A green and mild procedure to selective synthesis of diarylamine via domino reaction of aryl halides and arginine catalyzed by magnetic-MOF

Article abstract of DOI:10.1002/hc.21450

Efficient and selective direct synthesis of diarylamines from aryl halides and arginine as a nitrogen-donor reagent is reported. Arginine, which is an oral supplement, acts as a useful nitrogen source donor in the copper-catalyzed reaction. Fe₃O₄/Cu₃(BTC)₂, which was easily separated and recycled with a magnet, improved the rate and facilitation of the synthesis of diarylamines selectively. The introduction of a new and available N-source, simple magnetic separation process, normal atmospheric conditions, and excellent yields under mild reaction conditions are other important features of this work.

Full text of DOI:10.1002/hc.21450

Received: 9 July 2018
DOI: 10.1002/hc.21450
Revised: 11 October 2018
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R E S E A R C H A R T I C L E
A green and mild procedure to selective synthesis of diarylamine
via domino reaction of aryl halides and arginine catalyzed by
magnetic-MOF
Mohammad Soleiman-Beigi
Fariba Mohammadi
|
Department of Chemistry, Basic of Sciences
Faculty, Ilam University, Ilam, Iran
Abstract
Efficient and selective direct synthesis of diarylamines from aryl halides and arginine
as a nitrogen-donor reagent is reported. Arginine, which is an oral supplement, acts
as a useful nitrogen source donor in the copper-catalyzed reaction. Fe3O4/Cu3(BTC)2,
which was easily separated and recycled with a magnet, improved the rate and
facilitation of the synthesis of diarylamines selectively. The introduction of a new
and available N-source, simple magnetic separation process, normal atmospheric
conditions, and excellent yields under mild reaction conditions are other important
features of this work.
Correspondence
Mohammad Soleiman-Beigi, Department of
Chemistry, Basic of Sciences Faculty, Ilam
University, Ilam, Iran.
Emails: SoleimanBeigi@yahoo.com;
m.soleimanbeigi@mail.ilam.ac.ir
Funding information
Iranian National Science Foundation
(INSF), Grant/Award Number: 96003528
Problems in working with ammonia and aniline have led
organic chemists to use nitrogen-donor reagents.[6] Compared
1
INTRODUCTION
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Diarylamines are a very important class of chemicals that fre-
quently utilized for pharmaceuticals, agricultural chemicals,
dye preparation, stabilizers for explosives, as polymerization,
corrosion inhibitors, and radical-trapping antioxidants.[1]
They are also found widely in a variety of biologically active
molecules such as natural products and HIV-1 protease in-
hibitors.[2] Thus, development of diverse procedures for their
synthesis is of great importance.
to the impressive progress being made in the N-alkylation of
organic amines, reports dealing with the direct synthesis of
amines using nitrogen-donor reagents are scarcely available.
After a successful presentation of sulfur-transfer reagents in
our previous work,[7] herein we wish to report an economical
and environmentally friendly method for synthesis of dia-
rylamines from aryl halides and arginine as a new nitrogen-
donor reagent.
The most classic method for amine synthesis is by using
ammonia.[3a] However, there are practical problems associ-
ated with the use of ammonia, including its storage, handling,
and transportation.[3b,c] Also, this reaction usually results in a
mixture of primary, secondary, and tertiary amines.[3d,e]
The general method for the synthesis of diarylamines is
arylation of anilines using aryl halides and aryl metal or using
aromatic C–H bond activation.[4] Although these methods are
very efficient, employment of aniline and its derivatives for
the synthesis is often very annoying, because they undergo
oxidation when exposed to air.[5] Accordingly, the develop-
ment of methods for the selective synthesis of amines is an
obvious problem in organic chemistry.
Arginine is a very important biomolecule that is classified
as an essential amino acid. Almost all dietary proteins contain
arginine. They are also used widely in cell division, immune
function, the healing of wounds, the release of hormones, and
the removal of ammonia from the body.[8] We herein report
a new method of using arginine as a nitrogen-donor reagent
that is an oral supplement, odorless, stable, non-toxic, and
environmentally friendly. It is a basic, solid reagent that can
be easily available and handled.
