Efficient synthesis of functionalized 1,2,3-triazoles by catalyst-free 1,3-dipolar cycloaddition of nitroalkenes with sodium azide

Article abstract of DOI:10.1590/S0103-50532012000600017

A simple and efficient protocol has been developed for the synthesis of 1,2,3-triazole derivatives by catalyst-free 1,3-dipolar cycloaddition of nitroalkenes with sodium azide under mild conditions.

Full text of DOI:10.1590/S0103-50532012000600017

J. Braz. Chem. Soc., Vol. 23, No. 6, 1119-1123, 2012.
Printed in Brazil - ©2012 Sociedade Brasileira de Química
0103 - 5053 $6.00+0.00
Article
A
Efficient Synthesis of Functionalized 1,2,3-Triazoles by Catalyst-Free 1,3-Dipolar
Cycloaddition of Nitroalkenes with Sodium Azide
Ting Wang, Xiao-Chun Hu,* Xu-Jiao Huang, Xin-Sheng Li and Jian-Wu Xie*
Key Laboratory of the Ministry of Education for Advanced Catalysis Materials,
Department of Chemistry and Life Science, Zhejiang Normal University, 321004 Jinhua, P. R. of China
Foi desenvolvido um protocolo simples e eficiente para a síntese de derivados de 1,2,3-triazol
pela cicloadição 1,3-dipolar de nitroalquenos com azida de sódio, sem a necessidade de catalisador
e sob condições brandas.
A simple and efficient protocol has been developed for the synthesis of 1,2,3-triazole derivatives
by catalyst-free 1,3-dipolar cycloaddition of nitroalkenes with sodium azide under mild conditions.
Keywords: 1,2,3-triazoles, 1,3-dipolar cycloaddition, 3-nitrocoumarins, sodium azide,
catalyst-free
Introduction
that 1,3-dipolar cycloaddition would be possible between
the α-carbonyl-β-aryl analogs of nitroethene with sodium
azide, as outlined in Scheme 1. First, the reaction was
happened via 1,3-dipolar cycloaddition of nitroalkenes with
sodium ion as the key step. Then, elimination of the NaNO2
and migration of hydrogen atom afford 1,2,3-triazoles.
Five-membered nitrogen heterocycles play an important
role in biological systems.Among these, the 1,2,3-triazoles
and their derivatives are of considerable interest as they
possess a wide range of biological properties, such as
anti-HIV,1 anti-allergic,2 anti-fungal,3 anti-viral4 and
anti-microbial activity.5 1,2,3-Triazoles are important
in pharmacological applications due to its stability
toward light, moisture, oxygen, and metabolism in the
body.6 In addition, these moieties are widely applied as
photosensitizers, dyes,7 and commercially employed as
anti-corrosive agents8 in industry. Owing to the importance
of these compounds, a variety of methods are known in the
literature for the synthesis of pyrazoles, which include the
thermal 1,3-dipolar cycloaddition of azide with various
alkynes9 and cycloaddition reactions of terminal alkynes
with alkyl azides using Cu(I) as catalyst.10 In addition,
these molecules can also be prepared in one-pot procedure
from alkynes with azides.11 In fact, a straightforward
approach to 1,2,3-triazoles is interesting and catalyst-
free intermolecular 1,3-dipolar cycloaddition azides with
electron-deficient alkenes to afford 1,2,3-triazoles, has been
the subject of intensive research.12 Recently, sodium azide
has been used as a 1,3-dipole in 1,3-dipolar cycloaddition
for the synthesis of 1,2,3-triazoles.12 Considering the above
reports and encouraged by the good results, we envisaged
Results and Discussion
Coumarins are important heterocycles widely present in
natural products exhibiting a broad range of biological and
therapeutic activities and have been the subject of intensive
research.13 Recently, we have demonstrated the usefulness
of the catalyst-free intermolecular 1,3-dipolar cycloaddition
of 3-nitrocoumarins in the synthesis of functionalized
pyrazoles with good yields.14 We considered that the
incorporation of a 1,2,3-triazole heterocyclic unit into
3-nitrocoumarins might provide 1,2,3-triazole derivatives
that have important biological and pharmaceutical
activities. Thus, we turned our attention to the possible
synthesis of 1,2,3-triazoles using 3-nitrocoumarins 1 as
dipolarophiles for the electron-poor 3-nitrocoumarins
is a good dipolarophile with a good leaving group NO2.
The initial investigation started from the reaction between
sodium azide and 3-nitrocoumarin 1a (Table 1). It is known
from the literature that the optimal medium for the reaction
of sodium azide with nitroalkenes is DMSO.13 Then we
studied the reaction at different temperatures in DMSO,
and found out that the best yield was obtained at 80 oC after
*e-mail: sky34@zjnu.cn, xiejw@zjnu.cn

