Preparation and catalytic evaluation of a palladium catalyst deposited over modified clinoptilolite (Pd&at;MCP) for chemoselective N-formylation and N-acylation of amines

Article abstract of DOI:10.1016/j.molstruc.2020.129076

Novel palladium nanoparticles stabilized by clinoptilolite as a natural inexpensive zeolite prepared and used for N-formylation and N-acylation of amines at room temperature at environmentally benign reaction conditions in good to excellent yields. Pd (II) was immobilized on the surface of clinoptilolite via facile multi-step amine functionalization to obtain a sustainable, recoverable, and highly active nano-catalyst. The structural and morphological characterizations of the catalyst carried out using XRD, FT-IR, BET and TEM techniques. Moreover, the catalyst is easily recovered using simple filtration and reused for 7 consecutive runs without any loss in activity.

Full text of DOI:10.1016/j.molstruc.2020.129076

Journal of Molecular Structure 1225 (2021) 129076
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstr
Preparation and catalytic evaluation of a palladium catalyst deposited
over modified clinoptilolite (Pd@MCP) for chemoselective
N-formylation and N-acylation of amines
Mina Amirsoleimania, Mohammad A. Khalilzadeha,∗, Daryoush Zareyeea
a Department of Chemistry, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Novel palladium nanoparticles stabilized by clinoptilolite as a natural inexpensive zeolite prepared and
used for N-formylation and N-acylation of amines at room temperature at environmentally benign reac-
tion conditions in good to excellent yields. Pd (II) was immobilized on the surface of clinoptilolite via
facile multi-step amine functionalization to obtain a sustainable, recoverable, and highly active nano-
catalyst. The structural and morphological characterizations of the catalyst carried out using XRD, FT-IR,
BET and TEM techniques. Moreover, the catalyst is easily recovered using simple filtration and reused for
7 consecutive runs without any loss in activity.
Received 9 June 2020
Revised 11 August 2020
Accepted 12 August 2020
Keywords:
Formylation
Acylation
© 2020 Elsevier B.V. All rights reserved.
Amines
Palladium
Nano zeolite
Clinoptilolite
1. Introduction
the N-formylation and N-acylation of amines are continuously of
interest because of economic and environmental consideration. Ad-
Acetamides and formamides are important intermediates in the
synthesis of amide derivatives and are widely used in the synthe-
sis of many chemically valuable compounds [1]. The amide bond
is widely utilized in natural products and medicinal intermediates,
and about 25% of the known medicines have at least one amide
bond [2. In addition, formyl group is also applied for the protection
of the amino group during peptide synthesis [4]. Due to the signif-
icance of the amide bond, numerous strategies have been studied
for the formylation and acylation of amines and thus, development
of efficient methodologies and approaches to prepare these com-
pounds is still of interest [5–8]. In this regards, some amidation re-
actions catalyzed by metal or metal complex have developed using
copper [9], [Pd(OAc)2] [10], [Ni(quin)2] [11], ruthenium(II) [12], zir-
conium(IV) [13], ZnCl2 [14], Indium [15], ionic liquid [16], and ZnO
[17] as catalysts. Although many of all above mentioned methods
have some advantages in terms of good reaction yield and low re-
action time, but some of them suffered from a range of drawbacks,
namely deactivation of the metal catalyst, metal contamination, in-
evitability harsh reaction conditions, high temperature, poor solu-
bility, solvent usage, and recovery procedure [18,19]. So, the use
of efficient, available, recoverable, cheaper and simple catalysts for
ditionally, a number of palladium catalytic systems have also been
developed for these reactions as homogeneous and heterogeneous
catalytic systems [20–22]. While, homogeneous palladium catalysts
produce high yields of the products, the use of homogeneous pal-
ladium catalysts is still uneconomic due to the difficulties in sepa-
ration of the products from the catalysts [22].
On the other hand, easy separation and recycling of catalysts
from the reaction mixture are outstanding features of heteroge-
neous catalysts which make the processes more environmentally
friendly and economical [23–31]. The preparation of heterogeneous
catalysts relies on immobilization of palladium species onto an or-
ganic or inorganic solid support [32–36]. The support used for im-
mobilization, contributes greatly to the stability and reactivity of
these catalytic systems [37,38]. In recent years, the use of het-
erogeneous catalysts have received considerable attention in or-
ganic synthesis due to their greater selectivity, enhanced reac-
tion rates and environmental compatibility as well as simplic-
ity of operation and recoverability of the catalysts [39] and have
been used for amide bond formation [22,40], however, as far as
we know, there is no literature focusing on applying clinoptilo-
lite (CP) supported Pd catalyst in N-formylation and N-acylation of
aromatic and aliphatic amines. Clinoptilolite is a thermally stable,
environmentally friendly, nontoxic, inexpensive and commercially
available natural zeolite with an open aluminosilicate framework
∗
Corresponding author.
E-mail address: mkhalil3@ncsu.edu (M.A. Khalilzadeh).
https://doi.org/10.1016/j.molstruc.2020.129076
0022-2860/© 2020 Elsevier B.V. All rights reserved.

2
M. Amirsoleimani, M.A. Khalilzadeh and D. Zareyee / Journal of Molecular Structure 1225 (2021) 129076
Scheme 1. A representation pathway for the preparation of Pd@MCP.
structure, and a high internal surface area with broad applications
in chemistry and other industries. The low cost and special fea-
tures of clinoptilolite make it valuable in many applications [41].
In our continued efforts for the development of the solid het-
erogeneous catalysts for selective organic transformations [42–49],
herein we report a fast and chemoselective formylation of aromatic
amines in the presence of recyclable palladium catalyst deposited
over modified clinoptilolite (Pd@MCP) under ultrasonic conditions.
The results have indicated that the nanocatalyst could be easily re-
covered and reused for five times without any substantial loss of
its catalytic activity.
obtain the corresponding Pd (II) supported on modified clinoptilo-
lite (Pd@MCP) (Scheme 1).