Traditionally, synthetic procedures for the preparation
of diarylamines are under copper-mediated Ullmann-type
conditions.[9] Although these copper-catalyzed reactions are
effective, the major drawbacks of this method are reaction
harsh conditions and stoichiometric amounts of copper, and
the yields are not reproducible.
Contract grant sponsor: Iranian National Science Foundation (INSF).
Contract grant number: 96003528.
|
Heteroatom Chemistry. 2018;e21450.
https://doi.org/10.1002/hc.21450
wileyonlinelibrary.com/journal/hc
© 2018 Wiley Periodicals, Inc.
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TABLE 1 Optimization of the reaction conditions
Entry
Arginine (mmol)
Cata (mol%)
Solvent
Base (mmol)
Temp (°C)
Yield (%)b
1
2
3
4
5
6
7
8
1
1
5
10
10
10
10
10
10
10
10
10
10
10
10
10
DMF
DMF
DMF
DMF
DMSO
PEG
H2O
PEG
PEG
PEG
PEG
PEG
PEG
PEG
KOH (3)
KOH (3)
KOH (3)
KOH (2)
KOH (3)
KOH (3)
KOH (3)
KOH (3)
KOH (3)
KOH (3)
K2CO3 (3)
t-BuOK (3)
Et3N (3)
-
130
130
130
130
130
130
130
110
80
25
80
80
80
76
96
95
85
81
98
Trace
98
98
N.R.
65
80
58
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
9
10
11
12
13
14
80
N.R.
Notes. Reaction conditions: PhI (1.0 mmol), arginine (X mmol), base (X mmol), and time (2 h), in 2 mL solvent/H2O (10:1).
Bold indicates optimization amount.
aFe3O4/Cu3(BTC)2.
bIsolated yield.
The Pd-catalyzed C-N coupling reaction of aryl ha-
lides has received much attention than other methods for
laboratory-scale synthesis of the substituted arylamines.
However, copper-catalyzed coupling is still the best choice
for large and industrial scales.[10]
The past few decades have witnessed an exponential
growth in the number of research papers in the study of ma-
terials known as metal-organic frameworks (MOFs).[11] In
previous work, a highly porous metal-organic framework,
Cu3 BTC2 (copper (II)-benzene-1,3,5-tricarboxylate), which
is known as MOF-199, was used as an efficient and recycla-
ble catalyst.[12] In this study, a magnetic-MOF was synthe-
sized and developed. Combinations of MOFs and magnetic
nanoparticles have many advantages in adsorption and sep-
aration. Fe3O4/Cu3(BTC)2 exhibited both magnetic charac-
teristics and high porosity.[13] Magnetic characteristics led
to easy to collect with an external magnet and high porosity
characteristics led to an excellent catalyst for diarylamine
synthesis.
Certainly, the use of suitable solvents and catalysts is very
important in research areas of green chemistry.[14] Herein
magnetic-MOF and PEG have been used for advancing the
goals of green chemistry.
On the basis of this approach, this study sought to synthe-
size symmetrical diarylamines via domino reaction of aryl
halides and L-arginine through Fe3O4/Cu3(BTC)2 catalysis
(Scheme 1).
2
RESULTS AND DISCUSSION
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The reaction of iodobenzene with l-arginine in the presence
of Fe3O4/Cu3(BTC)2 was studied under normal atmospheric
conditions in order to optimize the reaction condition in
terms of temperature, type, and amount of base; amount
of l-arginine and catalyst; and solvent. At first performed
the optimization amount of Fe3O4/Cu3(BTC)2 for the
C–N coupling reaction of iodobenzene and arginine. The
reaction was not complete in the presence of 5 mol% Fe3O4/
Cu3(BTC)2. Diphenylamine was obtained in 98% yield with
10 mol% of catalyst (Table 1, Entries 1 and 2). We found
that decreasing the amount of KOH from 3 to 2 mmol led
H
N
NH
NH2
Magnetic-MOF
Ar2NH
Ar-X
+
O
PEG/H2O, KOH
80OC
H2N
OH
SCHEME 1 Selective synthesis of diarylamine compounds

SOLEIMAN-BEIGI ANd MOHAMMAdI
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TABLE 2 Checking of the effect of catalysts
solvent of H2O seldom. PEG was the best choice as a green
and efficiency solvent (Table 1, Entries 5-7). We found that
temperatures of 130°C, 110°C, and 80°C displayed a similar
and good behavior, but the temperature of 80°C was used to
be compatible with the principles of green chemistry.
