Nano MgBi2O4: A Novel Green Catalyst for the One-step Cascade Condensation of Arylamines, Acetone and Isatins in Water

Article abstract of DOI:10.1007/s12039-016-1183-0

Nano-size MgBi₂O₄ has been synthesized for the first time via a simple co-precipitation method using the surfactant N-cetyl- N,N,N-trimethylammonium bromide (CTAB). Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray powder diffraction (XRD) techniques were employed to characterize the nano-catalyst. Additionally, the reactivity of the prepared nanoparticles was investigated in the synthesis of 1^′-aryl-2^′-(2-oxoindolin-3-yl)spiro[indoline-3,5^′-pyrroline]-2,3^′-diones in a one-pot, one-step and pseudo four-component condensation of arylamine, acetone, and isatins at 50°C in water. Five new compounds were synthesized and identified. This procedure has various advantages such as, short reaction times, mild eco-friendly conditions and excellent yields to prepare a novel class of heteroaromatic compounds. MgBi₂O₄ possess superior qualities such as easy and economic preparation procedure and handling, stability, and non-toxicity. Its reusability has also been examined upto 4 runs without activity loss. [Figure not available: see fulltext.]

Full text of DOI:10.1007/s12039-016-1183-0

c
J. Chem. Sci. ꢀ Indian Academy of Sciences.
DOI 10.1007/s12039-016-1183-0
Nano MgBi2O4: A Novel Green Catalyst for the One-step Cascade
Condensation of Arylamines, Acetone and Isatins in Water
KOBRA NIKOOFAR∗, ZAHRA KHADEMI and MARYAM HAGHIGHI
Department of Chemistry, Faculty of Physics and Chemistry, Alzahra University, P.O. Box 1993893973,
Vanak, Tehran, Iran
e-mail: kobranikoofar@yahoo.com
MS received 10 July 2016; revised 18 August 2016; accepted 12 September 2016
Abstract. Nano-size MgBi2O4 has been synthesized for the first time via a simple co-precipitation method
using the surfactant N-cetyl-N, N, N-trimethylammonium bromide (CTAB). Fourier transform infrared (FT-
IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray powder
diffraction (XRD) techniques were employed to characterize the nano-catalyst. Additionally, the reactivity of
the prepared nanoparticles was investigated in the synthesis of 1ꢁ-aryl-2ꢁ-(2-oxoindolin-3-yl)spiro[indoline-
3,5ꢁ-pyrroline]-2,3ꢁ-diones in a one-pot, one-step and pseudo four-component condensation of arylamine, ace-
tone, and isatins at 50◦C in water. Five new compounds were synthesized and identified. This procedure has
various advantages such as, short reaction times, mild eco-friendly conditions and excellent yields to prepare
a novel class of heteroaromatic compounds. MgBi2O4 possess superior qualities such as easy and economic
preparation procedure and handling, stability, and non-toxicity. Its reusability has also been examined upto 4
runs without activity loss.
Keywords. MgBi2O4; spiro compound; multi-component reactions; green chemistry.
