Copper@PMO nanocomposites as a novel reusable heterogeneous catalyst for microwave-assisted green synthesis of β-hydroxy-1,2,3-triazoles through experimental design protocol

Article abstract of DOI:10.1002/aoc.3293

A microwave-assisted multicomponent reaction was used to prepare a series of β-hydroxy-1,2,3-triazoles in the presence of copper@PMO nanocomposites as a catalyst. Box-Behnken design and response surface methodology were used to optimize the influencing pa

Full text of DOI:10.1002/aoc.3293

Full Paper
Received: 6 December 2014
Revised: 17 January 2015
Accepted: 20 January 2015
Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI 10.1002/aoc.3293
Copper@PMO nanocomposites as a novel
reusable heterogeneous catalyst for
microwave-assisted green synthesis of β-
hydroxy-1,2,3-triazoles through experimental
design protocol
Hossein Naeimia*, Vajihe Nejadshafieea and Saeed Masoumb
A microwave-assisted multicomponent reaction was used to prepare a series of β-hydroxy-1,2,3-triazoles in the presence of
copper@PMO nanocomposites as a catalyst. Box–Behnken design and response surface methodology were used to optimize
the influencing parameters such as catalyst content, reaction time and microwave power, being an economical way of obtaining
the optimal reaction conditions based on restricted number of experiments. Aqueous reaction medium, easy recovery of catalyst,
efficient recycling and high stability of the catalyst render the protocol sustainable and economic. Copyright © 2015 John Wiley &
Sons, Ltd.
Additional supporting information may be found in the online version of this article at the publisher’s web site.
Keywords: nanocomposites; microwave; β-hydroxy-1,2,3-triazoles; catalyst; experimental design
One-pot synthesis of β-hydroxy-1,2,3-triazoles from epoxides,
Introduction
linked to dipolar cycloaddition with azide and alkyne through vari-
ous heterogeneous copper salts supported on zeolites,[20] silica,[21]
Microwave-assisted organic synthesis is considered as a ‘green’
activated carbon[22] and multi-walled carbon nanotubes,[23] has
technology, principally since many organic reactions can be
carried out in aqueous media or under solvent-free conditions.[1,2]
received significant attention in recent times.
It is well known that microwave-assisted organic synthesis has
shown broad applications as a very efficient way to accelerate a
great number of organic reactions, producing high yields, lower
quantities of side products and, especially, the reaction time
and energy input are supposed to be much reduced in reactions
that otherwise run for a long time at high temperatures under
conventional conditions.[3–6] Multicomponent reactions (MCRs),
specified as one-pot reactions in which at least three different
substrates combine through covalent bonds, have steadily
gained increasing importance in synthetic organic chemistry.
MCRs make possible the creation of several bonds in a single
procedure, with operational simplicity, and hence reducing the
number of workup and purification processes, rendering the
transformations green.[7] Furthermore, one-pot MCRs often give
higher chemical yields than multiple-step syntheses, with shorter
reaction periods, and therefore can reduce the use of energy
and personnel.[8,9]
In continuation of our previous research on the preparation of or-
ganometallic silica frameworks[21,24] and their applications in or-
ganic reactions, herein we report the in situ synthesis of
organoazides from corresponding epoxides and sodium azide,
whereupon they are entrapped by copper-imprinted periodic
mesoporous organosilica nanocomposite (Cu@PMO NC) acetylides,
forming the corresponding β-hydroxy-1,2,3-triazole. The products
are easily isolated by simple filtration.
