The Huisgen 1,3-dipolar cycloaddition reaction of organic azides and alkynes has gained considerable attention in recent years due to the introduction in 2001 of Cu(1) catalysis by Tornoe and Meldal, leading to a major improvement in both rate and regioselectivity of the reaction, as realized independently by the Meldal and the Sharpless laboratories. The great success of the Cu(1) catalyzed reaction is rooted in the fact that it is a virtually quantitative, very robust, insensitive, general, and orthogonal ligation reaction, suitable for even biomolecular ligation and in vivo tagging or as a polymerization reaction for synthesis of long linear polymers. The triazole formed is essentially chemically inert to reactive conditions, e.g. oxidation, reduction, and hydrolysis, and has an intermediate polarity with a dipolar moment of ∼5 D. The basis for the unique properties and rate enhancement for triazole formation under Cu(1) catalysis should be found in the high ∆G of the reaction in combination with the low character of polarity of the dipole of the noncatalyzed thermal reaction, which leads to a considerable activation barrier. In order to understand the reaction in detail, it therefore seems important to spend a moment to consider the structural and mechanistic aspects of the catalysis. The reaction is quite insensitive to reaction conditions as long as Cu(1) is present and may be performed in an aqueous or organic environment both in solution and on solid support.

Cu-catalyzed azide-alkyne cycloaddition.

Since the discovery of organic azides by Peter Griess more than 140 years ago, numerous syntheses of these energy-rich molecules have been developed. In more recent times in particular, completely new perspectives have been developed for their use in peptide chemistry, combinatorial chemistry, and heterocyclic synthesis. Organic azides have assumed an important position at the interface between chemistry, biology, medicine, and materials science. In this Review, the fundamental characteristics of azide chemistry and current developments are presented. The focus will be placed on cycloadditions (Huisgen reaction), aza ylide chemistry, and the synthesis of heterocycles. Further reactions such as the aza-Wittig reaction, the Sundberg rearrangement, the Staudinger ligation, the Boyer and Boyer-Aube rearrangements, the Curtius rearrangement, the Schmidt rearrangement, and the Hemetsberger rearrangement bear witness to the versatility of modern azide chemistry.

Organic Azides: An Exploding Diversity of a Unique Class of Compounds

CuI‐Catalyzed Alkyne–Azide “Click” Cycloadditions from a Mechanistic and Synthetic Perspective

Cu(I)-catalyzed azide–alkyne 1,3-dipolar cycloaddition (CuAAC), popularly known as the “click reaction”, serves as the most potent and highly dependable tool for facile construction of simple to complex architectures at the molecular level. Click-knitted threads of two exclusively different molecular entities have created some really interesting structures for more than 15 years with a broad spectrum of applicability, including in the fascinating fields of synthetic chemistry, medicinal science, biochemistry, pharmacology, material science, and catalysis. The unique properties of the carbohydrate moiety and the advantages of highly chemo- and regioselective click chemistry, such as mild reaction conditions, efficient performance with a wide range of solvents, and compatibility with different functionalities, together produce miraculous neoglycoconjugates and neoglycopolymers with various synthetic, biological, and pharmaceutical applications. In this review we highlight the successful advancement of Cu(I)...

Cu-Catalyzed Click Reaction in Carbohydrate Chemistry

This invention provides a method for preparing a 1,2,3-triazole compound comprising contacting an organic azide with a 2-substitued-1-haloalkyne, in the presence of a copper catalyst and a copper-coordinating ligand (preferably a tertiary amine) in a liquid reaction medium, thereby forming a 1,4,5-substituted-1,2,3-triazole compound including a halo substituent at the 5-position of the triazole, the organic portion of the organic azide at the 1-position of the triazole, and the substituent of the 1-iodoalkyne at the 4-position of the triazole. A method for preparing 1-iodoalkynes is also provided.

Copper catalyzed cycloaddition of organic azides and 1-haloalkynes

s: A method for the regiospecific synthesis of 1,4,5-trisubstituted-1,2,3-triazole catalyzed by copper(I) iodide was developed. This is the first example of a regiospecific synthesis of 5-iodo-1,4-disubstituted-1,2,3-triazole, which can be further elaborated to a range of 1,4,5-tri substituted-1,2,3-triazole derivatives.

Regiospecific synthesis of 1,4,5-trisubstituted-1,2,3-triazole via one-pot reaction promoted by copper(I) salt

Synthesis of monofluorinated indolizines and their derivatives by the 1,3-dipolar reaction of N-ylides with fluorinated vinyl tosylates

Regioselective synthesis of fluoroalkylated [1,2,3]-triazoles by Huisgen cycloaddition

The Suzuki, Heck and Sonogashira reactions of 1,4-disubstituted 5-iodo-1,2,3-trizaoles were studied. A versatile method for regioselective synthesis of 1,4,5-trisubstituted-1,2,3-triazoles was developed.

Juan Deng

Papers

Regiospecific synthesis of 1,4,5-trisubstituted-1,2,3-triazole via one-pot reaction promoted by copper(I) salt

Synthesis of monofluorinated indolizines and their derivatives by the 1,3-dipolar reaction of N-ylides with fluorinated vinyl tosylates

Regioselective synthesis of fluoroalkylated [1,2,3]-triazoles by Huisgen cycloaddition

Cross-Coupling Reaction of Iodo-1,2,3-triazoles Catalyzed by Palladium

One-pot synthesis of bromodifluoroacetimidoyl halides and its Suzuki coupling reactions with aryl boronic acids