[bmim]PF6/KOH: A recyclable catalytic system for an azide–arylacetaldehyde [3 + 2] cycloaddition

Article abstract of DOI:10.3184/174751917X15094552081152

A fast and green protocol for the synthesis of 1,4-disubstituted 1,2,3-triazoles from azides and arylacetaldehydes at room temperature was developed using [bmim]PF₆/KOH as the reaction medium. It was found that the in situ-generated carbene fro

Full text of DOI:10.3184/174751917X15094552081152

JOURNAL OF CHEMICAL RESEARCH 2017
VOL. 41 NOVEMBER, 631–635
RESEARCH PAPER 631
[bmim]PF6/KOH: a recyclable catalytic system for an azide–arylacetaldehyde
[3 + 2] cycloaddition
Yuqin Jiang, Kai Wu, Xuxia Tan, Dandan Zhang, Wenpei Dong, Wei Li, Guiqing Xu and Weiwei
Zhang*
HenanEngineeringLaboratoryofChemicalPharmaceuticalsandBiomedicalMaterials,CollaborativeInnovationCenterofHenanProvinceforGreenManufacturing
of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Chemical Engineering, Henan
Normal University, Xinxiang, 453007 Henan, P.R. China
A fast and green protocol for the synthesis of 1,4-disubstituted 1,2,3-triazoles from azides and arylacetaldehydes at room temperature was
developed using [bmim]PF6/KOH as the reaction medium. It was found that the in situ-generated carbene from [bmim]PF6/KOH acted as
the catalyst. In the absence of a transition-metal catalyst and organic solvent, this azide–arylacetaldehyde [3 + 2] cycloaddition proceeds
efficiently, with high levels of regioselectivity, broad range of substrates, excellent yields and simple operation under mild conditions.
Keywords: 1,4-disubstituted 1,2,3-triazoles, ionic liquid [bmim]PF6/KOH, arylacetaldehydes
1,4-Disubstituted-1,2,3-triazoles are widely used in the
pharmaceutical industry due to their considerable biological
activity. The best-known regioselective formation of
1,4-disubstituted-1,2,3-triazoles is the copper(i)-catalysed
azide–alkyne cycloaddition (CuAAC) reaction. Compared with
the classical thermal Huisgen reaction,1 the CuAAC reaction is
considered to be a very reliable and straightforward method for
the regioselective synthesis of 1,4-disubstituted-1,2,3-triazoles.
Although the CuAAC reaction has been widely used in organic
synthesis, medicinal chemistry, surface and polymer chemistry,
and bioconjugation applications, its use in chemical biology
has some limitations due to the cytotoxicity of copper ions in
living organisms. For this reason, a metal-free catalytic azide–
aldehyde [3 + 2] cycloaddition has been developed (Scheme 1,
previous work).2,3 In 2013, Wang and co-workers developed2
an inverse-electron-demand 1,3-dipolar cycloaddition reaction
between various azides and unsaturated aldehydes catalysed by
diethylamine in DMSO at 50 ºC using DBU as the base. This
has been used to synthesise 1,4-disubstituted 1,2,3-triazoles
with high levels of regioselectivity. In the following year,
Ramachary and co-workers reported3 a DBU-catalysed azide–
aldehyde [3 + 2] 1,3-dipolar cycloaddition reaction in DMSO
at room temperature between azides and enolisable aldehydes
to form 1,4-disubstituted 1,2,3-triazoles. Such metal-free
Previous works
a) enamine-mediated Azide-aldhyde [3+2] cycloaddition
N
Ar2
H
C O
N
H
N
N
(10mol%)
Ar2 N3
+
Ar1
Ar1
DBU (10 mol%)
DMSO, 50 oC
b) enolate-mediated Azide-aldhyde [3+2] cycloaddition
H
C O
N
r
A
DBU (10 mol%)
DMSO, r.t.
N
N
+
Ar N3
R
R
This work
H
C O
N
Ar
KOH (50 mol%)
[bmIm]PF6, r.t.
