conditions: ninhydrin 1.0 mmol, 1,2-diamino benzene 1.0 mmol, 1,3-indandione 2.0 mmol and anilines 1.0 mmol. Isolated yields.
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Table 3 Synthesis of various 5-phenyl-spiro[diindenopyridine-indenoquinoxaline]-dione derivatives using MnFe2O4@CS-Bu-SO3H MNPsa
a
Isolated yield.
Table 4 Comparison between previously reported work and the present work
En.
Catalyst
Cond.
Prod.
Time (h)
Yield (%)
Ref.
1
2
3
4
5
6
p-TSA (30 mol%)
MnFe2O4@CS-Bu-SO3H
p-TSA (30 mol%)
MnFe2O4@CS-Bu-SO3H
p-TSA (30 mol%)
MnFe2O4@CS-Bu-SO3H
H3CCN, 82 ꢀ
H3CCN, 75 ꢀ
H3CCN, 82 ꢀ
H3CCN, 75 ꢀ
H3CCN, 82 ꢀ
H3CCN, 75 ꢀ
C
C
C
C
C
C
5a
5a
5j
5j
5k
5k
16
3
16
3
16
3.5
71
95
95
97
62
83
6
This work
6
This work
6
This work
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Scheme 2 Plausible mechanism for the synthesis of spiro indenoquinoxalines.
In order to investigate any structural change of the catalyst, the a nano magnetic catalyst. High yields, a simple reaction
XRD pattern (Fig. 9) and FT-IR spectrum (Fig. 10) of the recovered process, easy work-up, shorter reaction times, reusability of the
catalyst were obtained. The results show well-dened peaks at the catalyst and low catalyst loading are some of the considerable
2q values of the XRD pattern related to the unused catalyst and advantages of the current protocol.
conformity of the FT-IR spectrum to that of the unused catalyst;
thus, there is no structural change in the catalyst aer the reaction.
4. Experimental method
4.1. Materials
3. Conclusions
The chemicals used in this work were obtained from Fluka and
Merck Chemical Companies and were used without
purication.
In this research, we have developed an effective procedure for
the
synthesis
of
5-phenyl-spiro[diindenopyridine-
one-pot four-
indenoquinoxaline]-dione derivatives by
a
component reaction of ninhydrin, 1,2-diamino benzene, 1,3-
indandione and anilines using MnFe2O4@CS-Bu-SO3H MNPs as
Fig. 8 Reusability of catalyst for synthesis of spiro indenoquinoxaline. Fig. 9 XRD pattern of recovered catalyst.
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MnCl2 and FeCl3 in water in the presence of sodium hydroxide.
Briey, MnCl2$4H2O and FeCl3$6H2O were used in the molar ratio
of Mn2+ : Fe3+ ¼ 1 : 2 to prepare a 0.4 mol Lꢁ1 metal ion solution of
100 ml containing 0.2 mol Lꢁ1 Mn2+ and 0.4 mol Lꢁ1 Fe3+ which
was then dropped slowly into 100 ml NaOH solution of 5 mol Lꢁ1
ꢀ
at the temperature of 97 C. Aer aging for 2 h with continuous
ꢀ
stirring, the mixture was ltered, washed and dried at 60 C for
24 h. Next, the reaction mixture was cooled and the catalyst was
isolated in a magnetic eld and washed three times with distilled
water. Subsequently, in order to prepare MnFe2O4–chitosan
nanoparticles, 1 g of the MnFe2O4 nanoparticles was dispersed in
120 ml distilled water under ultrasound irradiation and 0.5 g of
chitosan in 120 ml of 2.0 wt% acetic acid solution was slowly
added under vigorous stirring at 50 ꢀC for 1 h. The modied
MnFe2O4–chitosan nanoparticles were recovered by magnetic
decantation and washed with CH2Cl2. Finally, MnFe2O4–chitosan
nanoparticles were dried at 60 ꢀC.
Fig. 10 FT-IR spectrum of recovered catalyst.