1120
Efficient Synthesis of Functionalized 1,2,3-Triazoles
J. Braz. Chem. Soc.
N
H
N
N
N
N
R
Ar
H
N
−
N3
1,3-dipolar cycloaddition
Migration of hydrogen
R
−NO2
Ar
O2N
R
NO2
Ar
Scheme 1.
1 h (Table 1, entry 3). The structure was determined on the
basis of 1H NMR in comparison with the literature data.15
Under the optimized conditions, these findings
could be extended to the application of various other
3-nitrocoumarins 1a-1e, and the 1,3-dipolar cycloaddition
of 3-nitrocoumarins 1 to sodium azide proceeded smoothly
to afford the chromeno[3,4-d][1,2,3]triazol-4(3H)-ones
2a-2e as single regioisomers. The reaction’s scope proved to
be broad with respect to the 3-nitrocoumarins 1. Good yields
were obtained in the reactions of electron-withdrawing
substituent on the aryl ring of 3-nitrocoumarins 1 with
sodium azide (Table 2). In addition, an electron-donating
substituent on the aryl ring of 3-nitrocoumarins 1 substrates
tended to decrease their reactivity (Table 2, entry 5).
Having succeeded in synthesizing tricyclic 1,2,3-triazole
derivatives, we then turned our attention to extend the
scope of the 1,3-dipolar cycloaddition further. Acyclic
α-carbethoxy-1-nitroalkenes 1f-1j were utilized as
Table 1. Catalyst-free 1,3-dipolar cycloaddition of nitroalkenes with
sodium azide under different conditionsa
N
NH
N
NO2
O
DMSO
1 h
+
NaN3
O
O
O
1a
2a
Entry
T / oC
25
Yieldb / %
trace
53
1
2
3
50
80
89
aOtherwise noted, reactions performed with 0.1 mmol of 1a, 0.1 mmol of
NaN3 in 1 mL solvent. bIsolated yield.
Table 2. Reaction scopes of 3-nitrocoumarins 1 with sodium azide in DMSO at 80 oCa
N
NH
N
4
5
8
NO2
O
3
6
7
R
DMSO
80 oC, 1 h
2
+
NaN3
O
1
R
O
O
2
1
Entry
1
R (1)
Product
2
Yieldb /%
89
N
N
NH
H (1a)
2a
O
O
N
N
NH
F
2
3
4
5
6-F (1b)
6-Cl (1c)
2b
2c
2d
2e
82
80
79
66
O
O
N
NH
N
Cl
Br
O
O
N
NH
N
6-Br (1d)
O
O
N
N
NH
7-MeO (1e)
H3CO
O
O
aOtherwise noted, reactions performed with 1 mmol of 1 and 2 mmol of NaN3 in 2 mL DMSO at 80 °C for 1 h. bIsolated yield.