N
N
+
Ar N3
Scheme 1 Azide–aldehyde [3 + 2] cycloaddition reaction for synthesis of 1,4-disubstituted 1,2,3-triazoles.
* Correspondent. E-mail: zhangweiwei@htu.edu.cn

632 JOURNAL OF CHEMICAL RESEARCH 2017
azide–aldehyde [3 + 2] 1,3-dipolar cycloaddition reactions are
considered to be alternatives to the previous CuAAC reactions
due to their high rate and regioselectivity, mild reaction
conditions, easily available substrates and excellent yields.
However, the use of organic solvents (DMSO) and catalysts
(DBU and diethylamine) could potentially cause various
health and environmental concerns due to their volatility and
toxicity. The preferred green solvents used for the synthesis
of 1,4-disubstituted 1,2,3-triazoles are water,4–7 supercritical
carbon dioxide (ScCO2)8–10 and ionic liquids.11–13
An ionic liquid is a salt in the liquid state, which presents
unique properties, such as high thermal stability, good solvating
ability, negligible vapour pressure and ease of recyclability.
Among them, the room temperature ionic liquids usually
consisting of bulky and asymmetric organic cations, such as
1-alkyl-3-methylimidazolium, 1-alkylpyridinium, N-methyl-
N-alkylpyrrolidinium or ammonium ions, have shown great
promise as attractive alternatives to conventional volatile
and toxic organic solvents. To the best of our knowledge, the
azide–aldehyde [3 + 2] 1,3-dipolar cycloaddition reaction for
the synthesis of 1,4-disubstituted 1,2,3-triazoles performed in
a green ionic liquid has not been reported previously. Thus,
taking into account the economic and environmental aspects,
we decided to synthesise 1,4-disubstituted 1,2,3-triazoles in
ionic liquids using an inorganic base as the catalyst. Following
our previous work on the synthesis of 1,4-disubstituted
1,2,3-triazoles,4,5 the main work described in this paper reveals
a green protocol using [bmim]PF6/KOH as the reaction medium
and catalyst for the azide–aldehyde [3 + 2] cycloaddition
reaction with a much easier work-up and purification (Scheme
1, this work).
catalyst (10 mol%) and [bmim]PF6 (5.0 mL) at room temperature
to screen suitable inorganic base catalysts are shown in Table
1. The model reaction was initially carried out in the absence
of inorganic bases for 30 min and no products were obtained
(Table 1, entry 1). Meanwhile, when using a weak inorganic
base as the catalyst, such as Na2CO3, K2CO3 or KHCO3 (Table
1, entries 2–4), the model reaction yielded the products in less
than 5%, which indicated that the phenylacetaldehyde could
not be enolised by weak bases. Therefore, the strong inorganic
base KOH (10 mol%) was used and the yield increased to 20%
in 30 min. When increasing the catalyst loading of KOH to 40
mol% (Table 1, entries 5–8), the yield reached 90%. A further
increase in the catalyst loading of KOH to 50 mol% (Table 1,
entry 9) gave almost the same yield in 10 min. According to
these results, it was concluded that the stronger the alkaline,
the more loading of the catalyst, the faster the reaction rate. The
selected catalyst loading of KOH was 40 mol%.
A mechanism for the azide–aldehyde [3 + 2] cycloaddition
reaction in [bmim]PF6 in the presence of KOH was also proposed
and studied (Scheme 3). First, the [bmim]PF6 could react with
KOH to produce a mixture of carbene and water. Second, the
generated carbene could convert the aldehyde to its corresponding
enolate. Then the enolate reacted with aryl azides to form the
adduct 1,2,3-triazolines. The adducts subsequently underwent
elimination and were converted to the 1,4-disubstituted
1,2,3-triazoles.3 To provide some experimental support for the
mechanistic proposal, the 1H NMR spectra of [bmim]PF6 in [D6]
DMSO before and after the addition of KOH were determined
and the results are shown in ESI Fig. 1. It can be seen from ESI
Fig. 1a that the signal at 9.1 ppm was assigned to the C2–H in
[bmim]PF6. The disappearance of the signal at 9.1 ppm in
ESI Fig. 1b was clearly observed, which indicated that OH− is
removing the C2–H in [bmim]PF6 to generate the corresponding
carbene.14,15 In addition, the stability of the generated carbene was
tested by adding extra water to the system containing [bmim]PF6
and KOH in [D6]DMSO. It can be seen from ESI Fig. 1c that the
signal at 9.1 ppm did not recover and the signal of H2O could be
seen at 3.8 ppm, which indicated that this carbene was stable in
the presence of water.
