On water synthesis of pyran-chromenes via a multicomponent reactions catalyzed by fluorescent t-ZrO2 nanoparticles

Article abstract of DOI:10.1039/c5ra19290k

Here, we have demonstrated fluorescent tetragonal ZrO₂ nanoparticle (t-ZrO₂ NP) catalyzed green one-pot multicomponent protocol for the synthesis of diverse pyran-fused chromene analogues such as 2-aminochromene, dihydropyrano[3,2-c]

Full text of DOI:10.1039/c5ra19290k

View Article Online
View Journal
RSC Advances
This article can be cited before page numbers have been issued, to do this please use: S. Banerjee, A.
Saha and S. Payra, RSC Adv., 2015, DOI: 10.1039/C5RA19290K.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. This Accepted Manuscript will be replaced by the edited,
formatted and paginated article as soon as this is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/advances

Please do not adjust margins
RSC Advances
Page 1 of 9
View Article Online
DOI: 10.1039/C5RA19290K
RSC Advances
ARTICLE
On water synthesis of pyran-chromenes via multicomponent
reaction catalyzed by fluorescent t-ZrO2 nanoparticles
Arijit Saha,a Soumen Payraa and Subhash Banerjeea,*
Received 00th January 20xx,
Accepted 00th January 20xx
Here, we have demonstrated fluorescent tetragonal ZrO2 nanoparticles (t-ZrO2 NPs) catalyzed green one-pot
multicomponent protocol for the synthesis of diverse pyran fused chromene analogous such as 2-aminochromenes,
dihydropyrano[3,2-c]chromene, chromeno[4,3-b]chromene derivatives in water. The rate of the reactions and yields of the
products have increased significantly in water. In addition, t-ZrO2 NPs showed higher reactivity than monoclinic ZrO2 NPs.
The t-ZrO2 NPs were recycled and the gradual decrease in yield of the product using recycled catalyst could be possibly
due to the decrease in zrconium content associated with decrease in oxygen vacancies which were evident from
fluorescence and atomic absorption studies. However, the tetragonal phase of the catalyst remained intact even at 10th
cycle.
DOI: 10.1039/x0xx00000x
www.rsc.org/
nanoparticles,8 we have reported excellent catalytic activity of
ZrO2 NPs in MCRs leading pyrano[2,3-c]pyrazoles and
bezylpyrazolyl coumarins.8i In this paper, we have explored
Introduction
The development of green alternative multicomponent
reactions (MCRs) has attracted much attention as these
reactions produced important biological scaffolds1 and various
designers as well as marketed drugs2 in en environment-
friendly pathway. The reaction parameters such as, solvent,
catalyst etc. of a MCR determines the selectivity, versatility
and environmental acceptability. Water is the greenest solvent
among all and consequently it has been widely used as
reaction media for elementary organic transformations3a-e as
well as in MCRs.4 It has also been reported that water
accelerates the rate of the reaction due to its high polarity,
hydrogen bonding in the transition state and hydro-phobic
effect.3,4 On other side, catalyst also plays a crucial role in
determining the yield and selectivity. Thus, synthesis of bio-
active scaffolds via MCR using a mild and inexpensive catalyst
in green solvent like water is appreciated.
the catalytic activity of ZrO2 NPs in one-pot MCRs leading
various bioactive pyran fused chromene scaffolds namely, 2-
aminochromenes,
dihydropyrano[3,2-c]chromenes
and
chromeno[4,3-b]chromenes (scheme 1).
Recently, heterogeneous nano-catalysis have attracted
much interest due to their unique properties of large and
reactive surface areas, selective reactivity, reusability, greener
reactions reaction conditions5 and providing advantages of
both homogeneous and heterogeneous catalysis.6 Very
recently, metal oxide nanoparticles (NPs) have been widely
applied as catalysts because of their dual Lewis acid and Lewis
base nature and red-ox properties on the surface.7 As a part of
our continuous interest in catalysis by metal oxide
Scheme 1 ZrO2 NPs catalyzed synthesis of functionalized pyran
annulated chromene analogues.
Results & Discussion
At first we have tried to synthesize pyran fused 2-
aminochromene derivatives using ZrO2 NPs. These moieties
exhibited various biological and pharmaceutical activites9 such
Department of Chemistry, Guru Ghasidas Vishwavidyalaya, Bilaspur-495009,
Chhattisgarh, India. E-mail: ocsb2009@yahoo.com; Fax: +91 7752 260148;
Tel: +91-7587401979.
