Solvent-free synthesis of 1-amidoalkyl-2-naphthols using magnetic nanoparticle-supported?2-(((4-(1-iminoethyl)phenyl)imino)methyl)phenol Cu (II) or Zn (II) Schiff base complexes

Article abstract of DOI:10.1007/s11164-020-04142-7

Two magnetic nanoparticle-supported?2-(((4-(1-iminoethyl)phenyl)imino)methyl)phenols were successfully synthesized, characterized, and applied in the one-pot three-component reaction of substituted benzaldehydes, 2-naphthol, and amides for synthesis of 1-

Full text of DOI:10.1007/s11164-020-04142-7

Research on Chemical Intermediates
https://doi.org/10.1007/s11164-020-04142-7
Solvent‑free synthesis of 1‑amidoalkyl‑2‑naphthols using
magnetic nanoparticle‑supported 2‑(((4‑(1‑iminoethyl)
phenyl)imino)methyl)phenol Cu (II) or Zn (II) Schif base
complexes
Fatemeh Ghorbani1 · Hamzeh Kiyani1 · Seied Ali Pourmousavi1 · Davood Ajloo1
Received: 13 January 2020 / Accepted: 27 March 2020
© Springer Nature B.V. 2020
Abstract
Two magnetic nanoparticle-supported 2-(((4-(1-iminoethyl)phenyl)imino)methyl)
phenols were successfully synthesized, characterized, and applied in the one-pot
three-component reaction of substituted benzaldehydes, 2-naphthol, and amides for
synthesis of 1-amidoalkyl-2-naphthols. These three-component processes occurred
under solvent-free reaction conditions at 80 °C. The magnetically recoverable sup-
ported Schif base metal catalysts can be reused several times in the model reac-
tion. The synthesized catalysts are also easily separated from the reaction mixture by
applying an external magnet. This procedure ofers the advantages of simple, opera-
tional procedure as well as no use of hazardous organic solvents.
Keywords 1-Amidoalkyl-2-naphthols · 3-Aminopropyltrimethoxysilane · Magnetic
nanoparticle-supported 2-(((4-(1-iminoethyl)phenyl)imino)methyl)phenol · Three-
component reaction · Solvent-free · Silica-coated Fe3O4
Introduction
The 1-amidoalkyl-2-naphthol derivatives are important class of organic compounds
found in anti-infammatory, anthelmintic, antibacterial, and antiviral agents [1, 2].
The structures of some 1-amidoalkyl-2-naphthols with biological properties are
depicted in Table 1 [2–5]. Some 1-amidoalkyl-2-naphthols are well-known inter-
mediates for the synthesis of 1-aminoalkyl-2-naphthols (Betti bases) as pharma-
ceutically active molecules with depressor, hypertensive, and bradycardia [6–9].
Furthermore, derivatives of 1-amidoalkyl-2-naphthol act as precursors for the syn-
thesis of interesting molecules with biological activity, including antibiotic [10],
*
Hamzeh Kiyani
hkiyani@du.ac.ir
1
School of Chemistry, Damghan University, 36716-41167 Damghan, Iran
Vol.:(0123456789)
1 3

F. Ghorbani et al.
Table 1 The 1-amidoalkyl-2-naphthols with biological activities
A
A
A
A
A
A
A
A
A
A
antihypertensive [11], analgesic [12], antimalarial [13], antitumor [14, 15], antirheu-
matic [16], antianginal [17], and anticonvulsant [18]. Owing to the importance of
such biologically active scafolds and their occurrence in natural products, their syn-
thesis is of interest to researchers.
The multicomponent reactions (MCRs) are efcient approaches in modern organic
synthesis and medicinal chemistry, which are used for construction biologically active
compounds and drug candidates from three or more reactants in a one-pot reaction
[19]. Also, MCRs signifcantly reduce the number of chemical reaction steps, and steps
of separation and purifcation [20]. A one-pot MCR of β-naphthols, aldehydes, and
1 3