2.3. General procedure for N-formylation of amines
Amine (1 mmol) and HCO2H (1.2 mmol) were added to a
round-bottomed flask in the presence of Pd@MCP (0.012 g), and
the mixture was vigorously stirred at the room temperature for ap-
propriate times (Table 2). The progress of the reactions was moni-
tored by TLC visualized with UV short wavelengths followed by io-
dine. After completion, the mixture was diluted with ethyl acetate
(10 mL) and the nano catalyst was separated by filtration. The fil-
trate was washed with 1 M HCl (3 × 5 mL) and then the organic
layer was dried over anhydrous sodium sulfate, filtered, and con-
centrated in vacuum to obtain pure N-formylated without column
purification. For recycling the nanocatalyst, after washing Pd@MCP
with water and ethyl acetate totally, the nanocatalyst was recycled
and re-utilized for the next run. The products were characterized
by 1H NMR, and all data were compared to their physical data with
those of known formamides [50–56] and acetamides products [57–
64].
2. Experimental
2.1. Chemistry
All chemicals were purchased from commercial suppliers and
used without purification. Clinoptilolite which is a natural zeo-
lite was obtained from an Iranian company called Afrand Tooska
Company. Reactions were performed under air atmosphere. The 1H
NMR and 13C NMR spectra were recorded using a Bruker BioSpin
spectrometer at 400, and 100 MHz. Transmission electron mi-
croscopy (TEM) observations were performed on a JEOL JEM, 2011.
The BET specific surface area of the sample was determined by
adsorption-desorption of nitrogen at liquid nitrogen, using a se-
ries BEL sorp 18. The X-ray powder diffraction (XRD) of the cat-
alyst was conducted on a Bruker D8 Advanced x-ray diffractometer
2.4. General procedure for N-acylation of amines
Pd@MCP (0.012 g) was added to a mixture of amine (1 mmol)
and acetic acid (1.2 mmol) and the whole mixture was stirred in
a round bottomed flask at room temperature for the appropriate
time (Table 3). The reaction progress was followed by GC and TLC
(eluent, n-hexane:ethyl acetate, 4:1). After completion of the reac-
tion, EtOAc (10 mL) was added to the reaction mixture, and the
resulting mixture filtered. The filtrate was washed with 1 M HCl
(3 × 5 mL) and then the organic layer was dried over anhydrous
sodium sulfate, filtered, and concentrated in vacuum to obtain pure
N-acylated products.
using nickel filtered Cu k radiation at 40kv and 20Ma.
α
2.2.
Prepration of Pd (II) stabilized on modified clinoptilolite (Pd@MCP)
Initially, amine modified clinoptilolite was prepared by re-
fluxing a mixture of CP (3 g) and 4.5 mL of 3-aminopropyltr-
iethoxysilane (APTES) in 25 mL of anhydrous toluene for 18 h.
After filtration and drying in oven at 90°C, 1.5 g of dried CP-amine
and 2.1 mL of furfural (25 mmol) were added into 15 mL of abso-
lute ethanol. The reaction mixture was refluxed for 24 h, and then
the Schiff base modified clinoptilolite was separated by filtration
after removing of unreacted ketone with washing of mixture with
hot toluene and ethanol. Finally, for preparation of Pd nanocata-
lyst, 1.5 g of Schiff base modified clinoptilolite (MCP) was added to
a solution of palladium acetate (0.2 g) in dry toluene (15 mL). After
the reaction mixture was stirred at 70°C for 4 h, the solid product
was separated by filtration. Then, the achieved solid was washed
with ethanol and ether and dried in an oven at 90°C overnight to
3. Result and Discussion
3.1. Pd@MCP catalyst characterization
The surface modification of clinoptilolite was first investigated
by synthesis of Schiff base modified clinoptilolite (MCP). Ini-
tially, CP as a natural zeolite functionalized with 3- aminopropy-
ltriethoxysilane followed by condensation with furfural as a lig-
and, and then Pd (II) immobilized on the surface of functional-
ized CP to produce Pd@MCP. Due to some advantages like high
surface area, high thermal and hydrothermal stability, low-cost

M. Amirsoleimani, M.A. Khalilzadeh and D. Zareyee / Journal of Molecular Structure 1225 (2021) 129076
3
Fig. 1. FT-IR spectra of (a) Clinoptilolite (CP), (b) CP-NH2, (c) Schiff base CP, and (d) Pd@MCP catalyst.
Fig. 2. The powder XRD pattern of CP (a) and Pd@MCP (b).
cm−1 (methylene bending vibration) in the spectrum of clinoptilo-
lite amine modified (CP-NH2) (Fig. 1b). These new peaks presented
that 3- aminopropyltriethoxysilane molecules were attached on the
clinoptilolite. In the spectrum of Schiff base modified CP, a new
peak appeared at 1692 cm−1, which is assigned to the Schiff base
formation (Fig. 1c). In the case of Pd@MCP, the peaks correspond-
ing to the functional groups of MCP (Schiff base modified CP) were
found to shift to lower wavenumbers due to strong interaction of
Pd with MCP (Fig. 1d).
and non-hazardous features of clinoptilolite, this preparation pro-
cess provides simple pathway for the preparation of nanocatalyst
(Scheme 1).
The structure of the prepared Pd@MCP was thoroughly charac-
terized using XRD, TEM, and FT-IR spectroscopy.
The FT-IR spectra of clinoptilolite presented usual absorptions
at 3412 cm−1 (OH stretching), 1676 cm−1 (OH bending) and
1014 cm−1 (Al-O/Si-O stretching) (Fig. 1a) [65]. After the reac-
tion of clinoptilolite with 3- aminopropyltriethoxysilane, new ab-
sorption bands were indicated at 2911 and 2837 cm−1 (stretching
of aliphatic C-H), 1652 cm−1 (amine bending vibration) and 1523
Fig. 2 shows the X-ray diffraction (XRD) pattern of CP and
Pd@MCP nanoparticles. Besides to the typical peaks of CP (Fig. 2a)

4
M. Amirsoleimani, M.A. Khalilzadeh and D. Zareyee / Journal of Molecular Structure 1225 (2021) 129076
Fig. 3. TEM images of a) CP and b) Pd@MCP.
