Cu(II)-hydrotalcite as an efficient heterogeneous catalyst for Huisgen [3+2] cycloaddition.

Top Cat! Cu(II)-hydrotalcite (HT) is used as a catalyst for the regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles by [3+2] cycloaddition of various azides and alkynes. The catalyst enjoys advantages such as faster reactivity, good stability, reusability, high catalytic activity without any additives at room temperature, and does not require a nitrogen atmosphere for this "click-chemistry" transformation.

"Click chemistry" in zeolites: copper(I) zeolites as new heterogeneous and ligand-free catalysts for the Huisgen [3+2] cycloaddition.

For the first time, copper(I)-exchanged zeolites were developed as catalysts in organic synthesis. These solid materials proved to be versatile and efficient heterogeneous, ligand-free catalytic systems for the Huisgen [3+2] cycloaddition. These cheap and easy-to-prepare catalysts exhibited a wide scope and compatibility with functional groups. They are very simple to use, easy to remove (by filtration), and are recyclable (up to three times without loss of activity). Investigations with deuterated alkynes and deuterated zeolites proved that this Cu(I)-zeolite-catalyzed "click" reaction exhibited a mechanism different from that reported for the Meldal-Sharpless version.

Zeolite-directed cascade reactions: cycliacyarylation versus decarboxyarylation of alpha,beta-unsaturated carboxylic acids.

The interaction of alpha,beta-unsaturated carboxylic acids with benzene derivatives was investigated in H-zeolites and led to two distinct but competing processes, cycliacyarylation and decarboxyarylation. Interestingly, H-USY selectively induced the cycliacyarylation cascade reaction, whereas H-ZSM5 selectively promoted the decarboxyarylation cascade.

Click chemistry in CuI-zeolites: the Huisgen [3 + 2]-cycloaddition.

[reaction: see text] CuI-exchanged solids based on zeolite materials were investigated for the first time as catalysts in organic synthesis. The catalytic potential of these materials was evaluated in the Huisgen [3 + 2]-cycloaddition. Five CuI-exchanged zeolites were examined and CuI-USY proved to be a novel and efficient heterogeneous ligand-free catalyst for this "click chemistry"-type transformation.