Solvent-free synthesis of 1-amidoalkyl-2-naphthols using…
amides is an excellent practical synthetic technique for the synthesis of 1-amidoalkyl-
2-naphthols, catalyzed by several catalysts such as magnetite (Fe3O4)-supported
molybdenum oxide (MoO3) [21], homopiperazine sulfamic acid-functionalized
mesoporous silica (MSNs-HPZ-SO3H) [22], ZrOCl2·8H2O [23], zirconocene dichlo-
ride (Cp2ZrCl2) [24], ionic liquid immobilized on the Fe3O4 nanoparticles under ultra-
sonic irradiation [25], β-cyclodextrin-monosulphonic acid [26], Fe3O4 carbon nano-
tubes [27], sulfamic acid-functionalized magnetic nanoparticles (SA-MNPs) [28],
magnetic nanoparticle-supported acidic ionic liquid [29], 2-hydroxy-5-sulfobenzoic
acid (2-HSBA) [30], phthalimide-N-sulfonic acid [31], sulfonated polynaphthalene
(S-PNP) [32], nano-Fe3O4 using ultrasound [33], SO3H-MCM41@NiFe2O4 [34],
nanosulfur particles (S8-NPs) [35], silver nanoparticles [36], magnetic nanoparticle-
supported acidic ionic liquid (AIL@MNP) [29], deep eutectic solvent (DES) that con-
sists of urea and choline chloride [37], and zinc oxide nanoparticle (ZnO NPs) [38].
Functionalized magnetic solid nanoparticles as magnetically separable nano-
catalysts, on the other hand, have become valuable and efcient catalysts in green
organic transformations. The use of magnetic solid catalysts in chemical reactions
facilitates the recovery and separation of expensive catalysts from reaction mixtures,
due to the ease of separation with the help of an external magnetic feld avoiding the
need for tedious workup procedure [39–43]. Other features of these types of cata-
lysts include simple recovery, easy accessibility, high stability, and improved reus-
ability [44, 45]. Furthermore, magnetically recyclable solid catalysts were used for
the production of biodiesel [46–48] and trans-free plastic fats [49].
In this study, a one-vessel 3-CR has been applied to the synthesis a number of
1-amidoalkyl-2-naphthols (4a–v) in the presence of magnetic nanoparticle-sup-
ported (iminoethyl)phenyl)imino)methyl)phenol Cu (II) or Zn (II) Schif bases com-
plexes as catalysts under solvent-free conditions at 80 °C (Scheme 1). The novelty of
the present work is associated with the synthesis of efcient magnetic solid catalysts
and their potential applications in the synthesis of 1-amidoalkyl-2-naphthols from
available starting materials.
Scheme 1 Three-component synthesis of 1-amidoalkyl-2-naphthols (4a–v) in the presence of magnetic
nanoparticle-supported Schif base complexes (G1 and G2) catalysts under solvent-free conditions at
80 °C
1 3

F. Ghorbani et al.
Experimental
General
All chemicals were purchased from commercial sources and were used with-
out further purifcation, except aldehyde liquids and solvents which were dis-
tilled before using. The products were characterized by comparing their physi-
cal data with those of known samples or by their spectral data. Melting points
were measured on a Buchi 510 melting point apparatus and were uncorrected.
Nuclear magnetic resonance (NMR) spectra were recorded at ambient tempera-
ture on a BRUKER AVANCE DRX-400 MHz using CDCl3 or DMSO-d6 as the
solvent. Fourier-transform infrared spectroscopy (FT-IR) spectra were recorded
on a PerkinElmer RXI spectrometer. Thermogravimetric analysis (TGA) was
conducted from room temperature to 750 °C under argon atmosphere using a
BAHR-Thermoanalyse simultaneous thermal analyzer STA 503 instrument using
aluminum oxide reference. X-ray difraction (XRD) patterns of samples were
taken on a Philips X-ray difract meter Model PW 1840. The particle morphology
was examined by feld emission scanning electron microscopy (FESEM) (Philips
XL30 scanning electron microscope). Transmission electron microscopy (TEM)
observations were performed using a Zeiss TEM-LEO 910 apparatus operating
at 100 kV. The development of reactions was monitored by thin-layer chroma-
tography (TLC) analysis on Merck pre-coated silica gel 60 F254 aluminum sheets,
visualized by ultraviolet (UV) light.
Synthesis of 4‑(1‑((3‑(triethoxysilyl)propyl)imino)ethyl)aniline (C)
4-Aminoacetophenone (A) (1 mmol, 0.135 g) and 3-(triethoxysilyl)propan-1-amine
{(3-(aminopropyl)triethoxysilane (APTES), B) were dissolved in dry acetonitrile
(10 mL), and the mixture was stirred for overnight at rt. After completion of the
reaction, the mixture was fltered of and the resulting precipitate (product C) was
dried in vacuum oven for 6 h. The C was used for the next step without further
purifcation.
Synthesis of 2‑((E)‑((4‑((Z)‑1‑((3‑(triethoxysilyl)propyl)imino)ethyl)phenyl)imino)
methyl)phenol (D)
To 50-mL round-bottomed fask containing 4-(1-((3-(triethoxysilyl)propyl)imino)
ethyl)aniline (C) (1 mmol) was added dry ethanol (10 mL), and the mixture was
stirred at room temperature. Then, 2-hydroxbenzaldehyde (1 mmol) and sodium
acetate (0.1 g) was added; mixture was stirred under argon atmosphere for 24 h at
rt. After completion of reaction, the reaction mixture was fltered of using Buchner
funnel and the resulting precipitate was dried in vacuum oven for 6 h. The Schif
base crude product was used for the next step without further purifcation.
1 3