Table 1
N-formylation of aniline (1 mmol) without solvent at room
temperature for 20 min.
Entry
HCOOH (mmol)
Catalyst (g)
Yield (%)a
1
2
3
4
5
6
7
1.2
1.2
1.2
1.2
1.2
2.0
4.0
-
-
CP (0.012)
trace
89
97
97
97
96
Pd@MCP (0.010)
Pd@MCP (0.012)
Pd@MCP (0.015)
Pd@MCP (0.012)
Pd@MCP (0.012)
a
Isolated yields.
3.2. Catalytic activity performance of the Pd@MCP through the
formamides synthesis
Fig. 4. N2 adsorption – desorption isotherms of Pd@MCP.
The prepared nanocatalyst (Pd@MCP) confirmed excellent cat-
alytic performance in the N-formylation and N-acetylation of some
aromatic and aliphatic amines at room temperature without us-
ing any solvent. Indeed, in this research, we define a new way
for the activation of formic and acetic acid as N-formylating and
N-acylating agents using the Pd@MCP under solvent-free reaction
conditions. The effect of some factors such as amount of catalyst
and molar ratio of the reactants were considered for the formy-
lation and acylation of amines. At the outset, no reaction was
observed when a mixture of aniline (1.0 mmol) and formic acid
(1.2 mmol) was stirred for 25 h at room temperature, while ami-
dation reaction was rapidly increased in the presence of Pd@MCP
as a nanocatalyst (Table 1).
[41], new peaks were appeared at 40.4° (1 1 1), 47.4° (2 0 0), and
68.5° (2 2 0) in the XRD diagram of Pd@MCP (Fig. 2b), that match
to the face centered cubic (FCC) structure of Pd [66], approving the
creation of Pd particles on the prepared modified support.
CP (Fig. 3a) and Pd@MCP (Fig. 3b), were subjected to trans-
mission electron microscopy (TEM) to get additional insight into
the presence of the Pd nanoparticles onto the surface of nanocat-
alyst. Comparison of the transmission electron microscopy images
of CP (Fig. 3a) and Pd@MCP (Fig. 3b) shows the formation of Pd
NPs along with Pd (II), while there isn’t any reducing agent in this
reaction. These particles, which appear as small black spots in the
images (Fig. 3b), are probably due to the oxidation of unreacted
amines on the CP surface [67,68].
The N-formylation of aniline as model substrate using formic
acid was carried out with Pd@MCP, and the results listed in
Table 1. First, aniline was treated with 1.2 mmol of formic acid at
room temperature in the absent of catalyst and also in the pres-
ence of natural CP (0.010 g) as control reactions (Table 1, entries 1
and 2). After 20 min, only trace (less than 10%) of desired product
was obtained. Addition of Pd@MCP (0.010 g) as a heterogeneous
catalyst, meaningfully enhanced the rate of reaction and the de-
sired N-phenyl-formamide (3a) was isolated in 89% yield after 18 h
(Table 1, entry 3), indicating that Pd@MCP promotes N-formylation
reaction. Furthermore, in the presence of 0.012 g of catalyst, the
isolated yield was improved to 97% (Table 1, entry 4). We fur-
ther examined different loading of Pd@MCP and excess amounts
of formic acid, but no significant improvement on the reaction
The nitrogen adsorption–desorption isotherms for the nanocat-
alyst is shown in Fig. 4, displays moderate nitrogen uptake at rela-
tively low pressure (P/P0 < 0.05), which is a typical characteristic
of microporous solids. A linear increase in nitrogen sorption with
relative pressure at P/P0= 0.1–0.95 indicated the presence of gap
between the layers resulting in a variable pore size occupied by
nitrogen molecules. Additionally, according to the BET analysis, the
specific surface area of 364 m2/g and total pore size of 0.23 cm3/g
was obtained for Pd@MCP.
The inductively coupled plasma–atomic emission spectroscopy
(ICP-AES) analysis was performed to determine the amount of Pd
(5810.6 mg/Kg) in Pd@MCP.

M. Amirsoleimani, M.A. Khalilzadeh and D. Zareyee / Journal of Molecular Structure 1225 (2021) 129076
5
Scheme 2. Chemoselective N-formylation of amines.
Scheme 3. Plausible Mechanism for the N-formylation of amines.
time and yield was observed (Table 1, entries 5–7). It should be
noted that, the main reasons for the selection of CP as support are
abundance, very low-cost and safety of naturally occurring zeolite
CP. on the other hand, because of the unrecyclability of homoge-
nous palladium, the second reason is obtaining recoverable het-
erogeneous catalyst (Pd@MCP). Indeed, the major problems with
nanocatalysts are their recovery and reusability. However, Pd@MCP
as a heterogeneous nanocatalyst can address this problem as they
can be easily separated by filtrations technique.
diphenylamine was fully recovered. Similarly, aniline was exclu-
sively reacted to produce the desired N-formylated product in the
presence of α-methylbenzylamine.
Formylation of amines using formic acid usually take place un-
der acidic conditions. It seems, the Pd (II) stabilized on modified
clinoptilolite (Pd@MCP) has significant role in upgrade of the pre-
pared formamides as a Lewis acid (Scheme 3). The nanocatalyst
probably displays complexation to carbonyl group of formic acid
and therefore can increase the electrophilic property. It involves
activation of the carbonyl group over nanocatalyst surface and con-
sequent nucleophilic attack of the substrate and elimination of wa-
ter [69–71].
