Synthesis of novel magnetic nanoparticles with urea or urethane moieties: Applications as catalysts in the Strecker synthesis of α-aminonitriles

Article abstract of DOI:10.1002/aoc.3883

Four novel magnetic nanoparticle catalysts with urea or urethane moieties are reported. The silica-coated magnetic nanoparticles were simply functionalized via addition of 3-(triethoxysilyl)propylisocyanate (TESPIC), amine or amino alcohol. TESPIC with dual labile functional groups was used as a suitable precursor for the synthesis of urethane-based catalysts. The newly synthesized catalysts were fully characterized using a variety of techniques. These functionalized magnetic nanoparticles were used as reusable catalysts in the Strecker synthesis of α-aminonitrile derivatives under solvent-free conditions at 50?°C.

Full text of DOI:10.1002/aoc.3883

Received: 13 February 2017
DOI: 10.1002/aoc.3883
Revised: 7 April 2017
Accepted: 14 April 2017
F U L L PA P E R
Synthesis of novel magnetic nanoparticles with urea or urethane
moieties: Applications as catalysts in the Strecker synthesis of α‐
aminonitriles
Saeed Baghery1
Marc C.A. Stuart4
| Mohammad Ali Zolfigol1
| Andreas Nagl2
| Romana Schirhagl2 | Masoumeh Hasani2,3
|
1 Department of Organic Chemistry, Faculty
of Chemistry, Bu‐Ali Sina University,
Hamedan 6517838683, Iran
2 Groningen University, University Medical
Center Groningen, Antonius Deusinglaan 1,
9713 AV, Groningen, The Netherlands
3 Department of Analytical Chemistry,
Faculty of Chemistry, Bu‐Ali Sina
University, Hamedan 6517838683, Iran
4 Electron Microscopy, Groningen
Biomolecular Sciences and Biotechnology
Institute, University of Groningen,
Groningen, The Netherlands
Four novel magnetic nanoparticle catalysts with urea or urethane moieties are
reported. The silica‐coated magnetic nanoparticles were simply functionalized via
addition of 3‐(triethoxysilyl)propylisocyanate (TESPIC), amine or amino alcohol.
TESPIC with dual labile functional groups was used as a suitable precursor for
the synthesis of urethane‐based catalysts. The newly synthesized catalysts were fully
characterized using a variety of techniques. These functionalized magnetic nanopar-
ticles were used as reusable catalysts in the Strecker synthesis of α‐aminonitrile
derivatives under solvent‐free conditions at 50 °C.
KEYWORDS
3‐(triethoxysilyl)propylisocyanate, magnetic nanoparticle, Strecker synthesis, urea or urethane moiety, α‐
Correspondence
aminonitrile
Saeed Baghery or Mohammad Ali Zolfigol,
Department of Organic Chemistry, Faculty of
Chemistry, Bu‐Ali Sina University, Hamedan
6517838683, Iran.
Email: saadybaghery@yahoo.com;
zolfi@basu.ac.ir; mzolfigol@yahoo.com
1 | INTRODUCTION
Urea and urethane derivatives are significant types of
carbonyl compounds that can be used in a wide variety
With the development of self‐assembly processes, functional
self‐assembled materials have attracted more and more atten-
tion. 3‐(Triethoxysilyl)propylisocyanate (TESPIC) with dual
labile functional groups has been widely used as a reagent,
the structure of which includes isocyanate (─N═C═O) and
ethoxy (─O─CH2─CH3) functional groups. Because of the
high reactivity of these functional groups, TESPIC has been
used as a crosslinking reagent in various addition reactions.