Solvent-free synthesis of 1-amidoalkyl-2-naphthols using…
Synthesis of Schif base‑functionalized core–shell MNPs (F)
Silica-coated Fe3O4 nanoparticles (Fe3O4@SiO2 nanoparticles) (1 g) were soni-
cated in dry toluene (15 mL), and the Schif base crude product D was added.
Then, the mixture was stirred for 12 h under sonication. The obtained product
(F) was separated using an external magnet, washed with acetonitrile, and dried
under vacuum oven.
Synthesis of magnetic nanoparticle‑supported 2‑(((4‑(1‑iminoethyl)phenyl)
imino)methyl)phenol Cu (II) or Zn (II) Schif bases complexes (G1 and G2)
Schif base-functionalized core–shell MNPs (F) (1 g) were sonicated in 20 mL
THF at rt. Then, copper (II) acetate or zinc (II) acetate (1 g) was added. The mix-
ture was stirred for 72 h at rt. Then, the reaction mixture was fltered of using
Buchner funnel and the resulting precipitate was dried in vacuum oven for 12 h.
General procedure for the synthesis of 1‑amidoalkyl‑2‑naphthols (4a‑v)
A mixture of substituted benzaldehyde 1, 2-naphthol 2 (1 mmol), (1 mmol),
amide 3a–d (1 mmol) and 0.1 g catalyst was stirred at 80 °C in an oil bath.
After completion of the reaction (using TLC analysis), the reaction mixture was
allowed to cool to room temperature. Next, hot ethyl acetate was added to the
resulting mixture and the crude product was extracted using ethyl acetate and
catalyst was separated via magnetic separation. The catalyst was washed with the
small amount of proper solvent and dried, and then it was used for the subsequent
reaction. After evaporation of ethyl acetate, solid product was formed and dried.
If the further purifcation was needed, the products can be recrystallized from hot
ethanol. Spectral data for 4e, 4f, and 4u are as follows:
1
N‑((2‑Hydroxynaphthalen‑1‑yl)(3‑nitrophenyl)methyl)acetamide (4e) H NMR
(400 MHz, DMSO‐d6): δ=10.14 (s, 1H), 8.62 (d, J=8.0 Hz, 1H), 8.02–7.99 (m,
2H), 7.84 (br, 1H), 7.78 (t, J=8.6 Hz, 2H), 7.59–7.51 (m, 2H), 7.40 (t, J=7.6 Hz,
1H), 7.26 (t, J=7.4 Hz, 1H), 7.18 (d, J=8.7 Hz, 1H), 7.16 (t, J=8.0 Hz, 1H), 2.02
(s, 3H); 13C NMR (100 MHz, DMSO‐d6): δ=170.3, 153.9, 148.2, 145.9, 133.4,
132.7, 130.5, 130.1, 129.2, 128.9, 127.3, 123.2, 123.1, 121.8, 120.9, 118.9, 118.3,
48.2, 23.1.
1
N‑((2‑Hydroxynaphthalen‑1‑yl)(4‑nitrophenyl)methyl)acetamide (4f) H NMR
(400 MHz, DMSO-d6): δ=10.07 (s, 1H), 8.53 (d, J=7.9 Hz, 1H), 8.10 (d, J=8.8,
2H), 7.74–7.82 (m, 3H), 7.44–7.33 (m, 3H), 7.25 (t, J=7.5 Hz, 1H), 7.19 (d,
J=8.8 Hz, 1H), 7.14 (d, J=7.9 Hz, 1H), 1.98 (s, 3H).
1 3

F. Ghorbani et al.
1
1‑((2‑Hydroxynaphthalen‑1‑yl)(phenyl)methyl)urea (4u) H NMR (400 MHz,
DMSO-d6): δ=9.97 (s, 1H), 7.75–7.83 (m, 3H), 7.82 (d, J=7.9 Hz, 1H), 7.41–7.12
(m, 7H), 6.94 (s, 1H), 5.86 (s, 2H).
Results and discussion
The magnetic nanoparticles (Fe3O4) were synthesized by a chemical coprecipitation
technique using ferric and ferrous ions [50]. Core/shell Fe3O4@SiO2 nanoparticles
(E) were synthesized based on literature report [51]. 3-Aminopropyl)triethoxysilane
(APTES) (B) as a silylating agent reacted with the 4-aminoacetophenone (A) in ace-
tonitrile at room temperature (rt) to give the 4-(1-((3-(triethoxysilyl)propyl)imino)
ethyl)aniline (C), which was then reacted with the salicylaldehyde in EtOH at rt to
produce 2-(4)-1-((3-(triethoxysilyl)propyl)imino)ethyl)phenyl)imino)methyl)phenol
(D). Fe3O4@SiO2 NPs was functionalized by D to produce ligand-functionalized
core–shell magnetic NPs (F). Finally, surface-bound ligands were complexed with
copper(ΙΙ) and zinc(II) ions by using Cu(OAc)2 and Zn(OAc)2 to give nanocatalysts
(named as catalysts G1 and G2) (Scheme 2).
Scheme 2 Synthesis of magnetic nanoparticle-supported Schif base catalysts G1 and G2
1 3