To further improve the user-friendliness and efficiency of this
process, a practical MCR variant under microwave irradiation was
developed. At the outset of this study, to determine the optimized
conditions for the reaction, an experimental design (Box–Behnken
design) using response surface methodology was performed, and
hence the three variants of catalyst content, microwave power
and reaction time were selected to obtain the best results in terms
of yield of MCRs.[25]
One classical method for synthesis involves thermal 1,3-dipolar
cycloaddition of alkynes with organic azides.[10–12] However, this
procedure is associated with low yields, elevated temperature and
lack of selectivity. The Huisgen 1,3-dipolar cycloaddition of alkynes
and azides resulting in 1,2,3-triazoles is one of the most powerful
MCRs.[13] To overcome certain drawbacks, an improved procedure
involving copper-catalysed alkyne–azide 1,3-dipolar cycloaddition
was reported,[14–19] which provided high regioselectivity and room
temperature reaction.
*
Correspondence to: Hossein Naeimi, Department of Organic Chemistry, University
of Kashan, Kashan 87317, IR Iran. E-mail: naeimi@kashanu.ac.ir
a Department of Organic Chemistry, Faculty of Chemistry, University of Kashan,
Kashan 87317, IR Iran
b Department of Analytical Chemistry, Faculty of Chemistry, University of Kashan,
Kashan 87317, IR Iran
Appl. Organometal. Chem. (2015)
Copyright © 2015 John Wiley & Sons, Ltd.

H. Naeimi et al.
Table 1. Independent variables and their levels used in the Box–
behnken design
(CH3COO)2ꢀ6H2O, Ni(NO3)2 and Zn(CH3COO)2ꢀ2H2O) were supplied
by Fluka, Aldrich and Merck. FT-IR spectra were obtained as KBr pel-
lets with a PerkinElmer 781 spectrophotometer and a Nicolet Im-
Factor level
1
pact 400 FT-IR spectrophotometer. H NMR and 13C NMR spectra
Independent variable
ꢁ1
0
1
were recorded in CDCl3 and DMSO solvents using a Bruker DRX-
400 spectrometer with tetramethylsilane as internal reference.
TGA was carried out with an STA503 WinTA instrument at a heating
rate of 10 °C minꢁ1 under nitrogen atmosphere. X-ray diffraction
(XRD) patterns were recorded with an X-ray diffractometer (Bruker
D8 ADVANCE, Germany) using Cu Kα radiation (λ = 0.154056 nm)
in the range 2θ = 0.5–5°. Nitrogen adsorption–desorption analysis
(BET) was performed at ꢁ196 °C using an automated gas adsorp-
tion analyser (Tristar 3000, Micromeritics). The surface morphology
of the supported catalyst was studied using field-emission scanning
electron microscopy (FE-SEM). FE-SEM and elemental analysis were
carried out using a Jeol SEM instrument (VEGA/TESCAN) combined
with an INCA instrument for energy-dispersive X-ray spectroscopy
(EDS), with scanning electron electrode at 15 kV.
Microwave power (P)
Catalyst content (C)
Reaction time (t)
100
0.003
2
180
0.005
7
300
0.01
10
Figure 1. Structure of Schiff base ligand (1).
Experimental Design
A robustness study was carried out by means of a statistical exper-
imental design. A Box–Behnken design (BBD) was applied, which is
a class of rotatable second-order design based on three-level in-
complete factorial design. The number of experiments (N) required
for the development of the BBD is defined as N = 2f(f ꢁ 1) + nc
(where f is the number of influencing variables and nc is the number
of central points). In this study, three variables (catalyst content, mi-
crowave power and reaction time) were investigated. With this
number of variables and three centre points, a complete BBD would
result in a number of runs equal to 15.
The range of independent variables and their levels are pre-
sented in Table 1. The independent variables and their ranges were
chosen based on preliminary experiment results. The response
function (y) was the β-hydroxy-1,2,3-triazole production yield (%).
