Ni(II) immobilized on modified boehmite nanostructures: a novel, inexpensive, and highly efficient heterogeneous nanocatalyst for multicomponent domino reactions

Article abstract of DOI:10.1007/s11164-019-03787-3

Here we report the synthesis of Ni(II) immobilized on modified boehmite nanostructures as an environmentally friendly heterogeneous catalyst for the one-pot domino synthesis of benzo[a]pyrano[2,3-c]phenazine and benzo[a]benzo[6,7]chromeno[2,3-c]phenazine

Full text of DOI:10.1007/s11164-019-03787-3

Research on Chemical Intermediates
https://doi.org/10.1007/s11164-019-03787-3
Ni(II) immobilized on modifed boehmite nanostructures:
a novel, inexpensive, and highly efcient heterogeneous
nanocatalyst for multicomponent domino reactions
Arash Ghorbani‑Choghamarani1 · Rokhsareh Sahraei1 · Zahra Taherinia1
Received: 3 December 2018 / Accepted: 22 February 2019
© Springer Nature B.V. 2019
Abstract
Here we report the synthesis of Ni(II) immobilized on modifed boehmite nanostruc-
tures as an environmentally friendly heterogeneous catalyst for the one-pot domino
synthesis of benzo[a]pyrano[2,3-c]phenazine and benzo[a]benzo[6,7]chromeno[2,3-
c]phenazine in PEG as a green solvent. Elemental analysis, FT-IR, XRD, TGA,
SEM, EDX, and ICP-OEC confrmed the structure of this nanocatalyst. Importantly,
this nanocatalyst can be easily separated from the reaction media and reused for at
least four consecutive cycles without a discernible reduction in its catalytic activity.
Keywords Multicomponent · PEG · Boehmite · Recyclable · Heterogeneous
nanocatalyst · Benzo[a]pyrano[2,3-c]phenazine · Benzo[a]benzo[6,7]
chromeno[2,3-c]phenazine
Introduction
Much attention has been focused on the development of nanomaterials because of
their interesting properties and wide range of applications, from catalysis to elec-
tronics and optics [1–3]. Optical properties are strongly dependent on particle size,
as the quantum size efect causes an increase in the excitonic transition energy. In
this sense, during the past two decades, considerable eforts have been devoted to
the development of synthetic methods for well-defned nanocrystals. Template syn-
thesis represents a potential technique for achieving desirable nanostructured materi-
als. To date, various types of templates, including oxide materials [4, 5], graphene
[6], nanofbers [7], zeolites [8], polymeric and inorganic materials [9], and boehmite
[10], have been extensively employed for the preparation of targeted nanostruc-
tured materials. Boehmite is an aluminum oxyhydroxide (γ-AlOOH) which, due to
* Arash Ghorbani-Choghamarani
a.ghorbani@ilam.ac.ir; arashghch58@yahoo.com
1
Ilam University, Ilam, Iran
Vol.:(0123456789)
1 3

A. Ghorbani-Choghamarani et al.
its unique structure and remarkable properties including extra hydroxyl groups on
its surface, can be used for immobilization of diferent linkers and ligands that can
coordinate with metal ions [11].
Another important area of interest is the use of boehmite for the preparation of
ceramic catalysts [12], refractory materials [13], rheology control [14], and paint
detackifcation [15]. More recently, boehmite powder has been applied for surface
coating and as a polymer additive [16]. Research has revealed that the morphologi-
cal and structural characteristics of grown samples can be controlled by adjusting
certain parameters, such as the concentration of the solution, the reagent stoichiom-
etry, the temperature, and the pH [17]. Several studies have been devoted to the syn-
thesis of boehmite nanostructures via coprecipitation [18] or hydrothermal methods
[19].
These methods give boehmite various morphologies including nanopowders
[20], nanorods or nanofakes [21], nanofbers [22], hollow microspheres [23], nano-
architectures [24], cantaloupe-like structures [25], microspheres [26], and quarter-
sphere-like structures [27]. It is worth mentioning that multicomponent reactions
(MCRs) are extremely popular due to their facile execution, high atom efciency,
and high diversity of products [28, 29]. Therefore, the design of novel MCRs for
the synthesis of diverse groups of compounds, especially those that are biologically
active, has commanded considerable attention. Multicomponent reactions (MCRs)
can be employed to generate adducts bearing a variety of functional groups, and thus
have been regarded as valuable tools in total synthesis and drug discovery [30–32].
Phenazine systems are an important class of aza-polycyclic compounds that exhibit
a wide range of biological and pharmacological activity, including antimalarial [33,
34] trypanocidal [35], fungicidal [36], and antiplatelet efects [37]. Considering the
importance of phenazine derivatives, and in continuation of our study on multicom-
ponent reactions [38, 39], we report a one-pot domino reaction in the presence of
nickel (II), immobilized on modifed boehmite nanostructures, as a catalyst to aford
the corresponding phenazine pyran-annulated heterocyclic systems (Scheme 1).
Experimental section
Materials
All reactants were purchased from Merck and Aldrich Chemical Company and were
used without further purifcation.
Experimental
In a typical procedure, Al(NO3)3·9H2O (20 g) was added to a solution of NaOH
(6.4 g) in 50 mL of distilled water at room temperature in a beaker and was mag-
netically stirred to obtain a homogeneous solution. The resulting milky mixture was
then subjected to dispersion in an ultrasonic bath for 3 h at 25 °C. The resulting
boehmite was fltered, washed using distilled water, and kept in an oven at 220 °C
1 3

