D
Synlett
P. B. Sarode et al.
Letter
veloped protocol is versatile and tolerant of most functional
groups. The addition of DABCO improves the stability of the
N1–N2 bond by increasing the electron density at copper
and N1 and decreasing the binding energy of the C5-Cu
bond. AcOH accelerates the protonation of cuprated triazole
and buffers the basicity of DABCO. We further conclude that
delay in the protonation of the cuprated triazole intermedi-
ate results in ring opening with the cleavage of the N1–N2
bond to form the ketinimine intermediate which is trapped
with water to form N-sulfonyl amides. This study demon-
strates the role of AcOH in the development of an expedi-
tious protocol for CuAAC and also opens a way to control
the selectivity of formation of ring with regard to ring-
opened product during the reaction of electron-deficient
azides with alkynes.
(7) (a) Pachón, L. D.; Van Maarseveen, J. H.; Rothenberg, G. Adv.
Synth. Catal. 2005, 347, 811. (b) Molteni, G.; Bianchi, C. L.;
Marinoni, G.; Santo, N.; Ponti, A. New J. Chem. 2006, 30, 1137.
(
8) Himo, F.; Lovell, T.; Hilgraf, R.; Rostovtsev, V. V.; Noodleman, L.;
Sharpless, K. B.; Fokin, V. V. J. Am. Chem. Soc. 2005, 127, 210.
9) Shao, C.; Wang, X.; Zhang, Q.; Luo, S.; Zhao, J.; Hu, Y. J. Org.
Chem. 2011, 76, 6832.
(
(10) (a) Hein, J. E.; Fokin, V. V. Chem. Soc. Rev. 2010, 39, 1302.
(b) Chan, T. R.; Hilgraf, R.; Sharpless, K. B.; Fokin, V. V. Org. Lett.
2004, 6, 2853. (c) Lewis, W. G.; Magallon, F. G.; Fokin, V. V.;
Finn, M. G. J. Am. Chem. Soc. 2004, 126, 9152.
(
11) Shao, C.; Wang, X.; Xu, J.; Zhao, J.; Zhang, Q.; Hu, Y. J. Org. Chem.
2010, 75, 7002.
(
(
12) Hay, A. S. J. Org. Chem. 1962, 27, 3320.
13) 1,4-Diphenyl-1H-1,2,3-triazole (3a)
A mixture of CuSO ·5H O (0.03 mmol), sodium ascorbate (0.12
4
2
mmol), and DABCO (0.06 mmol) in H O (2 mL) was stirred vig-
2
orously at r.t. for 5 min. To this, AcOH (0.06 mmol), phenylacet-
ylene (1a) (1 mmol), and phenyl azide (2a, 1 mmol) were added
sequentially, and the resultant mixture was stirred until the
substrates had been completely consumed (TLC monitoring).
The reaction mixture was diluted by adding EtOAc (5 mL) and
Acknowledgment
Authors are grateful to UGC New Delhi, India (F. No. 41-335 /2012 (SR)
dt.13.07.2012) for the financial support.
aq NH Cl solution (3 mL). The mixture was stirred for an addi-
4
tional 30 min, and the two layers were separated. The aqueous
layer was extracted with EtOAc (2 × 5 mL). The combined
organic layers were dried over Na SO , filtered, and evaporated.
Supporting Information
2
4
The crude product thus obtained was recrystallized from EtOH
Supporting information for this article is available online at
to afford pure 1,4-diphenyl-1,2,3-triazole (3a) as a pale yellow
http://dx.doi.org/10.1055/s-0036-1588590.
S
u
p
p
ortioIgnfrm oaitn
S
u
p
p
ortioIgnfrm oaitn
1
solid; yield 0.160 g, 86%; mp 182–183 °C. H NMR (500 MHz,
CDCl ): δ = 8.20 (s, 1 H), 7.93–7.91 (m, 2 H), 7.81–7.79 (m, 2 H),
3
7
.58–7.54 (m, 2 H), 7.48–7.45 (m, 3 H), 7.39–7.36 (m, 1 H).
References and Notes
(
(
(
14) CCDC 1479799 contains the supplementary crystallographic
data for this paper. The data can be obtained free of charge from
(
(
(
1) Rostovtsev, V.; Green, L.; Fokin, V.; Sharpless, K. Angew. Chem.