†Electronic Supplementary Information (ESI) available: [details of experimental
procedure for preparation of catalysts and synthesis of pyran fused chromenes,
supplementary information available should be included here]. See
DOI: 10.1039/x0xx00000x
as
antimicrobial,10a
mutagenicity,10b
antiviral,10c
antiproliferative,10d sex pheromonal,10e antitumor,10f central
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 2 of 9
View Article Online
DOI: 10.1039/C5RA19290K
ARTICLE
Journal Name
nervous system activity10g etc. agent and influenza virus average particle size of 11.4 nm (See Fig. S1, †ESI 2a). Energy
sialidases inhibitors.10h Some selected bioactive 2- dispersive X-ray analysis (EDX) through HRTEM clearly
aminochromene derivatives are shown in Fig. 1. In addition, indicates that the sample is highly pure and does not contain
these moieties are present as essential component in many any impurity peaks (Fig. 3b). The EDX analysis also interprets
natural products and used as valuable constituent for the that the Zr/O ratio is slightly higher than the expected value
fabrication of commercially important products.11
which may be due to the creation of oxygen vacancies that
make the tetragonal phase more stable (See †ESI 2b).
Fig. 1 Biologically potent pyran fused 2-aminochromenes.
Typically, these moieties have been synthesized via three
components condensation reactions of aryl aldehyde,
malononitrile and activated phenols using
a catalyst or
reagent. However, most of them utilized homogeneous12-13
catalyst/reagent such as toxic nitrogen containing bases like
piperidine/triethylamine,12 basic reagents e.g. ammonium
salts,13a NaOH,13b K2CO3,13c I2/K2CO3,13d or Lewis acids (e.g.
TiCl4,13e InCl3,13f) and few have used heterogeneous catalyst.14
Moreover, most of the methods utilized hazardous organic
solvents e.g. DMF or acetonitrile.12 Thus, the synthesis of 2-
aminochromenes using a mild catalyst in green solvent like
water is in demand. Here, we have observed remarkable
catalytic activity of ZrO2 NPs in one-pot three component Fig. 2 (a) HRTEM image of t-ZrO2 NPs (b) SAED pattern of t-
reactions leading to 2-aminochromenes in water.
ZrO2 NPs
Initially, we have prepared ZrO2 NPs via sol-gel method by
the condensation of ZrO2Cl2.8H2O under basic medium8i (See
†ESI 1 for details) and the material was analyzed by different
analytical and spectroscopic techniques. The powder X-ray
diffraction (XRD) pattern of the material indicates the
formation of nano sized ZrO2 particles which contains purely
tetragonal phase and the average sizes of 12 nm (calculated
from XRD using Scherrer formula15). These results are in well
accordance with our previous report8i as well as results
reported by Xie et al.16
The morphology and particle size of the ZrO2 NPs were
further confirmed by high resolution transmission electron
microscopic (HRTEM) study. The HRTEM image (Fig. 2a)
revealed the formation of spherical size ZrO2 NPs. The selected
electron diffraction (SAED) pattern (inset, Fig.2b) reveals the d
values corresponding to the four brightest rings are 3.39, 1.84,
1.61, and 1.25 Å (from the inner to the outer) which are
associated with the {101}, {122}, {211} and {213} planes of t-
ZrO2 respectively (JCPDS no. 79-1771).17 Fig. 3a shows the
spare magnified image of ZrO2 NPs clearly illustrating the
associated lattice fringes with lattice spacing 0.295 nm
corresponding to {111} plane of t-ZrO2 (JCPDS card no. 17-
0923).18 The size distribution of the NPs was measured from
HRTEM study over 100 grains and a narrow size distribution of
ZrO2 NPs was observed and the Gaussian plot shows the
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 3 of 9
View Article Online
DOI: 10.1039/C5RA19290K
Journal Name
ARTICLE
product even after 2 hrs (entry 2, Table 1). The reaction also
failed to produce product in absence of the catalyst (entry 3,
Table 1). The ZrO2 NPs were found to be less reactive in
organic solvents like acetonitrile, toluene and dimethyl
formamide (DMF) (entries 4-6, Table 1). To study the effect of
phase of the catalyst, we have studied the reaction using
monoclinic ZrO2 (m-ZrO2) NPs and cubic (bulk) ZrO2 and it was
observed that both cubic and m-ZrO2 are less reactive than t-
ZrO2 (entries 7-8, Table 1). The phase pure monoclinic m-ZrO2
NPs were prepared by following our previous report8i (See †ESI
3 for detailed preparation). The t-ZrO2 NPs were also found to
be more reactive compared to Fe3O4, SiO2, CuO and ZnO etc.
NPs (entries 9-12, Table 1). Thus, the reaction using 10 mol%
of t-ZrO2 NPs in water at 80oC was considered as the optimized
reaction conditions (see †ESI 4 for details experimental
procedure).
Fig. 3 (a) Magnified HRTEM of t-ZrO2 NPs shows lattice fringes
Using optimized conditions, we have explored the scope of
the methodology for the synthesis of 2-aminochromene
derivatives. We have observed that the t-ZrO2 NPs were able
to produce a series of 2-aminochromene derivatives (1a-f,
with lattice spacing (b) HRTEM-EDX pattern of t-ZrO2 NPs.