Recent developments of using TESPIC in assembling hybrid
materials and in the synthesis of novel compounds have also
been reported.[1] The internal ester group of isocyanate in the
TESPIC molecule is expected to realize hydrogen transfer
reaction with some active molecules having reactive hydro-
gen atoms.[2]
of applications. They have found uses as antioxidants in
gasoline, as additives in the synthesis of amino‐plastics,
as plant protecting agents and in pharmaceutical and dye
chemistry.[3] Special attention has recently been paid to
urea derivatives since a number of them have been used
for brain cancer treatment, or have been confirmed to have
a marked inhibitory effect on HIV protease enzyme.[4]
These compounds are produced using several methods such
as the reaction between amine derivatives and compounds
like isocyanates, carbamates and formamides in the
presence of transition metal catalysts like Ru, Ni, Co, Pd,
Au and W.[5]
Bifunctional organo‐catalysts bearing both urea/thio-
urea hydrogen‐bond donors and a basic amine moiety
Appl Organometal Chem. 2017;e3883.
wileyonlinelibrary.com/journal/aoc
Copyright © 2017 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.3883

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BAGHERY ET AL.
have been reported as practical organo‐catalysts for asym-
metric transformations.[6] Takemoto and co‐workers[7]
showed that the introduction of a basic group in a thio-
urea catalyst leads to a synergistic interaction between
the functional groups in substrates. They reported that
bifunctional amine–thiourea organo compounds are effi-
cient catalysts in enantioselective Michael addition reac-
tions. Such a catalyst has been used in a wide range of
organic transformations.[8]
Nanoparticles of catalytic material provide the benefit
of high surface area that leads to an increased reaction
rate. Magnetic nanoparticles (MNPs) have been widely
studied as a support for catalysts because there is an
extensive interest in the attachment of various catalyst
molecules onto heterogeneous substrates.[9] They are valu-
able substrates for the immobilization of inorganic and
organic catalysts. Advantages are the easy separation from
the reaction mixture and recycling of the catalyst by a
simple magnetic separation.[10]
The Strecker reaction is a simple and efficient one‐pot
three‐component method for the preparation of α‐
aminonitriles, which employs aldehydes or ketones,
amines and a cyanide source in aqueous media.[11] α‐
Aminonitriles are valuable intermediates in the synthesis
of α‐amino acids and other biologically relevant mole-
cules.[12] They have also been investigated for their role
in the chemistry and prebiotic evolution of α‐amino
acids.[13] The Strecker synthesis has been widely extended
using numerous catalysts.[14]
SCHEME 1 Synthesis of novel compounds with urea or urethane
moieties using TESPIC as an efficient precursor
In continuation of our research in the area of developing
silica‐coated magnetic iron oxide nanoparticles with various
coating systems and their applications as catalysts in multi-
component reactions,[15] herein we describe the synthesis
and characterization of four types of novel MNPs functional-
ized with urea or urethane moieties (Schemes 1 and 2). Then,
the activity of these heterogeneous catalysts was investigated
in the Strecker synthesis of α‐aminonitrile derivatives by the
reaction between trimethylsilyl cyanide (TMSCN), various
aldehydes or ketones, and amines under solvent‐free condi-
tions at 50 °C (Scheme 3).
All the synthesized novel compounds containing urea or
urethane moieties (i.e. 6, 7, 8 and 9 in Scheme 1) were fully
identified and characterized using FT‐IR, 1H NMR, 13C
NMR and HRMS (refer to supporting information). The
MNPs functionalized with these new silane compounds (i.e.
10a–d in Scheme 2) were also fully characterized via FT‐IR,
TGA, DTG, DTA, DSC, XRD, TEM, BET, AFM, XPS and
VSM analyses (refer to supporting information). Development
of design and synthesis of functionalized MNP catalysts for
multicomponent reactions[16] was our main purpose because
these catalytic systems play a major role in organic functional
group transformations. With this purpose, 10a–d were used as
efficient and recyclable catalysts for the Strecker synthesis of
SCHEME 2 Synthesis of novel MNP catalysts with urea or urethane
moieties using TESPIC as an efficient precursor
α‐aminonitrile derivatives. This was achieved by reacting var-
ious aldehydes or ketones, TMSCN and amine derivatives
under solvent‐free conditions at 50 °C (Scheme 3).

BAGHERY ET AL.