Results and discussion
The reaction between phenylacetaldehyde and phenyl
azide was selected as the model reaction for optimising
the reaction conditions (Scheme 2). First, in the light of
economic and environmental concerns, the reaction conditions
were established as follows. The results of the reaction of
phenylacetaldehyde (1.0 mmol), phenyl azide (1.0 mmol),
Furthermore, it was confirmed by comparison of the 1H
NMR spectrum of [bmim]PF6 + KOH before and after addition
of phenylacetaldehyde in [D6]DMSO that the in situ-generated
carbene converted the aldehyde to its corresponding enolate. The
results are shown in ESI Fig. 2. As shown in ESI Fig. 2a,b, the
signals at 9.7 ppm and 9.1 ppm were assigned to the proton in
the aldehyde of phenylacetaldehyde and the C2–H in [bmim]PF6,
respectively. When KOH was added to [bmim]PF6, the C2–H in
[bmim]PF6 was removed and the corresponding carbene generated
(ESI Fig. 2c). At this time, phenylacetaldehyde was added. It can
be seen from ESI Fig. 2d that the signal at 9.7 ppm disappeared and
the signal at 9.1 ppm appeared. This indicated that the generated
carbene converted the aldehyde to its corresponding enolate.
In considering the economic and environmental aspects, the
lifetime and re-use of the ionic liquid and the catalyst are very
significant factors. The re-use of ionic liquids usually involves the
following procedures.6 After reaction completion, the products are
quantitatively recovered by simple pump filtration system. At the
same time, the catalytic carbene remains in the reaction mixture.
Fresh quantities of reactants are then introduced for another
reaction cycle. As can be seen from Table 2, the activity of the
remaining carbene was not lost after five cycles. No significant loss
of ionic liquid was observed.
N
CHO
N3
N
N
+
Scheme 2 Model reaction for optimising the reaction conditions.
Table 1 The model reaction was performed in [bmim]PF6 at room
temperaturea
Entry Catalyst
Catalyst loading (mol%) Time (min)
Yield (%)b
1
2
3
4
5
6
7
8
9
–
–
30
30
30
30
30
30
30
10
10
–
Na2CO3
K2CO3
KHCO3
KOH
KOH
KOH
KOH
KOH
10
10
10
10
20
30
40
50
<5
<5
<5
20
42
58
90
91
aReaction conditions: phenylacetaldehyde (1.0 mmol), phenyl azide (1.0 mmol), [bmim]
Finally, we considered that the optimised conditions are:
KOH (40 mol%), phenylacetaldehyde (1.0 mmol), phenyl azide
(1.0 mmol) and room temperature. With the optimised conditions
PF6 (5.0 mL) and room temperature.
bIsolated yields.

JOURNAL OF CHEMICAL RESEARCH 2017 633
N
PF6
N
-
H
KOH
N
N
O-
R
H
R
N
N
CH
CHO
+
KPF6
+H2O
Ar - N
HO
H
3
R
N
N
R
-H2O
N
N
Ar
N
Ar
N
Scheme 3 Proposed mechanism for the azide–aldehyde [3 + 2] cycloaddition catalysed by [bmim]PF6/KOH.
