Structural, CV and IR spectroscopic evidences for preorientation in PET-active phthalimido carboxylic acids.

Hydrogen bond and potassium cation mediated preorientation were detected for phthalimido acetic acid and the corresponding acetate. Evidence for these phenomena came from X-ray structure analysis as well as cyclic voltammetric and IR spectroscopic measurements. These interactions rationalize the photoinduced electron transfer (PET) reactivity of the substrates in photodecarboxylation reactions.

Radical cation ester cleavage in solution: mechanism of the mesolytic O-CO bond scission.

A wide range of enol carbonate, carbamate, and ester radical cations is characterized in solution by cyclic voltammetry and EPR spectroscopy. Preparative transformations using one-electron oxidants or anodic oxidation yield benzofurans after O-CO bond cleavage. Mechanistic investigations and direct detection of radical intermediates reveal that all enol radical cations undergo exclusively O-CO bond cleavage to provide alpha-carbonyl cations and acyl (or alternatively, alkoxyacyl and aminoacyl) radicals, respectively. The kinetics of the mesolytic fragmentation and the influence of nucleophilic additives have been determined using fast-scan cyclic voltammetry.

A highly regioselective sonogashira coupling as a key step in the preparation of the first phenanthroline with two diverse reactive groups in 3,8-positions

The preparation of 3,8-unsymmetric phenanthrolines is described. Desymmetrization of 3,8-dibromophenanthroline was achieved after monoarylation followed by regioselective Pd-catalyzed monoalkynylation that was controlled by the methoxy group of the dimethoxyphenyl substituent.

In vitro studies of ferritin iron release and neurotoxicity.

The increase in brain iron associated with several neurodegenerative diseases may lead to an increased production of free radicals via the Fenton reaction. Intracellular iron is usually tightly regulated, being bound by ferritin in an insoluble ferrihydrite core. The neurotoxin 6-hydroxydopamine (6-OHDA) releases iron from the ferritin core by reducing it to the ferrous form. Iron release induced by 6-OHDA and structurally related compounds and two other dopaminergic neurotoxins, 1-methyl-4-phenylpyridinium iodide (MPP+) and 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo), were compared, to identify the structural characteristics important for such release. 1,2,4-Trihydroxybenzene (THB) was most effective in releasing ferritin-bound iron, followed by 6-OHDA, dopamine, catechol, and hydroquinone. Resorcinol, MPP , and TaClo were ineffective. The ability to release iron was associated with a low oxidation potential. It is proposed that a low oxidation potential and an ortho-dihydroxyphenyl structure are important in the mechanism by which ferritin iron is mobilized. In the presence of ferritin, both 6-OHDA and THB strongly stimulated lipid peroxidation, an effect abolished by the addition of the iron chelator deferoxamine. These results suggest that ferritin iron release contributes to free radical-induced cell damage in vivo.