3 of 10
an isolated yield of 15%. This implies that the use of cat-
alyst is inevitable for this transformation. To determine
the optimal reaction conditions, optimization of the
amount of catalyst, temperature and solvent was carried
out. The catalyst quantity was optimized to achieve the
maximum catalytic activity and all the preliminary exper-
iments were done under solvent‐free condition. The results
given in Table 1 reveal that 1 mg of catalyst at 50 °C
(entry 7) gave the best yield which is equivalent to the
case of using twice as much catalyst at room temperature
(entry 17). There was no important modification in the
yield of product when large amounts of MNP catalysts
were used instead of 1 mg (Table 1, entries 18 and 20).
Further increasing the temperature to 100 °C and catalyst
quantity up to 5 mg did not have a pronounced influence
on the yield.
2 | RESULTS AND DISCUSSION
The Strecker synthesis of α‐aminonitrile derivatives via
the reaction between 4‐nitrobenzaldehyde, aniline and
TMSCN was chosen as a model reaction and the influ-
ence of the synthesized nanocatalysts (10a–d) on the yield
and reaction time was investigated (Table 1). In the
absence of 10a–d no product was obtained at room tem-
perature (Table 1, entry 1). By increasing the reaction
temperature to 50 °C, the product was synthesized with
Various solvents, namely water, C2H5OH, CH3CN,
CH2Cl2, n‐hexane, CH3CO2Et and toluene, were also
investigated. As evident from Table 1 (entries 10–16),
the model reaction in solvents either takes more time or
proceeds in lower yield compared to the solvent‐free
condition.
SCHEME 3 Strecker synthesis of α‐aminonitrile derivatives using
the new MNP catalysts with urea or urethane moieties
TABLE 1 Optimization of reaction conditions in synthesis of 2‐(4‐nitrophenyl)‐2‐(phenylamino)acetonitrilea
Catalyst
amount
(mg)
Reaction
temperature
(°C)
Reaction
time
(min)
Yield (%)b
10c
Entry
Solvent
10a
10b
10d
1
—
—
0.5
0.5
0.5
1
r.t.
50
r.t.
50
100
r.t.
50
75
100
50
50
50
50
50
50
50
r.t.
50
r.t.
50
—
—
60
60
60
60
60
30
15
15
15
30
15
15
30
60
30
60
30
15
30
15
—
15
35
53
53
71
93
93
93
78
91
88
83
73
81
74
71
93
68
91
—
15
28
41
41
63
85
85
85
68
82
78
76
62
73
65
63
85
61
83
—
15
30
46
46
65
88
88
88
70
85
80
79
64
75
67
65
88
63
85
—
15
33
52
52
69
90
90
90
74
88
83
81
69
77
71
69
90
65
87
2
3
—
4
—
5
—
6
—
7
1
—
8
1
—
9
1
—
10
11
12
13
14
15
16
17
18
19
20
1
H2O
C2H5OH
CH3CN
CH2Cl2
n‐hexane
CH3CO2Et
Toluene
—
1
1
1
1
1
1
2
2
—
5
—
5
—
aReaction conditions: 4‐nitrobenzaldehyde (1 mmol; 0.151 g), TMSCN (1.5 mmol; 0.149 g; 0.188 ml), aniline (1 mmol; 0.093 g; 0.092 ml).
bIsolated yield.

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BAGHERY ET AL.
TABLE 2 Strecker synthesis of α‐aminonitrile derivatives catalysed by 10a–d under solvent‐free conditions at 50°Ca
Yield (%)b
Entry
Product
M.p. (°C) (colour)
Time (min)
10a
10b
10c
10d
1
110–112 (yellow solid)[16a
]
20
91
83
86
88
2
3
4
5
6
7
8
9
215–217 (yellow solid)[16b
]
15
15
10
20
15
25
20
30
93
93
95
91
93
89
91
87
85
85
87
83
85
81
83
80
88
88
90
86
88
84
86
82
90
90
92
88
90
86
88
84
31–33 (red solid)[17a
85–87 (red solid)[17a
]
]
111–113 (brown solid)[17a
]
88–90 (brown solid)[17b
]
71–73 (green solid)[17a
]
104–106 (green solid)[17a
]
158–160 (yellow solid)[17c
]
10
11
103–105 (red solid)[17d
]
25
30
89
87
81
80
84
82
86
82–84 (green solid)[17a
]
84
(Continues)

BAGHERY ET AL.