Ni(II) immobilized on modifed boehmite nanostructures:…
Scheme 1 Synthesis of Ni-Gly-isatin@boehmite
for 4 h. Boehmite nanoparticles (I) (1 g) were dispersed in 20 mL of dimethylforma-
mide (DMF), and gly (1 g) was added at room temperature.
The resulting mixture was stirred at 120 °C for 24 h. It was then fltered, washed
with water and ethanol, and dried at 50 °C overnight. In the next step, Gly@boe-
hmite nanoparticles (1 g) were dispersed in ethanol for 30 min, and isatin (2.5 g)
was added to the resulting suspension. The mixture was refuxed for 24 h. Subse-
quently, the obtained Gly-isatin@boehmite was fltered, washed with ethanol,
and dried at 50 °C. Finally, Gly-isatin@boehmite (1 g) was added to a solution of
Ni(NO3)2·6H2O (2.5 mmol, 0.72 g) in absolute EtOH (5 mL), and was stirred at
80 °C for 24 h. The resulting Ni-Gly-isatin@boehmite nanoparticles were fltered,
washed with ethanol to remove the unreacted materials, and dried at 50 °C.
General procedure for the synthesis of benzo[a]pyrano[2,3‑c]phenazine
Ni-Gly-isatin@boehmite (40 mg) was added to a solution of 2-hydroxynaphthalene-
1,4-dione (1 mmol), and benzene-1,2-diamine (1 mmol), and the resulting mixture
was stirred at 80 °C. After completion of this step, benzaldehyde (1.0 mmol) and
malononitrile (1.5 mmol) were added to the resulting mixture. The mixture was
heated for 1 h at 80 °C, cooled to room temperature, and extracted with ethyl acetate
(15 mL). The organic layer was successively washed with water, dried over Na2SO4,
1 3