Vol. 23, No. 6, 2012
Wang et al.
1121
Table 3. Reaction scopes of acyclic α-carbethoxy-1-nitroalkenes 1f-1j with sodium azide in DMSO at 50 oCa
N
N
DMSO
NO2
NH
+
NaN3
Ar
50 oC, 1.5 h
Ar
COOEt
COOEt
1
2
Entry
1
R (1)
Product
2
Yieldb / %
76
N
N
NH
C6H5 (1f)
2f
COOEt
N
NH
N
N
2
3
4-ClC6H4 (1g)
4-BrC6H4 (1h)
2g
2h
67
62
COOEt
Cl
Br
N
NH
COOEt
N
N
NH
4
5
4-MeC6H4 (1i)
2-furyl (1j)
2i
2j
70
79
COOEt
H3C
N
NH
N
O
COOEt
aOtherwise noted, reactions performed with 1 mmol of 1, 2 mmol of NaN3 in 2 mL DMSO at 50 °C for 1.5 h. bIsolated yield.
dipolarophiles in the reaction with sodium azide.
Unfortunately, very poor results were observed when
the 1,3-dipolar cycloaddition of 1f-1j with sodium azide
was carried out at 80 oC. To our delight, good yields were
obtained when the reactions were carried out at 50 °C
after 1 h (Table 3). Table 3 shows that α-carbethoxy-1-
nitrostyrenes with electron-withdrawing or donating
substituents provided the 1,2,3-triazole derivatives 2f-2i
in moderate-to-good yields of 62-76% (entries 2-4). The
structures were also determined on the basis of 1H NMR
in comparison with the literature data.15
β-carboethoxy-β-nitrostyrenes global electrophilicity is
significantly lower (in particular: (1i) = 2.64, (1f) = 2.72,
(1g) = 2.93, (1h) = 2.93 eV), but remain in the range
typical for the strongly electrophilic dipolarophiles.19
Notably, these reactions can be considered as polar1,3-
dipolar cycloaddition (P-13DC).20 Detailed analysis of
the local electrophilicity indices on the reaction centers of
nitroalkenes also revealed that the reaction was determined
by the attack of nucleophilic atom of 1,3-dipole to
β-position of nitroalkene, similarly as in the reactions of
nitroethene with nitrones.21
To explain the key step of the reaction between azidium
ion and nitroalkenes, B3LYP/6-31g (d) calculations of
stationary structures of azidium ion and nitroalkenes
(1a-j) have been performed. It turned out that the global
electrophilicity of azidium ion equals to 1.6 eV. At the
same time it shows a strongly nucleophilic16 characteristics
(N = 7.97 eV). The nitrocoumarines (1a-e), on the other
hand, show strongly electrophilic properties (global
electrophilicity of (1a) = 3.28, (1b) = 3.55, (1c) = 3.62,
(1d)=3.62, (1e)=2.94eV).Theirelectrophilicityistherefore
much higher than of the corresponding β-nitrostyrenes17
and only slightly lower than of the corresponding
β-cyano-β-nitrostyrenes.18 In the case of a series of
Conclusions
In conclusion, an efficient method for the synthesis of
functionalized 1,2,3-triazoles by catalyst-free 1,3-dipolar
cycloaddition of nitroalkenes with sodium azide has been
investigated. The 1,3-dipolar cycloaddition can proceed
smoothly under mild conditions and provides pure
1,2,3-triazole derivatives in good yields. The reaction’s
scope proved to be quite broad. Notably, we incorporated a
1,2,3-triazole heterocyclic unit into coumarins and provided
substituted chromeno[3,4-d][1,2,3] triazol-4(1H)-one
that might have important biological and pharmaceutical