Synthesis of Functionalized LCu and Immobilization on Peri-
odic Mesoporous Silica
The
ligand
2,2′-((1E,1′E)-((6-amino-1,3,5-triazine-2,4-diyl)bis
(azanylylidene))bis(methanylylidene))diphenol (1) was synthesized by
dissolving salicylaldehyde (0.214 g, 2 mmol) and melamine (0.126 g,
1.0 mmol) in 5 ml of methanol and three drops of acetic acid. The reac-
tion mixture was heated under reflux at 100 °C for 4 h. After the
completion of the reaction, the ligand product was filtered, washed
with water and dried at ambient temperature resulting in the for-
mation of orange solid in 98% yield. FT-IR (KBr, ν, cmꢁ1): 3468,
3416, 3332, 3129, 1654, 1552, 1439, 1272. 1H NMR (400 MHz, DMSO,
δ, ppm): 10.71 (s, 2 H, HO-24), 10.24 (s, 2H, N¼CH, HC-7), 7.65–7.50
(m, 4 H, HC-2, HC-6, HC-20, HC-22), 6.98–6.63 (m, 4 H, HC-1, HC-3,
HC-19, HC-21), 6.04 (s, 2H, HN-25). 13C NMR (100MHz, DMSO, δ,
ppm): 178.34 (C-13), 174.44 (C-9, 11), 167.81 (C-4, 18), 164.94 (C-7,
16), 130.40 (C-6, 22), 128.82 (C-2, 20), 125.61 (C-1, 21), 121.09 (C-3,
19), 119.94 (C-5, 17), (C-3). Anal. Calcd for C17H14N6O2 (334.12) (%):
C, 61.07; H, 4.22; N, 25.14. Found (%): C, 61.10; H, 4.18; N, 25.15
(Fig. 1).
Scheme 1. General route for the synthesis of LCu (2), copper-imprinted
organopolysilane precursor (3) and Cu@PMO NC catalyst.
Experimental
To prepare the organometallic LCu (2), ligand 1 (0. 332 g, 1 mmol)
was dissolved in 15ml of dimethylformamide and treated with cop-
per acetate monohydrate (Cu(OAc)2ꢀH2O), heated under reflux for
3 h. Finally, the formed metal–ligand complex was filtered, washed
with 96% ethanol (50 ml) and dried for a day under vacuum to
Materials and Physical Measurements
Cetyltrimethylammonium bromide (CTAB), tetraethyl orthosilicate
(TEOS), 3-chloropropyltrimethoxysilane, 1,3,5-triazine-2,4,6-triamine
(melamine), salicylaldehyde and metal salts (Cu(CH3COO)2ꢀH2O, Co
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Appl. Organometal. Chem. (2015)

Copper@PMO nanocomposite-catalysed synthesis of triazoles
produce complex 2 as brown crystals in 95% yield. FT-IR (KBr, ν,
cmꢁ1): 3466, 3419, 3343, 3131, 1650, 1548, 1438, 1204.
water, and dried in a vacuum at 60°C for 12h. The surfactant was
removed by extracting the solid with a 0.05M ethanolic HCl solu-
tion at 60 °C for 6 h (50 ml of 0.05 ethanolic HCl for 1 g of solid ma-
terial). The obtained material is designated as Cu@PMO NCs.
A typical synthesis of Cu@PMO NCs was carried out as follows.
Complex 2 (0.5g, 1.3mmol) was dissolved in 60 ml of dry ethanol.