The reaction did not proceed at 25°C (Table 1, Entries 8-
10). The other bases, including K2CO3, t-BuOK, and Et3N,
resulted in reducing yields significantly; thus, of the bases
tested, KOH at a concentration of 3 mmol showed a superior
effect on the reaction yields and the reaction did not proceed
in the absence of a base (Table 1, Entries 11-14).
As shown in Table 2, the reaction did not proceed in the
absence of catalyst. The different catalysts were evaluated,
and it was found that MOF-199 as well as Fe3O4/Cu3(BTC)2
led to production of diarylamine. The reaction was not com-
plete in the presence of CuCl salt (Table 2, Entries 1-4).
The reaction produced a mixture of primary, secondary, and
tertiary amines in the presence of NiCl2·6H2O and Fe3O4
(Table 2, Entries 5 and 6). The reaction had different path-
ways in the presence of palladium and moved forward to pro-
duction of tertiary amine. This result was investigated with
other derivatives, and the same result was obtained (Table 2,
Entries 7-10).
Yield (%)a
Entry
Catalyst
ArNH2
Ar2NH
Ar3N
1
2
3
-
-
-
-
-
-
97
-
-
-
-
Fe3O4/Cu3(BTC)2
MOF-199
CuCl
96
4
71b
5
6
NiCl2·6H2O
Fe3O4
Trace
Trace
-
-
-
-
Trace
Trace
-
-
-
-
Trace
35
95
96c
91d
85e
7
8
9
10
K2PdCl4
K2PdCl4
K2PdCl4
K2PdCl4
Notes. Reaction conditions: PhI (1.0 mmol), arginine (0.5 mmol), cat (10 mol%),
KOH (3 mmol), and time (2 h), in 2 mL PEG/H2O (10:1).
aIsolated yield.
bReaction not complete.
cAryl halide in this reaction is 2-iodotoluene.
dAryl halide in this reaction is 4-iodoanisole.
eAryl halide in this reaction is 2-iodothiophene.
After the optimized reaction conditions were established,
a large number of aryl halides (and -OTs) were examined to
explore the scope of this reaction. As summarized in Table 3,
aryl iodides and aryl bromides were converted into the corre-
sponding diarylamines in higher yields than their chloro and
tosylate analogs (Table 3, Entries 1-4). The results show that
the aryl halide derivatives with different functional groups,
such as CH3, OCH3, and Br, provide good-to-excellent yields
to a decrease in the rate of reaction, and thus, 3 mmol KOH
was selected as the optimum amount (Table 1, Entries 3 and
4). Changingthe solvents to DMSO led to decrease yields
lightly, and the reaction proceeded in the presence of the
TABLE 3 The direct synthesis of
symmetrical diarylamines
Entry
Ar-X
Product
Time (h)
Yield (%)
1
2
3
4
5
6
7
8
PhI
PhBr
PhOTs
PhCl
o-MePh―I
p-MeOPh―I
o-MeOPh―I
p-BrPh―I
2-Iodothiophene
2-Bromothiophene
2-Chlorothiophene
p-MePh―Br
a
b
c
d
e
j
k
f
g
h
i
2
6
10
12
3
10
7
4
5
5
10
8
97
91
80
73
86
90
74
75
85
76
68
84
9
10
11
12
l
Note. Reaction conditions: Ar-X (1.0 mmol), arginine (0.5 mmol), Fe3O4/Cu3(BTC)2 (10 mol%), and KOH
(3 mmol), in 2 mL PEG/H2O (10:1).