A. Ghorbani-Choghamarani et al.
and fltered. The solvent was removed, and the corresponding product was purifed
by column chromatography (silica gel, n-hexane/ethyl acetate).
General procedure for benzo[a]benzo[6,7]chromeno[2,3‑c]phenazine
A solution of 2-hydroxynaphthalene-1,4-dione (1 mmol), benzene-1,2-diamine
(1 mmol), and Ni-Gly-isatin@boehmite (40 mg) was stirred at 80 °C. After the reac-
tion was completed, benzaldehyde (1.0 mmol) and 2-hydroxynaphthalene-1,4-dione
(1 mmol) were added to the reaction system. The mixture was then heated for 1 h
at 80 °C, after which it was cooled to room temperature and extracted with ethyl
acetate. The organic layer was washed with water, dried over Na2SO4, and fltered
of. The solvent was removed by a rotary evaporator, and the crude product was sub-
jected to column chromatography (silica gel, n-hexane/ethyl acetate) to aford the
coupling product.
Selected spectral data
3‑Amino‑1‑(4‑chlorophenyl)‑1H‑benzo[a]pyrano[2,3‑c]phenazine‑2‑carboni‑
trile (Table 3, entry 5), 1H NMR (DMSO, 400 MHz) δ 4.82 (s, 1H), 7.01 (d, J=4.4,
1H), 7.14(d, J=4.4, 1H), 7.27–7.26(m, 2H), 7.52–7.451(m, 5H), 7.82(d, J=6.4,
3H), 8.27(t, J=7.2, 2H).
3‑Amino‑1‑(4‑hydroxyphenyl)‑1H‑benzo[a]pyrano[2,3‑c]
phenazine‑2‑carboni‑
trile (Table 3, entry 5),1H NMR (DMSO, 300 MHz) δ 4.42 (s, 1H), 6.61–6.60 (m,
2H), 6.72–6.70(m, 2H), 7.0–6.95(m, 2H), 7.74–7.69(m, 2H), 7.95–7.93(m, 4H),
8.21–8.15(m, 2H), 9.19.47(s, 1H).
3‑Amino‑1‑(4‑fluorophenyl)‑1H‑benzo[a]pyrano[2,3‑c]phenazine‑2‑carbon‑
itrile (Table 3, entry 5), 1H NMR (DMSO, 300 MHz) δ 5.55(s, 1H), 7.06(t,
J=8.3 Hz, 2H), 7.19–7.17 (m, 5H), 7.81–7.74(m, 4H), 8.38–7.96(m, 3H).
17‑(4‑Chlorophenyl)‑16H‑benzo[a]benzo[6,7]chromeno[2,3‑ c]phena‑
zine‑11,16(17H)‑dione (Table 4, entry 1),1HNMR (DMSO, 400 MHz) δ 5.05(s,
1H), 7.03(t, J=8.82 Hz, 3H), 7.49–7.46 (m, 4H), 7.96–7.93(m, 6H), 8.29–8.18(m,
2H), 8.47–8.45(d, J=7.6, 1H).
17‑(4‑Methoxyphenyl)‑16H‑benzo[a]benzo[6,7]chromeno[2,3‑c]phena‑
zine‑11,16(17H)‑dione (Table 4, entry 3),1H NMR (DMSO, 300 MHz) δ 3.81(s,
1H), 4.76(s, 1H), 6.65–6.61(m, 3H), 7.01–7.69 (m, 3H), 7.85–7.84(m, 2H), 7.93–
7.90(m, 4H), 8.10–7.96(m, 4H).
17‑(4‑N itrophenyl)‑16H‑benzo[a]benzo[6, 7]chromeno[2, 3‑ c]phena‑
1
zine‑11,16(17H)‑dione (Table 4, entry 4), H NMR (DMSO, 400 MHz) δ 5.68(s,
1H), 7.65–7.28(m, 6H), 7.68–7.65 (m, 2H), 8.33–8.10(m, 8H).
1 3

Ni(II) immobilized on modifed boehmite nanostructures:…
Catalyst characterization
The prepared nanostructures were characterized using elemental analysis, Fourier
transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM),
thermogravimetric analysis (TGA), X-ray difraction (XRD), energy-dispersive
X-ray spectroscopy (EDX), and inductively coupled plasma/optical emission spec-
trometry (ICP-OES).
FT-IR is a suitable technique for determining the molecular structure of
organic–inorganic materials. Therefore, FT-IR spectra were recorded for boehmite
nanostructures (A), Gly@boehmite (B), Gly-isatin@boehmite (C), and Ni-Gly-
isatin@boehmite (D) (Fig. 1). The presence of boehmite is evidenced by the strong
adsorption bands at 490, 616, and 740 cm−1 that are related to the adsorption of
Al–O bonds (Fig. 1A). Also, the two absorption bonds at 1060 and 1073 cm−1 are
related to the symmetrical bending vibrations of hydrogen bands between Al–OH
groups at the surface of boehmite. The presence of two strong peaks at around 3268,
3087 cm−1 are attributed to both the symmetrical and asymmetrical modes of the
O–H bonds on the surface of the boehmite nanostructures. The presence of the
Fig. 1 FT-IR spectra of boehmite nanostructures (A), Gly@boehmite (B), Gly-isatin@boehmite (C), Ni-
Gly-isatin@boehmite (D)
1 3