To this, 0.5 ml (2.6 mmol) of 3-chloropropyltrimethoxysilane was
added dropwise under a nitrogen atmosphere in the presence of
NaH as base. The reaction mixture was stirred at 60 °C for 24 h under
nitrogen atmosphere. Subsequently, the reaction mixture was fil-
tered, concentrated under vacuum, purified with diethylether
(3× 50 ml) and dried under vacuum to afford copper-imprinted
organopolysilane precursor (3). Then 1.0g of CTAB (2.74mmol)
was dissolved in 47 ml of distilled water. The solution was stirred
for 10 min, followed by the addition of 11 ml of ammonia (25%)
and stirred for a further 30min to obtain a clear solution. A
premixed propanol solution of 3 and TEOS were added to the sur-
factant solution. The molar composition of the final synthetic mix-
ture was TEOS:3:CTAB:NH3:H2O:propanol= (1 + x):x:0.12:8.0:114:7,
where x =0.05 for Cu@PMO NCs. The reaction mixture was stirred
at 35 °C for 24 h. The final mixture was then crystallized at 90 °C
for 24 h. The resulting solid was filtered and washed with deionized
Typical Procedure for Microwave-Assisted Synthesis of
β-Hydroxy-1,2,3-Triazole Using Cu@PMO NCs as Catalyst
The three-component reaction was carried out with treatment of
NaN3 (72 mg, 1.1 mmol), epoxide (1mmol), alkyne (1mmol),
Cu@PMO NCs (6mg, 0.28 mol%) in water (3ml). The reaction flask
was irradiation in a microwave oven with a power of 277 W for
6.50 min. At the end of the reaction, the reaction mixture was
cooled to room temperature. In order to separate the catalyst, the
product was dissolved in hot methanol; subsequently, the whole
mixture was directly passed through a sintered glass filter funnel,
and the solvent was removed in vacuum to give the corresponding
Figure 2. XRD spectrum of Cu@PMO NCs.
Figure 3. FT-IR spectra of (a) ligand, (b) LCu and (c) Cu@PMO NCs.
Figure 4. (a) FE-SEM image and (b) EDS analysis of Cu@PMO NCs.
Appl. Organometal. Chem. (2015)
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H. Naeimi et al.
Results and Discussion
Analysis of Catalysts
The preparation of PMO functionalized with organocopper groups
was initially achieved by synthesis of ligand L (1) and its complex
LCu (2) as source of copper-imprinted organopolysilane precursor
(3). Furthermore, the Cu@PMO NC catalyst was obtained by stirring
surfactant, TEOS and precursor 3 under basic conditions in distilled
water (Scheme 1).
Characterization of Catalyst
The catalyst was characterized using various techniques including
FE-SEM, XRD, TGA), FT-IR spectroscopy, EDS, atomic absorption
spectroscopy and nitrogen adsorption–desorption analysis.
As shown in Fig. 2, the deflections at d (100), d (110) and d
(200) in the XRD pattern of Cu@PMO NCs confirm that the
ordered hexagonal symmetry was retained after copper-imprinted
organopolysilane (3) functionalization.
The FT-IR spectrum of Cu@PMO NCs exhibits a broad band in
the hydroxyl region at 3367 cmꢁ1. The C¼N stretching vibration
frequency of Cu@PMO NCs is observed at 1561 cmꢁ1. The bands
at 2853 and 2923 cmꢁ1 are assigned to the C–H stretching
vibrations of propyl and methyl groups, respectively. The peak at
1474 cmꢁ1 is characteristic of N–C vibrations of the aromatic
functional groups related to the Cu@PMO NCs. The band in the
range 1000–1100 cmꢁ1 is assigned to Si–O–Si groups and the band
at 961 cmꢁ1 is attributed to Si–OH groups (Fig. 3(c)).
As shown in Fig. 4(a) the FE-SEM image reveals the presence of
ordered mesostructures in the materials. However, the copper-
imprinted organopolysilane (3) groups on the surface were further
confirmed using the following calculations (Fig. 4(b)).
The nitrogen gas adsorption measurements show IV patterns
with H3 hysteresis loops[27] that are characteristic of mesoporous
Cu@PMO NCs. The BET surface area and total pore volume of
Cu@PMO NCsare462.40 m2 gꢁ1 and 0.5cm3 gꢁ1, respectively(Fig. 5
(a)). Furthermore, the pore diameter is calculated according to the
BJH model to be 3.98 nm (Fig. 5(b)).
Figure 5. (a) Nitrogen adsorption–desorption isotherm and (b) pore size
distribution curve of Cu@PMO NCs.
The thermogravimetric traces (Fig. 6) indicate a weight loss
between 100 and 250°C for all samples due to loss of water
adsorbed on the materials. The weight loss for Cu@PMO NCs in
the range 300 to 800 °C can be due mainly to the loss of copper-
imprinted organopolysilane (3) groups.
