Copper‐Catalyzed Synthesis of N‐Unsubstituted 1,2,3‐Triazoles from Nonactivated Terminal Alkynes

Abstract

The [3+2] cycloaddition of nonactivated terminal alkynes and trimethylsilyl azide proceeded smoothly in the presence of CuI catalyst and DMF/MeOH, to give the corresponding N‐unsubstituted triazoles in good to high yields. The reaction most probably proceeds through the in situ formation of a copper acetylide species and hydrazoic acid, followed by a successive [3+2] cycloaddition reaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Five‐Membered Heterocycles with Three Heteroatoms: Triazoles

“…Similarly, the fourcomponent coupling reactions of silylacetylenes, allyl carbonates, and trimethylsilyl azide catalyzed by a Pd(0)-Cu(I) bimetallic catalyst led to trisubstituted 1,2,3-triazoles [44]. The [3 þ 2] cycloaddition of non-activated terminal alkynes and trimethylsilyl azide proceeded smoothly in the presence of copper catalyst and N,N-dimethylformamide and methanol to give the corresponding N-unsubstituted-1,2,3-triazoles in good to high yields [45]. [3 þ 2]-Cycloadditions of alkyl azides with various unsymmetrical internal alkynes in the presence of Cp à RuCl(PPh 3 ) 2 as catalyst in refluxing benzene led to 1,4,5-trisubstituted-1,2,3-triazoles, whereas alkyl phenyl and dialkyl acetylenes underwent cycloadditions to afford mixtures of regioisomeric 1,2,3-triazoles and acyl-substituted internal alkynes reacted with complete regioselectivity [46].…”

Synthesis of N-unsubstituted 1,2,3-triazoles via a cascade including propargyl azides, allenyl azides, and triazafulvenes

“…Thus, their synthesis requires special azides and a sequence involving cycloaddition and deprotection steps. [12][13][14][15][16] Alternatively, NH-1,2,3-triazoles are available by treating alkynes with electron-withdrawing substituents, such as propynals, with sodium azide. 17,18 Other routes include starting compounds, which are quite different to alkynes, for example, β-nitrostyrenes, 19-21 1-bromo-1-alkenes, 22 3-aryl-2,3-dibromopropanoic acids, 23,24 α-haloacrylates, 25 α-chloroacrylonitriles, 25 or 1-substituted 5-amino-1H-1,2,3-triazoles 26,27 (Dimroth rearrangement).…”

Highly fluoroalkylated amphiphilic triazoles: Regioselective synthesis and evaluation of physicochemical properties

“…In addition, this good selectivity is observed whereas none catalyst (as Cu II ) is needed as for some other reactions. [31][32][33].…”