- Catalytic strategies for sustainable oxidations
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Several catalytic protocols for the oxidation of hydro-soluble substrates are presented that employ totally inorganic and robust polyoxometalate-based catalysts as well as porphyrin sensi-tizers, fullerenes and hybrid conjugates. Strategies for the imple-mentation of the system stability and efficiency are discussed.
- Carraro, Mauro,Sartorel, Andrea,Scorrano, Gianfranco,Carofiglio, Tommaso,Bonchio, Marcella
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experimental part
p. 1971 - 1978
(2009/04/07)
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- Selective Reduction by 2-Amino-4-methylpyridine Borane and 2-Aminopyrimidine Borane
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Stereo- and chemoselective reductions and synthetic utility of the title compounds are described.
- Okamoto, Yoshihisa,Osawa, Toshimitsu,Kurasawa, Yoshihisa,Kinoshita, Toshio,Takagi, Kaname
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p. 1383 - 1385
(2007/10/02)
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- The Radiolysis of Uracil in Oxygenated Aqueous Solutions. A Study by Product Analysis and Pulse Radiolysis
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Hydroxyl radicals are generated by the radiolysis of N2O-O2 (4:1 v/v)-saturated aqueous solutions of uracil.They add to the 5,6-double bond of the substrate .These radicals are converted by oxygen into the corresponding peroxyl radicals (I) and (II), respectively.Peroxyl radical (I) undergoes a base-induced O2(1-.) elimination (kobs 8x1E3 s-1 at pH 10.5).As an intermediate 5-hydroxy-isopyrimidine is formed which rearranges into isobarbituric acid and adds water forming 5,6-dihydro-5,6-dihydroxyuracil.Competing with this base-induced reaction of radical (I) there is a bimolecular decay of radicals (I) and (II).These processes become predominant at low pH.For this reason a strong pH dependence of G (products) is observed.The major products are (G values at pH 3 and 10 in parentheses) 5,6-dihydroxy-5,6-dihydrouracil (1.1; 2.4), isobarbituric acid (0; 1.2), N-formyl-5-hydroxyhydantoin (1.6; 0.2), 5-hydroxybarbituric acid (0.9; 0.2). 5-Hydroxybarbituric acid is formed in its keto form.Its deprotonation (k 4.4 s-1) has been followed by pulse conductometry.Details of the reaction mechanism, e.g. the involvement of oxyl radicals in the bimolecular decay of (I) and (II), are discussed.
- Schuchmann, Man Nien,Sonntag, Clemens von
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p. 1525 - 1532
(2007/10/02)
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- Reduction of Vicinal Tricarbonyl Compounds by Reduced Nicotinamide Adenine Dinucleotide Model and Electron-Transport Systems
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The reduction of vicinal tricarbonyl compounds such as alloxan (A) and ninhydrin (NY) with 1-benzyl-1,4-dihydronicotinamide (BNAH; NADH model) was investigated.In the reduction of A with BNAH, the radical anion (A-.Py+) of A as the 1-benzyl-3-carbamoylpyridinium salt and the dialuric acid (D) was obtained by one-electron and two-electron reduction,respectively.Similarly,hydrindantin (HDT) and 2-hydroxy-1,3-indandione (HID) were also afforded in the reduction of NY with BNAH.Further,the reductions of alloxantin (AT) and HDT with BNAH were performed to give D and HID,respectively.The reduction of lipoic acid (LA) and viologens (V2+) with BNAH, which could not be reduced without A or NY, proceeded smoothly in their presence,and they proved to be useful as mediators for catalytic reduction of LA and V2+.
- Endo, Takeshi,Okawara, Makoto
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p. 2663 - 2666
(2007/10/02)
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