Solvent-free synthesis of 1-amidoalkyl-2-naphthols using…
Fig. 1 Powder XRD patterns of Fe3O4@SiO2@Cu nanoparticles (a) and Fe3O4@SiO2@Zn (b) nanopar-
ticles
The nanocatalysts G1 and G2 were characterized by various microscopic and
spectroscopic techniques such as X-ray difraction (XRD), Fourier transform infra-
red (FTIR), feld emission scanning electron microscopy (FE-SEM), and inductively
coupled plasma (ICP). In XRD analysis (Fig. 1a), a peak at around 2θ=8.0° [52,
53] is attributed to Cu. In Fig. 1b, two peaks at 2θ=8.0° and 12.0° (110) [54] are
attributed to Zn. The characteristic peaks at 2θ=30.3°, 35.4°, 43.5°, 53.5°, 57.2°,
and 62.9° that correspond to (220), (311), (400), (422), (551), and (440) difraction
planes of Fe3O4 MNPs are in good agreement with the standard XRD data for the
cubic Fe3O4 phase of inverse spinel crystal structure [55, 56].
As can be seen in Figs. 2 and 3, the absorption peaks at around 560 cm−1 and
580 cm−1 can be assigned to the Fe–O absorption in the hematite. Signals at around
1460 cm−1 and 1480 cm−1 related to the aromatic C=C stretching as well as a sig-
nal at 1610 cm−1 and 1645 produced by C=N double bond confrm that the organic
linker was appropriately immobilized onto the core/shell surface. It is suggesting
that C=N bond is coordinated to copper and zinc through the lone pair of nitrogen
and oxygen [57].
Also, broad peaks at 3400 cm−1 and 3450 cm−1 are related to the O–H vibrations
as well as stretching vibrations of Si–O–Si (at about 1280 cm−1 and 1150 cm−1) and
vibrations of Si–OH (at around 840 cm−1 and 690 cm−1) are evidence to support the
existence of silica shell in all magnetic nanoparticles. Also, Fe–O–Si bonds shift
was observed at 1090 cm−1 (Fig. 3) [51].
The stability of two catalysts was determined by thermogravimetric analysis.
The thermogravimetric (TG) analysis of diagrams of Fe3O4@SiO2@Cu (a) and
Fe3O4@SiO2@Zn (b) was performed over the range of 25–800 °C, with a tem-
perature increase rate of 10 °C min−1 in a nitrogen atmosphere (Fig. 4). Accord-
ing to TG curve, the weight loss processes of Fe3O4@SiO2@Cu could be divided
1 3

F. Ghorbani et al.
Fig. 2 FT-IR spectra of Fe3O4 nanoparticles (a), Fe3O4@SiO2 (b) nanoparticles, and Fe3O4@SiO2@Zn
(c) nanoparticles in KBr
Fig. 3 FT-IR spectrum of Fe3O4@SiO2@Cu nanoparticles in KBr
into two stages. The frst weight loss in the range of 200–270 °C. The second
weight loss in the range of 270–350 °C was attributed to the decomposition of the
organic framework. Therefore, Fe3O4@SiO2@Cu is stable below about 200 °C,
1 3

Solvent-free synthesis of 1-amidoalkyl-2-naphthols using…
Fig. 4 The TG diagrams of Fe3O4@SiO2@Cu (a) and Fe3O4@SiO2@Zn (b)
Fig. 5 FESEM image of catalyst G1
which is enough for constant weight during the catalysis procedure of our experi-
ments. Also, the TG curve of G2 showed that the solid catalyst was stable below
280 °C.
The size of particles was evaluated by FE-SEM and TEM images of the Fe3O4@
SiO2@Cu catalyst (Figs. 5, 6). Both the TEM and SEM showed that the nanopar-
ticles of the Fe3O4@SiO2@Cu were present and the size of nanoparticles was less
than 100 nm.
1 3

F. Ghorbani et al.
Fig. 6 TEM image of catalyst G1
Fig. 7 FESEM image of catalyst G2
The morphology and size details of G2 catalyst were also examined by SEM
measurement (Fig. 7). The SEM image of the G2 clearly showed the parti-
cles of Fe3O4@SiO2@Zn were formed with the size of less than 50 nm and their
1 3