A. Ghorbani-Choghamarani et al.
anchored gly group in the boehmite nanostructures is confrmed by C–H stretching
vibrations that appear at 2770.3, 2925.5 cm−1(Fig. 1B). The peaks at the 1463−1 and
1453 cm−1 regions belong to C=C stretching vibrations in isatin (Fig. 1C). In the
spectra of Ni-Gly-isatin@boehmite (Fig. 1D), a shifting to higher wave numbers (to
1634 cm−1) has been observed for C=N (1623 cm−1) upon chelation.
XRD is a useful and versatile technique for the phase analysis and determination
of the crystal structure of materials. As shown in Fig. 2, the Ni-Gly-isatin@boe-
hmite phase was identifed by the peak positions at 2Ɵ=14.40, 28.41, 38.55, 46.45,
49.55, 55.02, 59.35, 65.56, 68.09, and 72.38 corresponding to the crystal planes of
boehmite nanostructures in the orthorhombic unit cell [40] (Fig. 2). The emergence
of new peaks at 2Ɵ=55 is related to Ni in the catalyst [41].
The size and morphology of the fresh Ni-Gly-isatin@boehmite and the recov-
ered Ni-Gly-isatin@boehmite were studied by SEM. SEM micrographs provided
precise information on the particle size and morphology of the catalyst (Figs. 3,
4). Figure 3 clearly shows the morphology of the nanostructures, with diame-
ters ranging from 24 nm to 1.17 μm. In addition, the SEM images of the fourth
recovered Ni-Gly-isatin@boehmite are shown in Fig. 4. Interestingly, no particle
agglomeration was observed even after four consecutive recycle runs. The ther-
mal behavior of the Ni-Gly-isatin@boehmite was studied by thermogravimetry/
diferential thermal analysis (TG–DTA) (Fig. 5). The initial weight loss up to
200 °C was due to the removal of water or the adsorbed solvent molecules on
the surface of the nanostructures. At 250–500 °C, a large weight loss occurred
because of the decomposition of the organic groups. Finally, the third weight loss
above 500 °C may be related to the phase transfer of the boehmite structure to the
alumina phase, which can be accompanied by OH elimination. The DTA curve
also shows an endothermic peak centered at 90 °C in the DSC curve, suggesting
Fig. 2 The XRD pattern of Ni-Gly-isatin@boehmite nanostructures
1 3

Ni(II) immobilized on modifed boehmite nanostructures:…
Fig. 3 SEM images of Ni-Gly-isatin@boehmite
that the weight loss is due to the elimination of physically adsorbed water. The
second endothermic peak at 450 °C can be attributed to the combustion process
of Schif base groups in Ni-Gly-isatin@boehmite.
In order to survey the type of elements in Ni-Gly-isatin@boehmite, the EDX
spectrum was recorded, and is shown in Fig. 6.
The composition of the as-synthesized catalyst (Ni-Gly-isatin@boehmite)
was confrmed by the presence of Al and Ni species in the Ni-Gly-isatin@boe-
hmite in the EDX spectrum (Fig. 6). The results of carbon, hydrogen, and nitro-
gen elemental analysis and the C/N ratio of Ni-Gly-isatin@boehmite are given in
Table 1. According to the ICP analysis, the exact amount of Ni in the heterogene-
ous catalyst was 1.7%. The Ni/N molar ratio was found to be 0.5%.
1 3

A. Ghorbani-Choghamarani et al.
Fig. 4 SEM images of Ni-Gly-
isatin@boehmite after recovery
Fig. 5 TGA and DSC diagram of Ni-Gly-isatin@boehmite
Catalytic study
After the preparation and characterization of the Ni-Gly-isatin@boehmite, we
decided to explore the catalytic activity of this compound in the synthesis of
benzo[a]pyrano[2,3-c]phenazine (Scheme 2). Our research began with the inspec-
tion of benzo[a]pyrano[2,3-c] phenazine derivative synthesis. A combination of
2-hydroxynaphthalene-1,4-dione, benzene-1,2-diamine, and 4-chlorobenzalde-
hyde was chosen as the model reaction to optimize the reaction conditions with
regard to the solvent, temperature, and the catalyst amount screening. In order to
reduce the formation of by-products, the 2-hydroxynaphthalene-1,4-dione and ben-
zene-1,2-diamine were mixed and stirred, after which 4-chlorobenzaldehyde and
1 3