4.2. Apparatus
FT-IR spectra were obtained with potassium bromide pellets in the
range 400–4000 cmꢁ1 with a PerkinElmer 550 spectrometer. 1H
NMR and 13C NMR spectra were recorded with a Bruker DRX-400
spectrometer at 400 and 100 MHz, respectively. NMR spectra were
reported as parts per million (ppm) downeld from tetramethylsi-
lane as the internal standard. The abbreviations used are singlet (s),
doublet (d), triplet (t) and multiplet (m). Nanostructures were char-
acterized using a Holland Philips Xpert X-ray powder diffraction
(XRD) diffractometer (CuKa, radiation, k ¼ 0.154056 nm) at a scan-
ning speed of 2ꢀ minꢁ1 from 10ꢀ to 100ꢀ (2q). A BANDELIN ultra-
sonic HD 3200 with probe model KE 76 with a diameter of 6 mm was
used to produce ultrasonic irradiation and homogenize the reaction
mixture. The piezoelectric crystal of this kind of probe normally
works in the range of 700 kHz, but by using the proper clamps, the
output frequency of the piezoelectric crystal was controlled and
reduced to 20 kHz. Therefore, the induced frequency of the probe for
the reaction mixture is equal to 20 kHz. A thermal method was used
for the calibration of ultrasonic power. Melting points were deter-
mined in open capillaries using an Electrothermal Mk3 apparatus
and are uncorrected. The purity determination of the substrates and
reaction monitoring were accomplished by TLC on silica-gel poly-
gram SILG/UV 254 plates (Merck). FE-SEM images of the products
were visualized by an Oxford Instruments Sigma ZEISS eld emis-
sion scanning electron microscope. The magnetic properties of the
nanoparticles were measured with a vibrating sample magnetometer
(VSM, PPMS-9T) at 300 K in Iran (University of Kashan).
4.4. Preparation of 1,4-butane sultone chitosan-
encapsulated manganese ferrite nanoparticles (MnFe2O4@CS-
n-Bu-SO3H MNPs)
MnFe2O4–chitosan nanoparticles and 1,4-butane sultone
(0.36 ml, 3 mmol) were mixed together without solvent and
stirred for 3 h at room temperature (25 ꢀC). Concentrated H2SO4
(0.154 ml, 3 mmol) was added to the above catalyst mixture and
reuxed for 2 h. The nal catalyst was washed repeatedly with
ethanol and then dried (Scheme 3).
4.5. General procedure for the synthesis of spiro
indenoquinoxalines catalyzed by MnFe2O4@CS-Bu-SO3H
MNPs
A mixture of ninhydrin (1 mmol), 1,2-diamino benzene (1 mmol),
and MnFe2O4@CS-Bu-SO3H MNPs (20 mg) in 5 ml acetonitrile was
heated at 75 ꢀC for 5 min, then 1,3-indandione (2 mmol) and
aniline (1 mmol) were added to the mixture and stirred for 3 h.
Progress of the reaction was continuously monitored by TLC. On
completion of the reaction, the reaction mixture was cooled to
room temperature and the catalyst was separated by an external
magnet. Then, the precipitated product was ltered and washed in
3 ml ethanol to afford the pure product.
4.3. Typical experimental procedure for the preparation of
chitosan-coated magnetic nanoparticles MnFe2O4@CS NPs
4.6. Representative spectral data
4.6.1 5-(4-Methoxyphenyl)-10H-spiro[diindeno[1,2-b:20,10-
In this research, the MnFe2O4 nanoparticles were prepared by e]pyridine-11,110-indeno[1,2-b]quinoxaline]-10,12(5H)-dione
following the reported standard protocol: co-precipitation of (5a). Dark red solid, Rf (n-hexane : ethylacetate): 7 : 3 (v/v) ¼
Scheme 3 Preparation steps of MnFe2O4@CS-Bu-SO3H MNPs.
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0.60; (mprep. 233)/(mplit 233–240 ꢀC).6 IR (KBr) n: 3436, 3060,
4.6.6 5-(2-Chlorophenyl)-10H-spiro[diindeno[1,2-b:20,10-e]
pyridine-11,110-indeno[1,2-b]quinoxaline]-10,12(5H)-dione (5f).