Solvent-free synthesis of 1-amidoalkyl-2-naphthols using…
morphology is spherical. The ICP analysis showed that the Cu and Zn contents
grafted on the Fe3O4@SiO2-imino compounds (G1 and G2) were about 5.5 mg/g
(8.66×10−2 mmol) and 3.0 mg/g (4.59×10−2 mmol), respectively.
The saturation magnetizations (Ms) of G1 and G2 catalysts were investigated by
vibrating-sample magnetometer (VSM) at rt (Fig. 8). As revealed in Fig. 8, the satu-
ration magnetizations of G1 and G2 are 7.0 and 6.4 emu/g at 300 K, respectively.
The saturation magnetization values display that the nanoparticles exhibit para-
magnetic characteristics at rt and indicate that they can be easily separated from the
reaction mixture by applying an external magnetic force.
After synthesizing and identifying catalysts, the model reaction using the three-
component reaction between benzaldehyde (1a) 2-naphthol (2) and acetamide (3a)
was optimized. The catalyst activity of G1 was investigated in the model reac-
tion. The results of optimization studies are given in Table 2. After performing the
reaction in solvent-free conditions without catalyst, no product was obtained after
120 min at 80 °C (Table 2, entry 1).
When 0.01 g loading of catalyst was applied for this reaction, it was observed
that the corresponding product 4a was formed in 10% yield (Table 2, entry 2). When
catalyst loading was increased to 0.1 g, the reaction was completed within 70 min
and up to 85% yield of desired product 4a was obtained (Table 2, entry 7). The
usage of higher amounts of catalyst did not improve the results. The efects of tem-
perature and solvent on the synthesis of 4a were also investigated in the presence of
0.1 g of the catalyst loading (Table 2, entries 8–15). The results were not satisfac-
tory. Therefore, 0.1 g of catalyst, 80 °C temperature, and no solvent were selected as
the best reaction conditions. Turnover number (TON) and turnover frequency (TOF)
also indicate that the best conditions are those optimized above. The TON and TOF
are calculated related to the moles of Cu NPs as follows [58]:
moles of product × yield (%)
TON
TON =
TOF in h−1 TOF =
moles of Cu NPs
Time of reaction (h)
The applicability of this method was studied by 3CR of structurally diverse aryl
aldehydes (1), 2-naphthol (2), and amides (3) under the optimized conditions. Rep-
resentative results are listed in Table 3. The reaction of aryl aldehydes substituted
with electron-withdrawing and electron-donating groups and sterically hindered aryl
aldehydes reacted with 2-naphthol (2) and amides (3a–d) to give the correspond-
ing 1-amidoalkyl-2-naphthols in good to excellent yields although in some cases
the reactions proceeded rather slowly. In all cases, 1-amidoalkyl-2-naphthols (4a–v)
were the sole products and no by-product was observed. The reaction of 2-naphthol
(1) and acetamide (3a) was also performed under the same optimal reaction condi-
tions in the presence of an aliphatic aldehyde, n-butyraldehyde; however, no cor-
responding 1-amidoalkyl-2-naphthol product was observed after 4 h. Similar results
were obtained when using the G2 as the catalyst (Table 3).
The recyclability of the G1 and G2 was also investigated (Figs. 9, 10). The cata-
lyst was recovered after each run and reused for subsequent cycles. It showed nearly
the same activity as a catalyst along but with a slight decrease in yield. The decreas-
ing of the yield of the product is probably related to a slight decrease in the catalytic
1 3

F. Ghorbani et al.
1 3

Solvent-free synthesis of 1-amidoalkyl-2-naphthols using…
Table 2 Screening reaction conditions for the synthesis of N-((2-hydroxynaphthalen-1-yl)(phenyl)
methyl)acetamide (4a)
Entry Catalyst (g) Solvent
Temp (℃) Isolated yields (%) Time (min)a TON TOF (h−1
)
1
2
3
4
0
–
–
–
–
–
–
–
–
80
80
80
80
80
80
80
25
0
10
20
40
60
70
85
Trace
50
65
Trace
10
30
20
120
120
120
120
80
80
70
120
100
80
120
120
120
120
120
0
34
67
0
17
34
0.01
0.02
0.05
0.07
0.08
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
135
202
234
286
0
168
219
0
68
5
152
177
247
0
101
164
0
17
51
34
51
6
7b
8
9
–
–
50
70
Refux
10
11
12
13
14
15
H2O
CH3CN Refux
Toluene Refux
THF
EtOH
34
101
67
Refux
Refux
30
101
Reaction conditions: a well-ground mixture of benzaldehyde (1a, 1 mmol), 2-naphthol (2, 1 mmol),
acetamide (3a, 1 mmol), and the catalyst was magnetically stirred
aProgress of the reaction was monitored with TLC analysis
bOptimized conditions shown in bold
TON =
moles of product × yield (% )
moles of Cu NPs
TON
TOF =
Time of reaction (h)
1 3