The optical properties of ZrO2 NPs have been analyzed Table 2) by the condensation of variety of substituted aryl
using electronic absorption (spectra not provided) and aldehydes with malononitrile and 1-napthol (entries 1-6, Table
fluorescence spectroscopy. The ZrO2 NPs showed maxima at 2). Excellent yields of the products were obtained within
261 nm (band gap ~ 4.76 eV) in UV-Vis spectrum8i and practical time period (30-55 minutes).
exhibited a sharp emission peak at 546 nm (λexcitation = 260 nm)
in water in the fluorescence spectrum (Fig. 4).
Table 1 Optimization of reaction conditions for the synthesis of
2-aminochromene derivatives
800
546 nm
600
400
200
0
Entry
Catalyst
Solvent/cond.
Time
(min)
30
Yield
(%)a
92
-
1
t-ZrO2 NPs
t-ZrO2 NPs
No catalyst
t-ZrO2 NPs
t-ZrO2 NPs
t-ZrO2 NPs
Bulk ZrO2
H2O/80oC
H2O/RT
H2O/80oC
CH3CN/80oC
Toluene/80oC
DMF/80oC
H2O/80oC
2
240
240
60
3
-
4
77
62
60
41
52
57
51
79
66
5
60
6
60
500
520
540
560
580
600
7
60
Wavelength (nm)
8
m-ZrO2 NPs H2O/80oC
30
9
Fe3O4 NPs
SiO2 NPs
CuO NPs
ZnO NPs
H2O/80oC
H2O/80oC
H2O/80oC
H2O/80oC
60
Fig. 4 Fluorescence spectrum of ZrO2 NPs in water (λexcitation
260 nm).
=
10
11
12
60
60
60
The red-shift of the emission band as compared to the bulk
ZrO2 (band gap 5.6 eV) indicates that the fluorescence involves
extrinsic states or defect states i.e. due to the arrangement of
oxygen vacancies.19-20
Reaction conditions: benzaldehyde (1 mmol), malononitrile
(1 mmol), 1-napthol (1 mmol), catalyst (10 mol %), solvent
(5 ml) with continuous stirring. aisolated yield, RT means
room temperature.
Next, the properly characterized t-ZrO2 NPs were then used
for the synthesis of pyrano fused 2-aminochromene
derivatives. When a mixture of benzaldehyde (1 mmol),
malononitrile (1 mmol), 1-napthol (1 mmol) and t-ZrO2 (12 mg,
We have also extended the scope of t-ZrO2 NPs catalyzed
reactions by using 2-napthol in place of 1-napthol and
observed that corresponding 2-aminochromene derivatives
(2a-c) were produced in good yields. Aryl aldehydes containing
both electron donating (e.g. –OMe, –CH3, –Cl etc.) and
electron withdrawing (e.g. –NO2) groups were participated in
o
10 mol%) is heated at 80 C in water (5 ml), excellent yield of
2-amino-3-cyano-4-phenyl-4H-benzo[h]chromene (92%) was
obtained after 30 minutes (entry 1, Table 1). However, at room
temperature the same reaction did not produce desired
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 4 of 9
View Article Online
DOI: 10.1039/C5RA19290K
ARTICLE
Journal Name
the reaction and no electronic effect was observed. The results
were presented in Table 2. All the products are solid and were
purified by recrystallization from ethanol and identified by
their melting points determination and nuclear magnetic
resonance spectroscopic study.
8
9
55
40
89
94
237- 238-
239 24013h
O
NH2
CN
(2b)
Br
O
187- 188-
190 18913h
NH2
CN
Table 2 t-ZrO2 NPs catalyzed synthesis of 2-aminochromenes
Ar
ArCHO
Ar
CN
NC
CN
OH
NC
CN
CN
(2c)
O
NH2
ZrO2 NPs
H2O, 80 o
OH
OMe
O
NH2
C
1a-f
2a-c
Reaction conditions: aryl aldehyde (1 mmol), malononitrile
(1 mmol), 1- or 2-napthol (1 mmol), t-ZrO2 NPs (10 mol%, 12
Entry Product
Time Yield M.P. (oC)b
(min) (%)a
o
a
mg) and H2O (5 ml) with continuous stirring at 80 C. Yields
Obs. Rep.ref
b
refer to that of pure isolated products. Melting points were
determined for the pure and recrystallized products.
1
40
92
205- 207-
207 21013h
O
NH2
CN
In order to compare the catalytic efficiency of t-ZrO2 NPs
for the synthesis of 2-aminochromene derivatives,
a
comparative study of catalytic performance of the present
catalyst with the reported ones is presented in Table 3.
(1a)
O
NH2
CN
Table 3 Comparative study of t-ZrO2 NPs for the synthesis of 2-
aminochromene derivatives
2
3
35
40
94
92
205- 206-
207 20813h
Ar
OH
(1b)
CN
OMe
O
ArCHO
+
+
CN
NC
O
NH2
234- 233-
237 23413h
NH2
CN
(1)
Entry Catalyst
Reaction
Yield
(%)
Time
Conditions
(min.)