Table 2 The reusablity of the ionic liquid system
Experimental
Cycle
Yield (%)
1
95
2
94
3
93
4
94
5
90
All reagents were purchased from commercial sources and used
without further treatment, unless otherwise indicated. The products
were characterised using 1H NMR and 13C NMR (Bruker Avance/400)
with CDCl3 as the solvent and TMS as internal standard at room
Table 3 Synthesis of 1,4-disubstituted 1,2,3-triazoles catalysed by KOH
temperature (20
2 ºC). Data are presented as follows: chemical
in [bmim]PF6a
shift, integration, multiplicity (s = singlet, d = doublet, dd = double of
doublets, t = triplet, q = quartet, m = multiplet, br = broad) and coupling
constants (J) in Hertz (Hz).
N
N
H
C
O
N
R1
-
R1 N3
R2
Synthesis of triazoles; general procedure
R2
The ionic liquid [bmim]PF6 (5.0 mL) was treated with KOH (40 mol%,
22.4 mg), azides (1.0 mmol) and aldehydes (1.0 mmol). Then the
reaction mixture was vigorously stirred at room temperature and
monitored by TLC. The products were filtrated from the reaction
mixtures and recrystallised using pentane (PE)/ethyl acetate (EA)
as the solvent. All the known compounds were characterised by their
1H NMR and 13C NMR spectra.
1,4-Diphenyl-1H-1,2,3-triazole (a):16 White solid; m.p. 180–182 °C
(lit.17 183–184 °C); IR (KBr) (υmax cm−1): 3122, 3098, 2360, 1505, 1384;
1H NMR (400 MHz, CDCl3): δ 7.93 (t, J = 7.7 Hz, 2H), 7.50–7.43 (m,
3H), 7.38 (t, J = 7.4 Hz, 1H); 13C NMR (100 MHz, CDCl3): δ 148.4,
137.1, 130.3, 129.8, 128.9, 128.4, 125.9, 120.5, 117.6. MS (ESI) m/z: 222
[M + H]+.
Entry R1
R2
Product
Time (min) Yield(%)b
1
C6H5
H
H
H
H
H
H
H
H
a
b
c
d
e
f
g
h
i
j
k
l
m
n
0
p
q
r
10
60
30
30
30
30
30
60
40
90
70
70
60
60
30
60
30
30
90
86
90
93
91
86
90
87
92
87
86
88
93
90
95
89
92
90
2
3
4
5
6
7
8
9
C6H5CH2
o-FC6H4
o-F3CC6H4
o-ClC6H4
o-MeC6H4
p-MeC6H4
2,4,6-MeC6H4
C6H5
p-MeO
H
p-MeO
p-EtO
p-Cl
10
11
12
13
14
15
16
17
18
EtOOCCH2
C6H5CH2
C6H5CH2
C6H5CH2
C6H5CH2
C6H5
C6H5CH2
C6H5
2-Me-5-NO2C6H5 p-Me
1-(3-Chlorobenzyl)-4-phenyl-1H-1,2,3-triazole (b):16 White solid;
m.p. 107–109 °C (lit.18 108–110 °C); IR (KBr) (υmax cm−1): 3084, 3064,
2359, 1460, 1437, 1223, 1078, 1047, 765, 754, 694; 1H NMR (400 MHz,
CDCl3): δ 7.73 (d, J = 7.1 Hz, 2H), 7.63 (s, 1H), 7.33 (t, J = 7.5 Hz, 2H),
7.28–7.20 (m, 4H), 7.09 (d, J = 6.9 Hz, 1H), 5.46 (s, 2H); 13C NMR (100
MHz, CDCl3): δ 147.4, 135.6, 134.0, 129.4, 129.3, 128.0, 127.8, 127.2,
127.0, 125.0, 124.7, 118.5, 52.5. MS (ESI) m/z: 270 [M + H]+.
