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Synthesis of 2H-1,2,3-triazoles
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Triazoles have been synthesized via a three-component coupling reaction of
unactivated terminal alkynes, allyl carbonate, and trimethylsiyl azide under
Pd(0)-Cu(I) bimetallic catalysis. The deallylation of the resulting
allyltriazoles is described.
S. Kamijo, T. Jin, Z. Huo, Y. Yamamoto, J. Am. Chem. Soc., 2003, 125, 7786-7787.
t-BuOK promoted an intermolecular cycloaddition of tosylhydrazones with
nitriles to provide 4,5-diaryl-2H-1,2,3-triazoles in very good yields.
Homocoupling of the tosylhydrazones was significantly inhibited by using xylene
as solvent.
S. Qiu, Y. Chen, X. Song, L. Liu, X. L. Liu, L. Wu, Synlett, 2021,
32,
86-90.
Reaction of 4-bromo-NH-1,2,3-triazoles with alkyl halides in the presence
of K2CO3 in DMF produced the corresponding 2-substituted
4-bromo-1,2,3-triazoles in a regioselective process. Subsequent Suzuki
cross-coupling reaction provided an efficient synthesis of 2,4,5-trisubstituted
triazoles, whereas hydrogenation furnished an efficient synthesis of
2,4-disubstituted triazoles.
X.-j. Wang, K. Sidhu, L. Zhang, S. Campbell, N. Haddad, D. C. Reeves, D.
Krishnamurthy, C. H. Senanayake, Org. Lett., 2009,
11, 5460-5493.
A Cu-catalyzed annulation reaction of azirines and aryldiazonium salts
provides fully substituted N2-aryl-1,2,3-triazoles. This
regiospecific method allows access to a broad spectrum of products substituted
with diverse aryl and alkyl moieties.
F.-F. Feng, J.-K. Li, X.-Y. Liu, F.-G. Zhang, C. W. Cheung, J.-A. Ma, J. Org. Chem., 2020, 85,
10872-10883.
A catalyst-free and regioselective N arylation enables the synthesis of N2-aryl-1,2,3-triazoles in
very good yields. This scalable postmodification protocol is
effective for a wide range of substrates.
S. Roshandel, M. J. Lunn, G. Rasul, D. S. M. Ravinson, S. C. Suri, G. K. S.
Prakash,
Org. Lett., 2019, 21, 6255-6258.
Phenyl esters of α-azido acids react with trialkylphosphines in THF/H2O
to give 5-substituted 2H-1,2,3-triazol-4-ols in very good yields, whereas
their reaction with PPh3 provides amino esters as the major product and no
triazoles.
S. D. Taylor, C. R. Lohani, Org. Lett.,
2016, 18, 4412-4415.
A palladium-catalyzed and ultrasonic promoted Sonogashira coupling/1,3-dipolar
cycloaddition of acid chlorides, terminal acetylenes, and sodium azide in one
pot enables an efficient synthesis of 4,5-disubstituted-1,2,3-(NH)-triazoles in
excellent yields.
J. Li, D. Wang, Y. Zhang, J. Li, B. Chen, Org. Lett., 2009,
11, 3024-3027.
A sequential C-N bond formation and electro-oxidative N-N coupling enables an
efficient synthesis of of N2-Aryl 1,2,3-triazoles in very good
yields under metal-free conditions from readily accessible 2-aminoacrylates and
aryldiazonium salts. This method displays excellent functional group tolerance.
M. Baidya, S. Mallick, S. D. Sarkar, Org. Lett.,
2022, 24, 1274-1279.
A Cu-mediated annulation reaction of alkyl 3-aminoacrylates with
aryldiazonium salts provides alkyl N2-aryl
1,2,3-triazole-carboxylates rapidly under mild conditions. Furthermore, alkyl
2-aminoacrylates are also viable substrates.
H.-N. Liu, H.-Q. Cao, C. W. Cheung, J.-A. Ma,
Org. Lett., 2020, 22, 1396-1401.
The reaction of 4,4-dichloro-1,2-diazabuta-1,3-dienes with sodium azide
provides extremely rare 1,1-bisazides. These highly unstable compounds are prone
to eliminate N2 to cyclize into 4-azido-1,2,3-triazoles bearing two
aryl groups at positions 2 and 5. This reaction enables a highly efficient
synthesis of various 4-azidotriazoles. These heterocycles are highly attractive
building blocks.
A. V. Shastin, B. T. Tsyrenova, P. G. Sergeev, V. A. Roznyatovsky, I. V. Smolyar,
V. N. Khrustalev, V. G. Nenajdenko, Org. Lett.,
2018, 20, 7803-7806.