Copper ferrite nanoparticles: An efficient and reusable nanocatalyst for a green one-pot, three-component synthesis of spirooxindoles in water

Article abstract of DOI:10.1021/co400057h

A green reaction of isatins, active cyanomethanes, and cyclic 1,3-dicarbonyl derivatives for the efficient and simple one-pot three-component synthesis of spirooxindole fused heterocycles in refluxing water by use of magnetically recoverable and reusable catalyst is reported. The features of this procedure are, the use of magnetically recoverable and reusable catalyst, mild reaction conditions, high to excellent product yields, operational simplicity, and easy workup procedures. Most importantly of all, easy magnetic separation of the catalyst eliminates the requirement of catalyst filtration after completion of the reaction. Furthermore, the catalyst remained highly active even after 5 repeated uses.

Full text of DOI:10.1021/co400057h

Technology Note
pubs.acs.org/acscombsci
Copper Ferrite Nanoparticles: An Efficient and Reusable Nanocatalyst
for a Green One-Pot, Three-component Synthesis of Spirooxindoles
in Water
Ayoob Bazgir,† Ghaffar Hosseini,† and Ramin Ghahremanzadeh*,‡
†Department of Chemistry, Shahid Beheshti University, G.C., P.O. Box 19396-4716, Tehran 1983963113, Iran
‡Nanobiotechnology Research Center, Avicenna Research Institute, ACECR, Tehran 1177-19615, Iran
S
* Supporting Information
ABSTRACT: A green reaction of isatins, active cyano-
methanes, and cyclic 1,3-dicarbonyl derivatives for the efficient
and simple one-pot three-component synthesis of spiroox-
indole fused heterocycles in refluxing water by use of
magnetically recoverable and reusable catalyst is reported.
The features of this procedure are, the use of magnetically
recoverable and reusable catalyst, mild reaction conditions,
high to excellent product yields, operational simplicity, and
easy workup procedures. Most importantly of all, easy magnetic separation of the catalyst eliminates the requirement of catalyst
filtration after completion of the reaction. Furthermore, the catalyst remained highly active even after 5 repeated uses.
KEYWORDS: multicomponent reaction, tandem reaction, spirooxindole, heterocyclic compound, green media, water,
magnetic nanoparticles
water, without the use of harmful and flammable organic
solvents is appealing to an environmentally conscious society.
Numerous studies have focused on finding water-compatible
and reusable catalysts.11−13
ombinatorial chemistry is extensively useful for the
1
Cdiscovery of novel biologically active compounds.
In
this framework, multicomponent reactions (MCRs) are an
effective tool in the current drug discovery process in terms of
lead finding and lead optimization, but the range of easily
accessible and functionalized small heterocycles is rather
limited.2 These strategies have emerged as flexible approaches
in organic synthesis due to their advantages over the
conventional multistep synthesis. In addition, they are eco-
friendly, have superior atom economy, require less time-
consuming and costly purification processes and avoid
protection−deprotection steps. Because of the range of readily
available starting materials, the simplicity of one-pot procedures
without the need for isolation of intermediates, and the
associated atom economy, MCRs have been broadly employed
in the synthesis of heterocyclic compounds.3−5 Therefore, the
design and development of novel, efficient, and green MCRs
focused on a target product is one of the most important
challenges in organic synthesis. The use of water as a green
solvent for organic synthesis has recently attracted considerable
attention.6 Since Breslow demonstrated hydrophobic effects
could strongly increase the rate of some organic reactions and
fostered the use of water as solvent in organic chemistry in
1980s,7 there has been a growing recognition that water is an
attractive medium for many organic reactions, such as Claisen
rearrangement, Diels−Alder, Reformatsky, and pinacol-cou-
pling reactions.8−10 The use of water can afford the noteworthy
benefit of a highly polar environment wherein miscible organic
compounds react rapidly and are subsequently easily separated
from the solvent. Furthermore, carrying out organic reactions in
The use of low-cost and readily available species as catalyst