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(Table 3, Entries 5-8). The reaction was carried out with high
chemoselectivity, and a single product was selectivity ob-
tained of reaction substrates with two halide groups (Table 3,
Entry 8).
In addition, symmetrical diheteroaryl amines were well
synthesized from the corresponding heteroaryl iodides, bro-
mides, and chlorides (Table 3, Entries 9-11).
Although we cannot clearly determine the catalytic re-
action pathway for the synthesis of diarylamines from aryl
halides and arginine, we proposed that the Cu-catalyzed re-
action may proceed through the mechanism in Scheme 2.
Initially, product (I) appears to be generated in the coupling
reaction between aryl halide and arginine. Then, product (I)
is hydrolyzed to the corresponding arylamine under the re-
action conditions. Finally, diarylamines appear to have been
generated in the coupling reaction between arylamine and
aryl halide during the one-step reaction (Scheme 2).[15]
FIGURE 1 FT-IR spectra of (a) Fe3O4, (b) Cu3(BTC)2, and (c)
Fe3O4/Cu3(BTC)2
2.1
Characterization of Fe3O4/Cu3(BTC)2
|
and relative intensity (Figure 2c), which match well with the
reported XRD of Fe3O4 (magnetite) and XRD of Cu3(BTC)2.
It implies that the spinal structure of Fe3O4 and Cu3(BTC)2
has been retained during the process of catalyst preparation.
Scanning electron microscopy (Figure 3) shows existence
crystals in nano-size. This study showed diameters of ~30-
90 nm for the magnetic nanoparticles. All of the data are sim-
ilar to those of other Fe3O4/Cu3(BTC)2 samples previously
mentioned in the literature.[13b,c]
In view of green chemistry, the use of magnetic ca-
talysis is important, because the magnetic catalysts offer
several advantages, including easy catalyst separation, re-
covery, and recycling. As can be seen from Tables 1 and
3, the catalytic system worked exceedingly well in the
selective synthesis of diarylamines with a wide range of
substrates under the optimized reaction conditions. Also,
Figure 1 shows the FT-IR spectra of (a) Fe3O4, (b)
Cu3(BTC)2, and (c) Fe3O4/Cu3(BTC)2. The Fe–O stretch-
ing vibration near 579 cm−1 and O-H stretching vibration
near 3401 cm−1 were observed (Figure 1a). The spectrum
of Cu3(BTC)2 shows absorption in the wave numbers 3423,
1640, and 1442 cm−1 that they are related to water mol-
ecule, carbonyl group of benzene tricarboxylic acid, and
double bonds of benzene, respectively (Figure 1b). For
Fe3O4/Cu3(BTC)2, the band at 1622-1709 cm−1 suggests
the presence of BTC. The peaks observed at 1441 cm−1 and
580 cm−1 are related to N-H and O-H vibration, respectively.
The broad peak at 3400 cm−1 was due to water molecule and
hydroxyl groups (Figure 1c).
Figure 2 shows the X-ray powder diffraction patterns of (a)
Cu3(BTC)2, (b) Fe3O4, and (c) Fe3O4/Cu3(BTC)2. The XRD
pattern of the Fe3O4/Cu3(BTC)2 shows characteristic peaks
NH NH
NH
NH NH
NH2
Fe3O4/Cu3(BTC)2
PEG/H2O, KOH
Ar
Ar-X
+
O
O
NH2
NH2
80 O
C
OH
(I)
OH
OH
NH NH
NH
NH NH2
Ar
Hydrolysis
+
Ar-NH2
O
O
O
NH2
NH2
OH
OH
(I)
Fe3O4/Cu3(BTC)2
PEG/H2O, KOH
Ar-NH-Ar
Ar-NH2
+
ArX
80O
C
SCHEME 2 Possible mechanisms for synthesis of
diarylamines
FIGURE 2 X-ray powder diffractogram of (a) Fe3O4, (b)
Cu3(BTC)2, and (c) Fe3O4/Cu3(BTC)2

SOLEIMAN-BEIGI ANd MOHAMMAdI
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FIGURE 4 Catalyst recycling studies
4
EXPERIMENTAL
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FIGURE 3 SEM micrograph of Fe3O4/Cu3(BTC)2
4.1
Synthesis of Fe3O4/Cu3(BTC)2
|
the reusability is one of the important properties of this
catalyst.
