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.

s, or keywords if they used Heck-type chemistry in their syntheses, because it became one of basic tools of organic preparations, a natural way to

http://aether.cmi.ua.ac.be/artikels/Artikels%20Gitte/Artikels/Reviews/Heck%20reactie%20Beletskaya%20%20Chem.%20Rev.%20003009.pdf

The heck reaction as a sharpening stone of palladium catalysis.

The use of biocatalysis for industrial synthetic chemistry is on the verge of significant growth. Biocatalytic processes can now be carried out in organic solvents as well as aqueous environments, so that apolar organic compounds as well as water-soluble compounds can be modified selectively and efficiently with enzymes and biocatalytically active cells. As the use of biocatalysis for industrial chemical synthesis becomes easier, several chemical companies have begun to increase significantly the number and sophistication of the biocatalytic processes used in their synthesis operations.

Industrial biocatalysis today and tomorrow

Small-molecule H-bond donors in asymmetric catalysis.

The 3,3'-pyrrolidinyl-spirooxindole unit is a privileged heterocyclic motif that forms the core of a large family of alkaloid natural products with strong bioactivity profiles and interesting structural properties. Significant recent advances in the synthesis of this fused heterocyclic system have led to intense interest in the development of related compounds as potential medicinal agents or biological probes.

Pyrrolidinyl-spirooxindole natural products as inspirations for the development of potential therapeutic agents.

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

Intramolecular reactions of N-acyliminium intermediates

This article reviews the applications of cinchona alkaloids as asymmetric catalysts. In the last few years, characterized by the resurgence of interest in asymmetric organocatalysis, cinchona derivatives have been shown to catalyze an outstanding array of chemical reactions, often with remarkable stereoselectivity. This work presents an overview of the transformations developed in the period from 2001 through 2009, highlighting applications in the synthesis of bioactive molecules and natural products.

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Cinchona Alkaloids in Asymmetric Organocatalysis

In the steadily expanding field of organocatalysis, cinchona alkaloids play a prominent role. Until the late 1990s, bifunctional catalysts based on this scaffold relied exclusively on the C9-hydroxy group as the hydrogen-bond donor. Recently, new cinchona catalysts have been developed that feature a phenolic OH group in the C6' position-a structural feature that allows a diverse set of reactions to be catalyzed in a highly stereoselective fashion. This Minireview describes the scope and modes of action of this new class of asymmetric bifunctional organocatalysts.

Henk Hiemstra

Papers

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

Intramolecular reactions of N-acyliminium intermediates

Cinchona Alkaloids in Asymmetric Organocatalysis

Cupreines and Cupreidines: An Emerging Class of Bifunctional Cinchona Organocatalysts

Asymmetric Organocatalytic Henry Reaction