Ni(II) immobilized on modifed boehmite nanostructures:…
Fig. 6 EDX spectrum of Ni-Gly-isatin@boehmite
Table 1 Elemental (C, O, N)
Compound
C (%)
11.5
O (%)
42.76
N (%)
3.45
Ni/N
0.5
analysis results of Ni-Gly-
isatin@boehmite
Ni-Gly-isatin@boehmite
Scheme 2 Synthesis of benzo[a]pyrano[2,3-c]phenazine
malononitrile were added to this mixture. First, the efect of the solvents was tested.
Surprisingly, polyethylene glycol (PEG) was the most efective solvent for obtaining
the desired product (Table 2). Among the various temperatures screened (e.g., 25,
80, and 100 °C), 80 °C was found to be the most efective (Table 2, entry 1). The
1 3

A. Ghorbani-Choghamarani et al.
infuence of catalyst amount was then studied. Table 1, entry 1, indicates that the
reaction was not completed after stirring in the absence of the catalyst. With opti-
mal conditions in hand, we then widened the scope of this synthesis by subjecting
a variety of aromatic aldehydes to reactions with 2-hydroxynaphthalene-1,4-dione
and benzene-1,2-diamine (Table 3). From these results, we observed that all of the
reactions produced the corresponding benzo[a]pyrano[2,3-c]phenazine in excel-
lent yields (77–90%). Aromatic aldehydes carrying electron-withdrawing substitu-
ents were found to have shorter reaction times. This catalytic system was then used
for the synthesis of 3-amino spiro[benzo[c]pyrano[3,2-a]phenazine]. For this pur-
pose, 2-hydroxy-1,4-naphthoquinone, 1,2-diamines, and malononitrile were com-
bined with isatin under optimized reaction conditions to aford the related product
(Table 3, entry 8). A reaction mechanism based on previous reports [41] is depicted
in Scheme 3. Initially, intermediate 3 was formed from condensation of 2-hydrox-
ynaphthalene-1,4-dione and benzene-1,2-diamine in the presence of Ni-Gly-isatin@
boehmite. Sequentially, a possible intermediate 7 was formed via Michael addition
of 6 with 2-benzylidenemalononitrile (intermediate 6 is formed via condensation of
aldehydes with malononitrile), followed by hydrogen bonding to form intermediate
8.
In another study, we decided to examine our methodology to aford the corre-
sponding benzo[a]benzo[6,7]chromeno[2,3-c]phenazine derivatives (Scheme 4)
under optimal reaction conditions obtained for the previous reaction. The results are
shown in Table 4. We observed that all of the reactions produced the corresponding
benzo[a]benzo[6,7]chromeno[2,3-c]phenazine in excellent yields (73–90%).
A plausible mechanism for the competitive multicomponent synthesis of benzo[a]
benzo[6,7]chromeno[2,3-c]phenazine on the basis of previous reports [42] is
depicted in Scheme 5, and a possible explanation for the reaction mechanism is pro-
posed in Scheme 2. The reaction might proceed via sequential condensation, addi-
tion, cyclization, and elimination. We hypothesized that, frst, 2 is tautomerized to
intermediate 4-hydroxy-1,2-naphthoquinone 3. This intermediate 3 then reacts with
Table 2 Optimization of
Entrya Cat. (mg) Solvent Temp. (°C) Yieldb (%) Time (h)
conditions for the synthesis of
3-amino-1-(4-chlorophenyl)-
1
2
3
4
5
6
7
8
9
40
40
40
40
40
40
60
–
PEG
DMSO
H2O
DMF
EtOH
–
PEG
PEG
PEG
80
80
80
80
80
80
100
80
90
65
2
2
2
2
2
2
1H-benzo[a]pyrano[2,3-c]
phenazine-2-carbonitrile
NR
58
Trace
NR
92
Trace
44
110 min
2
2
20
80
aReaction conditions: 2-hydroxynaphthalene-1,4-dione (1 mmol),
benzene-1,2-diamine (1 mmol), 4-chlorobenzaldehyde (1.0 mmol),
and malononitrile (1.5 mmol), catalyst and solvent (2 mL). bIsolated
yield
1 3