Statistical Analysis of Yield of β-Hydroxy-1,2,3-Triazole
Statistical experimental design was applied to determine the
influence of the operational conditions of the reaction.[25,28] A series
of experiments were performed with the standard reaction of
styrene oxide, phenylacetylene and sodium azide as a model reac-
tion. The effects of different variables such as microwave power,
catalyst content and reaction time in the three-component reaction
were investigated. The influence of these variables was observed
through a BBD using the response surface methodology. A series
of experiments was carried out by considering a BBD (Table 2).
Figure 6. TGA thermograms of Cu@PMO NCs.
Effects of Major Variables
Response surface methodology uses the BBD to fit a model using
the least-squares technique. Evaluation of the proposed model is
performed using the diagnostic checking test that is provided by
analysis of variance (ANOVA).
product. The resulting products were characterized and identified
by comparing their physical and spectral data with those of authen-
tic samples.[20–23,26]
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Copper@PMO nanocomposite-catalysed synthesis of triazoles
According to the results obtained from ANOVA, validation of the
model is based on the coefficient of determination R2 (99.99%) that
indicates good predictive ability of the model. The significance of
the model and the effect of influencing variables can be assessed
by F-test and P-values (Table 3). The P-values are used to determine
significance of the variables. Any variable or interaction of variables
with P < 0.05 is considered to be significant, and the insignificant
ones (P > 0.05) can be removed from the model. Results obtained
from ANOVA show that the microwave power, catalyst content,
reaction time and interaction between variables have important
effects on the yield of β-hydroxy-1,2,3-triazole.
Investigation of Three-Component Reaction Using Factorial
Design of Experiments
The influence of different variables in the reaction was now studied
using experimental design methodology and it reveals the
potential application of microwaves in the synthesis of β-hydroxy-
1,2,3-triazoles using Cu@PMO NC catalyst. When the reaction is
carried out under the optimized conditions (277 W (P), 0.006 g
(C, 0.28 mol% Cu) and 6.50min (t)), it gives excellent yields of
product in short reaction time. It is worth mentioning that this
methodology has also been developed for an experimentally
convenient in situ synthesis of β-hydroxy-1,2,3-triazoles from epox-
ides, sodium azide and phenylacetylene under green condition.
The results are summarized in Table 4. For the reaction with the aryl
epoxides, the yield of product is found to be relatively high and the
reaction is completed within 6.5min (Table 4, entries 1 and 2). The
reaction of alkyl epoxides in this procedure gives lower yields
(Table 4, entries 3–10). It is observed that bis-triazoles can be
In order to gain insight into the effect of each variable, three-
dimensional surface plots and two-dimensional contour plots
based on the polynomial function
y ¼ 94:40 þ 7:30P þ 0:125C þ 0:450t ꢁ 4:491P2 ꢁ 2:741C2
(1)
ꢁ 2:641t2 þ 0:650PꢂC þ 0:250Pꢂt ꢁ 4:000Cꢂt
to analyse the change in the response surface were also obtained,
as shown in Fig. 7. This shows the three- and two-dimensional plot
relationship between two variables and y (β-hydroxy-1,2,3-triazole
yield) at centre level of other variables. For example, the effect
of microwave power (P) and catalyst content (C) on β-hydroxy-
1,2,3-triazole yield (y) at centre level of reaction time (t) is shown
in Fig. 7(a). As shown in Fig. 7, there are nonlinear relations between
β-hydroxy-1,2,3-triazole yield and variables P, C and t.
Response optimization results of the nonlinear polynomial
model give the maximal yield of 97.54% at the optimal parameters
of P (0.818), C (0.091) and t (0.051), i.e. β-hydroxy-1,2,3-triazole yield
is 97.54% for the conditions of 277 W (microwave power), 0.006 g
(catalyst content) and 6.50 min (reaction time).
