Electrocatalytic reduction of CO2 by thiophene-substituted rhenium(i) complexes and by their polymerized films.

Three novel thiophene substituted bipyridine ligands and their corresponding rhenium complexes were synthesized and tested for the electrocatalytic reduction of CO2. Two complexes underwent oxidative electropolymerization on a glassy carbon electrode (GCE) surface. The conductive polymers chemically deposited on the GCE allow electron transport from the surface to the polymer-attached rhenium catalytic center in contact with the solution. The chemically modified electrodes show significant catalytic activities for CO2 reduction, and moderate relative higher stabilities when compared with the homogeneous solution counterparts.

Multicomponent versus domino reactions: One-pot free-radical synthesis of ß-amino-ethers and ß-amino-alcohols.

Following an optimized multicomponent procedure, an aryl amine, a ketone, and a cyclic ether or an alcohol molecule are assembled in a one-pot synthesis by nucleophilic radical addition of ketyl radicals to ketimines generated in situ. The reaction occurs under mild conditions by mediation of the TiCl4/Zn/t-BuOOH system, leading to the formation of quaternary ß-amino-ethers and -alcohols. The new reaction conditions guarantee good selectivity by preventing the formation of secondary products. The secondary products are possibly derived from a competitive domino reaction, which involves further oxidation of the ketyl radicals.

New advances in titanium-mediated free radical reactions.

Titanium complexes have been widely used as catalysts for C­C bond-forming processes via free-radical routes. Herein we provide an overview of some of the most significant contributions in the field, that covers the last decade, emphasizing the key role played by titanium salts in the promotion of selective reactions aimed at the synthesis of multifunctional organic compounds, including nucleophilic radical additions to imines, pinacol and coupling reactions, ring opening of epoxides and living polymerization.

New domino radical synthesis of aminoalcohols promoted by TiCl4-Zn/t-BuOOH system: selective hydroxyalkylation of amines in alcohol or in cyclic ether cosolvents.

We report a new and fast domino synthesis of aminoalcohols under mild conditions. The free-radical reaction of aliphatic and aromatic amines with alcohol cosolvents is promoted by means of the TiCl(4)-Zn/t-BuOOH system. According to the proposed mechanism, the amine reacts with two molecules of alcohol in an electrophilic-nucleophilic cascade process. This procedure, if compared with the TiCl(3)/t-BuOOH-mediated protocol previously reported, appears to be more selective, of more general applicability and affords the desired products in higher yields. Besides, with the same catalytic system it was possible to promote the reaction of primary arylamines with two molecules of cyclic ether, leading to the formation of a wider range of functionalized aminoalcohols.

SERCA-inhibiting activity of C-19 terpenolides from Thapsia garganica and their possible biogenesis.

An investigation of Thapsia garganica afforded a series of tetracyclic C-19 dilactones, whose production was dependent on the time and location of the collection. These unusual tetrahomosesquiterpenoids are presumably biosynthesized via a carbon dioxide-triggered electrophilic polyolefin cyclization. Despite the structural differences with thapsigargin, these compounds showed SERCA-inhibiting properties.

Inhibition of NF-kappaB activation and expression of inflammatory mediators by polyacetylene spiroketals from Plagius flosculosus.

Transcription factor NF-kappaB plays a key role for the inducible expression of genes mediating proinflammatory effects and is thus an important target for the development of antiinflammatory drugs. Here, we show that extracts from the plant Plagius flosculosus (L.) Alavi and Heyw. can inhibit the induction of NF-kappaB activity, and we describe the identification of three spiroketal compounds. Of those, only compound 1 could inhibit the phosphorylation and proteasomal degradation of IkappaB, thus preventing the nuclear import and DNA binding of NF-kappaB. Accordingly, compound 1, which is also found in the widely used medicinal herb chamomile, interfered with the LPS-induced production of IL-1, IL-6, TNF, and PGE2 in primary human monocytes.