Int. Ed. 2002, 41, 2596.
2) Tornøe, C. W.; Christensen, C.; Meldal, M. J. Org. Chem. 2002, 67,
The
Cambridge
Crystallographic
Data
Centre
via
www.ccdc.cam.ac.uk/getstructures.
15) (a) Yoo, E. J.; Ahlquist, M.; Kim, S. H.; Bae, I.; Fokin, V. V.;
3057.
Sharpless, K. B.; Chang, S. Angew. Chem. 2007, 119, 1760.
3) (a) Shao, C.; Cheng, G.; Su, D.; Xu, J.; Wang, X.; Hu, Y. Adv. Synth.
Catal. 2010, 352, 1587. (b) Liu, M.; Reiser, O. Org. Lett. 2011, 13,
(
(
b) Grünanger, P.; Finzi, P. V. Tetrahedron Lett. 1963, 4, 1839.
c) Huisgen, R. Angew. Chem., Int. Ed. Engl. 1980, 19, 947.
1
102. (c) Candelon, N.; Lastecoueres, D.; Diallo, A. K.; Aranzaes,
J. R.; Astruc, D.; Vincent, J. M. Chem. Commun. 2008, 741.
d) Díez-González, S.; Nolan, S. P. Angew. Chem. 2008, 120, 9013.
16) 2-Phenyl-N-tosylacetamide (4a)
A mixture of CuSO ·5H O (0.03 mmol), sodium ascorbate (0.12
mmol), and DABCO (0.06 mmol) in H O (2 mL) was stirred vig-
orously at r.t. for 5 min. Alkyne 1a (1 mmol) and p-toluenesulfo-
nyl azide (2j, 1 mmol) were added sequentially, and the resul-
tant mixture was stirred until the substrates had been
completely consumed (TLC monitoring). The reaction mixture
4
2
(
2
(
4) (a) Wu, P.; Feldman, A. K.; Nugent, A. K.; Hawker, C. J.; Scheel, A.;
Voit, B.; Pyun, J.; Frechet, J. M.; Sharpless, K. B.; Fokin, V. V.
Angew. Chem. Int. Ed. 2004, 43, 3928. (b) Helms, B.; Mynar, J. L.;
Hawker, C. J.; Fréchet, J. M. J. Am. Chem. Soc. 2004, 126, 15020.
(
c) Rodionov, V. O.; Fokin, V. V.; Finn, M. G. Angew. Chem. Int. Ed.
005, 44, 2210.
5) (a) Cho, S. H.; Yoo, E. J.; Bae, I.; Chang, S. J. Am. Chem. Soc. 2005,
27, 16046. (b) Yoo, E. J.; Bae, I.; Cho, S. H.; Han, H.; Chang, S.
was diluted by adding EtOAc (5 mL) and aq NH Cl solution (3
4
2
mL), the mixture was stirred for an additional 30 min, and the
two layers were separated. The aqueous layer was extracted
with EtOAc (2 × 5 mL), the combined organic layers were dried
over Na SO , filtered, and evaporated. The crude product so
obtained was purified by recrystallization from EtOH to afford
pure 2-phenyl-N-tosylacetamide (4a) as a white solid; yield
(
1
Org. Lett. 2006, 8, 1347. (c) Bae, I.; Han, H.; Chang, S. J. Am.
Chem. Soc. 2005, 127, 2038. (d) Chang, S.; Lee, M.; Jung, D. Y.;
Yoo, E. J.; Cho, S. H.; Han, S. K. J. Am. Chem. Soc. 2006, 128, 12366.
2
4
(e) Cassidy, M. P.; Raushel, J.; Fokin, V. V. Angew. Chem. Int. Ed.
1
0
7
2
.095 g, 64%; mp 148–149 °C. H NMR (500 MHz, CDCl ): δ =
.87 (d, 2 H), 7.81 (br s, 1 H), 7.33 (m, 5 H), 7.14 (d, 2 H) 3.58 (s,
H), 2.44 (s, 3 H).
3
2006, 45, 3154. (f) Whiting, M.; Fokin, V. V. Angew. Chem. Int.
Ed. 2006, 45, 3157.
(6) Hein, J. E.; Fokin, V. V. Chem. Soc. Rev. 2010, 39, 1302.
©
Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–D