With the best condition in hand, to study the effect of the
nature of groups on the phenyl ring of the aniline, different
formamides were prepared from various aniline derivatives con-
taining both electron-releasing and electron-withdrawing groups
(Table 2). Interestingly, we found that the electronic nature and
substitution pattern of the functional group on the phenyl ring of
aromatic amines had minor effect on the result of this reaction
(Table 2, 3a-3g). Different N-formylated aromatic amines were ob-
tained in good to excellent yields ranging from 86% to 98%. The
synthesized product’s yields were slightly reduced when different
electron-withdrawing groups such as halo and nitro groups at para
position on the benzene ring were used (Table 2, 3d-3i), probably
due to the reduced nucleophilicity. Due to the lower yields of the
ortho-substituted anilines, the N-formylation reaction seemed to
be sensitive to the steric hindrance (Table 2, 3h-3k). To investigate
the generalization of this novel protocol, a series of aromatic, het-
erocyclic and aliphatic amines were utilized in the N-formylation
reaction. Regarding to the outcomes summarized in Table 2, all
the different utilized amines such as heteroaryl amines, primary
and secondary amines reacted efficiently to give the correspond-
ing products in convenient yields and using of the various amines
did not affect the outcome of this procedure although long reac-
tion times are required to ensure good conversion for secondary
amines than the primary type and aliphatic amines compared to
aromatics (Table 2, 3l-3r).
Encouraged by the beyond significant outcomes, all of these
amines were evaluated for N-acylation via acetic acid as the acy-
lating agent in the presence of Pd@MCP (Table 3). Primary aro-
matic amines with different substituents at the para position gave
a good conversion with excellent yields (Table 3, 4b–4g). While
the electronic nature of groups had not had much of an effect on
the yields, the steric hindrance has had a great impact on reduc-
ing the reaction efficiency and also the yields of products, partic-
ularly for product 4k. The aliphatic amines like cyclohexylamine
provided the lower activity and needed more time (4m-4o). It may
be the reason that the nucleophilic ability of the aliphatic amines
was decreased due to the interaction by the d orbitals of Pd (II)
and p orbitals of Al of clinoptilolite. Furthermore, heterocyclic aro-
matic amine and secondary amines also provided reasonable yields
(4p–4r).
Based on the significant importance of reusability factors in de-
sign of nanocatalyst, the catalytic recyclability of Pd@MCP was ex-
amined in synthesis of N-(4-nitrophenyl)formamide. As shown in
Fig. 5, without any distinctive reduction in catalytic activity, it was
found that the Pd@MCP can be simply recycled at least for seven
runs. After each reaction completion, the nanocatalyst was simply
separated from reaction media with ethanol. To show the effect
of leaching of the catalyst, another reaction of para-nitro aniline
and formic acid in the presence of Pd@MCP was performed and
then quenched after 10 min and filtered off (~59% conversion). The
residue was then subjected to further reaction. We found that no
These results encouraged us to carry out an intermolecular
competition experiments (Scheme 2). In an equimolar mixture
of aniline and diphenylamine under the optimized conditions,
only aniline was reacted with excellent chemoselectivity, while

6
M. Amirsoleimani, M.A. Khalilzadeh and D. Zareyee / Journal of Molecular Structure 1225 (2021) 129076
Table 2
Synthesis of formaides by Pd@MCP using formic acida.
a
b
Reaction conditions: Amine (1 mmol), formic acid (1.2 mmol), r.t., solventlees. Isolated yields.
further catalytic activity was observed after 20 min, thus show-
ing the reaction is actually proceeding in a heterogeneous pathway
and no leaching was performed.
benzylamine with some recently reported catalysts (Table 4). A
glance survey on the results in Table 4 clearly elucidate that some
protocols took much longer time [18,50,55,72,74], some have low
isolated yield [18], some used non-recovered catalyst [53,60,72–
74], or some used organic solvents [50,56,73].
In order to show the catalytic potentiality of Pd@MCP in the
formylation reaction, we compare the formamide synthesis from

M. Amirsoleimani, M.A. Khalilzadeh and D. Zareyee / Journal of Molecular Structure 1225 (2021) 129076
7
Table 3
Synthesis of acetamides by Pd@MCP using acetic acida.
4a (98%b, 20 min.)
4d (92%, 20 min.)
4b (98%, 20 min.)
4c (99%, 15 min.)
4f (92%, 15 min.)
4e (82%, 20 min.)
4h (70%, 20 min.)
4i (79%, 20 min.)
4g (92%, 15 min.)
4j (75%, 20 min.)
4m (82%, 35 min.)
4k (65%, 20 min.)
4n (85%, 35 min.)
4l (85%, 35 min.)
4o (87%, 35 min.)
4r (78%, 35 min.)
4p (80%, 35 min.)
4q (80%, 35 min.)
a
b
Reaction conditions: Amine (1 mmol), Acetic acid (1.2 mmol), r.t., solventlees. Isolated yields.
Table 4
Comparison of the activity of some catalysts in the N-formylation of benzylamine.
Yield (%) [Ref.]
92 [-]a
b,c
Time (min)
Temperature
Solvent
Formylating method
Entry
30
r.t.
Solvent free
Solvent free
Toluene
This work
1
2
3
4
5
6
7
8
85 [72]
150
120
90
r.t.
HCO2H (4 mM), HCOONa
Methyl formate, bicyclic guanidine
HCO2H (3 mM), ZnCl2
b,c,e
94 [50]
r.t.
70 oC
90 [53]b
80 [73]b,e
Solvent free
MeOH
75
r.t.
MeOH, H2O2, Copper salt
HCO2H (3 mM), Amberlite IR-120
HCO2NH4 (1.5 mM),
b,c
92 [74]
95
MW (320 W)
reflux
Solvent free
CH3CN
88 [55]b,c,e
c,d
360
360
42 [18]
r.t.
Solvent free
HCO2H (3 mM), PEG-400
a
This work.
b
Non-recoverable catalyst.
Long reaction time.
Low yield.
c
d
e
Toxic solvent used.

8
M. Amirsoleimani, M.A. Khalilzadeh and D. Zareyee / Journal of Molecular Structure 1225 (2021) 129076
Fig. 5. Recyclability of the Pd@MCP for N-formylation of 4-nitroaniline with formic acid.
4. Conclusions
[3] S.D. Roughley, A.M. Jordan, The medicinal chemist’s toolbox: An analysis of re-
actions used in the pursuit of drug candidates, J. Med. Chem. 54 (2011) 3451–
3479, doi:10.1021/jm200187y.