1-(2-Fluorophenyl)-4-phenyl-1H-1,2,3-triazole (c):19 White solid;
m.p. 99–101 °C (lit.19 101–102 °C); IR (KBr) (υmax cm−1): 3149, 3067,
2360, 2342, 1511, 1474, 1244, 1214, 1038, 1022, 817, 763, 691; 1H NMR
(400 MHz, CDCl3): δ 8.23 (d, J = 2.8 Hz, 1H), 7.98–7.92 (m, 1H),
7.87–7.81 (m, 2H), 7.39 (t, J = 7.6 Hz, 3H), 7.32–7.26 (m, 2H), 7.25–7.20
(m, 1H); 13C NMR (100 MHz, CDCl3): δ 154.5, 152.0, 148.2, 130.4,
130.0, 129.0, 128.5, 125.9, 125.3, 124.8, 120.7, 117.2, 117.0. MS (ESI)
m/z: 240 [M + H]+.
p-F
p-EtO
p-Me
p-Me
aReaction conditions: azide (1.0 mmol), aldehyde (1.0 mmol), KOH (40 mol%) and room
temperature
bIsolated yields
in hand, a series of 1,4-disubstituted 1,2,3-triazole derivatives
were synthesised (Table 3). Azides and aldehydes with various
substituents, including electron-donating groups and electron-
withdrawing groups, were all compatible with the optimal reaction
conditions.
In summary, we have developed a rapid, efficient and green
protocol for the synthesis of 1,2,3-triazoles from various azides
and arylacetaldehydes. It is noteworthy that the reaction proceeds
efficiently in ionic liquid [bmim]PF6 in the presence of KOH.
Obvious features of this transformation include the operational
simplicity, the low cost of reagents, and the high rate and
regioselectivity. This should arouse more research on the green
synthesis of triazoles.
4-Phenyl-1-(2-(trifluoromethyl)phenyl)-1H-1,2,3-triazole
(d):20
White solid; m.p. 206–208 °C (lit.20 204–205 °C); IR (KBr) (υmax
cm−1): 3132, 3080, 2360, 1606, 1512, 1463, 1316, 1271, 1137, 768, 693,
639; 1H NMR (400 MHz, CDCl3): δ 8.06 (s, 1H), 7.90 (dd, J = 11.3, 8.3
Hz, 3H), 7.73 (dt, J = 27.0, 7.5 Hz, 2H), 7.62 (d, J = 7.6 Hz, 1H), 7.47 (t,
J = 7.5 Hz, 2H), 7.38 (t, J = 7.4 Hz, 1H); 13C NMR (100 MHz, CDCl3):
δ 147.8, 134.9, 133.1, 130.5, 130.0, 129.0, 128.5, 127.4, 126.4, 125.9,
124.0, 122.2, 121.3, 100.0. MS (ESI) m/z: 290 [M + H]+.
1-(2-Chlorophenyl)-4-phenyl-1H-1,2,3-triazole (e):21 White solid;
m.p. 128–129 °C (lit.22 128–130 °C); IR (KBr) (υmax cm−1): 3131, 3080,
2360, 1606, 1512, 1316, 1271, 1235, 1137, 768, 711, 693, 639; 1H NMR
(400 MHz, CDCl3): δ 8.21 (s, 1H), 7.95–7.90 (m, 2H), 7.68 (dd, J = 6.1,

634 JOURNAL OF CHEMICAL RESEARCH 2017
3.4 Hz, 1H), 7.62–7.57 (m, 1H), 7.50–7.43 (m, 4H), 7.37 (t, J = 7.4 Hz,
1H); 13C NMR (100 MHz, CDCl3): δ 147.6, 134.9, 130.8, 130.2, 129.0,
128.5, 128.0, 127.8, 125.9, 121.6. MS (ESI) m/z: 256 [M + H]+.
1H NMR (400 MHz, CDCl3): δ 7.77 (dd, J = 8.7, 5.4 Hz, 2H), 7.65 (s, 1H),
7.36 (m, 5H), 7.09 (t, J = 8.7 Hz, 2H), 5.57 (s, 2H); 13C NMR (100 MHz,
CDCl3): δ 163.9, 161.4, 147.4, 134.6, 129.2, 128.9, 128.1, 127.5, 127.4,
126.8, 119.3, 115.9, 115.7, 54.3. MS (ESI) m/z: 254 [M + H]+.