1122
Efficient Synthesis of Functionalized 1,2,3-Triazoles
J. Braz. Chem. Soc.
activities in the future. This novel methodology should be
of great interest for natural product synthesis for the mild
reaction conditions.
References
1. Alvarez,R.;Velazquez,S.;San,F.;Aquaro,S.;De,C.;Perno,C.F.;
Karlsson, A.; Balzarini, J.; Camarasa, M. J.; J. Med. Chem.
1994, 37, 4185.
Experimental
2. Buckle, D. R.; Rockell, C. J. M.; Smith, H.; Spicer, B. A.;
J. Med. Chem. 1986, 29, 2262.
All commercially available reagents and solvents were
obtained from commercial providers and used without
further purification. Reactions were monitored by TLC
using silica gel 60 UV254 Macherey-Nagel pre-coated
silica gel plates; detection was by means of a UV lamp.
Column chromatography was performed using silica gel
(200-300 mesh) eluting with ethyl acetate and petroleum
ether. Organic layers were dried over anhydrous MgSO4 or
Na2SO4 prior to evaporation on a rotary evaporator. 1H NMR
spectra were recorded at 400 MHz, and 13C NMR spectra
were recorded at 100 MHz (BrukerAvance). Chemical shifts
(d) are reported in ppm downfield from CDCl3 (d 7.26 ppm)
3. Vicentini, C. B.; Brandolini,V.; Guarneri, M.; Giori, P.; Farmaco
1992, 47, 1021; Joan, C. F. T.; Elizabeth, H.; Beatrice, M.;
Daniel, P. B.; Antimicrob. Agents Chemother. 1998, 42, 313.
4. Palhagen, S.; Canger, R.; Henriksen, O.; van Parys, J. A.;
Riviere, M. E.; Karolchyk, M. A.; Epilepsy Res. 2001, 43, 115.
5. Genin, M. J.;Allwine, D.A.;Anderson, D. J.; Barbachyn, M. R.;
Emmert, D. E.; Garmon, S. A.; Graber, D. R.; Grega, K. C.;
Hester, J. B.; Hutchinson, D. K.; Morris, J.; Reischer, R. J.; Ford,
C. W.; Zurenko, G. E.; Hamel, J. C.; Schaadt, R. D.; Stapert, D.;
Yagi, B. H.; J. Med. Chem. 2000, 43, 953.
6. Bourne,Y.; Kolb, H. C.; Radic, Z.; Sharpless, K. B.; Taylor, P.;
Marchot, P.; Proc. Natl. Acad. Sci. U. S. A. 2004, 101, 1449.
7. Willis, R. J.; Marlow, I. D.; Eur. Pat. Appl. 400842, 1990. (CA
1991, 114, 164247b)
1
for H NMR and relative to the central CDCl3 resonance
(d 77.0 ppm) for 13C NMR spectroscopy. Coupling constants
(J) are given in Hz. ESI-HRMS spectrometer was measured
with a Finnigan LCQDECA ion trap mass spectrometer. 2-Aryl-
1-carboethoxy-1-nitroethenes 1 were prepared according
to reported procedure.22 Triazoles 2a, 2c, 2e, 2f and 2g are
known compounds.15 Triazoles 2b, 2d and 2h-j are new
compounds and their physical and spectral properties are
reported in Supplementary Information section.
8. Morgan, N. H.; (CHOMERICS) Eur. Pat. Appl. EP 437979A2
19910724, 1991.
9. Huisgen, R.; Szeimies, G.; Moebius, L.; Chem. Ber. 1967,
100, 2494; Huisgen, R.; 1,3-Dipolar Cycloaddition Chemistry,
Wiley: NewYork, NY, 1984, pp. 1-176; Huisgen, R.; Pure Appl.
Chem. 1989, 61, 613.
10. Kolb, H. C.; Finn, M. G.; Sharpless, K. B.; Angew. Chem., Int.
Ed. 2001, 40, 2004.
General procedure for the synthesis of 1,2,3-triazoles 2
under the optimized conditions
11. Beckmann,H.S.G.;Wittmann,V.;Org.Lett.2007,9,1;Barral,K.;
Moorhouse, A. D.; Moses, J. E.; Org. Lett. 2007, 9, 1809.
12. Zefirov, N. S.; Chapovskaya, N. K.; Kolesnikov, V. V.; Chem.
Commun. 1971, 1001; Anisimova, N. A.; Berestovitskaya,
V. M.; Berkova, G. A.; Makarova, N. G.; Russ. J. Org.
Chem. 2007, 43, 652; Ugrak, B. I.; Zubanova, N. I.; Russ.
Chem. Bull. 1992, 41, 751; Sheremet, E. A.; Tomanov, R. I.;
Trukhin, E. V.; Berestovitskaya, V. M.; Russ. J. Org. Chem.
2004, 40, 594; Anisimova, N. A.; Makarova, N. G.; Berkova,
G. A.; Berestovitskaya, V. M.; Russ. J. Gen. Chem. 2006, 76,
1545.
To the solution of the nitroalkenes 1 (1 mmol) in DMSO
(2 mL) was added sodium azide (2 mmol). The mixture was
then heated at 80 oC until the starting material was totally
consumed as indicated by TLC. After cooling, water was
added and the resulting precipitate was filtered, washed with
excess of water, and dried to give the desired triazole, which
was recrystallized. When no precipitate was observed, the
triazole was isolated after extraction with ethylacetate.
Further purification was done by column chromatography
using ethylacetate/petroleum ether as eluent.
13. Sugino, T.; Tanaka, K.; Chem. Lett. 2001, 513; Brufola, G.;
Fringuelli, F.; Yavari, I.; Hekmat-Shoar, R.; Zonouzi, A.;
Tetrahedron Lett. 1998, 39, 2391; Dittmer, D. C.; Li, Q.;Avilov,
D. V.; J. Org. Chem. 2005, 70, 4682; Alexander, V. M.; Bhat,
R. P.; Samant, S. D.; Tetrahedron Lett. 2005, 46, 6957; Jia, C.;
Piao, D.; Kitamura, T.; Fujiwara, Y.; J. Org. Chem. 2000, 65,
7516; Selles, P.; Mueller, U.; Org. Lett. 2004, 6, 277; Li, K.;
Zeng,Y.; Neuenswander, B.; Tunge, J. A.; J. Org. Chem. 2005,
70, 6515;Aoki, S.; Macloed, A. M.; Grimwood, S.; Barton, C.;
Bristow, L.; Saywell, K.; Marshall, G. R.; Ball, G.; J. Med.
Chem. 1995, 38, 2239.
Supplementary Information
Supplementary data are available free of charge at
http://jbcs.sbq.org.br as PDF file.
Acknowledgments
We are grateful for the financial support from China
(NSFC: 20902083 and NSFZPY: 4090082).