In conclusion, in this study, we have introduced Pd@MCP as
a new highly effective heterogeneous and environmentally benign
catalyst for the solvent-free conversion of a variety of amines to
their corresponding formamides and acetamides. This nanocatalyst
was found as an efficient catalyst for the synthesis of different N-
formylated and N-acylated amine derivatives at ambient tempera-
ture and under green reaction conditions with excellent yields. Be-
sides, the reactions give formamides chemoselectively. As the cata-
lyst is heterogeneous, the work-up process is very simple. The cat-
alyst can be recovered by filtering the reaction mixture by adding
the ethanol as green solvent and recycled 7 times in the synthesis
of N-(4-nitrophenyl)formamide. However, ambient reaction condi-
tions, faster synthesis, inexpensive reactants, easy catalyst recovery,
and recyclability make this methodology a potential candidate for
sustainable synthesis.
[4] M. Suchy, A.A.H. Elmehriki, R.H.E. Hudson, A remarkably simple protocol for
the N-formylation of amino acid esters and primary amines, Org. Lett. 13
(2011) 3952–3955, doi:10.1021/ol201475j.
[5] K. Ishihara, Dehydrative condensation catalyses, Tetrahedron 65 (2009) 1085–
1109, doi:10.1016/j.tet.2008.11.004.
[6] R.M. Lanigan, T.D. Sheppard, Recent developments in amide synthesis: Direct
amidation of carboxylic acids and transamidation reactions, Eur. J. Org. Chem.
2013 (2013) 7453–7465, doi:10.1002/ejoc.201300573.
[7] H. Lundberg, F. Tinnis, N. Selander, H. Adolfsson, Catalytic amide formation
from non-activated carboxylic acids and amines, Chem. Soc. Rev. 43 (2014)
2714–2742, doi:10.1039/C3CS60345H.
[8] X. Wang, Challenges and outlook for catalytic direct amidation reactions, Na-
ture Catal. 2 (2019) 98–102, doi:10.1038/s41929-018-0215-1.
[9] R.B. Sonawane, N.K. Rasal, D.S. Bhange, S.V. Jagtap, Copper-(II) catalyzed N-
Formylation and N-Acylation of aromatic, aliphatic, and heterocyclic amines
and a preventive study in the C-N cross coupling of amines with aryl halides,
ChemCatChem 10 (2018) 3907–3913, doi:10.1002/cctc.201800609.
[10] D.W. Gu, X.X. Guo, Synthesis of N-arylcarboxamides by the efficient transami-
dation of DMF and derivatives with anilines, Tetrahedron 71 (2015) 9117–9122,
doi:10.1016/j.tet.2015.10.008.
[11] R.B. Sonawane, N.K. Rasal, S.V. Jagtap, Nickel-(II)-catalyzed N-formylation and
N-acylation of amines, Org. Lett. 19 (2017) 2078–2081, doi:10.1021/acs.orglett.
7b00660.
Declaration of Competing Interest
[12] M. Nirmala, G. Prakash, P. Viswanathamurthi, J.G. Malecki, An attractive route
to transamidation catalysis: Facile synthesis of new o-aryloxide-N-heterocyclic
carbene ruthenium (II) complexes containing trans triphenylphosphine donors,
J. Mol. Catal. A: Chem. 403 (2015) 15–26, doi:10.1016/j.molcata.2015.03.015.
[13] H. Lundberg, F. Tinnis, H. Adolfsson, Direct amide coupling of non-activated
carboxylic acids and amines catalysed by zirconium(IV) chloride, Chem. Eur. J.
18 (2012) 3822–3826, doi:10.1002/chem.201104055.
The authors declare that they have no known competing finan-
cial interests or personal relationships that could have appeared to
influence the work reported in this paper.
Supplementary materials
[14] A.Chandra Shekhar, A.Ravi Kumar, G. Sathaiah, V. Luke Paul, M. Sridhar,
P. Shanthan Rao, Facile N-formylation of amines using Lewis acids as novel cat-
alysts, Tetrahedron Lett. 50 (2009) 7099–7101, doi:10.1016/j.tetlet.2009.10.006.
[15] J.G. Kim, D.O. Jang, Facile and highly efficient N-formylation of amines using a
catalytic amount of iodine under solvent-free conditions, Synlett 2010 (2010)
2093–2096, doi:10.1055/s-0030-1258518.
Supplementary material associated with this article can be
found, in the online version, at doi:10.1016/j.molstruc.2020.129076.
[16] S. Majumdar, J. De, J. Hossain, A. Basak, Formylation of amines catalysed by
protic ionic liquids under solvent-free condition, Tetrahedron Lett. 54 (2013)
262–266, doi:10.1016/j.tetlet.2012.11.017.
CRediT authorship contribution statement
Mina Amirsoleimani: Validation, Methodology, Data curation,
[17] M. Hosseini-Sarvari, H. Sharghi, ZnO as a new catalyst for N-formylation of
amines under solvent-free conditions, J. Org. Chem. 71 (2006) 6652–6654,
doi:10.1021/jo060847z.
[18] B. Das, M. Krishnaiah, P. Balasubramanayam, B. Veeranjaneyulu, D. Nandan Ku-
mar, A remarkably simple N-formylation of anilines using polyethylene glycol,
Tetrahedron Lett. 49 (2008) 2225–2227, doi:10.1016/j.tetlet.2008.02.050.
[19] T. Kondo, T.A. Mitsudo, Metal-catalyzed carbon-sulfur bond formation, Chem.
Rev. 100 (2000) 3205–3220, doi:10.1021/cr9902749.
Writing
- original draft. Mohammad A. Khalilzadeh: Supervi-
sion, Investigation, Conceptualization, Writing - review & editing.
Daryoush Zareyee: Visualization, Resources, Formal analysis.
References
[20] P. Gautam, R. Gupta, B.M. Bhanage, Pd/C in Propylene Carbonate: A Sustainable
Catalyst–Solvent System for the Carbonylative Suzuki–Miyaura Cross-Coupling
Using N-Formylsaccharin as a CO Surrogate, Eur. J. Org. Chem. 2017 (2017)
3431–3437, doi:10.1002/ejoc.201700543.