1
2
3
4
5
t-ZrO2 NPsa
12 mg/H2O/ 88-94 35-55
80oC
(1c)
NO2
O
Rochelle Salt14d 60 mg/
EtOH/reflux
TFMO-114e
75-90 240-480
NH2
CN
40 mg/neat/ 86-92 240-360
110oC
4
5
45
55
89
88
233- 232-
235 23413h
14c
Basic Al2O3
500 mg/
83-96 180
(1d)
Cl
O
H2O/Reflux
H2O/Reflux
14f
Na2CaP2O7
72-94 240-300
192- 190-
194 19213h
NH2
CN
a Present work
The above comparison clearly indicates that the present
method is better in terms of reaction time, environmental
safety and catalyst loading.
(1e)
OH
O
6
7
50
45
90
91
206- 206-
209 20813h
The phase of played a significant role and the tetragonal
phase of ZrO2 showed higher reactivity compared to its
monoclinic phase. This phenomenon was in accordance with
our previous report8i and also reported by others.21a,b The
observed higher activity of the tetragonal phase was possibly
due to the presence of oxygen vacancies, which are
responsible for stability and higher surface activity for pure t-
ZrO2.21a-c The presence of oxygen vacancies was also evident
from the fluorescence study of t-ZrO2 NPs.
NH2
CN
(1f)
Me
O
279- 283-
281 28513h
NH2
CN
(2a)
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 5 of 9
View Article Online
DOI: 10.1039/C5RA19290K
Journal Name
ARTICLE
Next, we have investigated the stability of t-ZrO2 NPs chromeno[4,3-b]chromene derivatives are of much interest as
checking its reusability for the synthesis of 2-amino-3-cyano-4- these moieties have shown diverse biological activities and act
phenyl-4H-benzo[h]chromene (1a).
as anti-cancer,22a emetic,22b anti-HIV,22c anti-tumor,22d anti-
alzheimer,22e anti-bacterial,22f anti-malaria,22g diuretic,22h
spasmolytic,22i anti-leukemic,22j anti-anaphylactic22k and anti-
coagulant22l agents. Few selected such bio-active molecules are
shown in Fig. 6.
100
92
91 91
90
88
87
85
85
81
80
80
60
40
20
0
1
2
3
4
5
6
7
8
9
10
No. of Run
Fig. 6 Diverged bioactive coumarin fused 4H-chromenes.
Fig. 5 Represents reusability of t-ZrO2 for the synthesis of 2-
amino-3-cyano-4-phenyl-4H-benzo[h]chromene (1a).
When a mixture benzaldehyde (1 mmol), malononitrile (1
mmol), 4-hydroxy-coumarin (1 mmol) and t-ZrO2 (12 mg) was
After each cycle, the t-ZrO2 NPs were recovered by reacted under the above mentioned optimized conditions i.e.
centrifugation, washed, dried and reused. The tetragonal heating in water at 80 oC, good yield (90%) of white solid
phase of the t-ZrO2 NPs (confirmed by powder XRD; see Fig. S3, product was isolated and identified as dihydropyrano[3,2-
†ESI 5) was remained intact even after 10th cycle (Fig. 5). The c]chromene (3a) (see †ESI
6 for details experimental
decrease in yield may possibly due to loss of surface hydroxyl procedure).
groups8i or decrease of Zr-content which eventually associated
The scope of this reaction for the synthesis of
with decrease of oxygen vacancies. The decrease of oxygen dihydropyrano[3,2-c]chromenes (3a-e) has been presented in
vacancies was evident from the fluorescence measurement of Table 3. By replacing malononitrile with 5,5-dimethyl-1,3-
the recycled ZrO2 NPs with a blue shift (~20 nm) of emission cyclohexanedione, in the said reaction, we have also
maximum of ZrO2 NPs (see Fig. S4, †ESI 5). Further, the synthesized chromeno[4,3-b]chromene derivatives (4a-d) (see
decrease of Zr-content in recycled ZrO2 NPs was evident from †ESI 7 for details experimental procedure).
atomic absorption spectroscopic (AAS). The AAS results have
been presented in table 1, †ESI 5. Moreover, no peak
corresponding to the NPs were observed in the FT-IR spectra Table 4 t-ZrO2 NPs catalyzed synthesis of dihydropyrano[3,2-
(Fig S5, ESI 5) of recycled product.
c]chromene and chromeno[4,3-b]chromene derivatives
Motivated by the previous results next, we have tried to
explore the catalytic efficiency of t-ZrO2 NPs for synthesis of
related pyran annulated heterocyclic compounds such as
dihydropyrano[3,2-c]chromene (3) and chromeno[4,3-
b]chromene derivatives (4) by the condensation of aldehyde,
malononitrile (for synthesis of 3) or 5,5-dimethyl-1,3-
cycloheadione (for the synthesis of 4) and 4-hydroxy-coumarin
(Scheme 2).