F. Ghorbani et al.
Table 3 3-CR of aldehydes, 2-naphthol (2) and amides (3a–d) to synthesis of 1-amidoalkyl-2-naphthols
(4a–v) at 80 °C using G1 and G2 catalysts
Structure of products (4a-v) Time (min),
Isolated yields m.p./°C
Entry
Aa/Bb
70/60
(%), Aa/Bb
85/84
232-233
1
4a
60/50
70/70
60/65
70/45
87/90
235-236
2
3
4
5
4b
4c
4d
86/88
87/75
94/94
194-196
227-229
240-242
4e
70/40
97/88
240-242
6
1 3

Solvent-free synthesis of 1-amidoalkyl-2-naphthols using…
Table 3 (continued)
4f
70/50
80/60
86/88
78/90
208-210
240-241
180-181
7
4g
8
4h
4i
80/60
70/60
70/65
96/94
80/85
90/90
9
10
11
4j
198-200
4
k
60/60
65/65
85/88
89/91
233-234
225-227
12
13
4l
4m
1 3

F. Ghorbani et al.
Table 3 (continued)
100/60
90/55
80/84
85/80
234-236
14
4n
15
224-226
265-267
227-229
4o
16
100/60
55/60
80/88
75/75
4p
17
4q
18
60/60
73/80
198-200
4r
19
75/60
65/65
78/80
84/80
213-215
219-221
4s
20
4t
1 3

Solvent-free synthesis of 1-amidoalkyl-2-naphthols using…
Table 3 (continued)
60/60
80/79
87/85
219-221
168-170
21
4u
60/50
22
4v
aThe reaction is implemented using G1 catalyst
bThe reaction is implemented using G2 catalyst
90
80
70
60
50
40
30
20
10
0
1
2
3
4
Runs
Fig. 9 Recycling experiments of catalyst G1 for the reaction of benzaldehyde (1a) with β-naphthol (2)
and acetamide (3a)
activity of the catalyst or could be attributed to the loss of catalyst recovery in the
course of the reaction.
In order to evaluate the efciency of the synthesized catalysts G1 and G2 with
other catalysts, we compared them with several reported catalysts (Table 4). Some
procedures require organic solvents (Table 4, entries 1, 3, 9, and 10), or lower prod-
uct yields have been gained (Table 4, entries 2, 4, 5, 7, and 9). In addition, some
methods require relatively higher reaction temperatures (Table 4, entries 4–8) or
specifc devices, such as an ultrasound device (Table 4, entries 1–3 and 10), to per-
form the reaction. From this perspective, this method is comparable to some meth-
ods in terms of reaction time, the yield of reaction, reaction temperature, and no
need for special tools. They are also the best catalysts for the synthesis of 1-ami-
doalkyl-2-naphthols in terms of TON and TOF.
1 3

F. Ghorbani et al.
Fig. 10 Recycling experiments of catalyst G2 for the reaction of benzaldehyde (1a) with 2-naphthol (2)
and acetamide (3a)
Table 4 Comparison of G1 and G2 catalysts with previously reported catalytic systems for the synthesis
of 4e
Entry Catalyst
Conditions
Time (min) Yield (%) TOF (h−1
)
References
a
1
2
3
4
5
6
7
8
MNPs-IL-OAc
MNPs-IL-OAc
Nano-Fe3O4
NiFe2O4@SiO2-PPA
RGO/CoFe2O4@Cu(II) SF/100 °C
DCE/US, 30 °C
SF/US, 30 °C
AcOH/US, 80 °C
SF/120 °C
20
65
60
7
30
10
20
100
50
22
70
45
98
60
98
85
91
94
92
93
60
92
94
94
–
–
[25]
[25]
[33]
[39]
[59]
[60]
[61]
[22]
[62]
[62]
This work
This work
a
76.3
a
–
a
–
a
MNPs–PhSO3H
SPION-ACl2
MSNs-HPZ-SO3H
IL@MNP
IL@MNP
G1
SF/120 °C
SF/100 °C
SF/120 °C
DCE/30 °C
DCE/US, 30 °C
SF/80 °C
–
47
a
–
a
9
–
a
10
11
12
–
497
660
G1
SF/80 °C
US ultrasound irradiation, MNPs-IL-OAc ionic liquid 1-methyl-3-(3-trimethoxysilylpropyl) imidazo-
lium acetate was immobilized on the Fe3O4 nanoparticles, DCE 1,2-dichloroethane, PPA polyphosphoric
acid, SF solvent-free, MNPs–PhSO3H sulfanilic acid-functionalized silica-coated nano-Fe3O4 particles,
SPION-ACl2 1,3,5-triazine-functionalized bisimidazolium dichloride tethered to superparamagnetic iron
oxide nanoparticles, MSNs mesoporous silica nanoparticles, HPZ-SO3H homopiperazine sulfamic acid,
IL@MNP magnetic nanoparticle-supported ionic liquid
aNo. moles of catalyst or no. moles of catalytic active part has not been reported, so TON and TOF cal-
culations were not possible
Conclusions
In summary, magnetic nanoparticle-supported 2-(((4-(1-iminoethyl)phenyl)imino)
methyl)phenols were synthesized and were used as catalyst in the environmentally
benign three-component synthesis of 1-amidoalkyl-2-naphthols in good to excellent
1 3