plays a significant role for economical feasibility of the chemical
processes. Recently, research has been directed toward the
synthesis and application of metal oxide nanoparticles in view
of their unique properties compared to the bulk metals. Among
various metal oxide nanoparticles, magnetic nanoparticles have
received considerable attention because of their unusual
properties and potential applications in diverse fields. Iron,
the most ubiquitous of the transition metals and the fourth
most plentiful element in the Earth’s crust, is the structural
backbone of our modern infrastructure. Magnetic nanoparticles
are receiving increasing interest in recent years and are being
used widely as a useful group of heterogeneous catalysts for
organic synthesis due to their remarkable advantages such as
the remarkable catalytic activity, easy synthesis, operational
simplicity, eco-friendliness, and recoverability with an external
magnetic field. Magnetic separation is an attractive alternative
to filtration or centrifugation as it prevents the loss of catalyst
and enhances reusability, rendering the catalyst cost-effective
and is promising for industrial applications.14−18 These
advantages encouraged us to explore copper ferrite nano-
Received: May 6, 2013
Revised: August 31, 2013
© XXXX American Chemical Society
A
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ACS Combinatorial Science
Technology Note
particles as a recoverable and reusable catalyst for the synthesis
of spirooxindole derivatives.
times. Moreover, as clearly stated by Sheldon, it is generally
recognized that “the best solvent is no solvent and if a solvent
(diluent) is needed it should preferably be water”.30
Compounds with an indole moiety exhibit antibacterial and
antifungal activities. Furthermore, it has been reported that
spiroindoline derivatives have highly enhanced biological
activity.19 The presence of a sterically constrained spiro
structure in some natural products also adds to the interest
in the investigations of spiro compounds.20 The development
of synthetic methods for these compounds, including the ones
with new substitution patterns, is therefore of high importance
in organic chemistry. For example, spirotryprostatins A and B
(Figure 1) are cytostatic alkaloids, pteropodine, and isopter-
opodine have been shown to modulate the function of
muscarinic serotonin receptors.21
In a pilot experiment, the reaction of 3-hydroxy-1H-
phenalen-1-one 1(1), malononitrile 2(1), and isatin 3(1) in
the presence of CuFe2O4 (10 mol %) as an inexpensive,
magnetically recoverable, and reusable catalyst proceeded
rapidly in refluxing water. The progress of the reaction was
monitored by TLC. After completion of the reaction (30 min),
the product 10′-amino-1,2-dihydro-2,7′-dioxospiro[3H-indole-
3,8′(7H,8H)-phenaleno[1,2-b]pyran]-9′-carbonitrile 4{1,1,1}
1
was obtained in 90% yield (Scheme 2). H and 13C NMR
spectra of the crude product clearly confirmed the formation of
spirooxindole 4{1,1,1}.
Scheme 2. Model Reaction
Figure 1. Spirooxindole-containing compounds.
Considering the above reports, the development of simple
multicomponent methods for the efficient preparation of
spirooxindoles is therefore an interesting challenge. Multi-
component reactions of malononitrile or alkyl cyanoacetate,
isatins, and 1,3-dicarbonyl compounds are a powerfull methods
for the synthesis of spirooxindoles22−27 (Scheme 1). In most of
Encouraged by this success and to delineate this approach,
particularly in regard to library construction, this methodology
was evaluated by using different cyclic 1,3-dicarbonyl
compounds, active cyanomethanes and isatins. Four cyclic
1,3-dicarbonyl derivatives 1(1−4) four active cyanomethanes
2(1−4), and seven substituted isatins 3(1−7) were chosen for
the library validation (Figure 2). Corresponding 43 spiroox-
indole fused heterocycles 4 were selectively synthesized by the
tandem three-component condensation of cyclic 1,3-dicarbon-
yls 1, active cyanomethanes 2 and isatin 3 in good yields in
boiling H2O in the presence of CuFe2O4 for 30 min. The
results can be summarized as shown in Table 1. The yields and
Scheme 1. Previous Synthetic Strategies
these methods expensive catalysts were used, which are
incompatible with industrial demands for cost-efficiency.