Entry
Product
Time
(min)
Yield M.P. (oC)b
(%)a
Obs. Rep. ref
O
O
Ar
O
Ar
O
1
30
90
256- 256-
259
25823n
ArCHO
CN
NC
CN
O
O
O
OH
O
OH
O
NH2
O
ZrO2 NPs
(4)
(3)
O
O
O
Scheme 2 t-ZrO2 NPs catalyzed synthesis of dihydropyrano[3,2-
c]chromene(3) and chromeno[4,3-b]chromene derivatives(4)
derivatives.
(3a)
Synthesis of coumarin fused pyran annulated 4H-
chromenes, in particular, dihydropyrano[3,2-c]chromene and
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 6 of 9
View Article Online
DOI: 10.1039/C5RA19290K
ARTICLE
Journal Name
2
26
95
246- 248-
Reaction condition: aryl aldehyde (1 mmol), malononitrile or
dimedone (1 mmol), 4-hydroxycoumarin (1 mmol), t-ZrO2
NPs (10 mol%, 12.3 mg) and H2O (5 ml) with continuous
249
25023n
o
a
b
stirring at 80 C. Yield of pure isolated products. melting
point was determined for the pure recrystallized products.
(3b)
All the reactions listed in Table 3 are very clean and afforded
excellent yields of the products. Although, various
catalysts/reagents23 have been used for the synthesis of
dihydropyrano[3,2-c]chromene derivatives, however, only
three reports24 are available in literature for the synthesis of
chromeno[4,3-b]chromene derivatives. The present protocol
offered several advantages such as (i) use of mild ZrO2 NPs as
catalyst, (ii) water as solvent, (iii) faster reaction rate (less than
1 hr), (iv) good to excellent yields of the products, (v) simple
isolation and purification of products etc. The products were
identified by their melting points determination and
spectroscopic analysis (See ESI 8). These values are in well
accordance with the values reported in literature.
3
4
5
30
35
38
93
91
89
254- 256-
256
25823n
(3c)
258- 260-
261
26223n
Finally, a plausible mechanism has been suggested in
Scheme 3 for the formation 2-amino-3-cyano-4-phenyl-4H-
benzo[h]chromene (1a) in consultation with previously
reported8i,14e mechanisms. The reaction believed to proceeds
via initial Knoevenagel condensation to produce 2-
phenylidenemalononitrile (I). Subsequently, the Michael
addition reaction of the intermediate (I) with 1-napthol
followed by tautomerization and intra-molecular cyclization
furnished the desired product.
(3d)
253- 253-
255
25623n
(3e)
(4a)
6
7
25
25
91
94
224- 22624b
226
188- 19024b
190
(4b)
8
30
93
209- 21224b
211
(4c)
9
35
89
169- 17224c
171
Scheme 3 Plausible mechanism for t-ZrO2 NPs catalysed
synthesis of 2-aminochromene derivative (1a).
In our previous study,8i we have established that the surface of
ZrO2 NPs contains active hydroxyl, oxide and Zr+4; which were
reported to exhibit Lewis acidic or basic properties.21c Thus,
(4d)
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 7 of 9
View Article Online
DOI: 10.1039/C5RA19290K
Journal Name
ARTICLE
8
(a) S. Banerjee, J. Das and S. Santra, Tetrahedron Lett., 2009,
50, 124; (b) S. Banerjee and S. Santra, Tetrahedron Lett.,
2009, 50, 2037; (c) S. Banerjee and G. Sereda, Tetrahedron
Lett., 2009, 50, 6959; (d) S. Banerjee, J. Das, R. Alverez and S.
Santra, New J. Chem., 2010, 34, 302; (e) V. Rajpara, S.
Banerjee and G. Sereda, Synthesis, 2010, 2835; (f) S.
Banerjee, V. Balasanthiran, R. Koodali and G. Sereda, Org.
these groups play an important role during the
multicomponent synthesis of pyran fused 2-aminochromenes.
Conclusions
In conclusion, we have demonstrated MCRs leading to
biologically active pyran fused chromene derivatives namely,
2-amino chromenes, dihydropyrano[3,2-c]chromene and
chromeno[4,3-b]chromene derivatives using fluorescent t-ZrO2
NPs as mild and reusable catalyst under aqueous medium. The
fluorescent t-ZrO2 NPs were characterized by analytical and
spectroscopic methods. The present protocol offered several
novelties such as (i) shorter reaction time (25-55 min.), (ii) high
isolated yields of the products (88-95%), (iii) use of water as
green reaction medium, (iv) the products were purified by re-
crystallization from ethanol and thus the use of organic
solvents were avoided totally and finally, (v) reusability of ZrO2
NPs made the protocol environmentally benign. Further, in
addition to the stability of tetragonal phase of recycled ZrO2
NPs, here we have established that the decrease of catalytic
activities of recycled ZrO2 NPs associated with the loss of yield
of the product was due to decrease of Zr-content which
eventually associated with decrease of oxygen vacancies.
Biomol. Chem., 2010, 8, 4316; (g) S. Banerjee, A. Horn, H.