Dark red solid, Rf (n-hexane : ethylacetate): 7 : 3 (v/v) ¼ 0.62; mp
281 ꢀC. IR (KBr) n: 3435, 3061, 2922, 1703, 1578, 1386, 1337,
1003 cmꢁ1; 1H NMR (400 MHz, DMSO-d6) d: 8.19 (m, 1H, ArH),
8.15 (m, 1H, ArH), 8.06 (m, 1H, ArH), 8.02 (m, 1H, ArH), 7.94 (m,
1H, ArH), 7.87 (m, 3H, ArH), 7.78 (m, 2H, ArH), 7.73 (m, 1H,
ArH), 7.62 (m, 1H, ArH), 7.54 (m, 1H, ArH), 7.27 (m, 1H, ArH),
7.18 (m, 1H, ArH), 7.12 (m, 1H, ArH), 7.05 (m, 1H, ArH), 6.94 (m,
1H, ArH), 5.59 (d, J ¼ 4.0 Hz, 2H, ArH) ppm. Anal. calcd for
1
2924, 1699, 1511, 1383, 1252, 1000 cmꢁ1; H NMR (400 MHz,
DMSO-d6) d: 8.23 (d, J ¼ 8.0 Hz, 1H, ArH), 8.18 (m, 2H, ArH),
7.99 (t, J ¼ 8.0 Hz, 2H, ArH), 7.87 (d, J ¼ 8.0 Hz, 1H, ArH), 7.78 (d,
J ¼ 8.0 Hz, 2H, ArH), 7.60 (t, J ¼ 4.0 Hz, 2H, ArH), 7.33 (m, 2H,
ArH), 7.22 (m, 4H, ArH), 7.09 (d, J ¼ 8.0 Hz, 2H, ArH), 5.97 (d, J ¼
4.0 Hz, 2H, ArH), 3.98 (s, 3H, OCH3) ppm. Anal. calcd for
C
40H23N3O3: C, 80.93; H, 3.91; N, 7.08. Found: C, 80.88; H,
3.86; N, 7.04.
4.6.2 5-(3-Chlorophenyl)-10H-spiro[diindeno[1,2-b:20,10-e]
pyridine-11,110-indeno[1,2-b]quinoxaline]-10,12(5H)-dione (5b).
Dark red solid, Rf (n-hexane : ethylacetate): 7 : 3 (v/v) ¼ 0.55; mp
284 ꢀC. IR (KBr) n: 3432, 3063, 2922, 1700, 1578, 1384, 1301,
C
39H20ClN3O2: C, 78.33; H, 3.37; N, 7.03. Found: C, 78.27; H,
3.29; N, 6.98.
4.6.7 5-Phenyl-10H-spiro[diindeno[1,2-b:20,10-e]pyridine-
11,110-indeno[1,2-b]quinoxaline]-10,12(5H)-dione (5g). Dark red
solid, Rf (n-hexane : ethylacetate): 7 : 3 (v/v) ¼ 0.64; (mprep. 277
1
999 cmꢁ1; H NMR (400 MHz, DMSO-d6) d: 8.22 (d, J ¼ 8.0 Hz,
1H, ArH), 8.17 (d, J ¼ 4.0 Hz, 2H, ArH), 8.13 (t, J ¼ 8.0 Hz, 1H,
ArH), 8.02 (d, J ¼ 8.0 Hz, 2H, ArH), 7.86 (m, 3H, ArH), 7.77 (s, 1H,
ArH), 7.60 (d, J ¼ 4.0 Hz, 2H, ArH), 7.23 (m, 4H, ArH), 7.11 (d, J ¼
4.0 Hz, 2H, ArH), 5.60 (d, J ¼ 4.0 Hz, 2H, ArH) ppm; 13C NMR
(100 MHz, DMSO-d6): d 46.2, 113.4, 121.7, 122.1, 122.8, 124.7,
129.4, 129.6, 129.7, 129.8, 130.3, 130.9, 131.4, 132.4, 132.7,
132.9, 133.2, 136.5, 136.6, 137.4, 139.5, 141.5, 142.3, 151.9,
155.0, 156.6, 156.7, 190.1 ppm. Anal. calcd for C39H20ClN3O2: C,
78.33; H, 3.37; N, 7.03. Found: C, 78.28; H, 3.33; N, 6.96.