5 of 10
TABLE 2 (Continued)
Yield (%)b
Entry
Product
M.p. (°C) (colour)
Time (min)
10a
10b
10c
10d
12
103–105 (green solid)[17a
]
25
89
81
84
86
13
Yellow oil[17e
]
25
92
81
85
86
14
15
Yellow oil[17e
]
25
25
93
94
84
85
87
87
89
90
Yellow oil[17e
]
16
17
71–73 (yellow solid)[17e
]
25
30
91
90
81
79
83
82
87
83
Yellow oil[17e
]
18
Yellow oil[17e
]
30
91
82
85
87
81
19
20
120–122 (yellow solid)[17e
]
30
30
85
83
78
80
80
82
Yellow oil[17e
]
84
(Continues)

6 of 10
BAGHERY ET AL.
TABLE 2 (Continued)
Yield (%)b
Entry
Product
M.p. (°C) (colour)
Time (min)
10a
10b
10c
10d
21
134–136 (yellow solid)[17c
]
30
89
77
79
81
22
54–56 (yellow solid)[17c
]
30
90
78
81
83
23
24
Yellow oil[17b
]
30
30
85
84
83
81
84
82
86
85
57–59 (white solid)[17f
]
aReaction conditions: aldehyde or ketone (1 mmol), TMSCN (1.5 mmol; 0.149 g; 0.188 ml), amine derivatives (1 mmol).
bIsolated yield.
Under the optimized reaction conditions, various α‐
aminonitrile derivatives were prepared through Strecker
synthesis catalysed by our heterogeneous bifunctional
organo‐catalysts. In all cases, aromatic aldehydes with
substituents carrying either electron‐donating or electron‐
withdrawing groups reacted effectively and provided the
products in high to excellent yields. It was found that aro-
matic aldehydes with electron‐withdrawing groups reacted
faster than those with electron‐donating groups. Also
aromatic aldehydes reacted faster than aliphatic aldehydes
and ketones. The data in Table 2 show that aliphatic amines
TABLE 3 Reusability of 10a–d in synthesis of 2‐(4‐nitrophenyl)‐2‐
(phenylamino)acetonitrile in 15 mina
Yield (%)b
Run
10a
10b
10c
10d
1
2
3
4
5
6
7
93
93
93
92
92
91
91
85
85
84
84
83
83
82
88
88
87
87
87
86
86
90
90
89
89
88
88
87
aReaction conditions: 4‐nitrobenzaldehyde (1 mmol; 0.151 g), TMSCN
(1.5 mmol; 0.149 g; 0.188 ml), aniline (1 mmol; 0.093 g; 0.092 ml).
bIsolated yield.
SCHEME 4 Plausible mechanism for Strecker synthesis of α‐
aminonitriles catalysed by 10d

BAGHERY ET AL.
7 of 10
TABLE 4 Comparison of catalytic efficacy of MNP catalysts with other catalystsa
Entry
Catalyst/amount
10a/1 mg
Conditions
Time (min)
Yield (%)b
1
Solvent‐free, 50 °C
Solvent‐free, 50 °C
Solvent‐free, 50 °C
Solvent‐free, 50 °C
EtOH, r.t.
20
20
20
20
90
1.3
3
91
83
86
88
2
10b/1 mg
3
10c/1 mg
4
10d/1 mg
5
B‐MCM‐41/50 mg
Choline chloride.2ZnCl2
Chitosan/6 mg
98[17b
99[17d
]
]
6
Solvent‐free, r.t.
Solvent‐free, r.t.
Solvent‐free, r.t.
CH2Cl2, 50 °C
H2O, r.t.