Vol. 23, No. 6, 2012
Wang et al.
1123
14. Xie, J.-W.; Wang, Z.;Yang , W.-J.; Kong, L.-C.; Xu, D.-C.; Org.
Biomol. Chem. 2009, 7, 4352 .
18. Jasiński, R.; Barański, A.; THEOCHEM 2010, 949, 8.
19. Pėrez, P.; Domingo, L. R.; Aurell, M. J.; Contreras, R.;
Tetrahedron 2003, 59, 3117.
15. D’Ambrosio G.; Fringuelli, F.; Pizzo F.; Vaccaro, L.; Green
Chem. 2005, 7, 874; Haryu, K.; Vahermo, M.; Mutikainen, I.;
Yli-Kauhauloma, J.; J. Comb. Chem. 2003, 5, 826;Amantini, D.;
Fringuelli, F.; Piermatti, O.; Pizzo, F.; Zunino, E.; Vaccaro, L.;
J. Org. Chem. 2005, 70, 6526.
20. Domingo, L. R.; Sáez, J.A.; Org. Biomol. Chem. 2009, 7, 3576.
21. Jasiński, R.; Koifman, O. I.; Barański,A.; Mendeleev Commun.
2011, 21, 262.
22. Ploypradith, P.; Petchmanee, T.; Sahakitpichan, P.; Litvinas,
N. D.; Ruchirawat, S.; J. Org. Chem. 2006, 71, 9440.
16. Domingo, L. R.; Chamorro, E.; Pėrez, P.; J. Org. Chem. 2008,
73, 4615.
17. Jasiński, R.; Kwiatkowska, M.; Barański, A.; J. Phys. Org.
Chem. 2011, 24, 843.
Submitted: December 13, 2011
Published online: May 24, 2012