1. Introduction
So, a variety methods have been reported for the syn-
thesis of spirooxindole-fused heterocycles.18,19 Recent
synthetic methods to access spirocyclicoxindoles include
cycloaddition,20,21 Morita-Baylis Hillman reaction,22,23
and other cyclization reactions such as photoinduced
reactions,24 and electrocyclization.25
Metal oxides play a critical role in different fields such as
chemistry, physics and material science.1 4 In technolog-
ical applications, metal oxides are used in the manufac-
ture of microelectronic circuits, sensors, piezoelectric
devices, fuel cells, and coatings for the passivation of
surfaces against corrosion.5 7 Metal oxides are used
for their acid/base properties in the context of cataly-
sis. The key features essential for their application as
acid/base catalysts is the coordination environment of
surface and possessing s or p electrons in their valence
orbitals.8 They also demonstrate unequaled physical
and chemical properties due to their limited size and a
high density of corner or edge surface sites.9 Liquid-
solid transformations are possibly the most broadly used
methods for the preparation of metal oxides in order to
control morphological characteristics with certain che-
mical versatility.10 Other than the above mentioned trans-
formations, some other broadly used specific methods
are: co-precipitation methods,11 sol-gel processing,12
microemulsion technique,13 solvothermal methods,14
and template/surface derivatized methods.15
In the past few years different multicomponent or
domino reactions based on the versatile reactivity of
isatins have been utilized for the preparation of various
spirooxindoles.26 29 Among the wide-spread functional
groups which reacted with isatin core, arylamines are
one of the important motifs. Yan and co-workers report-
ed the preparation of cyclopentyl-fused spiro[dihydro-
pyridine-oxindoles] by three-component reaction of
arylamine, isatin and cyclopentane-1,3-dione.30 Perumal
and coworkers successfully reported the synthesis of
spiro[indole-3,4ꢁ-pyridines] derivatives by four-compo-
nent reaction of arylamines, acetylenedicarboxylates,
malononitrile, and isatins.31 The base promoted do-
mino four-component reaction of hydrated hydrazine,
dimethyl acetylenedicarboxylate, isatin and malono-
nitrile or ethyl cycanoacetate in ethanol in the presence
of triethylamine also afforded the polysubstitutedspiro
[indoline-3,4ꢁ-pyrano[2,3-c]pyrazole] derivatives.32 Wet
cyanuric chloride catalyzed the one-pot condensation
of isatins, 3-methyl-1-phenyl-1H-pyrazol-5-amine and
Meldrum’s acid to afford spiro[pyrazolo[3,4-b]pyri-
The spirooxindole system is the core structure of
many pharmacological agents and natural alkaloids.16,17
∗For correspondence

Kobra Nikoofar et al.
dine-4,3ꢁ-indoline] derivatives.33 Pore and Mane pre-
pared some florescent 1-H-spiro[isoindoline-1,2ꢁ-quina-
zoline]-3,4ꢁ(3ꢁH)-diones via the sulphamic acid catalyzed
reaction of isatins and anthranilamide in ethanol.34
Recently, Yan et al., reported the first synthesis of
1ꢁ-aryl-2ꢁ-(2-oxoindolin-3-yl)spiro[indoline-3,5ꢁ-pyrro-
line]-2,3ꢁ-diones via one-pot domino reaction of ary-
lamines, acetone, and isatins in acetic acid.35 Acetic
acid seemed to be both promotor and also reaction
medium. In continuation of research interest in N-
containing heterocycles and nanocatalysts,36 47 herein
we prepared magnesium bismuth tetroxide (MgBi2O4)
as a novel nano compound by a simple co-precipitation
method and characterized by SEM, FT-IR, XRD, and
EDX techniques. The catalytic activity of the prepared
nanocrystalline MgBi2O4, has been examined in the
preparation of 1ꢁ-aryl-2ꢁ-(2-oxoindolin-3-yl)spiro[indo-
line-3,5ꢁ-pyrroline]-2,3ꢁ-diones via one-pot and one-
step condensation of arylamines, acetone, and isatins
at 50◦C in water medium (Scheme 1). Five of the eight
reported derivatives are new compounds.
thick layer of Merck silica gel PF254, prepared by apply-
ing the silica as slurry and drying in air. The scanning
electron microscope (SEM, model ZEISS AMA) was
used to characterize the nanostructures. All products
were characterized by their spectral and physical data.
An ultrasound bath (Wise Clean, Korea) was used for
sonication. The XRD pattern was obtained by an X-ray
diffractometer, Philips (xꢁpert MPD, The Netherland)
with CuKα1 radiation, cobalt anode with wavelength
1.7889 Å at 40 kV and 40 mA. The centrifuge appara-
tus was a RST16 full digital model with rpm 300 cycle
min−1.
2.1 Preparation of Nano MgBi2O4
In a typical preparation, deionized water (100 mL) was
added to stoichiometric amounts of magnesium nitrate
hexahydrate (Mg(NO3)2.6H2O) (4.0 mmol, 1.024 g)
and bismuth nitrate pentahydrate (Bi(NO3)3.5H2O)
(4.0 mmol, 1.940 g) and sonicated in ultrasound bath for
20 min. Then, N-cetyl-N, N, N-trimethylammonium
bromide (CTAB) (2.0 g) was added and the pH of the
solution adjusted to 9 by dropwise addition of concen-
trated ammonia under continuous stirring. After pre-
cipitation, the slurry was sonicated for another 30 min
and subsequently refluxed at 80◦C for 24 h under con-
tinuous stirring. Then the mixture was cooled to room
temperature and centrifuged. The final product is dried
at 100◦C for 24 h and calcined at 800◦C for 6 h. The
pale yellow powder is nano-size magnesium bismuth
tetroxide.