Solvent-free synthesis of 1-amidoalkyl-2-naphthols using…
yields and relatively shorter reaction times. The three-component reactions were
implemented under thermal solvent-free conditions. The magnetically separable
catalysts were recycled and reused in consecutive runs. The use of these magneti-
cally recoverable catalysts for the synthesis of 1-amidoalkyl-2-naphthols has several
advantages, some of which are: clean reaction profles, lack of side reactions, green
synthesis, simple experimental procedure, and easy workup.
Acknowledgements The authors are thankful to Damghan University Research Council.
References
1. I. Mohanram, Meshram. J. Med. Chem. Res. 23, 939 (2014)
2. W.S.I. Abou-Elmagd, A.I. Hashem, Med. Chem. Res. 22, 2005 (2013)
3. A. Deepam, J. Viswanadhan, Orient. J. Chem. 33, 1354 (2017)
4. A.P.G. Nikalje, M. Patel, Y. Ranade, R. Deshpande, D. Rajani, Der Pharm. Sinica 3, 462 (2012)
5. H. Darbandi, H. Kiyani, Curr. Organocatal. 7, 34 (2020)
6. A.Y. Shen, C.T. Tsai, C.L. Chen, Eur. J. Med. Chem. 34, 877 (1999)
7. E.J. Corey, X.M. Cheng, The Logic of Chemical Synthesis (Wiley, New York, 1989), p. 423
8. J. Safaei Ghomi, S. Zahedi, Monatsh. Chem. 144, 687 (2013)
9. J. Safaei Ghomi, S. Zahedi, M.A. Ghasemzadeh, Monatsh. Chem. 145, 1191 (2014)
10. Y. Kusakabe, J. Nagatsu, M. Shibuya, O. Kawaguchi, C. Hirose, S. Shirato, J. Antibiot. 25, 44
(1972)
11. J.L. Peglion, J. Vian, B. Gourment, N. Despaux, V. Audinot, M. Millan, Bioorg. Med. Chem. Lett.
7, 881 (1997)
12. G.Y. Lesher, A.R. Surrey, J. Am. Chem. Soc. 77, 636 (1955)
13. H. Ren, S. Grady, D. Gamenara, H. Heinzen, P. Moyna, S. Croft, H. Kendrick, V. Yardley, G.
Moyna, Bioorg. Med. Chem. Lett. 11, 1851 (2001)
14. S. Remillard, L.I. Rebhun, G.A. Howie, S.M. Kupchan, Science 189, 1002 (1975)
15. A.V. Shelke, B.Y. Bhong, N.N. Karade, Synthesis 46, 752 (2014)
16. H. Matsuoka, N. Ohi, M. Mihara, H. Suzuki, K. Miyamoto, N. Maruyama, K. Tsuji, N. Kato, T.
Akimoto, Y. Takeda, K. Yano, T. Kuroki, J. Med. Chem. 40, 105 (1997)
17. F. Benedini, G. Bertolini, R. Cereda, G. Donia, G. Gromo, S. Levi, J. Mizrahi, A. Sala, J. Med.
Chem. 38, 130 (1995)
18. H.S. Mosher, M.B. Frankel, M. Gregory, J. Am. Chem. Soc. 75, 5326 (1953)
19. C. Cardellicchio, M.A.M. Capozzi, F. Naso, Tetrahedron Asymmetry 21, 507 (2010)
20. D. Dumbre, M.H. Amin, Q. Loh, V.R. Choudahry, P.R. Selvakannan, S.K. Bhargava, RSC Adv. 6,
69334 (2016)
21. S.R. Bankar, S.N. Shejke, Res. Chem. Intermed. 44, 3507 (2018)
22. Z. Nasresfahani, M.Z. Kassaee, E. Eidi, New J. Chem. 40, 4720 (2016)
23. S.S. Mansoor, K. Aswin, K. Logaya, S.P.N. Sudhan, J. Saudi Chem. Soc. 20, 138 (2016)
24. S. Khanapure, M. Jagadale, R. Salunkhe, G. Rashinkar, Res. Chem. Intermed. 42, 2075 (2016)
25. J. Safari, Z. Zarnegar, Ultrason. Sonochem. 21, 1132 (2014)
26. N. Madankumar, K. Pitchumani, Chem. Select 2, 10798 (2017)
27. J. Safari, Z. Zarnegar, J. Indust. Engin. Chem. 20, 2292 (2014)
28. H. Yarahmadi, H.R. Shaterian, J. Chem. Res. 36, 52 (2012)
29. Q. Zhang, Y.H. Gao, S.L. Qin, H.X. Wei, Catalysts 7, 351 (2017)
30. H. Kiyani, H. Darbandi, A. Mosallanezhad, F. Ghorbani, Res. Chem. Intermed. 41, 7561 (2015)
31. H. Kiyani, H. Darbandi, Bulg. Chem. Commun. 49, 562 (2017)
32. S.A. Pourmousavi, P. Moghimi, F. Ghorbani, M. Zamani, J. Mol. Struct. 1144, 87 (2017)
33. M. Mokhtary, M. Torabi, J. Saudi Chem. Soc. 21, S299 (2017)
34. Z. Cai, C. Shu, Y. Peng, Monatsh. Chem. 145, 1681 (2014)
35. V.K. Das, M. Borah, A.J. Thakur, J. Org. Chem. 78, 3361 (2013)
36. F. Hakimi, Inorg. Nano Met. Chem. 47, 994 (2017)
37. N. Azizi, M. Edrisi, Res. Chem. Intermed. 43, 379 (2017)
1 3