Ni(II) immobilized on modifed boehmite nanostructures:…
Table 3 Synthesis of benzo[a]pyrano-[2, 3-c]phenazine derivatives
TOF (h–1)
Entrya
Aldehyde
Product
Time
(h)
Yieldb
(%)
M.P
Find
Reported
1
45 min 96
94.11
285–288 288–291 [42]
2
3
2
3
90
80
33.08
19.6
282–284 286–288 [43]
290–293 295 [43]
4
5
3
3
85
83
20.83
20.34
273–276 273 [43]
249–252 > 250 [44]
6
7
8
1
2
77
83
57.46
30.97
137.3
273–275 278–279 [42]
269–272 275 [43]
30 min 92
250–253 > 250 [45]
aReaction conditions: 2-hydroxynaphthalene-1,4-dione (1 mmol), benzene-1, 2-diamine (1 mmol), ben-
b
zaldehyde or isatin (1.0 mmol) and malononitrile (1.5 mmol), Catalyst (40 mg) and PEG (2 mL). Iso-
lated yield
1,2-benzenediamine to give intermediate 7. In the next step, olefn 5 is produced by
knoevenagel condensation of intermediate 1 with carbonyl groups of aldehyde or
cyclic ketone in the presence of the catalyst. The Michael addition of 7 with olefn 5
provides intermediate 8, which causes the inner molecular ring to be formed after a
tautomeric proton shift to produce the fnal product.
1 3

A. Ghorbani-Choghamarani et al.
Scheme 3 Proposed mechanism for the synthesis of benzo[a]pyrano[2,3-c]phenazine
Scheme 4 Synthesis of benzo[a]benzo[6,7]chromeno[2,3-c]phenazine
Catalyst recyclability
The recyclability of Ni-Gly-isatin@boehmite was examined using the reaction of
2-hydroxynaphthalene-1,4-dione, benzene-1,2-diamine, and 4-chlorobenzaldehyde
under the optimized reaction conditions. After the completion of the reaction, as
indicated by thin-layer chromatography (TLC), the mixture was cooled to room
temperature and extracted several times with ethyl acetate, after which the catalyst
was separated from the reaction mixture and reused for subsequent reactions. Fig-
ure 7 shows the catalytic efciency of the Ni-Gly-isatin@boehmite nanostructures
after four cycles. The results reveal that the catalytic activity of the Ni-Gly-isatin@
1 3

Ni(II) immobilized on modifed boehmite nanostructures:…
Table 4 Synthesis of benzo[a]benzo[6,7]chromeno[2,3-c]phenazine
Entrya
Aldehyde
Product
Time (h)
Yieldb (0/0) M.P
Find
Reported
1
5
90
80
322–324
325–327 [46]
2
3
4
5
7
7
4
6
330–333
340–342
270–272
301–332
335–337 [46]
442–344 [46]
273 [46]
82
78
88
301–333 [46]
6
7
5.5
4.5
73
75
293–295
270–273
294–296 [46]
273 [46]
8
2.5
85
293–295
297–299 [43]
aReaction conditions: 2-hydroxynaphthalene-1,4-dione (2 mmol), benzene-1, 2-diamine (1 mmol), ben-
zaldehyde or isatin (1.0 mmol), Catalyst (40 mg) and PEG (2 mL). bIsolated yield
boehmite nanostructure was slightly decreased after four cycles of catalysis experi-
ments. Also, in order to quantitatively determine the exact amount of nickle in the
fresh and reused Ni-Gly-isatin@boehmite, an ICP-OES technique was applied for
the synthesis of 3-amino-1-(4-chlorophenyl)-1H-benzo[a]pyrano[2,3-c]phenazine-
2-carbonitrile. The results revealed that the amount of Ni in the fresh and recovered
catalyst after four runs was 1.7×10−4mol/g and 1.53×10−4mol/g, respectively, indi-
cating that the nickel leaching of the catalyst is very low.
1 3

A. Ghorbani-Choghamarani et al.
Scheme 5 Proposed mechanism for the synthesis of benzo[a]benzo[6,7]chromeno[2,3-c]phenazine
Fig. 7 Catalyst recycling study
for the synthesis of 3-amino-1-
(4-chlorophenyl)-1H-benzo[a]
pyrano[2,3-c]
1 3

