Iron-catalyzed stereospecific olefin synthesis by direct coupling of alcohols and alkenes with alcohols.

An efficient Fe(III)-catalyzed direct coupling of alkenes with alcohols and cross-coupling of alcohols with alcohols to give the corresponding substituted (E)-alkenes stereospecifically is demonstrated. Additionally, this reaction could be scaled up. The kinetic isotope effect (KIE) experiments indicated a typical secondary isotope effect in this process. Although benzylic alcohols were effective substrates, mild conditions, atom efficiency, environmental soundness, and stereospecificity are features that make this procedure very attractive.

Pd(II)-catalyzed decarboxylative allylation and Heck-coupling of arene carboxylates with allylic halides and esters.

This work demonstrates an alternative method to prepare allylated arenes and aryl-substituted allylic esters via catalytic decarboxylative C-C bond formation using aromatic carboxylic acids and allylic halides and esters.

Determinations of the inclusion complex between gossypol and beta-cyclodextrin.

Features of the inclusion complex between gossypol (Gos) and beta-cyclodextrin (CD), such as its aqueous solubility, association constant, characteristics in the solid state and crystalline morphology, as well as the stoichiometry of this complex have been determined. The phase-solubility diagram drawn using UV detections belongs to an AN-type. Fluorescence detection and calculation with the modified Benesi-Hidebrond equation provide an 1:2 stoichiometry for the complex. Its apparent stability constant has been determined to be 3,203 M(-1) by fluorescence technique and confirmed by the calculation from UV spectroscopy. X-ray powder diffractions (XRD) and Scanning Electron Microscopy (SEM) observations showed a clear difference in the crystal morphology of the complex from those of both Gos and beta-CD.

Study on structure and characterization of inclusion complex of gossypol/beta cyclodextrin.

The inclusion complex of beta-cyclodextrin with gossypol was synthesized by using a convenient method of microwave irradiation. The structure of the complex was determined by 1H NMR, IR spectroscopy, and as well as the elemental analysis; the thermal stability was studied by means of differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The association constant between gossypol and beta-cyclodextrin measured via UV spectroscopy was 4462M(-1) at room temperature, following stoichiometry 1:2.

Evidence for alpha-tocopherol regeneration reaction of green tea polyphenols in SDS micelles.

The synergistic antioxidant mechanism of alpha-tocopherol (vitamin E) with green tea polyphenols, i.e., (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), and gallic acid (GA), was studied by assaying the kinetics of the reaction of alpha-tocopheroxyl radical with green tea polyphenols by stopped-flow electron paramagnetic resonance, the inhibition of linoleic acid peroxidation by these antioxidants, and the decay of alpha-tocopherol during the peroxidation. It was found that the green tea polyphenols could reduce alpha-tocopheroxyl radical to regenerate alpha-tocopherol with rate constants of 0.45, 1.11, 1.31, 1.91, and 0.43 x 10(2) M(-1) s(-1) for EC, EGC, ECG, EGCG, and GA, respectively, in sodium dodecyl sulfate micelles. In addition, these second-order rate constants exhibited a good linear correlation with their oxidation potentials, suggesting that electron transfer might play a role in the reaction.

Antioxidant effects of resveratrol and its analogues against the free-radical-induced peroxidation of linoleic acid in micelles.

The antioxidant effect of resveratrol (3,4',5-trihydroxy-trans-stilbene) and its analogues, that is, 4-hydroxy-trans-stilbene (4-HS), 3,5-dihydroxy-trans-stilbene (3,5-DHS), 4,4'-dihydroxy-trans-stilbene (4,4'-DHS), 3,4-dihydroxy-trans-stilbene (3,4-DHS), 3,4,5-trihydroxy-trans-stilbene (3,4,5-THS) and 3,4,4'-trihydroxy-trans-stilbene (3,4,4'-THS), against the peroxidation of linoleic acid has been studied in sodium dodecyl sulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB) micelles. The peroxidation was initiated thermally by a water-soluble azo initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH), and the reaction kinetics were studied by monitoring the formation of linoleic acid hydroperoxides. The synergistic antioxidant effect of these compounds with alpha-tocopherol (vitamin E) was also studied by following the decay kinetics of alpha-tocopherol and the reaction intermediate, the alpha-tocopheroxyl radical. Kinetic analysis of the antioxidant process demonstrates that these compounds are effective antioxidants in micelles used either alone or in combination with alpha-tocopherol. The antioxidative action involves trapping the propagating lipid peroxyl radical and reducing the alpha-tocopheroxyl radical to regenerate alpha-tocopherol. It was found that the antioxidant activity of resveratrol analogues depends significantly on the position of the hydroxyl groups, the oxidation potential of the molecule and the reaction medium. Molecules with ortho-dihydroxyl and/or para-hydroxyl functionalities possess high activity.