7
95[17a
92[19a
]
8
Ga‐TUD/20 mg
PVP‐SO2/100 mg
PEG‐OSO3H/180 mg
Sn‐montmorillonite/10 mg
MCM‐41‐SO3H/5 mg
p‐TSA/10 mol%
Zr(HSO4)4/2–6 mol%
K2PdCl4/10 mol%
I2/51 mg
30
360
10
6
]
9
89[19b
]
10
11
12
13
14
15
16
92[17f
90[19c
]
Solvent‐free, r.t.
EtOH, r.t.
]
30
15
10
30
60
98[19d
]
EtOH, r.t.
87[16a
85[17c
91[19e
]
]
]
Solvent‐free, r.t.
H2O, r.t.
CH3CN, r.t.
90[19f
]
aReaction conditions: 4‐chlorobenzaldehyde (1 mmol; 0.140 g), TMSCN (1.5 mmol; 0.149 g; 0.188 ml), aniline (1 mmol; 0.093 g; 0.092 ml).
bIsolated yield.
have shorter reaction time and afford higher yields of prod-
ucts than aromatic amines. This is because the electron pair
in aliphatic amines is not in resonance with any functional
groups and aromatic rings, so these compounds have a more
nucleophilic property and can attack carbonyl compounds
faster than can aromatic amines.
catalysts are fully recyclable and reusable for several runs
preserving the catalytic activity (Table 3).
To investigate the efficacy of the synthesized MNPs
with urea or urethane moieties as catalysts for the
Strecker synthesis, we compared the results obtained in
this work with those reported in the literature for Strecker
reaction mediated by other catalysts (Table 4). It is clear
that our new MNP urethane catalysts (10a–d) efficiently
catalyse the Strecker reaction. The new catalysts are com-
parable in some cases with those previously reported for
Strecker synthesis and in some cases are superior. The
greatest advantages of the present catalysts in comparison
to previously reported ones are high surface area, easy
separation, Takemoto catalyst‐like nature, short reaction
time and mild and solvent‐free conditions that make this
method from the green chemistry point of view more
environmentally friendly.
The possible mechanism of the Strecker reaction begins
with the activation of the carbonyl group of the aldehyde or
ketone (11) by the ─NH amide groups of the catalysts (10d
is shown in Scheme 4 as an example) via hydrogen bonding.
This makes the nucleophilic attack of the amine (13) on the
carbonyl group to produce the corresponding imine (16) more
favoured. Water removal from the intermediate (15) can also
be considered as a driving force for imine formation. In the
next step, the ─NH amide groups of 10d can further activate
imine nitrogen through hydrogen bonding and at the same
time the silicon atom in TMSCN can be coordinated by the
lone pair electrons of the pyridine nitrogen atom of the cata-
lyst. The imine is then attacked by the cyanide group of
TMSCN to provide the desired α‐aminonitrile derivative.[18]
As the recyclability of a heterogeneous catalyst is a sig-
nificant factor, we investigated the recyclability and reusabil-
ity of all the newly synthesized catalysts on repeated use in
the model reaction. After the reaction was completed (moni-
tored by TLC) the catalyst was separated simply using an
external magnet, washed with ethanol and reused for the next
run (seven times). The yield of the product and reaction time
remained unchanged after seven cycles, indicating that the
3 | CONCLUSIONS
In summary, we have developed a novel and facile pro-
cess for the synthesis of Fe3O4@SiO2@urea and
Fe3O4@SiO2@urethane catalysts using TESPIC as an effi-
cient precursor. These easily recyclable catalysts were
used efficiently for one‐pot multicomponent synthesis of
α‐aminonitriles in Strecker reaction using numerous alde-
hydes or ketones, TMSCN and amines under solvent‐free

8 of 10
BAGHERY ET AL.
conditions at 50 °C. Due to the integrative combination
of various advantages such as facile synthesis, ease of
recovery and solvent‐free reaction conditions, the protocol
presented can be considered as an environmentally benign
approach for synthesizing α‐aminonitriles via the Strecker
reaction. This investigation can open up a new insight
into the course of design, synthesis and applications of
urea or urethane fertilizer‐based MNP catalysts for sus-
tainable methods.