Ni(II) immobilized on modifed boehmite nanostructures:…
Table 5 Comparison of
Entry
Catalyst
Yielda (%)
Time (h)
Refs.
Ni-Gly-isatin@boehmite for
spiro[benzo[c]pyrano[3,2-a]
phenazines] with previously
reported procedures
1
2
3
DABCO
l-proline
93
94
5
4
[45]
[47]
This work
Ni-Gly-isatin@ 92
30 min
boehmite
aIsolated yields
Hot fltration
The metal leaching of the catalyst was evaluated using a hot fltration test. This was
performed for the synthesis of 3-amino-1-(4-chlorophenyl)-1H-benzo[a]pyrano[2,3-
c]phenazine-2-carbonitrile by the reaction of p-Cl-benzaldehyde (1 mmol),
2-hydroxynaphthalene-1,4-dione (1 mmol), benzene-1,2-diamine (1 mmol), and
malononitrile (1.5 mmol). When the reaction was nearly 50% complete, the catalyst
was separated from the reaction mixture and the fltrate was allowed to react further.
We found that no further reaction occurred after the separation of the catalyst after
2 h, which means that the Ni catalyst remains on the support at elevated tempera-
tures during the reaction.
Finally, in order to assess the present protocol with respect to other reported
methods, the spiro[benzo[c]pyrano[3,2-a]phenazines] of 2-hydroxynaphthalene-
1,4-dione, benzene-1,2-diamine, isatin, and malononitrile, the catalytic performance
of the Ni-Gly-isatin@boehmite was compared with some previously reported cat-
alysts (Table 5). The Ni-Gly-isatin@boehmite demonstrated good reaction time
and higher yield than the previously reported catalysts. More importantly, Ni-Gly-
isatin@boehmite was able to be reused at least four times without any signifcant
loss of catalytic activity (Table 4).
Conclusions
In this study, a novel type of boehmite, as a recoverable nanocatalyst (Ni-Gly-
isatin@boehmite), was prepared and characterized. It was found to be an efcient
and recyclable nanocatalyst for the preparation of benzo[a]pyrano[2,3-c]phenazine
and benzo[a]benzo[6,7]chromeno[2,3-c] phenazine in green solvent (PEG). The pre-
sent synthetic methodology shows attractive characteristics including short reaction
times, good to excellent yields, and the use of PEG as a green solvent. In addition,
the nanocatalyst can be easily recovered and reused at least four times with minimal
deterioration of catalytic activity.
Acknowledgements The authors thank the research facilities of Ilam University, Ilam, Iran, for fnancial
support of this research project.
1 3