Furthermore, in some cases catalyst recovery is difficult and
the prolonged reaction times were needed.
In continuation of our investigations on the synthesis of
heterocyclic compounds,28 recently, we have reported efficient
methods for spirooxindole synthesis via new multicomponent
reactions.29 Herein, we performed the synthesis of spiroox-
indole fused heterocycles through tandem three-component
reactions of isatins, active cyanomethanes, and cyclic 1,3-
dicarbonyl compounds employing water as the reaction
medium in the presence of copper ferrite nanoparticles as a
powerfuul catalyst. Compared to alternative reports for
preparation of these molecules, the present method not only
benfits from magnetically recoverable catalysis but also the
products were obtained in higher yields and shorter reaction
Figure 2. Diversity of reagents.
B
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ACS Combinatorial Science
Technology Note
product purity were remarkable in presence of CuFe2O4, while
without catalyst the yields of products were low (23%).
Table 2. Different Amount of the CuFe2O4 Nanoparticles As
Catalyst in Model Reaction
a
b
entry
CuFe2O4 nanoparticles (mol %)
time (min)
yield (%)
Table 1. Synthesis of Spiro[indoline-
pyrazolopyridopyrimidine] Derivatives
1
2
3
4
5
2
5
60
60
30
30
45
78
86
90
90
89
10
15
20
a
The reaction was carried out using isatin (1 mmol), malononitrile (1
mmol), and 2-hydroxynaphthalene-1,4-dione (1 mmol) in the
presence of catalyst and H2O (5 mL). Isolated yield of the pure
b
product 4
yield (%)
product 4
yield (%)
4{1,1,1}
4{1,1,2}
4{1,1,3}
4{1,1,4}
4{1,1,5}
4{1,1,6}
4{1,1,7}
4{1,2,1}
4{1,2,4}
4{1,3,5}
4{1,4,1}
4{1,4,4}
4{2,1,1}
4{2,1,2}
4{2,1,3}
4{2,1,4}
4{2,1,5}
4{2,1,6}
4{2,1,7}
90
83
85
94
90
92
96
90
91
95
88
85
90
97
88
86
85
93
94
4{2,2,1}
4{2,2,2}
4{2,2,5}
4{2,3,4}
4{2,4,1}
4{2,4,4}
4{2,4,5}
4{3,1,1}
4{3,1,5}
4{3,1,7}
4{3,3,1}
4{3,3,5}
4{4,1,1}
4{4,1,5}
4{4,1,7}
4{4,2,1}
4{4,3,1}
4{4,3,4}
4{4,3,5}
89
92
94
92
85
87
89
87
82
81
94
92
84
82
81
91
93
96
93
compound.
the next reaction runs. The procedure was repeated and the
results indicated the recycled catalyst could be used five times.
The isolated yields were similar and remained with no
detectable loss, until the fifth recycling, 90%, 90%, 89%, 88%,
and 80% (Figure 3).
Figure 3. Recyclability of CuFe2O4 on the synthesis of product
4{2,1,1}.
As shown in Table 1, it was found that the method works
with a wide variety of substrates, and this made it possible to
synthesize a series of spirooxindole fused heterocycles.
The workup of these very clean reactions involves only a
filtration and simple washing step with EtOH. After completion
of the reaction, the mixture was magnetically concentrated with
the aid of a magnet to separate the catalyst. Using this simple
purification protocol the desired products are obtained in high
purity. Compounds 4 are stable solids whose structures were
We expect this method to find extensive application in the
field of combinatorial chemistry, diversity-oriented synthesis,
and drug discovery. This method, based on green tandem
three-component CuFe2O4-catalyzed reaction in water, is the
most simple, convenient and would be applicable for the
synthesis of different types of spirooxindole fused heterocycles.