4.1.2 | Nitrilotris(ethane‐2,1‐diyl)tris((3‐
(triethoxysilyl)propyl)carbamate) (7)
4 | EXPERIMENTAL
4.1 | General procedure for synthesis of
compounds with urea or urethane moieties
(6–9)
Yellow viscous liquid; yield 94%. IR (KBr, ν, cm−1):
3370, 3237, 3090, 2979, 2932, 2915, 1692, 1598, 1483,
1
1417, 1306, 1109, 1105, 961, 781. H NMR (400 MHz,
DMSO‐d6, δ, ppm): 7.02 (s, 1H, ─NH), 3.71 (q,
J = 6.9 Hz, 6H, H─C7), 3.39 (dd, J = 16.6, 6.7 Hz, 4H,
H─C1 and H─C2), 2.91 (q, J = 6.1 Hz, 2H, H─C5), 1.42 (t,
J = 7.0 Hz, 2H, H─C4), 1.12 (t, J = 7.0 Hz, 6H, H─C8),
1.04 (t, J = 7.0 Hz, 5H, H─C6 and H─C8). 13C NMR
(100 MHz, DMSO‐d6, δ, ppm): 166.8 (C3), 62.8 (C1), 48.3
(C4), 46.2 (C2), 38.9 (C7), 27.8 (C6), 23.8 (C5), 17.1 (C8).
TESPIC (5 mmol; 1.237 g; 1.238 ml) was added to sub-
strates 2 to 5 (5 mmol) in a round‐bottom flask and the
resulting mixture was stirred for 30 min at 50 °C
(Scheme 1). After completion of the reaction, the
resulting mixture was washed repeatedly with diethyl
ether (10 ml) to remove any unreacted starting materials
and to obtain the highest possible purity. The resulting
viscous liquids were then dried under vacuum at 50 °C
for 30 min. All the synthesized compound 6–9 were iden-
HRMS (ESI/TOF‐Q) m/z: [M
+
H]+. Calcd for
C36H79O15N4Si3: 891.48492; found: 891.48442.
1
tified using FT‐IR, H NMR, 13C NMR and HRMS (refer
to supporting information; Figures S1–S24).
4.1.3 | 1‐(Pyridin‐2‐yl)‐3‐(3‐(triethoxysilyl)
propyl)urea (8)
4.1.1 | N1,N4‐Bis(3‐(triethoxysilyl)propyl)
piperazine‐1,4‐dicarboxamide (6)
Orange viscous liquid; yield 96%. IR (KBr, ν, cm−1):
3377, 3245, 2978, 1691, 1590, 1484, 1108, 1105, 964, 781.
1H NMR (400 MHz, DMSO‐d6, δ, ppm): 9.15 (s, 1H,
─NH), 8.24 (s, 1H, ─NH), 8.12 (d, J = 4.2 Hz, 1H,
H─C1), 7.62 (t, J = 7.8 Hz, 1H, H─C2), 7.31 (d,
J = 8.4 Hz, 1H, H─C3), 6.86 (t, J = 6.8 Hz, 1H, H─C4),
3.71 (q, J = 7.0 Hz, 6H, H─C10), 3.43 (q, J = 7.0 Hz, 1H,
H─C8), 3.14 (q, J = 7.0 Hz, 1H, H─C8), 1.51 (t,
J = 7.2 Hz, 2H, H─C7), 1.11 (t, J = 7.0 Hz, 6H, ─H─C11),
1.04 (t, J = 7.0 Hz, 5H, H─C9 and H─C11). 13C NMR
(100 MHz, DMSO‐d6, δ, ppm): 157.8 (C6), 156.6 (C5),
149.6 (C1), 141.1 (C2), 119.6 (C4), 114.6 (C3), 60.7 (C7),
59.1 (C10), 44.6 (C9), 26.3 (C8), 21.2 (C11). HRMS (ESI/
TOF‐Q) m/z: [M + H]+. Calcd for C15H28O4N3Si:
342.18428; found: 342.18436.