Khatri and G. Sereda, Tetrahedron Lett., 2011, 52, 1878; (h)
S. Banerjee and A. Saha, New J. Chem., 2013, 37, 4170; (i) A.
Saha, S. Payra and S. Banerjee, Green Chem., 2015, 17, 2859;
(j) S. Banerjee, S. Payra, A. Saha and G. Sereda, Tetrahedron
Lett., 2014, 55, 5515.
9
S. Laskar and G. Brahmachari, J. Org. Biomol. Chem., 2014, 2,
1.
10 (a) M. M. Khafagy, A. H. F. A. El-Wahab, F. A. Eid, and A. M.
El- Agrody, Farmaco, 2002, 57, 715; (b) K. Hiramoto, A.
Nasuhara, K. Michikoshi, T. Kato and K. Kikugawa, Mutat.
Res., 1997, 395, 47; (c) A. Mart´ınez-Grau and J. L. Marco,
Bioorg. Med. Chem. Lett., 1997, 7, 3165; (d) C. P. Dell and C.
W. Smith, European Patent Applications EP 537 949 21 Apr 1.
993; Chem. Abs., 1993, 119, 139102d; (e) G. Bianchi and A.
Tava, Agri. Biological Chem., 1987, 51, 2001; (f) S. J. Mohr,
M. A. Chirigos, F. S. Fuhrman, and J. W. Pryor, Cancer Res.,
1975, 35, 3750; (g) F. Eiden and F. Denk, Archiv der
Pharmazie, 1991, 324, 353; (h) P. W. Smith, S. L. Sollis and P.
D. Howes, J. Med. Chem., 1998, 41, 787.
11 (a) E. A. A. Hafez, M. H. Elnagdi, A. G. A. Elagamey and F. M.
A. A. El-Taweel, Heterocycles, 1987, 26, 903; (b) G. P. Ellis, in
The Chemistry of Heterocyclic of Compounds. Chromenes,
Harmones and Chromones, ed. A. Weissberger and E. C.
Taylor, John-Wiley, New York, 1977, ch. II, pp. 11–13; (c) G.
Acknowledgements
We are pleased to acknowledge the funding agencies
Department of Science and Technology, New Delhi, Govt. of
India (NO.SB/FT/CS-023/2012). AS and SP also thank Guru
Ghasidas Vishwavidyalaya for their fellowship. Special thanks
to Prof. B. C. Ranu and his group for their help in NMR studies.
A. Reynolds and K. H. Drexhage, Opt. Commun., 1975, 13
,
222; (d) H. Zollinger, Color Chemistry, VHCA, Zurikh,
Switzerland, 3rd edn, 2003; (e) E. R. Bissell, A. R. Mitchell and
R. E. Smith, J. Org. Chem., 1980, 45, 2283; (f) C. G. Knight and
T. Stephens, J. Biol. Chem., 1989, 25, 8683.
12 (a) A. G. A. Elagemey and F. M. A. A. El-Taweel, Indian J.
Chem., 1990, 29B, 885; (b) A. G. A. Elagemey, F. M. A. A. El-
Taweel, M. N. M. Khodeir and M. H. Elnagdi, Bull. Chem. Soc.
Jpn., 1993, 66, 464; (c) J. Bloxham, C. P. Dell and C. W. Smith,
Heterocycles, 1994, 38, 399.
Notes and references
1
2
3
(a) I. Ugi and A. Domling, Angew. Chem. Int. Ed., 2000, 39,
3168; (b) L.F. Tietze and A. Modi, Med. Res. Rev., 2000, 20,
304.
(a) G. H. Posner, Chem. Rev., 1986, 86, 831; (b) L. A.
Wessjohann, D. G. Rivera and O. E. Vercillo, Chem. Rev.,
2009, 109, 796.
(a) C. J. Li, Chem. Rev., 2005, 105, 3095; (b) W. Wei, C. C. K.
Keh, C. J. Li and R. S. Varma, Clean Tech. Environ. Policy,
2005, 7, 62; (c) B. C. Ranu and S. Banerjee, Tetrahedron Lett.,
13 (a) R. Ballini, G. Bosica, M. L. Conforti, R. Maggi, A.
Mazzacanni, P. Righi and G. Sartori, Tetrahedron, 2001, 57,
1395; (b) T. S. Jin, J. C. Xiao, S. J. Wang, T. S. Li and X. R. Song,
Synlett, 2003, 2001; (b) A.-Q. Zhang, M. Zhang,H.-H. Chen, J.
Chen and H.-Y. Chen, Synth. Commun., 2007, 37, 231; (c) M.
Kidwai, S. Saxena, M. K. Rahman Khan and S. S. Thukral,
Bioorg. Med. Chem. Lett., 2005, 15, 4295; (d) Y. Ren and C.
Cai, Catal. Commun., 2008,
9, 1017; (e) B. S. Kumar, N.
2007, 48, 141; (d) S. Banerjee and S. Santra, Tetrahedron
Lett., 2009, 50, 2037; (e) S. Banerjee, New J. Chem., 2015, 39,
5350.
(a) M. C. Pirrung and K. Das Sarma, J. Am. Chem. Soc., 2004,
126, 444 and references cited therein.
