What is intermolecular cycloaddition reaction?

What is intermolecular cycloaddition reaction?

A cycloaddition is a chemical reaction in which “two or more unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity.” The resulting reaction is a cyclization reaction.

What is CuAAC reaction?

The CuAAC reaction was a breakthrough in triazole chemistry. The reactions of organic azides with terminal alkynes were shown to be accelerated by copper ions and to proceed regioselectively under these conditions, giving the 1,4-disubstituted 1,2,3-triazole regioisomer exclusively.

Why is it called click chemistry?

“Click Chemistry” is a term that was introduced by K. B. Sharpless in 2001 to describe reactions that are high yielding, wide in scope, create only byproducts that can be removed without chromatography, are stereospecific, simple to perform, and can be conducted in easily removable or benign solvents.

What is Staudinger ligation?

The Staudinger ligation is used to site-specifically incorporate organic molecules (such as fluorescent dyes) into recombinant polypeptides containing unnatural azide-conjugated amino acids (incorporated, for instance, via suppression of the amber stop codon: https://pubs.acs.org/doi/pdf/10.1021/ja027007w)

Why 2 2 cycloaddition is not possible thermally?

However, under thermal conditions, the cycloaddition reaction will not take place. This is because of poor overlap between molecular orbitals. Only under photochemical conditions is there a bonding interaction taking place in a single concerted step.

Why are azides used in cycloadditions?

Some success has been found with non-metal-catalyzed cycloadditions, such as the reactions using dipolarophiles that are electron-poor olefins or alkynes. Although azides are not the most reactive 1,3-dipole available for reaction, they are preferred for their relative lack of side reactions and stability in typical synthetic conditions.

What is the mechanism of cycloaddition of dipolarophiles?

When the dipolarophile is an alkyne, aromatic rings are generally produced. Originally two proposed mechanisms describe the 1,3-dipolar cycloaddition: first, the concerted pericyclic cycloaddition mechanism, proposed by Rolf Huisgen; and second, the stepwise mechanism involving a diradical intermediate, proposed by Firestone.

Can cycloaddition between azides and allenes be used to synthesize highly functionalised 1-3-triazoles?

In particular, the 1,3-dipolar cycloaddition between azides and allenes suggests a useful method for the synthesis of highly functionalised 1,2,3-triazoles that are difficult to obtain by other routes.

What is the mechanism of cycloaddition?

Mechanistic overview. Originally two proposed mechanisms describe the 1,3-dipolar cycloaddition: first, the concerted pericyclic cycloaddition mechanism, proposed by Rolf Huisgen; and second, the stepwise mechanism involving a diradical intermediate, proposed by Firestone.