Yellow viscous liquid; yield 95%. IR (KBr, ν, cm−1):
3379, 2982, 2968, 2918, 1638, 1548, 1396, 1259, 1114,
1
1107, 962, 796. H NMR (400 MHz, DMSO‐d6, δ, ppm):
6.49 (s, 1H, ─NH), 4.32 (t, J = 4.9 Hz, 2H, H─C3), 3.71
(q, J = 7.0 Hz, 6H, H─C6), 3.42 (t, J = 4.9 Hz, 2H,
H─C5), 3.20 (s, 4H, H─C1), 2.96 (q, J = 7.0 Hz, 2H,
H─C4), 1.12 (t, J = 7.0 Hz, 6H, H─C7), 1.04 (t,
J = 7.0 Hz, 3H, H─C7). 13C NMR (100 MHz, DMSO‐d6,
δ, ppm): 160.4 (C2), 60.7 (C1), 59.1 (C3), 46.2(C6), 46.0
(C5), 21.6 (C4), 21.3 (C7). HRMS (ESI/TOF‐Q) m/z:
[M + H]+. Calcd for C24H53O8N4Si2: 581.33988; found:
581.33964.

BAGHERY ET AL.
9 of 10
(1.5 mmol; 0.149 g; 0.188 ml) and amine derivatives
(1 mmol) under solvent‐free conditions at 50 °C. The prog-
ress of the reaction was monitored by TLC (n‐hexane–ethyl
acetate, 5:2). At the end of the reaction, the product was
washed with ethanol and the catalyst was separated using
an external magnet (the products are soluble in ethanol).
The recycled catalyst was used in the next run of the model
reaction without significant loss of activity. The solvent of
the organic layer was removed and the crude product was
purified using a short column of silica gel (n‐hexane–ethyl
acetate, 20:1) to yield pure products.
4.1.4 | 1‐(Pyridin‐4‐yl)‐3‐(3‐(triethoxysilyl)
propyl)urea (9)
Red viscous liquid; yield 97%. IR (KBr, ν, cm−1): 3407,
3314, 2986, 1712, 1600, 1554, 1213, 1111, 1087, 828. H
ACKNOWLEDGEMENTS
1
We thank Bu‐Ali Sina University and Iran National Science
Foundation (INSF) for financial support (grant of
AllamehTabataba‘i's Award, grant no. BN093) and the
National Elites Foundation.
NMR (400 MHz, DMSO‐d6, δ, ppm): 8.85 (s, 1H, ─NH),
8.30 (dd, J = 33.5, 5.8 Hz, 2H, H─C3), 7.40 (dd, J = 30.2,
5.9 Hz, 2H, H─C2), 4.38 (s, 1H, ─NH), 3.73 (t,
J = 7.0 Hz, 2H, H─C5), 3.68 (t, J = 7.0 Hz, 2H, H─C7),
3.43 (q, J = 7.0 Hz, 6H, H─C8), 3.06 (q, J = 7.0 Hz, 2H,
H─C6), 1.12 (t, J = 7.0 Hz, 6H, H─C9), 1.04 (t,
J = 7.0 Hz, 3H, H─C9). 13C NMR (101 MHz, DMSO, δ,
ppm): 157.6 (C4), 153.2 (C1), 152.9 (C3), 151.9 (C2), 60.7
(C5), 59.1 (C8), 44.8 (C7), 21.5 (C6), 21.2 (C9). HRMS
(ESI/TOF‐Q) m/z: [M + H]+. Calcd for C15H28O4N3Si:
342.18439; found: 342.18436.
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SUPPORTING INFORMATION
Additional Supporting Information may be found online in
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How to cite this article: Baghery S, Zolfigol MA,
Schirhagl R, Hasani M, Stuart MCA, Nagl A.
Synthesis of novel magnetic nanoparticles with urea or
urethane moieties: Applications as catalysts in the
Strecker synthesis of α‐aminonitriles. Appl
Organometal Chem. 2017;e3883. https://doi.org/
10.1002/aoc.3883
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