Srinivasulu, R. H. Udupi, B. Rajitha, Y. T. Reddy, P. N. Reddy
and P. S. Kumar, J. Heterocycl. Chem., 2006, 43, 1691; (f) G.
Shanthi and P. T. Perumal, Tetrahedron Lett., 2007, 48, 6785;
(g) M. M. Heravi, K. Bakhtiari, V. Zadsirjan, F. F. Bamoharram
and O. M. Heravi, Bioorg. Med. Chem. Lett., 2007, 17, 4262;
(h) M. G. Dekamin and M. Eslami, Green Chem., 2014, 16,
4914; (i) A. Shaabani, R. Ghadari, S. Ghasemi, M. Pedarpour,
A. H. Rezayan, A. Sarvary and S. Weng Ng, J. Comb. Chem.,
2009, 11, 956.
4
5
(a) D. Astruc, Nanoparticles and Catalysis, Wiley-VCH Verlag
GmbH & Co. KGaA, 2008, 1; (b) D. Costenaro, F. Carniato, G.
Gatti, L. Marchese and C. Bisio, New J. Chem., 2013, 37
,
2103; (g) M. B. Gawande, A. K. Rathi, I. D. Nogueira, R. S.
Varma and P. S. Branco, Green Chem., 2013, 15, 1895; (e) V.
Polshettiwar and R. S. Varma, Green Chem., 2010, 12, 743.
(a) M. Gawande, P. Branco and R. S. Varma, Chem. Soc. Rev.,
2013, 42, 3371; (b) S. Hamid and A. Morteza, Catal. Sci.
14 (a) D. Kumar, V. B. Reddy, B. G. Mishra, R. K. Rana, M. N.
Nadagaouda and R. S. Varma, Tetrahedron, 2007, 63, 3093;
(b) M. P. Surpur, S. Kshirsagar and S. D. Samant, Tetrahedron
Lett., 2009, 50, 719; (c) R. Maggi, R. Ballini, G. Sartori and R.
Sartorio, Tetrahedron Lett., 2004, 45, 2297; (d) A. M. El-
Maghraby, Org. Chem. Int., 2014, 2014, Article ID 715091; (e)
J. Mondal, A. Modak, M. Nandi, H. Uyama and A. Bhaumik,
6
7
Technol., 2013, 3, 425.
(a) A. Bell, Science, 2003, 299, 1688; (b) H. Kung, Transition
metal oxides: Surface chemistry and catalysis, 1989, 45, 1; (c)
S. Ibrahim, Catal. Rev., 2003, 45, 205.
RSC Adv., 2012,
2, 11306; (f) A. Solhy, A. Elmakssoudi, Rachid
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 8 of 9
View Article Online
DOI: 10.1039/C5RA19290K
ARTICLE
Tahir, M. Karkouri, M. Larzek, M. Bousmina and M. Zahouily,
Green chem., 2010, 12, 2261.
Journal Name
15 (a) P. Scherrer, Göttinger Nachrichten Gesell., 1918,
A. Patterson, Phys. Rev., 1939, 56, 978.
16 P. Zhang, Y. Su, F. Teng, Y. He, C. Zhao, G. Zhang and E. Xie,
2, 98; (b)
CrystEngComm, 2014, 16, 1378.
17 H. Zhu, D. Yang, Z. Xi and L. Zhu, J. Am. Ceram. Soc., 2007, 90
,
1334.
18 W. Li, H. Huang, H. Li, W. Zhang and H. Liu, Langmuir, 2008,
24, 8358.
19 A. Emeline, G. V. Kataeva, A. S. Litke, A. V. Rudakova, V. K.
Ryabchuk and N. Serpone, Langmuir, 1998, 14, 5011.
20 J. Joo, T. Yu, Y. W. Kim, H. M. Park, F. Wu, J. Z. Zhang and T.
Hyeon, J. Am. Chem. Soc., 2003, 125, 6553.
21 (a) R. Malakooti, H. Mahmoudi, R. Hosseinabadi, S. Petrovb
and A. Miglioric, RSC Adv., 2013,
M. Zhang and K. Tao, Catal. Commun., 2002,
Karapetrova, R. Platzer, J. A. Gardner, E. Torne, J. A.
Sommers and W. E. Evenson, J. Am. Ceram. Soc., 2001, 84
3, 22353; (b) Y. Zhao, W. Li,
3, 239; (c) E.
,
65.
22 (a) J. G. Cannon and R. R. Khonji, J. Med. Chem., 1975, 18
,
110; (b) W. O. Foye, Principidi Chimica Farmaceutica Piccin-
Padova, Italy, 1991; (c) Y. Kashman, K. R. Gustafson, R. W.
Fuller, J. H. Cardellina, J. B. McMahon, M. J. Currens, R. W.
Buckheit, S. H. Hughes, G. M. Gragg and M. R. Boyd, J. Med.
Chem., 1992, 35, 2735; (d) F. W. Perrella, S. F. Chen, D. L.
