- Synthesis and in vitro studies of pyrone derivatives as scavengers of active oxygen species
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The antioxidant properties of eleven αpyrones and four γ-pyrones were evaluated by means of three different tests: reduction of the stable free radical, 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion scavenging assay and lipid peroxidation assay. In the DPPH test, 6-aryl-5,6-dihydro-4-hydroxypyran2-ones (3) and 4-hydroxypyran-2-one (5f) were the most active derivatives with IC50 values ranging from 36.7 to 394 μmol/1. Potent superoxide anion scavenging properties appeared in derivatives possessing phenol moieties. Thus phenolic pyrones 5e and 5f exhibited a note- worthy activity (IC50 = 0.180 and 0.488 mmol/l, respectively) when reference compound, ascorbic acid, demonstrated only 24 % inhibition at a concentration of 1 mg/ml. In addition derivative 5f significantly inhibited the Fe2+/ADP/ascorbate-induced lipid peroxidation of rat liver microsomes with an IC50 value of 0.069 mmol/l. Due to its multiple mechanism of protective action, compound 5f may be useful for the treatment of oxidative tissue injury in human disease.
- Weber,Coudert,Duroux,Leal,Couquelet,Madesclaire
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p. 877 - 884
(2007/10/03)
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- N-Acyl-2-methylaziridines: Synthesis and utility in the C-acylation of β-ketoester derived dianions
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A 'one pot' method for the preparation of N-acyl-2-methylaziridines is described, and the utility of these compounds in the C-acylation of dianions derived from β-ketoesters investigated. Application of the methodology to the synthesis of the polyketide natural product yangonin is also described.
- Lygo, Barry
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p. 12859 - 12868
(2007/10/02)
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- RHODIUM-CATALYZED REACTIONS WITH STRAINED OLEFINS. V. REACTION OF (METHYLENECYCLOPROPYL)BENZENE WITH 3-BUTENOIC ACID
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Double addition of 3-butenoic acid to (methylenecyclopropyl)benzene takes place to a substantial extent along with monoaddition in a rhodium(I)-catalyzed reaction.The initial formation of a rhodacycle is postulated, while formation of two rhodacycles in sequence is suggested to account for the double addition.
- Chiusoli, Gian Paolo,Costa, Mirco,Schianchi, Paolo,Salerno, Giuseppe
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p. 371 - 374
(2007/10/02)
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- Photochemical Reaction of 2-Acyloxy-1-methoxycarbonylcyclohexenes: an Efficient Aliphatic Photo-Fries Rearrangement and a Novel 1,5-Aroyl Migration
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Upon irradiation 2-acyloxy-1-methoxycarbonylcyclohexenes readily undergo photo-Fries rearrangement to give 2-acyl-2-methoxycarbonylcyclohexanones in good yields and among them 2-aroyloxy-1-methoxycarbonylcyclohexenes also undergo a novel 1,5-aroyl migration according to irradiation conditions to give 4-aroyl-2-methoxycarbonylcyclohexanones, which result from 1,3-aroyl migration following photo-Fries rearrangement.
- Seto, Hideharu,Kosemura, Hajime,Fujimoto, Yasuo
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p. 908 - 910
(2007/10/02)
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- SYNTHESIS OF PHENOLS BY POLYKETIDE CONDENSATION AND AN EFFICIENT SYNTHESIS OF 3,5-DIOXOALKANOATES FROM AMIDES
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Several phenols were synthesized from dimethyl β,β',δ,δ'-tetraoxoalkanedioates, which were prepared by the condensation of methyl acetoacetate dianion with N,N,N',N'-tetramethyl-alkanediamides in the presence of BF3*OEt2.
- Yamaguchi, Masahiko,Shibato, Keisuke,Hirao, Ichiro
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p. 1145 - 1148
(2007/10/02)
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