2. Experimental
All chemicals were purchased from Merck, Aldrich and
Alfa Aesar and were used as received. N-Benzylisatin
was synthesized from isatin according to the reported
procedure.48 IR spectra were recorded from KBr disk
using FT-IR Bruker Tensor 27 instrument. Melting
points were determined on an Electrothermal 9200
1
analyzer and are uncorrected. H NMR spectra were
recorded with a Bruker drx (400 MHz) machine.
Elemental analyses were determined using a Thermo-
Finnigan Flash EA 1112 Series. Progress of the reac-
tion was monitored by thin layer chromatography
(TLC) technique using commercially available silica
2.2 General procedure for the preparation of 1ꢁ-Aryl-
2ꢁ-(2-oxoindolin-3-yl)spiro[indoline-3,5ꢁ-pyrroline]-2,
3ꢁ-diones
gel sheets. Preparative layer chromatography (PLC) A mixture of isatins 1 (2.0 mmol), arylamines 2 (1.0
carried out on 20 × 20 cm2 plates, coated with a 1 mm mmol), acetone 3 (2.0 mL) and MgBi2O4 (0.55 mmol,
R1
O
R1
O
RN
O
O
N
MgBi2O4 (0.28 g, 0.55 mmol)
H2O, 50oC
O
+
+
NR
N
R
O
NH2
2a
: R1 = H
1a
: R = H
1b: R = CH2Ph
3
4(a-h)
2b: R1 = Cl
2c
: R1 = Br
2d: R1 = NO2
2e
: R1 = Me
2f: R1 = OMe
Scheme 1. Synthesis of 1ꢁ-phenyl-2ꢁ-(2-oxoindolin-3-yl)spiro[indoline-3,5ꢁ-
pyrroline]-2,3ꢁ-dione derivatives 4(a–h) in the presence of nano MgBi2O4.

Condensation of Arylamines, Acetone and Isatins
0.28 g) in water (5 mL) was stirred at 50◦C for the for C39H30N3ClO3: C 75.05, H 4.84, N 6.73%. Found:
desired reaction time. The progress of the reaction was C 74.86, H 4.79, N 6.68%.
monitored by TLC, (n-hexan/EtOAc, 1:1). After com-
pletion of the reaction, the mixture was extracted with
2.2e 1ꢁ-4-Bromo-2ꢁ-(2-oxoindolin-1-benzyl-3-yl)spiro
CHCl3 (2 × 10 mL). Purification of the product was
gained by PLC eluted with n-hexan/EtOAc (1:1) to give
dark yellow solids 4(a–h) in 71–95% isolated yields.
The characterization data of the new compounds are as
follows.
[indoline-3,5ꢁ-pyrroline]-2,3ꢁ-dione (4h): M.p. 230◦C.
FT-IR (KBr): υ = 3320, 2922, 2854, 1699, 1616, 1494,
1
1465, 1430, 1179, 1106, 754 cm−1. HNMR (DMSO-
d6): δ 3.12–3.18 (m, 2H), 3.47 (d, J = 14.17 Hz, 1H),
4.79 (d, J = 21.05 Hz, 1H), 4.89 (d, J = 21.18 Hz, 1H),
6.18–6.21 (m, 2H), 6.72 (d, J = 10.36 Hz, 2H), 7.15
(d, J = 10.18 Hz, 4H), 7.22–7.26 (m, 2H), 7.30–7.34
(m, 3H), 7.41 (d, J = 9.8 Hz, 2H) ppm. Anal. Calcd.
for C39H30N3BrO3: C 70.06, H 4.52, N 6.28%. Found:
C 69.94, H 4.60, N 6.08%.