Table 3. Effect of parameter estimates for β-hydroxy-1,2,3-triazole
production
Variable
Effect
Standard
error
F-test
P-value
Mean
94.530
7.300
0.111
0.068
0.068
0.068
0.100
0.100
0.100
0.096
0.096
0.096
—
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
<0.0001
0.004
Microwave power (P)
41256.77
12.10
Catalyst content (C)
0.125
Reaction time (t)
0.450
156.77
7208.96
2685.88
2493.52
163.55
24.19
P × P
C × C
t × t
ꢁ4.491
ꢁ2.741
ꢁ2.641
0.650
P × C
P × t
C × t
0.250
ꢁ4.000
6193.55
<0.0001
Table 2. Experimental design and results of BBD for β-hydroxy-1,2,3-triazole productiona
Entry
Microwave power
Catalyst contenta
Reaction time
Yield (%)
1
100 (ꢁ)
180 (0)
100 (ꢁ)
100 (ꢁ)
300 (+)
180 (0)
180 (0)
100 (ꢁ)
180 (+0)
300 (+)
180 (0)
180 (0)
180 (0)
300 (+)
300 (+)
0.005 (0)
0.01 (+)
2 (ꢁ)
10 (+)
7 (ꢁ)
7 (ꢁ)
2 (ꢁ)
2 (0)
79.8
85.7
79.5
80.6
94.0
84.6
94.5
80.3
94.6
93.8
94.5
92.9
93.4
95.5
95.3
2
3
0.01 (+)
4
0.003 (ꢁ)
0.005 (0)
0.003 (ꢁ)
0.005 (0)
0.005 (0)
0.005 (0)
0.003 (ꢁ)
0.005 (0)
0.01 (+)
5
6
7
7 (0)
8
10 (0)
7 (0)
9
10
11
12
13
14
15
7 (0)
7 (0)
2 (ꢁ)
10 (+)
10 (+)
7 (0)
0.003 (ꢁ)
0.005 (0)
0.01 (+)
a+ upper, 0 central, ꢁ, lower.
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H. Naeimi et al.
obtained from the predictable ring opening of epoxides related to
entries 9 and 10. Also cyclooctene oxide and cyclododecene oxide
do not react in this case and remain unchanged even after -
extended reaction time for microwave irradiation for 8 h (Table 4,
entries 11 and 12). This can be related to the steric hindrance
effect of epoxide on the nucleophilic attack of NaN3. However,
it is not so unexpected since the azidolysis of cyclooctene oxide
and cyclododecene oxide was already described as problematic
in the literature. Consequently, the results show that Cu@PMO
NC is a highly efficient catalytic system for the azidolysis of alkyl
and aryl epoxides followed by the cycloaddition of resulting az-
ido alcohols with phenylacetylene to afford β-hydroxy-1,2,3-
triazoles.
Mechanistic Aspects
A proposed mechanism for the formation of β-hydroxy-1,2,3-
triazole[21] may involve two possible pathways in which Cu@PMO
NCs have a dual catalytic role as a bifunctional catalyst which com-
bines two reactions in one-pot ring opening. Firstly, Cu@PMO NCs
catalyse the formation of 2-azido-1-aryl/alkyl ethanol intermediate
(I) from epoxide and sodium azide (Scheme 2). Also, a π-complex
is formed between phenylacetylene and Cu@PMO NCs to afford
the copper(II) acetylide intermediate (II), with the phenylacetylene
consumption and also the generation and disappearance of the
2-azido-1-phenylethanol intermediate being monitored by TLC.
Finally, the 1,3-dipolar cycloaddition between the intermediates
Figure 7. (a, c, e) Response surface plots and (b, d, f) contour plots corresponding to predicted yield for the reaction.
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Copper@PMO nanocomposite-catalysed synthesis of triazoles
(II) and (I) would afford the copper(II) β-hydroxytriazolide intermedi-
ate (III). After protonolysis of intermediate (IV), β-hydroxy-1,2,3-
triazole is obtained in high yield and short reaction time.