[1] B.C. Chen, M.S. Bednarz, R. Zhao, J.E. Sundeen, P. Chen, Z. Shen, A.P. Sk-
oumbourdis, J.C. Barrish,
A new facile method for the synthesis of 1-
arylimidazole-5-carboxylates, Tetrahedron Lett. 41 (2000) 5453–5456, doi:10.
1016/S0040-4039(00)00910-2.
[21] Behzad Zeynizadeh, Farkhondeh Mohammad Aminzadeh, Hossein Mousavi,
Two different facile and efficient approaches for the synthesis of various
N-arylacetamides via N-acetylation of arylamines and straightforward one-
[2] B. Alcaide, P. Almendros, C. Aragoncillo, β-Lactams: Versatile building blocks
for the stereoselective synthesis of non-β-Lactam products, Chem. Rev. 107
(2007) 4437–4492, doi:10.1021/cr0307300.

M. Amirsoleimani, M.A. Khalilzadeh and D. Zareyee / Journal of Molecular Structure 1225 (2021) 129076
9
pot reductive acetylation of nitroarenes promoted by recyclable CuFe2O4
nanoparticles in water, Green Process. Synth. 8 (2019) 742–755, doi:10.1515/
gps-2019-0044.
[48] J. Ghanaat, M.A. Khalilzadeh, D. Zareyee, KF/CP NPs as an efficient nanocata-
lyst for the synthesis of 1,2,4-triazoles: Study of antioxidant and antimicrobial
activity, Eur. Chem. Commun. 2 (2020) 202–212, doi:10.33945/SAMI/ECC.2020.
2.6.
[22] H. Lundberg, F. Tinnis, N. Selander, Adolfsson H, Catalytic amide formation
from non-activated carboxylic acids and amines, Chem. Soc. Rev. 43 (2014)
2714–2742, doi:10.1039/C3CS60345H.
[49] R. Oladee, D. Zareyee, M.A. Khalilzadeh, KF/clinoptilolite nanoparticles as an
efficient nanocatalyst for the Strecker synthesis of α-aminonitriles, Monat-
[23] Molnar, A. Efficient, selective, and recyclable palladium catalysts in
carbon−carbon coupling reactions, Chem. Rev. 111 (2011) 2251–2320,
doi:10.1021/cr100355b.
shefte für Chemie
s00706-020-02574-w.
- Chemical Monthly 151 (2020) 611–615, doi:10.1007/
[50] G. Brahmachari, S. Laskar, A very simple and highly efficient procedure for
N-formylation of primary and secondary amines at room temperature under
solvent-free conditions, Tetrahedron Lett. 51 (2010) 2319–2322, doi:10.1016/j.
tetlet.2010.02.119.
[24] V. Polshettiwar, C. Len, A. Fihri, Silica-supported palladium: sustainable cata-
lysts for cross-coupling reactions, Coord. Chem. Rew. 253 (2009) 2599–2626,
doi:10.1016/j.ccr.2009.06.001.
[25] Subodh, N.K. Mogha, K. Chaudhary, G. Kumar, D.T. Masram, Fur-imine-
functionalized graphene oxide-immobilized copper oxide nanoparticle catalyst
for the synthesis of xanthene derivatives, ACS Omega 3 (2018) 16377–16385,
doi:10.1021/acsomega.8b01781.
[51] A.Chandra Shekhar, A.Ravi Kumar, G. Sathaiah, V. Luke Paul, M. Sridhar, S. Rao,
Facile N-formylation of amines using Lewis acids as novel catalysts, Tetrahe-
dron Lett. 50 (2009) 7099–7101, doi:10.1016/j.tetlet.2009.10.006.
[52] J. Deutsch, R. Eckelt, A. Köckritz, A. Martin, Catalytic reaction of methyl formate
with amines to formamides, Tetrahedron 65 (2009) 10365–10369, doi:10.1016/
j.tet.2009.10.047.
[26] Subodh, K. Chaudhary, K. Prakash, D.T. Masram, TiO2 nanoparticles immobi-
lized organo-reduced graphene oxide hybrid nanoreactor for catalytic applica-
tions, Appl. Surf. Sci. 509 (2020) 144902, doi:10.1016/j.apsusc.2019.144902.
[27] D. Yadav, S.K. Awashti, An unsymmetrical covalent organic polymer for
catalytic amide synthesis, Dalton Trans. 49 (2020) 179–186, doi:10.1039/
C9DT03931G.
[53] H. Tumma, N. Nagaraju, K. Vijayakumar Reddy, A facile method for the N-
formylation of primary and secondary amines by liquid phase oxidation of
methanol in the presence of hydrogen peroxide over basic copper hydroxyl
salts, J. Mol. Catal. A: Chem. 310 (2009) 121–129, doi:10.1016/j.molcata.2009.
06.007.
[28] Subodh, K. Prakash, K. Chaudhary, D.T. Masram, A new triazine-cored cova-
lent organic polymer for catalytic applications, Appl. Catal. A: Gen. 593 (2020)
117411-, doi:10.1016/j.apcata.2020.117411.
[54] M.Reddy Muthukur Bhojegowd, A. Nizam, M. Afzal Pasha, Amberlite IR-
120,
A reusable catalyst for N-formylation of amines with formic acid us-
[29] Subodh, K. Prakash, D.T. Masram, A reversible chromogenic covalent organic
polymer for gas sensing applications, Dalton Trans. 49 (2020) 1007–1010,
doi:10.1039/C9DT04788C.
[30] K Chaudhary, Subodh, K. Prakash, N.K. Mogha, D.T. Masram, Fruit waste (Pulp)
decorated CuO NFs as promising platform for enhanced catalytic response and
its peroxidase mimics evaluation, Arab. J. Chem. 13 (2020) 48694861, doi:10.
1016/j.arabjc.2019.09.007.
ing microwaves, Chin. J. Catal. 31 (2010) 518–520, doi:10.1016/S1872-2067(09)
60064-4.