4.6.3 5-(4-Hydroxyphenyl)-10H-spiro[diindeno[1,2-b:20,10-e]
pyridine-11,110-indeno[1,2-b]quinoxaline]-10,12(5H)-dione (5c).
Dark red solid, Rf (n-hexane : ethylacetate): 7 : 3 (v/v) ¼ 0.51;
mp: 251 ꢀC. IR (KBr) n: 3431, 3041, 2938, 1728, 1568, 1382, 1335,
ꢀC)/(mplit > 280 C).6 IR (KBr) n: 3430, 3062, 2910, 1696, 1579,
ꢀ
1385, 1336, 999 cmꢁ1; 1H NMR (400 MHz, DMSO-d6) d: 8.88 (m,
3H, ArH), 8.05 (m, 3H, ArH), 7.92 (m, 2H, ArH), 7.83 (m, 3H,
ArH), 7.62 (m, 2H, ArH), 7.23 (m, 2H, ArH), 7.10 (m, 4H, ArH),
5.59 (d, J ¼ 8.0 Hz, 2H, ArH) ppm. Anal. calcd for C39H21N3O2: C,
83.11; H, 3.76; N, 7.46. Found: C, 83.07; H, 3.69; N, 7.38.
4.6.8 5-(o-Tolyl)-10H-spiro[diindeno[1,2-b:20,10-e]pyridine-
11,110-indeno[1,2-b]quinoxaline]-10,12(5H)-dione (5h). Dark
red solid, Rf (n-hexane : ethylacetate): 7 : 3 (v/v) ¼ 0.61; mp
201 ꢀC. IR (KBr) n: 3438, 3061, 2927, 1697, 1578, 1386, 1337,
1000 cmꢁ1; 1H NMR (400 MHz, DMSO-d6) d: 8.21 (m, 2H, ArH),
8.19 (m, 1H, ArH), 8.02 (m, 2H, ArH), 7.86 (m, 2H, ArH), 7.83 (m,
2H, ArH), 7.77 (m, 2H, ArH), 7.67 (m, 1H, ArH), 7.23 (m, 1H,
ArH), 7.21 (m, 1H, ArH), 7.15 (m, 1H, ArH), 7.12 (m, 1H, ArH),
6.96 (m, 1H, ArH), 6.88 (m, 1H, ArH), 5.55 (d, J ¼ 8.0 Hz, 2H,
ArH), 1.21 (s, 3H, CH3) ppm; 13C NMR (100 MHz, DMSO-d6) d:
17.7, 46.4, 121.9, 122.1, 122.8, 124.7, 128.6, 129.1, 129.5, 129.8,
130.3, 130.8, 130.0, 131.4, 132.1, 132.4, 132.9, 133.2, 133.3,
136.4, 136.8, 137.1, 137.4, 138.2, 141.5, 142.6, 151.9, 154.9,
156.8, 156.2, 190.1 ppm. Anal. calcd for C40H23N3O2: C, 83.17;
H, 4.01; N, 7.27. Found: C, 83.11; H, 3.96; N, 7.17.
1
1198 cmꢁ1; H NMR (400 MHz, DMSO-d6) d: 8.18 (s, 1H, ArH),
8.15 (s, 1H, ArH), 8.14 (s, 1H, ArH), 8.12 (s, J ¼ 8.0 Hz, 1H, ArH),
8.07 (s, 1H, ArH), 7.91 (s, 1H, ArH), 7.89 (s, 1H, ArH), 7.86 (s, 3H,
ArH), 7.72 (s, 1H, ArH), 7.70 (s, 1H, ArH), 7.68 (s, 1H, ArH), 7.30
(s, 1H, ArH), 7.29 (s, 1H, ArH), 7.25 (s, 1H, ArH), 7.21 (s, 1H,
ArH), 7.08 (s, 1H, OH), 5.71 (d, J ¼ 4.0 Hz, 2H, ArH) ppm. Anal.
calcd for C39H21N3O3: C, 80.82; H, 3.65; N, 7.25. Found: C, 80.75;
H, 3.60; N, 7.19.
4.6.4 5-(4-Chlorophenyl)-10H-spiro[diindeno[1,2-b:20,10-e]
pyridine-11,110-indeno[1,2-b]quinoxaline]-10,12(5H)-dione (5d).