J. Braz. Chem. Soc., Vol. 23, No. 6, S1-S10, 2012.
Printed in Brazil - ©2012 Sociedade Brasileira de Química
0103 - 5053 $6.00+0.00
Supplementary Information
SI
Efficient Synthesis of Functionalized 1,2,3-Triazoles by Catalyst-Free 1,3-Dipolar
Cycloaddition of Nitroalkenes with Sodium Azide
Ting Wang, Xiao-Chun Hu,* Xu-Jiao Huang, Xin-Sheng Li and Jian-Wu Xie*
Key Laboratory of the Ministry of Education for Advanced Catalysis Materials,
Department of Chemistry and Life Science, Zhejiang Normal University, 321004 Jinhua, P. R. of China
Experimental
Further purification was done by column chromatography
using ethylacetate/petroleum ether as eluent.
General methods
Chromeno[3,4-d][1,2,3]triazol-4(3H)-one (2a)1
1H NMR (400 MHz, DMSO) d 8.03 (d, 1H, J 7.7 Hz),
7.64 (dd, 1H, J 11.4, 4.2 Hz), 7.53 (d, 1H, J 8.3 Hz), 7.47
(t, 1H, J 7.5 Hz).
All commercially available reagents and solvents were
obtained from commercial providers and used without
further purification. Reactions were monitored by TLC
using silica gel 60 UV254 Macherey-Nagel pre-coated
silica gel plates; detection was by means of a UV lamp.
Column chromatography was performed using silica gel
(200-300 mesh) eluting with ethyl acetate and petroleum
ether. Organic layers were dried over anhydrous MgSO4
or Na2SO4 prior to evaporation on a rotary evaporator.
1H NMR spectra were recorded at 400 MHz, and 13C NMR
spectra were recorded at 100 MHz (Bruker Avance).
Chemical shifts (d) are reported in ppm downfield from
CDCl3 (d 7.26 ppm) for 1H NMR and relative to the central
CDCl3 resonance (d 77.0 ppm) for 13C NMR spectroscopy.
Coupling constants (J) are given in Hz. ESI-HRMS
spectrometer was measured with a Finnigan LCQDECA ion
trap mass spectrometer. Triazoles 2a, 2c, 2e, 2f and 2g are
known compounds.1 Triazoles 2b, 2d and 2h-j are new
compounds and their physical and spectral properties are
reported below.
8-Fluorochromeno[3,4-d][1,2,3]triazol-4(3H)-one (2b)
Solid, mp 315 oC (dec.).1H NMR (400 MHz, DMSO-d6)
d 7.75 (m, 1H), 7.56 (m, 1H), 7.47 (m, 1H); 13C NMR
(100 MHz, DMSO-d6) d 164.7, 162.3, 159.5, 153.8, 124.7,
124.0, 123.7, 114.5, 114.3; IR (KBr) nmax/cm-1: 856, 1009,
1140, 1472, 1523, 1642, 1744, 3215; ESI-HRMS: calc. for
C9H4FN3O2 +Na 228.0181, found 228.0178.
8-Chlorochromeno[3,4-d][1,2,3]triazol-4(3H)-one (2c)1
1H NMR (400 MHz, DMSO) d 8.07 (d, 1H, J 2.5 Hz),
7.56 (dd, 1H, J 8.8, 2.3 Hz), 7.37 (d, 1H, J 8.8 Hz).
8-Bromochromeno[3,4-d][1,2,3]triazol-4(3H)-one (2d)
Solid, mp 336 oC (dec.).1H NMR (400 MHz, DMSO-d6)
d 7.98 (d, 1H, J 2.3 Hz), 7.63 (dd, 1H, J 8.9, 2.4 Hz),
7.53 (d, 1H, J 8.9 Hz), 2.46 (s, 1H); 13C NMR (100 MHz,
DMSO-d6) d 154.7, 151.3, 131.5, 129.2, 123.1, 119.8,
113.9; IR (KBr) nmax/cm-1: 848, 1002, 1131, 1452, 1513,
1612, 1726, 3218; ESI-HRMS: calc. for C9H4BrN3O2+Na
287.9381, found 287.9377.
A typical procedure for synthesis of 2a-2e
To the solution of the nitroalkenes 1 (1 mmol) in DMSO
(2 mL) was added sodium azide (2 mmol). The mixture was
then heated at 80 oC until the starting material was totally
consumed as indicated by TLC. After cooling, water was
added and the resulting precipitate was filtered, washed with
excess of water, and dried to give the desired triazole, which
was recrystallized. When no precipitate was observed, the
triazole was isolated after extraction with ethylacetate.
7-Methoxychromeno[3,4-d][1,2,3]triazol-4(3H)-one (2e)1
1H NMR (400 MHz, CDCl3) d 7.82 (d, 1H, J 9.1 Hz),
6.81 (d, 2H, J 7.5 Hz), 3.76 (s, 3H).
A typical procedure for synthesis of 2f-j
To the solution of the nitroalkenes 1 (1 mmol) in DMSO
*e-mail: sky34@zjnu.cn, xiejw@zjnu.cn
(2 mL) was added sodium azide (2 mmol). The mixture was