2.2a 1ꢁ-Phenyl-2ꢁ-(2-oxoindolin-3-yl)spiro[indoline-
3,5ꢁ-pyrroline]-2,3ꢁ-dione(4a): M.p. 224◦C. FT-IR
(KBr): υ = 3380, 2924, 2855, 1726, 1621, 1467, 1375,
753 cm−1. 1H NMR (DMSO-d6): δ 2.95–3.04 (m, 1H),
3.23–3.33 (m, 1H), 5.07 (d, J = 14.56 Hz, 1H), 5.98(br
s, 1H, NH), 6.44 (d, J = 13.72 Hz, 1H), 6.76 (d, J =
9.62 Hz, 2H), 6.86–6.91 (m, 2H), 6.98–7.07 (m, 1H),
7.13–7.28 (m, 8H), 10.23 (br s, 1H, NH) ppm. Anal.
Calcd. for C25H19N3O3: C 73.33, H 4.67, N 10.26%.
Found: C 72.87, H 4.53, N 10.05%.
3. Results and Discussion
The FT-IR spectrum nano MgBi2O4 at 450–4000 cm−1
is shown in Figure 1. The broad band at 3424 cm−1
shows the stretching vibration of hydroxyl group related
to the adsorbed water on the catalyst surface. The
peak at 1636 cm−1 shows the bending vibration of
water molecule. The major peaks at 880 and 512 cm−1
are related to the characteristic absorption peaks of
Mg-O and Bi-O vibrations, respectively. The bands in
the region of 2923, 2853 cm−1, which belong to the
symmetrical and unsymmetrical methylene groups of
CTAB, are absent in the FT-IR spectra. The band at
1005 cm−1 may belong to Mg-Bi vibration.
2.2b 1ꢁ-4-Bromoaniline-2ꢁ-(2-oxoindolin-3-yl)spiro
[indoline-3,5ꢁ-pyrroline]-2,3ꢁ-dione (4c): M.p. 222◦C.
FT-IR (KBr): υ = 3373, 3171, 2958, 2923, 2853, 1721,
1
1619, 1460, 754 cm−1. H NMR (DMSO-d6): δ 2.98
(m, 1H), 3.31 (m, 1H), 4.45 (m, 2H), 6.08 (br s, 1H,
NH), 6.75–6.88 (m, 4H), 6.88–7.01 (m, 1H), 7.15–7.18
(m, 3H), 6.24–7.26 (m, 4H), 10.28 (br s, 1H, NH) ppm.
Anal. Calcd. for C25H18N3BrO3: C 61.48, H 3.71, N
8.60%. Found: C 61.21, H 3.67, N 8.21%.
The SEM pattern of nano MgBi2O4 is shown at
Figure 2. This image reveals that the product consists
of particles with the average size of 70–200 nm, with
semi-spherical morphology. The wide range could be
due to thermal variation or surfactant concentration
change. Also, the average crystallite size is estimated
using Scherrer formula (d = kλ/β cos θ), where λ is
the wavelength of the X-ray (λ = 1.78 Å), k is a con-
stant between 0.89 and 1.0, and θ is the Bragg’s diffrac-
2.2c 1ꢁ-4-Nitroanilin-2ꢁ-(2-oxoindolin-3-yl)spiro[in-
doline-3,5ꢁ-pyrroline]-2,3ꢁ-dione (4d): M.p. 201◦C.
FT-IR (KBr): υ = 3415, 2924, 2855, 1730, 1647, 1459,
1
1425, 1387, 1037, 875, 789, 467 cm−1. H NMR
(DMSO-d6): δ 2.98 (m, 1H), 3.28 (m, 1H), 4.11–4.13
(m, 2H), 5.98 (br s, 1H, NH), 6.76 (d, J = 10.12 Hz,
2H), 6.88 (t, J = 9.86 Hz, 2H), 7.15 (t, J = 9.90 Hz,
2H), 7.22 (d, J = 9.56 Hz, 2H), 7.64–7.72 (m, 4H),
10.23 (s, 1H, NH) ppm. Anal. Calcd. for C25H18N4O5:
C 66.07, H 3.99, N 12.33%. Found: C 65.95, H 3.89, N
12.05%.
tion angle. The β is sum of the βsize, βins and βstrain
.