Dark red solid, Rf (n-hexane : ethylacetate): 7 : 3 (v/v) ¼ 0.63; mp
289 ꢀC. IR (KBr) n: 3431, 3042, 2923, 1728, 1569, 1383, 1337,
1197 cmꢁ1; 1H NMR (400 MHz, DMSO-d6) d:1H NMR (400 MHz,
DMSO-d6): d (ppm) 8.18 (s, 1H, ArH), 8.15 (s, 1H, ArH), 8.14 (s,
1H, ArH), 8.12 (s, 1H, ArH), 8.09 (s, 2H, ArH), 7.95 (s, 1H, ArH),
7.89 (s, 3H, ArH), 7.87 (s, 2H, ArH), 7.70 (t, J ¼ 8.0 Hz, 2H, ArH),
7.22 (s, 1H, ArH), 7.20 (s, 1H, ArH), 7.10 (d, J ¼ 4.0 Hz, 3H, ArH),
5.65 (d, J ¼ 4.0 Hz, 2H, ArH) ppm. Anal. calcd for C39H20ClN3O2:
C, 78.33; H, 3.37; N, 7.03. Found: C, 78.26; H, 3.30; N, 6.98.
4.6.5 5-(3-Nitrophenyl)-10H-spiro[diindeno[1,2-b:20,10-e]
pyridine-11,110-indeno[1,2-b]quinoxaline]-10,12(5H)-dione (5e).
Dark red solid, Rf (n-hexane : ethylacetate): 7 : 3 (v/v) ¼ 0.58; mp
181 ꢀC. IR (KBr) n: 3439, 3067, 2911, 1701, 1535, 1383, 1343,
1000 cmꢁ1; 1H NMR (400 MHz, DMSO-d6) d: 8.24 (d, J ¼ 8.0 Hz,
2H, ArH), 8.18 (d, J ¼ 8.0 Hz, 1H, ArH), 8.11 (m, 3H, ArH), 7.88
(m, 3H, ArH), 7.63 (t, J ¼ 8.0 Hz, 3H, ArH), 7.24 (d, J ¼ 8.0 Hz,
2H, ArH), 7.14 (m, 4H, ArH), 5.97 (d, J ¼ 8.0 Hz, 2H, ArH) ppm.
Anal. calcd for C39H20N4O5: C, 75.00; H, 3.23; N, 8.97. Found: C,
74.95; H, 3.18; N, 8.91.
4.6.9 5-(2,4-Dimethylphenyl)-10H-spiro[diindeno[1,2-
b:20,10-e]pyridine-11,110-indeno[1,2-b]quinoxaline]-10,12(5H)-
dione (5i). Dark red solid, Rf (n-hexane : ethylacetate): 7 : 3 (v/v)
¼ 0.58; mp 234 ꢀC. IR (KBr) n: 3428, 3062, 2923, 1702, 1573,
1385, 1337, 999 cmꢁ1; 1H NMR (400 MHz, DMSO-d6) d: 8.18 (d, J
¼ 8.0 Hz, 1H, ArH), 8.15 (s, 1H, ArH), 8.13 (s, 2H, ArH), 8.01 (d, J
¼ 8.0 Hz, 1H, ArH), 7.92 (s, 2H, ArH), 7.89 (d, J ¼ 8.0 Hz, 2H,
ArH), 7.73 (d, J ¼ 8.0 Hz, 2H, ArH), 7.61 (s, 1H, ArH), 7.52 (s, 1H,
ArH), 7.46 (d, J ¼ 8.0 Hz, 1H, ArH), 7.22 (d, J ¼ 8.0 Hz, 2H, ArH),
7.16 (d, J ¼ 8.0 Hz, 1H, ArH), 7.08 (s, 2H, ArH), 5.63 (d, J ¼
4.0 Hz, 2H, ArH), 2.56 (s, 3H, CH3), 2.38 (s, 3H, CH3) ppm. Anal.
calcd for C41H25N3O2: C, 83.23; H, 4.26; N, 7.10. Found: C, 83.18;
H, 4.19; N, 7.01.
