Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition
- Regina Berg and
- Bernd F. Straub
Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308
Graphical Abstract
Scheme 1: Exemplary 1,3-dipolar cycloaddition of phenylacetylene with phenyl azide [6].
Scheme 2: CuAAC reaction of benzyl azide with (prop-2-yn-1-yloxy)benzene [12].
Scheme 3: Bioconjugation reaction of capsid-bound azide groups with alkynyl-functionalized dye molecules (cow...
Figure 1: Tris(triazolylmethyl)amine ligands for CuAAC applications in bioorganic chemistry: TBTA = tris[(1-b...
Figure 2: Derivatives of 2,2’-bipyridine and 1,10-phenanthroline, commonly used ligands in CuAAC reactions un...
Scheme 4: CuAAC reaction with copper(II) precursor salt and rate-accelerating monodentate phosphoramidite lig...
Scheme 5: Synthesis of 1-(adamant-1-yl)-1H-1,2,3-triazol-4-ylcarbonyl-Phe-Gly-OH by solid-supported Click cat...
Scheme 6: CuAAC reaction with re-usable copper(I)-tren catalyst [129].
Scheme 7: CuAAC test reaction with chlorido[tris(1-benzyl-1H-1,2,3-triazol-4-yl)methanol-κ3N3]copper(I) and a...
Scheme 8: CuAAC model reaction with [Cu2(μ-TBTA-κ4N2,N3,N3’,N3’’)2][BF4]2 [131].
Scheme 9: Application of a (2-aminoarenethiolato)copper(I) complex as homogeneous catalyst for the CuAAC test...
Scheme 10: Application of [CuBr(PPh3)3] as homogeneous catalyst for the CuAAC test reaction of benzyl azide wi...
Figure 3: Phosphinite and phosphonite copper(I) complexes presented by Díez-González [144].
Scheme 11: Effect of additives on the CuAAC test reaction with [(SIMes)CuCl] [149].
Scheme 12: Initiation of the catalytic cycle by formation of the copper acetylide intermediate from [(ICy)2Cu]...
Scheme 13: Early mechanistic proposal by Sharpless [12,42].
Scheme 14: Chemoselective synthesis of a 5-iodo-1,4-disubstituted 1,2,3-triazole [156].
Scheme 15: Mechanistic proposals for the copper-catalyzed azide–iodoalkyne cycloaddition [156].
Scheme 16: 1,3-Dipolar cycloaddition of 3-hexyne catalyzed by [(SIMes)CuBr] [146].
Scheme 17: Mechanistic picture for the cycloaddition of internal alkynes catalyzed by NHC-copper(I) complexes ...
Scheme 18: Catalytic cycle of the CuAAC reaction on the basis of the proposed mechanistic scheme by Fokin and ...
Figure 4: Schematic representation of the single crystal X-ray structures of copper(I) acetylide complexes [Cu...
Figure 5: Acetylide-bridged dicopper complexes with tris(heteroarylmethyl)amine ligand(s) as key intermediate...
Scheme 19: Off-cycle equilibrium between unreactive polymeric copper(I) acetylide species (right) and reactive...
Figure 6: Categories of tris(heteroarylmethyl)amine ligands regarding their binding ability to copper(I) ions ...
Scheme 20: Mechanistic scheme for ligand-accelerated catalysis with tripodal tris(heteroarylmethyl)amine ligan...
Scheme 21: Synthesis of supposed intermediates in the CuAAC’s catalytic cycle [164,187].
Figure 7: Tetranuclear copper acetylide complexes as reported by Weiss (left) [176] and Tasker (middle) [185] and model...
Figure 8: Gibbs free energy diagram for the computed mechanistic pathway of the CuAAC reaction starting from ...
Figure 9: Energy diagram by Ahlquist and Fokin [125].
Scheme 22: Mechanistic proposal for the CuAAC reaction based on DFT calculations by Fokin [125] and our group [186] ([Cu...
Figure 10: ORTEP plot [202,203] of the X-ray powder diffraction crystal structure of (phenylethynyl)copper(I) [(PhC≡CCu)...
Scheme 23: Synthesis of [(PhC≡CCu)2]n as co-product in the Glaser coupling of phenylacetylene in the presence ...
Scheme 24: Mechanistic explanation for the isotopic enrichment in the product triazolide in the presence of th...
Scheme 25: Homogeneous CuAAC catalysis with a bistriazolylidene dicopper complex (0.5 mol %) and comparison wi...