[55] B. Das, M. Krishnaiah, P. Balasubramanayam, B. Veeranjaneyulu, D. Nandan Ku-
mar, A remarkably simple N-formylation of anilines using polyethylene glycol,
Tetrahedron Lett. 49 (2008) 2225–2227, doi:10.1016/j.tetlet.2008.02.050.
[56] P.Ganapati Reddy, G.D.Kishore Kumar, S. Baskaran, A convenient method for
the N-formylation of secondary amines and anilines using ammonium formate,
Tetrahedron Lett. 41 (2000) 9149–9151, doi:10.1016/S0040-4039(00)01636-1.
[57] Z.K. Chen, R.Z. Fu, W. Chai, H. Zheng, L. Sun, Q. Lu, R.X. Yuan, An eco-benign
and highly efficient procedure for N-acylation catalyzed by heteropolyanion-
based ionic liquids using carboxylic acid under solvent-free conditions, Tetra-
hedron 70 (2014) 2237–2245, doi:10.1016/j.tet.2014.02.042.
[31] G. Kumar, N.K. Mogha, M. Kumar, D.T.Masram Subodh, NiO nanocompos-
ites/rGO as a heterogeneous catalyst for imidazole scaffolds with applications
in inhibiting the DNA binding activity, Dalton Trans. 49 (2020) 1963–1974,
doi:10.1039/C9DT04416G.
[32] G. Scheuermann, M. Rumi, L. Steurer, P. Bannwarth, W.J. Mulhaupt, Palladium
nanoparticles on graphite oxide and its functionalized graphene derivatives as
highly active catalysts for the Suzuki−Miyaura coupling reaction, J. Am. Chem.
Soc. 131 (2009) 8262–8270, doi:10.1021/ja901105a.
[58] R.B. Sonawane, N.K. Rasal, S.V. Jagtap, Nickel-(II)-catalyzed N-formylation and
N-acylation of amines, Org. Lett. 19 (2017) 2078–2081, doi:10.1021/acs.orglett.
7b00660.
[33] D. Yadav, S.K. Awashti,
A
Pd NP-confined novel covalent organic polymer
[59] D.D.S. Sharley, J.M.J. Williams, Acetic acid as a catalyst for the N-acylation of
amines using esters as the acyl source, Chem. Commun. 53 (2017) 2020–2023,
doi:10.1039/C6CC09023K.
for catalytic applications, New J. Chem. 44 (2020) 1320–1325, doi:10.1039/
C9NJ05827C.
[34] D. Yadav, S.K. Awashti, A Pd confined hierarchically conjugated covalent or-
ganic polymer for hydrogenation of nitroaromatics: catalysis, kinetics, thermo-
dynamics and mechanism, Green Chem. 22 (2020) 4295–4303, doi:10.1039/
D0GC01469A.
[35] R. Nie, J. Shi, W. Du, Z. Hou, Ni2O3-around-Pd hybrid on graphene oxide: an
efficient catalyst for ligand-free Suzuki–Miyaura coupling reaction, Appl. Catal.
A. 473 (2014) 1–6, doi:10.1016/j.apcata.2013.12.029.
[60] Z.Y. Tan, Z.H. Li, Y. Ma, J.J. Qin, C.M. Yu, Potassium tert-Butoxide Prompted
Highly Efficient Transamidation and Its Coordination Radical Mechanism, Eur.
J. Org. Chem. 28 (2019) 4538–4545, doi:10.1002/ejoc.201900666.
[61] N. Vodnala, R. Gujjarappa, C.K. Hazra, D. Kaldhi, A.K. Kabi, U. Beifuss,
C.C. Malakar, Copper-Catalyzed Site-Selective Oxidative C-C Bond Cleavage of
Simple Ketones for the Synthesis of Anilides and Paracetamol, Adv. Synth.
Catal. 361 (2019) 135–145, doi:10.1002/adsc.201801096.
[36] R. Nie, J. Wang, L. Wang, Y. Qin, P. Chen, Z. Hou, Platinum supported on re-
duced graphene oxide as a catalyst for hydrogenation of nitroarenes, Carbon
50 (2012) 586–596, doi:10.1016/j.carbon.2011.09.017.
[62] H.M. Savanur, S.S. Malunavar, P.P. Sutar, R.G. Kalkhambkar, K.K. Laali, Synthesis
of diverse libraries of carboxamides via chemoselective N-acylation of amines
by carboxylic acids employing Brønsted acidic IL [BMIM(SO3H)][OTf], Tetrahe-
dron Lett. 60 (2019) 151–159, doi:10.1016/j.tetlet.2019.151159.
[63] R.B. Sonawane, N.K. Rasal, D.S. Bhange, S.V. Jagtap, Copper-(II) catalyzed N-
formylation and N-acylation of aromatic, aliphatic, and heterocyclic amines
and a preventive study in the C-N cross coupling of amines with aryl halides,
ChemCatChem 10 (2018) 3907–3913, doi:10.1002/cctc.201800609.
[64] L.Y. Jiao, M. Oestreich, Oxidative Palladium(II)-Catalyzed Dehydrogenative
CH/CH CrossCoupling of 2,3-Substituted Indolines with Arenes at the C7 Po-
sition, Chem. Eur. J. 19 (2013) 10845–10848, doi:10.1002/chem.201302140.
[65] E. Eren, Removal of copper ions by modified Unye clay, Turkey, J. Hazard.
Mater. 159 (2008) 235–244, doi:10.1016/j.jhazmat.2008.02.035.
[37] R. Chanthateyanonth, H. Alper, The first synthesis of stable palladium(II) PCP-
type catalysts supported on silica-application to the Heck reaction, J. Mol.
Catal. 201 (2003) 23–31, doi:10.1016/S1381-1169(03)00158-4.
[38] W. Liu, D. Wang, Y. Duan, Y. Zhang, F. Bian, Palladium supported on poly (ionic
liquid) entrapped magnetic nanoparticles as a highly efficient and reusable
catalyst for the solvent-free Heck reaction, Tet. Lett. 56 (2015) 1784–1789,
doi:10.1016/j.tetlet.2015.02.047.