Behrens, R. F. Kaltenbach and S. P. Seitz, J. Med. Chem. 1994,
37, 2232; (e) T. A. Bayer, S. Schafer, H. Breyh, O. Breyhan, C.
Wirths and G. A. Treiber, Clin Neuropathol., 2006, 25, 163; (f)
L. R. Morgan, B. S. Jursic, C. L. Hooper, D. M. Neumann, K.
Thangaraj and B. Leblance, Bioorg. Med. Chem. Lett., 2002,
12, 3407; (g) A. Bolognese, G. Correale, M. Manfra, A.
Levecchia, O. Mazzoni, E. novellino, P. Lacolla, G. Sanna and
R. Loddo, J. Med. Chem., 2004, 47, 849; (h) E. A. A. Hafez, M.
H. Elnaghi, A. G. A. Elagamey and F. M. A. A. El-Taweel,
Heterocycles, 1987, 26, 903; (i) G. P. Ellis, The Chemistry of
Heterocyclic Compounds. In Chromenes; Chromenes, and
Chromenes; Weissberger; Taylor, A.; Eds, E. C.; John Wiley;
New York. 1977; (j) P. Beagley, M. A. L. Blackic, K. Chibale, C.
Clarkson, R. Meijboom, J. R. Moss, P. Smith and H. Su, Dalton
Trans., 2003, 3046; (k) N. Fokialakis, P. Magiatis, L. Chinou, S.
Mitaka and F. Tillequin, Chem. Pharm. Bull., 2002, 50, 413; (l)
G. M. Cingolani, F. Gualtteri and M. Pigin, J. Med. Chem.,
1961, 12, 531.
23 (a) A. S. Mohammadi and S. Balalaie, Tetrahedron Letters,
2007, 48, 3299; (b) M. Kidwai and S. Saxena, Synth.
Commun., 2006, 36, 2737; (c) J. M. Khurana and S. Kumar,
Tetrahedron Lett., 2009, 50, 4125; (d) M. M. Heravi, B. A.
Jani, F. Derikvand, F. F. Bamoharram, and H. A. Oskooie,
Catal. Commun., 2008, 10, 272; (e) H. J. Wang, J. Lu, and Z. H.
Zhang, Monatshefte f¨ur Chemie, 2010, 141, 1107; (f) A.
Shaabani, S. Samadi, Z. Badri, and A. Rahmati, Catal. Lett.,
2005, 104, 39; (g) G. V. Ramin, T. S. Zahra, and K. N. Rahman,
J. Braz. Chem. Soc., 2011, 22, 905; (h) H. R. Shaterian and A.
R. Oveisi, J. Iran. Chem. Soc., 2011, 8, 545; (i) H. R. Shaterian,
M. Arman, and F. Rigi, J. Mol. Liq., 2011, 158, 145; (j) N.
Tavakoli-Hoseini, M. M. Heravi, F. F. Bamoharram, and A.
Davoodnia, Asian J. Chem., 2011, 23, 3599; (k) M. G.
Dekamin, M. Eslami, and A. Maleki, Tetrahedron, 2013, 69
,
1074; (l) M. Hossein and K. M. Maryam, Chin. Chem. Lett.,
2011, 22, 1419; (m) D. S. Raghuvanshi and K. N. Singh,
ARKIVOC, 2010, 10, 305; (n) H. Mehrabi and H. Abusaidi, J.
Iran. Chem. Soc., 2010, 78, 890; (n) M. J. Khurana, B. Nand
and P. Saluja, Tetrahedron, 2010, 66, 5637.
24 (a) Z. Chen, Q. Zhu and W. Su, Tetrahedron Lett., 2011, 52
,
2601; (b) K. Pradhan, S. Paul and A. R. Das, Tetrahedron Lett.,
2013, 54, 3105; (c) H. A. Ardakani, R. Ghanavatian and M.
Akbari, World Appl. Sci. J., 2013, 22, 802.
8 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 9 of 9
RSC Advances
View Article Online
DOI: 10.1039/C5RA19290K
Graphical Abstract
On water synthesis of pyran-chromenes via multicomponent reaction catalyzed by fluorescent t-
ZrO2 nanoparticles
Here, we have demonstrated fluorescent tetragonal ZrO2 nanoparticles (t-ZrO2 NPs) catalyzed green one-pot multicomponent protocol for
the synthesis of diverse pyran fused chromene analogous such as 2-aminochromenes, dihydropyrano[3,2-c]chromene, chromeno[4,3-
b]chromene derivatives in water. The rate of the reactions and yields of the products have increased significantly in water. In addition, t-
ZrO2 NPs showed higher reactivity than monoclinic ZrO2 NPs. The t-ZrO2 NPs were recycled and the gradual decrease in yield of the
product using recycled catalyst could be possibly due to the decrease in zrconium content associated with decrease in oxygen vacancies
which were evident from fluorescence and atomic absorption studies. However, the tetragonal phase of the catalyst remained intact even
at 10th cycle.