S2
Efficient Synthesis of Functionalized 1,2,3-Triazoles
J. Braz. Chem. Soc.
then heated at 50 oC until the starting material was totally
consumed as indicated by TLC. After cooling, water was
added and the resulting precipitate was filtered, washed with
excess of water, and dried to give the desired triazole, which
was recrystallized. When no precipitate was observed, the
triazole was isolated after extraction with ethylacetate.
Further purification was done by column chromatography
using ethylacetate/petroleum ether as eluent.
Ethyl 5-(p-tolyl)-1H-1,2,3-triazole-4-carboxylate (2i)
Solid, mp 297-298 oC.1H NMR (400 MHz, DMSO-d6)
d 7.66 (d, 2H, J 7.6 Hz), 7.29 (d, 2H, J 7.7 Hz), 4.28
(m, 2H), 2.36 (s, 3H), 1.25 (t, 3H, J 7.1 Hz); 13C NMR
(100 MHz, DMSO-d6) d 158.4, 156.0, 153.2, 129.3, 61.1,
21.3, 14.4; IR (KBr) nmax/cm-1: 864, 991, 1145, 1473, 1536,
1616, 1749, 2997; ESI-HRMS: calc. for C12H13N3O2+Na
254.0902, found 254.0897.
Ethyl 5-phenyl-1H-1,2,3-triazole-4-carboxylate (2f)1
1H NMR (400 MHz, DMSO-d6) d 7.86-7.67 (m, 2H),
7.53-7.40 (m, 3H), 4.27 (m, 2H), 1.22 (t, 3H, J 7.1 Hz).
Ethyl 5-(furan-2-yl)-1H-1,2,3-triazole-4-carboxylate (2j)
Solid, mp 141-142 oC.1H NMR (400 MHz, DMSO-d6)
d 7.89 (s, 1H), 7.37 (s, 1H), 6.67 (dd, 1H, J 3.2, 1.7 Hz),
4.34 (m, 2H), 1.30 (t, 3H, J 7.1 Hz); 13C NMR (100 MHz,
DMSO-d6) d 160.9, 154.3, 144.9, 129.5, 113.6, 112.5,
110.1, 61.3, 14.5; IR (KBr) nmax/cm-1: 851, 1007, 1125,
1453, 1526, 1609, 1750, 2996; ESI-HRMS: calc. for
C9H9N3O3+Na 230.0538, found 230.0531.
Ethyl 5-(4-chlorophenyl)-1H-1,2,3-triazole-4-carboxylate
(2g)1
1H NMR (400 MHz, DMSO-d6) d 7.80 (d, 2H, J 8.4 Hz),
7.55 (d, 2H, J 8.6 Hz), 4.28 (m, 2H), 1.25 (t, 3H, J 7.1 Hz).
Ethyl 5-(4-bromophenyl)-1H-1,2,3-triazole-4-carboxylate
(2h)
Reference
Solid, mp 173-174 oC.1H NMR (400 MHz, DMSO-d6)
d 7.73 (d, 2H, J 8.1 Hz), 7.66 (d, 2H, J 8.3 Hz), 4.28 (dd, 2H,
J 14.1, 7.0 Hz), 1.24 (t, 3H, J 7.1 Hz); 13C NMR (100 MHz,
DMSO-d6) d 161.3, 158.9, 152.8, 131.5, 123.2, 61.3, 14.3;
IR (KBr) nmax/cm-1: 846, 989, 1141, 1426, 1532, 1625, 1730,
2986; ESI-HRMS: calc. for C11H10BrN3O2+Na 294.9950,
found 294.9943.
1. D’Ambrosio, G.; Fringuelli, F.; Pizzo, F.; Vaccaro, L.; Green
Chem. 2005, 7, 874; Haryu, K.; Vahermo, M.; Mutikainen, I.;
Yli-Kauhauloma, J.; J. Comb. Chem. 2003, 5, 826; Amantini,
D.; Fringuelli, F.; Piermatti, O.; Pizzo, F.; Zunino, E.; Vaccaro,
L.; J. Org. Chem. 2005, 70, 6526.
NMR spectra
Figure S1. 1H NMR spectrum (400 MHz, DMSO-d6) of chromeno[3,4-d][1,2,3] triazol-4(3H)-one (2a).