[39] M.J. Climent, A. Corma, S. Iborra, Heterogeneous catalysts for the one-pot
synthesis of chemicals and fine chemicals, Chem. Rev. 111 (2011) 1072–1133,
doi:10.1021/cr1002084.
[40] C.L. Allen, J.M.J Williams, Metal-catalysed approaches to amide bond forma-
tion, Chem. Soc. Rev. 40 (2011) 3405–3415, doi:10.1039/C0CS00196A.
[41] H. Keipour, M.A. Khalilzadeh, A. Hosseini, A. Pilevar, D. Zareyee, An active
and selective heterogeneous catalytic system for Michael addition, Chin. Chem.
Lett. 23 (2012) 537–540, doi:10.1016/j.cclet.2012.02.006.
[42] J.V. Smith, Topochemistry of zeolites and related materials. 1. Topology and
geometry, Chem. Rev. 88 (1988) 149–182, doi:10.1021/cr00083a008.
[43] M.A. Khalilzadeh, S. Salmanpour, A. Hosseini, KF/Clinoptilolite: An Efficient
Promoter for the Synthesis of Thioethers, Comb. Chem. High Throughput
Screen. 16 (2013) 339–344, doi:10.2174/1386207311316050002.
[66] M. Nasrollahzadeh, Z. Issaabadi, R. Safari, Synthesis, characterization and ap-
plication of Fe3O4@SiO2 nanoparticles supported palladium(II) complex as
a
magnetically catalyst for the reduction of 2,4-dinitrophenylhydrazine, 4-
nitrophenol and chromium(VI): A combined theoretical (DFT) and experimen-
tal study, Separ. Purif. Technol. 209 (2019) 136–144, doi:10.1016/j.seppur.2018.
07.022.
[67] M. Nasrollahzadeh,
T Baran, N.Y. Baran, M. Sajjadi, M.R. Tahsili, M. Shok-
ouhimehr, Pd nanocatalyst stabilized on amine-modified zeolite: Antibacterial
and catalytic activities for environmental pollution remediation in aqueous
medium, Separ. Purif. Technol. 239 (2020) 116542, doi:10.1016/j.seppur.2020.
116542.
[44] M.A. Khalilzadeh, A. Hossein, A. Pilevar, Potassium fluoride supported on natu-
ral nanoporous zeolite: a new solid base for the synthesis of diaryl ethers, Eur.
J. Org. Chem. 2011 (2011) 1587–1592, doi:10.1002/ejoc.201001447.
[45] M.A. Khalilzadeh, H. Sadeghifar, R. Venditti, Natural clinoptilolite/KOH: an effi-
cient heterogeneous catalyst for carboxymethylation of hemicellulose, Ind. Eng.
Chem. Res. 58 (2019) 11680–11688, doi:10.1021/acs.iecr.9b02239.
[46] J. Balou, M.A. Khalilzadeh, D. Zareyee, An efficient and reusable nano cata-
lyst for the synthesis of benzoxanthene and chromene derivatives, Sci. Rep.
9 (2019) 3605, doi:10.1038/s41598- 019-40431-x.
[68] M. Sajjadi, N.Y. Baran, T. Baran, M. Nasrollahzadeh, M.R. Tahsili, M. Shok-
ouhimehr, Palladium nanoparticles stabilized on a novel Schiff base modified
Unye bentonite: Highly stable, reusable and efficient nanocatalyst for treating
wastewater contaminants and inactivating pathogenic microbes, Separ. Purif.
Technol. 237 (2020) 116383, doi:10.1016/j.seppur.2019.116383.
[69] D. Habibi, M. Nasrollahzadeh, H. Sahebekhtiari, Green synthesis of formamides
using the Natrolite zeolite as a natural, efficient and recyclable catalyst, J. Mol.
Catal. A: Chem. 378 (2013) 148–155, doi:10.1016/j.molcata.2013.04.001.
[70] C. Garkoti, J. Shabir, S. Mozumdar, An imidazolium based ionic liquid sup-
ported on Fe3O4@SiO2 nanoparticles as an efficient heterogeneous catalyst
for N-formylation of amines, New J. Chem. 41 (2017) 9291–9298, doi:10.1039/
C6NJ03985E.
[47] J. Balou, M.A. Khalilzadeh, D. Zareyee, KF/Nano-clinoptilolite catalyzed Aldol-
type reaction of aldehydes with ethyl diazoacetate, Catal. Lett. 147 (2017)
2612–2618, doi:10.1007/s10562-017-2158-6.

10
M. Amirsoleimani, M.A. Khalilzadeh and D. Zareyee / Journal of Molecular Structure 1225 (2021) 129076
[71] M. Nasrollahzadeh, S.M. Sajadi, A. Hatamifard, Anthemis xylopoda flowers
aqueous extract assisted in situ green synthesis of Cu nanoparticles supported
on natural Natrolite zeolite for N-formylation of amines at room temperature
under environmentally benign reaction conditions, J. Colloid Interf. Sci. 460
(2015) 146–153, doi:10.1016/j.jcis.2015.08.040.
[72] S.H. Jung, J.H. Ahn, S.K. Park, J.-K. Choi, A practical and convenient procedure
for the N-formylation of amines using formic acid, Bull. Korean Chem. Soc. 23
(2002) 149–150, doi:10.5012/bkcs.2002.23.1.149.
[73] M. Tajbakhsh, B. Mohajerani, M.M. Heravi, A.N. Ahmadi, Natural HEU type
zeolite catalyzed Biginelli reaction for the synthesis of 3,4-dihydropyrimidin-
2(1H) one derivatives, J. Mol. Catal. A: Chem. 236 (2005) 216–219, doi:10.1016/
j.molcata.2005.04.033.
[74] S. Siffert, L. Gaillard, B.-L. Su, Alkylation of benzene by propene on a series of
Beta zeolites: toward a better understanding of the mechanisms, J. Mol. Catal.
A: Chem. 153 (2000) 267–279, doi:10.1016/S1381-1169(99)00357-X.