4-Phenyl-1-(o-tolyl)-1H-1,2,3-triazole (f):21 White solid; m.p.
72–73 °C (lit.22 73 °C); IR (KBr) (υmax cm−1): 3131, 2920, 2361, 1505,
4-(4-Ethoxyphenyl)-1-phenyl-1H-1,2,3-triazole
(o):26
White
1
1480, 1461, 1229, 1046, 1035, 773, 765, 691; H NMR (400 MHz,
solid; m.p. 161–163 °C (lit.27 164.7 °C); IR (KBr) (υmax cm−1): 3432,
3136, 2971, 2360, 1617, 1496, 1474, 1246, 1230, 1182, 1045, 845, 755;
1H NMR (400 MHz, CDCl3): δ 8.10 (s, 1H), 7.79 (dd, J = 18.4, 8.2 Hz,
4H), 7.51 (t, J = 7.8 Hz, 2H), 7.42 (t, J = 7.4 Hz, 1H), 6.96 (d, J = 8.7 Hz,
2H), 4.06 (q, J = 7.0 Hz, 2H), 1.43 (t, J = 7.0 Hz, 3H); 13C NMR (100
MHz, CDCl3): δ 159.2, 148.3, 137.1, 129.8, 128.6, 127.2, 122.8, 120.4,
116.8, 114.9, 77.4, 77.1, 76.8, 63.5, 14.8. MS (ESI) m/z: 266 [M + H]+.
1-Benzyl-4-(p-tolyl)-1H-1,2,3-triazole (p):28 White solid; m.p.
153–154 ºC (lit.29 155–157 °C); IR (KBr) (υmax cm−1): 3143, 3018,
2917, 2361, 1496, 1457, 1348, 1223, 1182, 1136, 1066, 1047, 973, 828,
793, 721, 513; 1H NMR (400 MHz, CDCl3): δ 7.69 (d, J = 7.9 Hz, 2H),
7.62 (s, 1H), 7.38 (d, J = 5.5 Hz, 3H), 7.30 (d, J = 5.8 Hz, 2H), 7.20
(d, J = 7.7 Hz, 2H), 5.55 (s, 2H), 2.36 (s, 3H); 13C NMR (100 MHz,
CDCl3): δ 147.4, 137.1, 133.8, 128.6, 128.2, 127.8, 127.1, 126.8, 124.7,
118.3, 53.3, 20.4. MS (ESI) m/z: 250 [M + H]+.
CDCl3): δ 7.97 (s, 1H), 7.94–7.91 (m, 2H), 7.40–7.35 (m, 7H), 2.28 (s,
3H); 13C NMR (100 MHz, CDCl3): δ 147.6, 136.5, 133.8, 131.6, 130.4,
130.0, 129.0, 128.4, 126.9, 125.9, 121.2, 18.0. MS (ESI) m/z: 236 [M +
H]+.
4-Phenyl-1-(p-tolyl)-1H-1,2,3-triazole (g):19 White solid; m.p.
156–158 °C (lit.19 159–160 °C); IR (KBr) (υmax cm−1): 3131, 3080, 2360,
1606, 1512, 1482, 1463, 1316, 1271, 1235, 1169, 1137, 768, 711, 693,
1
639; H NMR (400 MHz, CDCl3): δ 8.16 (s, 1H), 7.91 (d, J = 7.1 Hz,
2H), 7.66 (d, J = 8.4 Hz, 2H), 7.46 (t, J = 7.5 Hz, 2H), 7.35 (dd, J = 16.8,
7.9 Hz, 3H), 2.43 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 148.3, 138.9,
134.8, 130.3, 128.9, 128.4, 125.9, 120.4, 117.7, 21.1. MS (ESI) m/z: 236
[M + H]+.
1-Mesityl-4-phenyl-1H-1,2,3-triazole (h):20 White solid; m.p.
