Fe2+ Catalyzes Vitamin E-Induced Fragmentation of Hydroperoxy and Hydroxy Endoperoxides That Generates γ-Hydroxy Alkenals
摘要:
The formation of cytotoxic gamma-hydroxyalkenals has been generally viewed as the consequence of free radical-induced oxidation of polyunsaturated fatty acyls through the decomposition of lipid peroxides. Vitamin E (Vit E) would be expected to inhibit such autoxidation. In a model study, we now find that fragmentation of a hydroperoxy endoperoxide generated the lactone of a gamma-hydroxyalkenal. With 1 equiv of Fe2+, or with a catalytic amount (0.1 equiv) of Fe2+ and 1 equiv of Vit E, the yields are 43-50%. However, Vit E alone did not promote the fragmentation, and a catalytic amount of Fe2+ alone only afforded a low yield (about 5%). Vit E could contribute to, as opposed to preventing, the formation of gamma-hydroxyalkenals by converting redox-active metal ions into their reduced forms that promote the rapid fragmentation of hydroperoxy endoperoxides.
The Diels-Alder cycloadditions of the alpha-acetoxynitroso dienophile in water are reported. The rapid and high yielding synthesis of structurally diverse 3,6-dihydro-1,2-oxazines complements the straightforward elaboration of aminoalcohols obtained from the alpha-acetoxynitroso derivative in anhydrous medium. A rationale for this solvent-dependent product distribution is proposed.
Reducing Characteristics of Borohydride Exchange Resin–CuSO<sub>4</sub>in Methanol
作者:Tae Bo Sim、Nung Min Yoon
DOI:10.1246/bcsj.70.1101
日期:1997.5
characteristics of borohydrideexchange resin (BER)–CuSO4 (cat.) were studied in methanol at room temperature. Carbon–carbon double bonds conjugated with benzene or carbonyl group were more rapidly reduced than was the case with isolated double bonds. Carbonyl groups were readily reduced, whereas esters and amides were inert, and nitriles were slowly reduced. High chemoselectivity was also observed in halide reductions:
Chemistry of Dienyl Anions. I. Crystalline Dienyl Anions by Direct Reaction of Conjugated and Non-conjugated Dienes with Alkali Metals in the Presence of Et<sub>3</sub>N
Series of acyclic and cyclic dienyl anions were prepared from both conjugated and non-conjugated dienes by direct metalation with alkalimetals (Li, Na, K, Rb, and Cs) in tetrahydrofuran in the pre...
A rapidly reversible degenerate cope rearrangement
作者:W. von E. Doering、W.R. Roth
DOI:10.1016/s0040-4020(01)99207-5
日期:1963.1
The occurrence of a structurally degenerateCoperearrangement which proceeds rapidly at room temperature is revealed by the examination, at varying temperatures, of the N.M.R. spectrum of bicyclo[5.1.0]octa-2,5-diene (I). This molecule is made by the cyclopropanation of cycloheptatriene in the 3, 4 position according to Gaspar-Roth. Its structure is assigned by virtue of its conversion to bicyclo[5
Organic photochemistry in the far-ultraviolet: unusual wavelength dependence in solution-phase irradiations
作者:Ra Srinivasan、Thomas Baum、Karen Brown、Jose Ors、Lloyd S. White、Angelo R. Rossi、Gary A. Epling
DOI:10.1039/c39810000973
日期:——
In the region from 185 to 215 nm certain compounds show extreme selectivity in their photodecomposition modes in solution depending on the wavelength even though such compounds possess only one intense absorption in this region.