A. Ghorbani-Choghamarani et al.
References
1. D. Jariwala, V.K. Sangwan, L.J. Lauhon, T.J. Marks, M.C. Hersam, Chem. Soc. Rev. 42, 2824 (2013)
2. E.E. Perl, W.E. McMahon, J.E. Bowers, D.J. Friedman, Opt. Express 22, A1243 (2014)
3. C. Guo, J. Zhong, L. Gao, J. Gao, S. Huang, J. Saudi Chem. Soc. 16, 307 (2017)
4. L.S. Zhang, L.Y. Jiang, C.Q. Chen, W. Li, W.G. Song, Y.G. Guo, Chem. Mater. 22, 414 (2009)
5. M.A. Zolfgol, A.R. Moosavi-Zare, P. Moosavi, V. Khakyzadeh, A. Zare, C. R. Chim. 6, 962 (2013)
6. Y. Wang, F. Wang, H. Wang, M. Song, Sci. Rep. 7, 16510 (2017)
7. A. Ghorbani-Choghamarani, Z. Taherinia, NJC 41, 9414 (2017)
8. S. Narayanan, A. Sultana, K. Krishna, P. Mériaudeau, C. Naccache, Catal. Lett. 34, 129 (1995)
9. S. Li, M. Meng Lin, M.S. Toprak, D.K. Kim, M. Muhammed, Nano Rev. 1, 5214 (2010)
10. B. Tahmasbi, A. Ghorbani-Choghamarani, Catal. Lett. 147, 649 (2017)
11. V. Vatanpour, S.S. Madaeni, L. Rajabi, S. Zinadini, A.A. Derakhshan, J. Membr. Sci. 401, 132 (2017)
12. M. Abdollahifar, M. Hidaryan, P. Jafari, Bol. Soc. Esp. Ceram. V. 57, 66 (2018)
13. R.W.N. Denigres Filho, G.D.A. Rocha, C.R. Montes, A.C. Vieira-Coelho, Mater Res. 19, 659 (2016)
14. M.K. Naskar, M. Chatterjee, D. Ganguly, Bull. Mater. Sci. 25, 115 (2002)
15. S. Brühne, S. Gottlieb, W. Assmus, E. Alig, M.U. Schmidt, Cryst. Growth Des. 8, 489 (2008)
16. B.Y. Yeom, E. Shim, B. Pourdeyhimi, Macromol. Res. 18, 884 (2010)
17. Y. Mathieu, B. Lebeau, V. Valtchev, Langmuir 23, 9435 (2007)
18. H.W. Hou, Y. Xie, Q.N. Yang, Q.X. Guo, C.R. Tan, Nanotechnology 16, 741 (2005)
19. B. Tang, J.C. Ge, L.H. Zhuo, G.L. Wang, J.Y. Niu, Z.Q. Shi, Y.B. Dong, Eur. J. Inorg. Chem. 21, 4366
(2005)
20. Z.Q. Yu, C.X. Wang, T. Gu, C. Li, J. Lumin. 106, 153 (2002)
21. X.Y. Chen, S.W. Lee, Chem. Phys. Lett. 438, 279 (2007)
22. Y. Li, J. Liu, Z. Jia, Mater. Lett. 60, 3586 (2006)
23. W. Cai, J. Yu, S. Gu, M. Jaroniec, Cryst. Growth Des. 10, 3977 (2010)
24. M. Abdollahifar, R.M. Zamani, E. Beiygie, H. Nekouei, J. Serb. Chem. Soc. 79, 1007 (2014)
25. Y. Feng, W. Lu, L. Zhang, X. Bao, B. Yue, Y. Lv, X. Shang, Cryst. Growth Des. 8, 1426 (2008)
26. L. Zhang, Y.J. Zhu, J. Phys. Chem. C. 112, 16764 (2008)
27. Y. Zhu, H. Hou, G. Tang, Q. Hu, Eur. J. Inorg. Chem. 6, 872 (2010)
28. A. Váradi, T.C. Palmer, R. Notis Dardashti, S. Majumdar, Molecules 21, 19 (2015)
29. R.C. Cioc, E. Ruijter, R.V. Orru, Green Chem. 16, 2958 (2014)
30. B.B. Toure, D.G. Hall, Chem. Rev. 109, 4439 (2009)
31. C. Hulme, V. Gore, Curr. Med. Chem. 10, 51 (2003)
32. M. Haji, Beilstein J. Org. Chem. 12, 1269 (2016)
33. P.W. Crawford, R.G. Scamehorn, U. Hollstein, M.D. Ryan, P. Kovacic, Chem. Biol. Interact. 60, 67
(1986)
34. C. Neves-Pinto, V.R. Malta, M.D.C.F. Pinto, R.H. Santos, S.L. de Castro, A.V. Pinto, J. Med. Chem. 45,
2112 (2002)
35. S. Sun, L. Zhou, K. Jin, H. Jiang, Y.W. He, Sci. Rep. 6, 30352 (2016)
36. S.K. Ku, H. Yoo, W. Zhou, M. Na, J.S. Bae, Anim. Cells Syst. 18, 204 (2014)
37. A. Ghorbani-Choghamarani, G. Azadi, RSC Adv. 5, 9752 (2015)
38. T. Tamoradi, M. Ghadermazi, A. Ghorbani-Choghamarani, Catal. Lett. 148, 857 (2018)
39. A. Ghorbani-Choghamarani, P. Moradi, B. Tahmasbi, RSC Adv. 6, 56638 (2016)
40. J. Geng, D.A. Jeferson, B.F. Johnson, ChemComm 9, 969 (2007)
41. S.L. Wang, F.Y. Wu, C. Cheng, G. Zhang, Y.P. Liu, B. Jiang, S.J. Tu, ACS. Comb. Sci. 13, 135 (2011)
42. S. Abbasi Pour, A. Yazdani-Elah-Abadi, M. Afradi, Appl. Organomet. Chem. 31, e3791 (2017)
43. H.R. Shaterian, M. Mohammadnia, J. Mol. Liq. 177, 162 (2013)
44. J. Gao, M. Chen, X. Tong, H. Zhu, H. Yan, D. Liu, Y. Lu, Comb. Chem. High 18, 960 (2015)
45. S.A. Mirmiran-Yazdi, A.Y.E. Abadi, N. Shams, R. Mohebat, Turk. J. Chem. 41, 567 (2017)
46. A. Hasaninejad, S. Firoozi, Mol. Divers 17, 499 (2013)
47. A. Yazdani-Elah-Abadi, R. Mohebat, M. Kangani, J. Chem. Res. 40, 722 (2016)
Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published
maps and institutional afliations.
1 3