113–115 °C (lit.17 113–116 °C); IR (KBr) (υmax cm−1): 3137, 2956, 2922,
2360, 1607, 1494, 1477, 1438, 1380, 1222, 1072, 1034, 768, 989, 856,
817, 767, 693; 1H NMR (400 MHz, CDCl3): δ 7.95–7.91 (m, 2H), 7.84
(s, 1H), 7.46 (t, J = 7.6 Hz, 2H), 7.40–7.33 (m, 1H), 7.01 (s, 2H), 2.37 (s,
3H), 2.02 (s, 6H); 13C NMR (100 MHz, CDCl3): δ 147.6, 140.1, 135.1,
133.5, 130.5, 129.0, 128.3, 125.8, 121.5, 21.2, 17.4. MS (ESI) m/z: 264
[M + H]+.
1-Phenyl-4-(p-tolyl)-1H-1,2,3-triazole (q):19 White solid; m.p.
162–155 ºC (lit.17 166–169 °C); IR (KBr) (υmax cm−1): 3109, 3061, 2916,
1599, 1508, 1495, 1463, 1238, 1228, 1042, 814, 756, 686, 536; 1H NMR
(400 MHz, CDCl3): δ 8.14 (s, 1H), 7.78 (dd, J = 7.8, 5.9 Hz, 4H), 7.53 (t,
J = 7.7 Hz, 2H), 7.44 (t, J = 7.4 Hz, 1H), 7.26 (d, J = 8.1 Hz, 2H), 2.39 (s,
3H); 13C NMR (100 MHz, CDCl3): δ 148.7, 138.5, 137.3, 129.9, 129.8,
128.0, 127.6, 125.9, 120.7, 117.5, 21.5. MS (ESI) m/z: 236 [M + H]+.
4-(4-Methoxyphenyl)-1-phenyl-1H-1,2,3-triazole (i):16 White solid;
m.p. 158–159 °C (lit.17 160–161 °C); IR (KBr) (υmax cm−1): 3106, 3059,
3004, 2360, 1616, 1560, 1493, 1507, 1464, 1248, 1176, 1034, 837, 815,
764, 690; 1H NMR (400 MHz, CDCl3): δ 8.11 (s, 1H), 7.82 (d, J = 8.7
Hz, 2H), 7.77 (d, J = 7.7 Hz, 2H), 7.51 (t, J = 7.8 Hz, 2H), 7.42 (t, J = 7.4
Hz, 1H), 6.97 (d, J = 8.7 Hz, 2H), 3.83 (s, 3H); 13C NMR (100 MHz,
CDCl3): δ 159.8, 148.3, 137.1, 129.8, 128.7, 127.2, 122.9, 120.4, 116.8,
114.3, 55.3. MS (ESI) m/z: 252 [M + H]+.
1-(2-Methyl-5-nitrophenyl)-4-(p-tolyl)-1H-1,2,3-triazole
(r):10
White solid; m.p. 102–103 ºC (lit.10 128–130 °C); IR (KBr) (υmax
cm−1): 3135, 3117, 3065, 3030, 2980, 2921, 2859, 1633, 1600, 1521,
1440, 1380, 1350, 810, 797, 739, 706; 1H NMR (400 MHz, CDCl3): δ
8.29 (d, J = 6.8 Hz, 2H), 8.02 (s, 1H), 7.80 (d, J = 8.0 Hz, 2H), 7.60
(d, J = 9.1 Hz, 1H), 7.28 (d, J = 7.9 Hz, 2H), 2.44 (s, 3H), 2.41 (s, 3H);
13C NMR (100 MHz, CDCl3): δ 148.1, 146.3, 141.5, 138.5, 136.7, 132.5,
129.6, 126.8, 125.6, 124.1, 121.0, 120.6, 21.2, 18.5. MS (ESI) m/z: 295
[M + H]+.