The βstrain, that identified the micro strain of crystal,
is negligible. The instrumental broadening effect (βins),
which was measured by XRD instrument, is 0.0033
radian. Then the true value of βsize is calculated by βsize
2.2d 1ꢁ-4-Chlorophenl-2ꢁ-(2-oxoindolin-1-benzyl-3-
yl)spiro[indoline-3ꢁ,5-prrolin]-2,3-dione (4g): M.p. = β – βins. The mean crystal size is calculated as 63
238–245◦C. FT-IR (KBr): υ = 3316, 2923, 2853, 1699, nm which corresponds to the minimum size in the SEM
1617, 1494, 1467, 1431, 1386, 1181, 1079, 1003, 755, image (70 nm, Figure 2). This calculation revealed that
733 cm−1. H NMR (DMSO-d6): δ 3.15 (d, J = 22.62 the CTAB amount, that could control the particle size,
1
Hz, 1H), 3.42 (d, J = 22.67 Hz, 1H), 4.79 (d, J = is suitable for the preparation of small nanoparticles.
21.2 Hz, 2H), 4.81 (d, J = 21.04 Hz, 2H), 6.16–6.21
EDX in Figure 3 shows that the catalyst is mainly
(m, 2H), 6.71 (d, J = 10.12 Hz, 2H), 6.94 (t, J = made up of magnesium and bismuth. The weight
9.72 Hz, 4H), 7.15 (t, J = 10.23 Hz, 4H), 7.24–7.31 percent of the product confirms the molecular formula
(m, 10H), 7.41 (d, J = 9.57 Hz, 2H) ppm. Anal. Calcd. of MgBi2O4. The amount of Au is negligible.

Kobra Nikoofar et al.
Figure 1. FT-IR spectrum of synthesized nano MgBi2O4.
Figure 2. SEM image of nano-size MgBi2O4.
The morphology and phase identification of the syn- temperature effects revealed that performing the reac-
thesized nanocatalyst was investigated using XRD pat- tion at 50◦C in water medium yielded the best results
tern (Figure 4). According to Figure 4, the peaks were (Table 1, entries 1–8). Changing the catalyst amount,
observed at the scattering angles 32.03, 34.63, 36.85, affirmed that 0.55 mmol (0.28 g) of the nano MgBi2O4
37.49, 39.17, 43.05, 44.11, 47.49, 58.27 and 63.03 is the best choice (Table 1, entries 5, 9, and 10).
degrees witht related normalized intensities of 18.36,
Eventually, on the basis of optimized conditions, the
16.80, 55.55, 62.22, 100, 14.40, 40.13, 21.125, 32.65, pseudo four-component condensation of various isatins,
and 24.07, respectively. The impurities such as Au anilines, and acetone was performed in the presence of
could change the peak locations.
In order to achieve the optimum conditions, the mo- of water at 50◦C. The results are summarized in Table 2.
del condensation of isatin 1a (2 mmol), 4-bromoaniline As could be seen at Table 2, the protocol is very
nano-size MgBi2O4 (0.55 mmol 0.28 g) in the presence
2c (1 mmol), and acetone 3 (2 mL) in the presence of effective for the condensation of isatin (1a) with differ-
MgBi2O4 (0.55 mmol, 0.28 g) was chosen. Solvent and ent anilines consisting electron-withdrawing (entries 1–4)

Condensation of Arylamines, Acetone and Isatins
Figure 3. EDX image of synthesized MgBi2O4 nano catalyst.
2 (deg)
Figure 4. XRD spectrum of synthesized nano MgBi2O4.
as well as electron-donating groups (entries 6, 7). runs. According to optimized reaction conditions, isatin
N-Benzylisatin (1b), as an electron-donating isatin, 1a (4 mmol), 4-bromoaniline 2c (2 mmol), and acetone
reacted with 4-chloro- and 4-bromoaniline, respec- 3 (4 mL) in H2O (10 mL) at 50◦C in the presence of
tively, to obtain 3g and 3h (entries 7, 8) succesfully. We MgBi2O4 (1.1 mmol, 0.56 g) mixed and stirred magnet-
also performed the reaction with electron-withdrawing ically until completion of reaction (15 min); Then the
isatins such as 5-nitroisatin with anilines but the data mixture was diluted with ethanol (20 mL). The catalyst
was not satisfactory.
was separated by filtration, washed with more ethanol
The reusability of nano-size MgBi2O4 for the MCR (10 mL) and air-dried. Subsequently the residue was
to afford 4c was also investigated for three additional heated in oven at 100◦C for 20 min and used for another

Kobra Nikoofar et al.
