http://http://dspace.unitus.it:80 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Mon, 20 May 2013 16:56:08 GMT 2013-05-20T16:56:08Z http://hdl.handle.net/2067/1572 Title: New and efficient syntheses of hydroxytyrosol and its lipophilic derivatives Authors: Barontini, Maurizio; Crisante, Fernanda; Fabrizi, Giancarlo; Mincione, Enrico Abstract: New and efficient oxidative procedures to synthesize hydroxytyrosol and its lipophilic derivatives are described. Starting materials are available and natural compounds such as tyrosol and homovanillyl alcohol. The oxidants of choice are both homogeneous and heterogeneous 2-iodoxybenzoic acid (IBX and IBX-polystyrene) able to perform the aromatic hydroxylation and the oxidative demethylation of phenolic compounds with a chemo and regioselectivity similar to that of the polyphenol oxidase and cytochrome P450. The reactions proceed quickly and the final products are isolated in good yields and high purity. After the first oxidation, IBX-polystyrene is recovered by simple filtration, regenerated and reused for more cycles of oxidation reactions without loss of efficiency Thu, 31 Dec 2009 23:00:00 GMT http://hdl.handle.net/2067/1572 2009-12-31T23:00:00Z http://hdl.handle.net/2067/1879 Title: Dimethyl carbonate: an environmentally friendly solvent for hydrogen peroxide (H2O2)/methyltrioxorhenium (CH3ReO3, MTO) catalytic oxidations Authors: Bernini, Roberta; Mincione, Enrico; Barontini, Maurizio; Crisante, Fernanda; Fabrizi, Giancarlo; Gambacorta, Augusto Abstract: Environmentally friendly oxidations of various organic compounds with the hydrogen peroxide (H2O2)/methyltrioxorhenium(CH3ReO3, MTO) catalytic system have been described in dimethyl carbonate (DMC), a cheap commercially available and benign chemical having interesting solvating properties, low toxicity and high biodegradability. Oxidations proceeded with good conversions and in good yields. Spectrophotometric analysis demonstrated that the [CH3ReO(O–O)2] complex was formed in DMC and that it was stable for several days at room temperature. Description: L'articolo è disponibile sul sito dell'editore: http://www.sciencedirect.com Sun, 31 Dec 2006 23:00:00 GMT http://hdl.handle.net/2067/1879 2006-12-31T23:00:00Z http://hdl.handle.net/2067/1881 Title: Chemoselective and efficient carboxymethylation of the alcoholic chain of phenols by dimethyl carbonate (DMC). Authors: Bernini, Roberta; Mincione, Enrico; Crisante, Fernanda; Barontini, Maurizio; Fabrizi, Giancarlo; Gentili, Patrizia Abstract: The efficiency of dimethyl carbonate (DMC) as chemoselective carbomethoxylating agent of the alcoholic chain of phenols has been investigated. In the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or sulfuric acid as catalysts. New carbomethoxylated phenolic compounds were obtained in quantitative yields. A new efficient derivatization of the aliphatic alcoholic chain of the precious natural hydroxytyrosol is described, which increases the lipophilicity of the hydroxytyrosol. The antioxidant activity of this new carboxymethylated hydroxytyrosol 8 has been investigated using DPPH radical scavenging test. The results showed that this new compound has an antioxidant activity similar to hydroxytyrosol. Description: L'articolo è disponibile sul sito dell'editore: http://www.sciencedirect.com Sun, 31 Dec 2006 23:00:00 GMT http://hdl.handle.net/2067/1881 2006-12-31T23:00:00Z