[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.

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.

Within the green chemistry context, heterogeneous catalysis is more and more applied to organic synthesis. The well known ‘click chemistry’ and especially its flagship, the copper-catalyzed azide–alkyne cycloaddition reaction (CuAAC), is now catch up by such heterogenisation process and copper ions or metals have been grafted or deposited on or into various solids, such as (bio)polymers, charcoal, silica, zeolites, POM or MOF.

Keywords: Natural products / Dyes/Pigments / Anthocyanins / Polyphenols / Ellagitannins Kinetic and thermodynamic UV/Vis and structural NMR spectroscopic investigations on the anthocyano-ellagitannin hybrid 1-deoxyvescalagin-(1βǞ8)-oenin revealed that its enhanced color stability relative to that of the red-colored pigment oenin and resulting bathochromism can be rationalized in terms of an intramolecular π-stacking between the grape-

No abstract

Oxidative stress mediated by reactive oxygen or nitrogen species (ROS/RNS) seems to be implicated in several diseases including neurodegenerative ones. In one of them, namely Alzheimer's disease, there is a large body of evidence that the aggregation of the peptide amyloid-beta (Abeta) is implicated in the generation of the oxidative stress. Redox active metal ions play a key role in oxidative stress, either in the production of ROS/RNS by enzymes or loosely bound metals or in the protection against ROS, mostly as catalytic centers in enzymes. In Alzheimer's disease, it is thought that metals (mostly Cu, Fe and heme) can bind to amyloid-beta and that such systems are involved in the generation of oxidative stress. In the present article, we review the role of ROS/RNS produced by redox active Cu ions and heme compounds in the context of the amyloid cascade. We focus on (i) the coordination chemistry of Cu and heme to Abeta; (ii) the role of the corresponding Abeta adducts in the (catalytic) production of ROS/RNS; (iii) the subsequent degradation of Abeta by these reactive species and (iv) the use of antioxidants, in particular metal sequestering compounds and direct antioxidants like polyphenols as a therapeutic strategies.

Winding it up: The plant polyphenolic metabolite vescalagin fulfills all the requirements for use as an antiactin agent in cellular biological investigations. Despite its high hydrophilicity, it rapidly enters cells and disturbs the organization of the actin cytoskeleton in a dose‐dependent reversible manner by binding fibrillar actin and forcing the actin filaments (left) to wind themselves into ball‐like fibrillar aggregates (right).

Acetylenic acids and esters as well as acetylenic ketones were efficiently and stereoselectively converted in one step to the corresponding vinyl triflates or fluorosulfonates in triflic or fluorosulfonic acids. Depending on the reaction conditions the E or the Z isomer can be obtained very conveniently in high isolated yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)