F. Ghorbani et al.
38. R.K. Singh, R. Bala, S. Kumar, Indian J. Chem. 55B, 381 (2016)
39. B. Maleki, E. Sheikh, E. Rezaei Seresht, H. Eshghi, S.S. Ashraf, A. Khojastehnezhad, H. Veisi,
Org. Prep. Proced. Int. 48, 37 (2016)
40. S. Roy, K.K. Senapati, P. Phukan, Res. Chem. Intermed. 41, 5753 (2015)
41. M. Samadizadeh, S. Nouri, F. Kiani Moghadam, Res. Chem. Intermed. 42, 6089 (2016)
42. M.M. Dutta, K.K. Rajbongshi, P. Phukan, Synth. Commun. 47, 2330 (2017)
43. M.S.T. Rocha, J. Rafque, S. Saba, J.B. Azeredo, D. Back, M. Godoi, A.L. Braga, Synth. Commun.
47, 291 (2017)
44. W.-J. Liu, K. Tian, H. Jiang, H.-Q. Yu, Sci. Rep. 3, 2419 (2013)
45. J. Kothandapani, S.S. Ganesan, Curr. Org. Chem. 23, 313 (2019)
46. W. Xie, F. Wan, Fuel 220, 248 (2018)
47. W. Xie, H. Wang, Renew. Energy 145, 1709 (2020)
48. W. Xie, J. Wang, Energy Fuels 28, 2624 (2014)
49. W. Xie, X. Zang, Food Chem. 257, 15 (2018)
50. M. Mamaghani, F. Shirini, M. Sheykhan, M. Mohsenimehr, RSC Adv. 5, 44524 (2015)
51. M. Gholinejad, M. Razeghi, C. Najera, RSC Adv. 5, 49568 (2015)
52. Y. Guo, X. Hu, X. Zhang, X. Pu, Y. Wang, RSC Adv. 9, 41737 (2019)
53. J.S. Kirar, S. Khare, Rsc Adv. 8, 18814 (2018)
54. S. Park, B.L. Clark, D.A. Keszler, J.P. Bender, J.F. Wager, T.A. Reynolds, G.S. Herman, Science
297, 55 (2002)
55. A. Bayat, M. Shakourian-Fard, N. Ehyaei, M. Mahmood Hashemi, RSC Adv. 4, 44274 (2014)
56. T. Karimpour, E. Safaei, B. Karimi, RSC Adv. 9, 14343 (2019)
57. M. Gupta, M. Gupta, Rajnikant, V.K. Gupta, New J. Chem. 39, 3578 (2015)
58. A. Elhage, A.E. Lanterna, J.C. Scaiano, Chem. Sci. 10, 1419 (2019)
59. M. Kooti, M. Karimi, E. Nasiri, J. Nanopart. Res. 20, 16 (2018)
60. H. Moghanian, A. Mobinikhaledi, A.G. Blackman, E. Sarough-Farahani, RSC Adv. 4, 28176 (2014)
61. M. Shafee, A.R. Khosropour, I. Mohammadpoor-Baltork, M. Moghadam, S. Tangestaninejad, V.
Mirkhani, Catal. Sci. Technol. 2, 2440 (2012)
62. H.N. Dadhania, D.K. Raval, A.N. Dadhania, Res. Chem. Intermed. 44, 117 (2018)
Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published
maps and institutional afliations.
1 3