Furthermore, as is evident from Table 4 (entries 9 and 10), it is not
any tosyl-substituted azide compound, but bis-triazole that is pro-
duced in the reaction. The pathway for preparation of bis-triazole
(i) in this reaction can be due to the presence of good leaving
groups (Cl, OTs) in the structure of related epoxides. The various
steps of the formation of bis-triazole (i) are shown in Scheme 3.
To the best of our knowledge, epoxide 4 and diazido alcohol 5
are initially formed as reaction intermediates. The diazido alcohol
5 in the click reaction with phenylacetylene and Cu@PMO NCs as
a catalyst is converted to the bis-triazole (i).
Recycling of Catalyst
The Cu@PMO NC catalyst is easily recyclable at least six times
(Table 5). Upon completion of the reaction, the catalyst was recov-
ered from the reaction mixture by simple filtration, washed with
double-distilled water and dried at 100°C in an oven for 3 h, and
was then used in the next reaction run. The fresh catalyst as well
as the recycled catalyst shows remarkably constant catalytic activity
in all six cycles (Table 5).
Scheme 2. Proposed mechanism for the synthesis of β-hydroxy-1,2,3-
triazole catalysed by Cu@PMO NCs.
effective in the study of the influence of different variables on this
process. These optimum conditions can be used for future upscaled
Cu@PMO NC production of β-hydroxy-1,2,3-triazole by considering
all of the environmental and economic evaluations. This synthetic
method, using a combination of supported catalyst and microwave
Conclusions
The use of a BBD for the optimization of the synthesis of β-hydroxy-
1,2,3-triazole using Cu@PMO NCs as a nanocatalyst was found to be
Table 4. Three-component synthesis of β-hydroxy-1,2,3-triazoles from epoxides 1a–l, phenylacetylene and sodium azide catalysed by Cu@PMO NCs in
watera
Entry
R1
Product
Yield (%)b
TONc/TOFd
1
Ph
a
b
c
d
e
f
97.54
98
86
80
86
89
79
76
74
78
—
366/52.28
366/73.2
333/15.13
322/10.06
377/23.56
340/34
2
P-CH3C6H4
n-But-1,4-diyl
C4H9
3
4
5
C2H5
6
PhOCH2
7
(CH3)2CHOCH2
C2H2CO2CH2
Cl-CH2
g
h
i
329/20.56
344/8.6
299/9.96
311/18.29
—
8
9e
10e
11
12
TsO-CH2
i
n-Hex-1,6-diyl
n-Dec-1,10-diyl
j
k
—
—
aReaction conditions: epoxide (1 mmol), phenylacetylene (1 mmol), NaN3 (1.1 mmol), Cu@PMO NCs (0.28 mol%, 6 mg), H2O, under microwave power
(277 W), reaction time 7 min.
bIsolated yields.
cTON: mole of β-hydroxy-1,2,3-triazole formed per mole of catalyst.
dTOF: TON per time (min).
eThe reaction was done with 1:2:2 mol ratio of epoxide, alkyne and NaN3, respectively.
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H. Naeimi et al.
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Table 5. Test of recyclability of catalyst using synthesis of β-hydroxy-
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Run
Time (min)
Power (W)
Yield (%)
1st
7
7
7
7
7
7
277
277
277
277
277
277
97.54
97.54
95.50
95.50
95.50
93.40
2nd
3rd
4rd
5th
6th
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power, has advantages because it involves less costly, nontoxic re-
agents, green reaction conditions, short times and high conversions
and uses an easily recyclable catalyst that shows no leaching and
generates high yields of products. Furthermore, the availability
and nontoxicity of copper as well as the mild synthetic and
reaction conditions involved make the synthetic process appealing
from an environmental point of view.
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Acknowledgement
The authors are grateful to the University of Kashan for supporting
this work through grant no. 159148/44.
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Supporting Information
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Appl. Organometal. Chem. (2015)