The yields and product purity were remarkable in presence
of CuFe2O4, while without catalyst the yields of products were
low. We reconsider the model reaction in absence of any
catalyst and the yield of product was determined 23% after
purification by a column chromatography. We also evaluated
the amount of catalyst required for this transformation. The
model reaction was performed in the presence of 2, 5, 10, 15,
and 20 mol % of catalyst. It was found that using 10 mol %
copper ferrite nanoparticles as a catalyst in water is sufficient to
push the reaction forward. Increasing the amount of nano
CuFe2O4 particles to more than 10 mol % showed no
substantial improvement in the yield. Thus, 10 mol % of
catalyst was chosen as suitable quantity of the catalyst for the
reaction (Table 2).
Finally, The possibility of recycling the magnetic catalyst was
examined by using the reaction of isatin 3(1), malononitrile
2(1), and 2-hydroxynaphthalene-1,4-dione 1(2) as model
substrates under optimized conditions. After completion of
the reaction, while the reaction mixture is still hot enough to
keep the product in solution, the catalyst was removed from the
hot reaction solution immediately with an external magnet,
washed with acetone, and the recycled catalyst was saved for
1
established by IR, H, 13C NMR spectroscopy, and elemental
analysis.
In conclusion, an efficient, clean, atom-economical and
simple method for the preparation of spirooxindoles using
readily available starting materials by tandem one-pot three-
component reaction is reported. Prominent among the
advantages of this new method are operational simplicity,
high to excellent product yields and easy workup procedures
employed. Most important of all, easy magnetic separation of
the catalyst eliminates the requirement of catalyst filtration after
completion of the reaction, which is an additional green
attribute of this reaction.
EXPERIMENTAL PROCEDURES
■
General. Melting points were measuring on an Electro-
thermal 9100 apparatus and are uncorrected. 1H and 13C NMR
spectra were recorded on a BRUKER DRX-300 AVANCE
1
spectrometer at 300.13 and 75.47 MHz, respectively. H and
13C NMR spectra were obtained on solutions in DMSO-d6
using TMS as internal standard. IR spectra were recorded using
an FTIR apparatus. Elemental analyses were performed using a
Heraeus CHN-O-Rapid analyzer.
C
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ACS Combinatorial Science
Technology Note
The chemicals used in this study were obtained from Fluka
and Merck and were used without purification.
AUTHOR INFORMATION
Corresponding Author
*Tel: +98-21-22432020; Fax; +98-21-22432021. E-mail: r.
ghahremanzadeh@avicenna.ac.ir,.
■
Typical Experimental Procedure for the Preparation
of Catalyst. CuFe2O4 nanoparticles were prepared by
coprecipitation of Cu(NO3)2 and Fe(NO3)3 in water in the
presence of sodium hydroxide. Briefly, a solution of Fe(NO3)3·
9H2O (2.02 g, 5 mmol) and Cu(NO3)2·3H2O (0.604 g, 2.5
mmol) in distiller water (10 mL) was treated with aqueous
NaOH (4M, 7.5 mL, 30 mmol) at room temperature over a
period of 10 min to form a reddish-black precipitate. The
reaction mixture was warmed to 90 °C and stirred. After 2 h, it
was cooled to room temperature and the formed magnetic
particles were separated by a magnetic separator. Then, the
catalyst was washed with water and kept in air oven overnight
at 80 °C. Then the catalyst was ground in a mortar-pestle and
kept in a furnace at 800 °C at a heating rate of (2 °C/min) and
cooled to 100 °C at (5 °C/min) in air. The XRD patterns of
calcinated precipitate indicate that the powder is mainly
composed of CuFe2O4 (Figure 4).31 The position and relative
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We gratefully acknowledge financial support from the Avicenna
Research Institute.
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S
* Supporting Information
Additional materials including NMR data and additional
experimental details. This material is available free of charge
via the Internet at http://pubs.acs.org.
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