Ethyl 2-(4-phenyl-1H-1,2,3-triazol-1-yl)acetate (j):23 White solid;
m.p. 97–99 °C (lit.24 93–95 °C); IR (KBr) (υmax cm−1): 3134, 3004,
2361, 1606, 1755, 1467, 1442, 1347, 1216, 1199, 1144, 1076, 1050,
1
Electronic Supplementary Information
1016, 766, 694; H NMR (400 MHz, CDCl3): δ 7.85 (s, 1H), 7.77 (d,
J = 7.1 Hz, 2H), 7.36 (t, J = 7.5 Hz, 2H), 7.27 (t, J = 7.4 Hz, 1H), 5.13
(s, 2H), 4.20 (q, J = 7.1 Hz, 2H), 1.23 (t, J = 7.1 Hz, 3H); 13C NMR (100
MHz, CDCl3): δ 165.0, 146.9, 129.3, 127.8, 127.3, 124.8, 120.0, 61.3,
49.9, 13.0. MS (ESI) m/z: 232 [M + H]+.
1-Benzyl-4-(4-methoxyphenyl)-1H-1,2,3-triazole (k):25 White solid;
m.p. 145–146 °C (lit.26 143–144 °C); IR (KBr) (υmax cm−1): 3136, 2927,
2836, 2361, 1616, 1558, 1500, 1455, 1349, 1251, 1217, 1171, 1070, 1049,
1028, 834, 796, 720; 1H NMR (400 MHz, CDCl3): δ 7.73 (d, J = 8.7 Hz,
2H), 7.60 (s, 1H), 7.41–7.28 (m, 5H), 6.94 (d, J = 8.7 Hz, 2H), 5.55 (s,
2H), 3.83 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 159.6, 148.1, 134.8,
129.1, 128.7, 128.1, 127.0, 123.3, 118.8, 114.2, 55.3, 54.2. MS (ESI) m/z:
266 [M + H]+.
1-Benzyl-4-(4-ethoxyphenyl)-1H-1,2,3-triazole (l):26 White solid;
m.p. 136–138 °C (lit.26 139–140 °C); IR (KBr) (υmax cm−1): 3088, 2972,
2932, 2360, 1618, 1502, 1452, 1251, 1176, 1116, 1046, 835, 815, 716;
1H NMR (400 MHz, CDCl3): δ 7.72 (d, J = 8.8 Hz, 2H), 7.59 (s, 1H),
7.42–7.34 (m, 3H), 7.33–7.28 (m, 2H), 6.93 (d, J = 8.8 Hz, 2H), 5.55 (s,
2H), 4.05 (q, J = 7.0 Hz, 2H), 1.43 (t, J = 7.0 Hz, 3H); 13C NMR (100
MHz, CDCl3): δ 159.0, 148.1, 134.8, 129.1, 128.7, 128.0, 127.0, 123.1,
118.7, 114.8, 63.5, 54.2, 14.8. MS (ESI) m/z: 280 [M + H]+.
1-Benzyl-4-(4-chlorophenyl)-1H-1,2,3-triazole (m):26 White solid;
m.p. 131–133 °C (lit.26 130–132 °C); IR (KBr) (υmax cm−1): 3442, 3117,
3039, 2360, 1479, 1452, 1433, 1226, 1186, 1135, 1091, 1069, 1051, 813,
708, 698, 514; 1H NMR (400 MHz, CDCl3): δ 7.74 (d, J = 8.4 Hz, 2H),
7.69 (s, 1H), 7.45–7.29 (m, 7H), 5.58 (s, 2H); 13C NMR (100 MHz,
CDCl3): δ 134.5, 133.9, 129.2, 129.1, 129.0, 128.9, 128.1, 126.9, 54.3.
MS (ESI) m/z: 270 [M + H]+.
1-Benzyl-4-(4-fluorophenyl)-1H-1,2,3-triazole (n):25 White solid;
m.p. 113–115 °C (lit.26 109–110 °C); IR (KBr) (υmax cm−1): 3151, 3102,
3082, 2360, 1496, 1452, 1223, 1157, 1046, 846, 833, 799, 730, 715, 523;
The ESI is available through: http://ingentaconnect.com/
content/stl/jcr/2017/00000041/00000011
Received 20 September 2017; accepted 3 October 2017
Paper 1705011
https://doi.org/10.3184/174751917X15094552081152
Published online: 9 November 2017
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