Vol. 23, No. 6, 2012
Wang et al.
S3
Figure S2. 1H NMR and 13C NMR spectra (400 MHz, DMSO-d6) of fluorochromeno[3,4-d][1,2,3]triazol-4(3H)-one (2b).

S4
Efficient Synthesis of Functionalized 1,2,3-Triazoles
J. Braz. Chem. Soc.
Figure S3. 1H NMR spectrum (400 MHz, DMSO-d6) of 8-chlorochromeno[3,4-d][1,2,3]triazol-4(3H)-one (2c).

Vol. 23, No. 6, 2012
Wang et al.
S5
Figure S4. 1H NMR and 13C NMR spectra (400 MHz, DMSO-d6) of 8-bromochromeno[3,4-d][1,2,3]triazol-4(3H)-one (2d).

S6
Efficient Synthesis of Functionalized 1,2,3-Triazoles
J. Braz. Chem. Soc.
Figure S5. 1H NMR spectrum (400 MHz, DMSO-d6) of 7-methoxychromeno[3,4-d][1,2,3]triazol-4(3H)-one (2e).
Figure S6. 1H NMR spectrum (400 MHz, DMSO-d6) of ethyl 5-phenyl-1H-1,2,3-triazole-4-carboxylate (2f).

Vol. 23, No. 6, 2012
Wang et al.
S7
Figure S7. 1H NMR spectrum (400 MHz, DMSO-d6) of ethyl 5-(4-chlorophenyl)-1H-1,2,3-triazole-4-carboxylate (2g).

S8
Efficient Synthesis of Functionalized 1,2,3-Triazoles
J. Braz. Chem. Soc.
Figure S8. 1H NMR and 13C NMR spectra (400 MHz, DMSO-d6) of ethyl 5-(4-bromophenyl)-1H-1,2,3-triazole-4-carboxylate (2h).

Vol. 23, No. 6, 2012
Wang et al.
S9
Figure S9. 1H NMR and 13C NMR spectra (400 MHz, DMSO-d6) of ethyl 5-(p-tolyl)-1H-1,2,3-triazole-4-carboxylate (2i).

S10
Efficient Synthesis of Functionalized 1,2,3-Triazoles
J. Braz. Chem. Soc.
Figure S10. 1H NMR and 13C NMR spectra (400 MHz, DMSO-d6) of ethyl 5-(furan-2-yl)-1H-1,2,3-triazole-4-carboxylate (2j).