The procedure to prepare MOF-199 was according to Ref.
[13]. Fe3O4 nanoparticles were prepared by chemical copre-
cipitation of Fe3+ and Fe2+ ions with a molar ratio of 2:1
that has been reported previously. Then, 4 mmol/L mercap-
toacetic acid (MAA) was added to Fe3O4 nanoparticles (1 g)
and the resultant mixture was stirred for 24 hours. The result-
ing was isolated by magnetic decantation, washed twice with
ethanol, and dried at 50°C under vacuum.
Briefly, 0.5 g MAA-functionalized Fe3O4 microspheres
and 3.68 g Cu(NO3)2 were dispersed in 100 mL ethanol and
ultrasonicated for 30 minutes. Then, 1.74 g benzene-1,3,5-
tricarboxylic acid (H3BTC) was added to the above suspen-
sion and the mixture was stirred mechanically for 2 hours.
The final product, Fe3O4/Cu3(BTC)2, was separated by an ex-
ternal magnet, washed with ethanol several times, and dried
in an oven overnight.[13b]
2.2
Reusability
|
In order to consider the heterogeneity of the catalyst, we decided
to investigate the recoverability and reusability of the Fe3O4/
Cu3(BTC)2 catalyst over five successive runs. The reaction
was performed in PEG/H2O (10:1) at 80°C, using iodobenzene
(1 mmol), arginine (0.5 mmol), and KOH (3 mmol) in the
presence of 10 mol% Fe3O4/Cu3(BTC)2 catalyst. After each
run, the catalyst was separated from the reaction mixture by a
magnetic field and washing and then reusing it. The recovered
Fe3O4/Cu3(BTC)2 catalyst was dried and was then reused in the
further reaction under identical conditions to those of the first
run. The recyclability of Fe3O4/Cu3(BTC)2 was investigated for
these reactions. The separated catalyst was reused for 5 runs in
the synthesis of diphenylamine and without any significant loss
of its activity, and it demonstrated excellent recoverability and
reusability (Figure 4).
4.2
Symmetrical diarylamine synthesis:
|
typical experimental procedure
A mixture of aryl halide (1.0 mmol), arginine (0.5 mmol)
and Fe3O4/Cu3(BTC)2 (10 mol%) were added to a flask
containing 3 mmol KOH and 2 mL PEG/H2O (10:1). The
reaction continued at temperature 80°C under atmospheric
conditions. The reaction progress was controlled by thin-
layer chromatography. The solvent was evaporated under
vacuum. Than crude reaction mixture was purified by
column chromatography (n-hexane/ethyl acetate 4:1) to give
the diaryl amines in good yields (see in Data S1)
3
CONCLUSION
|
In summary, we have developed a novel, effective and selec-
tive direct synthesis of diarylamines from aryl halides and
arginine in PEG/H2O. The important feature of this method
is using Fe3O4/Cu3(BTC)2 as a recyclable, porous, and che-
moselective catalyst and also using arginine as a nitrogen
source donor that led to selective synthesis of diarylamines
in high yield. This protocol has several advantages: normal
atmospheric conditions, the use of a less amount of catalyst,
an easily available and low-cost reagent, and the use of PEG
as a green solvent instead of the usually used organic solvents
to carry out the reactions.
ACKNOWLEDGMENTS
We gratefully acknowledge the financial support from the
Iranian National Science Foundation (INSF, Grant No.
96003528).

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How to cite this article: Soleiman-Beigi M,
Mohammadi F. A green and mild procedure to
selective synthesis of diarylamines via domino
reaction of aryl halides and arginine catalyzed by
magnetic-MOF. Heteroatom Chem. 2018;e21450.
https://doi.org/10.1002/hc.21450
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