4.6.10 5-(4-Methylphenyl)-10H-spiro[diindeno[1,2-b:20,10-e]
pyridine-11,110-indeno[1,2-b]quinoxaline]-10,12(5H)-dione (5j).
Dark red solid, Rf (n-hexane : ethylacetate): 7 : 3 (v/v) ¼ 0.64;
(mprep. 197 ꢀC)/(mplit 193–205 ꢀC).6 IR (KBr) n: 3432, 3061, 2923,
1697, 1577, 1386, 1337, 997 cmꢁ1; 1H NMR (400 MHz, DMSO-d6)
d: 8.24 (s, 1H, ArH), 8.19 (d, J ¼ 8.0 Hz, 1H, ArH), 8.13 (s, 1H,
ArH), 8.05 (d, J ¼ 8.0 Hz, 3H, ArH), 7.92 (d, J ¼ 8.0 Hz, 1H, ArH),
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7.87 (t, J ¼ 4.0 Hz, 2H, ArH), 7.79 (d, J ¼ 8.0 Hz, 1H, ArH), 7.73 (d,
J ¼ 8.0 Hz, 2H, ArH), 7.60 (d, J ¼ 4.0 Hz, 2H, ArH), 7.24 (s, 1H,
ArH), 7.22 (d, J ¼ 8.0 Hz, 1H, ArH), 7.16 (t, J ¼ 8.0 Hz, 1H, ArH),
7.09 (d, J ¼ 4.0 Hz, 1H, ArH), 5.97 (d, J ¼ 8.0 Hz, 2H, ArH), 1.22
(s, 3H, CH3) ppm; Anal. calcd for C40H23N3O2: C, 83.17; H,
4.01; N, 7.27. Found: C, 83.09; H, 3.93; N, 7.18.
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pyridine-11,110-indeno[1,2-b]quinoxaline]-10,12(5H)-dione (5k). 10 W. C. Conner and J. L. Falconer, Spillover in Heterogeneous
Dark red solid, Rf (n-hexane : ethylacetate): 7 : 3 (v/v) ¼ 0.56;
Catalysis, Chem. Rev., 1995, 95, 759–788.
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1705, 1578, 1339, 1308, 1001 cmꢁ1; 1H NMR (400 MHz, DMSO-
nanoparticles for asymmetric catalysis a perfect match,
d6) d: 8.24 (m, 1H, ArH), 8.22 (m, 1H, ArH), 8.18 (m, 1H, ArH),
Catal. Sci. Technol., 2011, 1, 13–22.
¨
8.09 (m, 2H, ArH), 7.93 (m, 2H, ArH), 7.89 (m, 1H, ArH), 7.77 (m, 12 A.-H. Lu, E. L. Salabas and F. Schuth, Magnetic
1H, ArH), 7.75 (m, 1H, ArH), 7.32 (m, 2H, ArH), 7.23 (m, 1H,
Nanoparticles: Synthesis, Protection, Functionalization,
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calcd for C39H20N4O4: C, 76.97; H, 3.31; N, 9.21. Found: C, 76.90; 13 A. Maleki, M. Aghaei and N. Ghamari, Synthesis of
H, 3.27; N, 9.15.
Benzimidazolo[2,3-b]quinazolinone Derivatives via a One-
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Conflicts of interest
14 C. Yuwei and W. Jianlong, Preparation and characterization
of magnetic chitosan nanoparticles and its application for
Cu(II) removal, Chem. Eng. J., 2011, 168, 286–292.
15 G.-Y. Li, Y.-R. Jiang, K.-L. Huang, P. Ding and J. Chen,
Preparation and properties of magnetic Fe3O4–chitosan
nanoparticles, J. Alloys Compd., 2008, 466, 451–456.
16 H. Wang, J. Wang, J. Wang, R. Zhu, Y. Shen, Q. Xu and X. Hu,
Spectroscopic method for the detection of 2,4-
dichlorophenoxyacetic acid based on its inhibitory effect
towards catalase immobilized on reusable magnetic Fe3O4-
chitosan nanocomposite, Sens. Actuators, B, 2017, 247,
146–154.
There are no conicts to declare.
Acknowledgements
The authors are grateful to the University of Kashan for sup-
porting this work by grant no. 159148/77.
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