Table 1. Screening the reaction conditions in the preparation of 4c.a
Entry
Conditions
Time (min)
Yield (%)b
1
2
3
4
5
6
7
8
9
MgBi2O4 (0.28 g), r.t., solvent-free
MgBi2O4 (0.28 g), 80◦C, solvent-free
MgBi2O4 (0.28 g), r.t., H2O (5 mL)
MgBi2O4 (0.28 g), 40◦C, H2O (5 mL)
MgBi2O4 (0.28 g), 50◦C, H2O (5 mL)
MgBi2O4 (0.28 g), reflux, H2O (2 mL)
MgBi2O4 (0.28 g), r.t., CH3CN (5 mL)
MgBi2O4 (0.28 g), reflux, CH3CN (5 mL)
MgBi2O4 (0.20 g), 50◦C, H2O (5 mL)
MgBi2O4 (0.32 g), 50◦C, H2O (5 mL)
135
450
35
25
15
41
92
91
91
93
93
43
92
91
93
15
135
570
40
10
15
a1a (2 mmol), 2c (1 mmol), and 3 (2 mL).
bIsolated yields.
Table 2. Synthesis of 1ꢁ-aryl-2ꢁ-(2-oxoindolin-3-yl)spiro[indoline-3,5ꢁ-pyrroline]-
2,3ꢁ-diones in the presence of MgBi2O4.a
Entry
R
R1
Product Time (min) Yield (%)b M.p. (◦C) Lit M.p. (◦C)
1
2
3
4
5
6
7
8
H
H
H
H
H
H
Cl
Br
NO2
CH3
OCH3
Cl
4a
4b
4c
4d
4e
4f
35
15
15
45
35
15
45
45
95
92
93
71
90
93
91
94
224
251-254
222
–
248-251
–
–
201
228-233
235-239
238-243
230
232-235
238-241
H
PhCH2
PhCH2
4g
4h
–
–
Br
aReaction conditions: isatins (2 mmol), anilines (1 mmol) and acetone (2 mL) in H2O
(5 mL) at 50◦C in the presence of MgBi2O4 (0.55 mmol, 0.28 g).
bIsolated yields.
cycle without a considerable loss of catalytic activity could be successfully recycled and reused at least for 4
during 3 runs. The yields for runs 1–4 were 93%, 92%, runs without significant loss in activity.
90% and 90%, respectively.
Supplementary Information (SI)
All additional information pertaining to characteriza-
4. Conclusions
tion of the derivatives 4a, 4c–d, and 4g–h, IR spectra
1
(Figures S1, S3, S5, S7, S10) and H NMR spectra
In conclusion, nanocrystalline MgBi2O4 has been pre-
(Figures S2, S4, S6, S8, S10) are available in Supple-
pared for the first time via a simple co-precipitation
mentary Information at www.ias.ac.in/chemsci.
method using available salt precursors and CTAB as
organic surfactant. The characterization has been per-
formed via SEM, FT-IR, EDX, and XRD techniques. Its
Acknowledgements
catalytic activity has been examined for the synthesis of
novel 1ꢁ-aryl-2ꢁ-(2-oxoindolin-3-yl)spiro[indoline-3,5ꢁ-
pyrroline]-2,3ꢁ-diones successfully. This research have
several advantages such as, short reaction times, high
yields of products, absence of any bi-products due to
the aldol condensation of acetone, ambient temperature,
and utilizing easy to handle, inexpensive and non-toxic
nano catalyst. The procedure happened in water media
and hasn’t required and hazardous organic solvents,
which follows the green chemistry. Also the catalyst
Authors greatly appreciate the Iran National Science
Foundation (INSF) for the financial support for this
study.
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