Synthesis and Structure/Antioxidant Activity Relationship of Novel Catecholic Antioxidant Structural Analogues to Hydroxytyrosol and Its Lipophilic Esters
摘要:
A large panel of novel catecholic antioxidants and their fatty acid or methyl carbonate esters has been synthesized in satisfactory to good yields through a 2-iodoxybenzoic acid (IBX)-mediated aromatic hydroxylation as the key step. The new catechols are structural analogues of naturally occurring hydroxytyrosol (3,4-DHE). To evaluate structure/activity relationships, the antioxidant properties of all catecholic compounds were evaluated in vitro by ABTS assay and on whole cells by DCF fluorometric assay and compared with that of the corresponding already known hydroxytyrosyl derivatives. Results outline that all of the new catechols show antioxidant capacity in vitro higher than that of the corresponding hydroxytyrosyl derivatives. Less evident positive effects have been detected in whole cells experiments. Cytotoxicity experiments, using MTT assay, on a representative set of compounds evidenced no influence in cell survival.
Chemoselective and efficient carbomethoxylation of the alcoholic chain of phenols by dimethyl carbonate (DMC)
摘要:
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. (c) 2007 Elsevier Ltd. All rights reserved.
Synthesis of five- and six-membered heterocycles by dimethyl carbonate with catalytic amounts of nitrogen bicyclic bases
作者:F. Aricò、S. Evaristo、P. Tundo
DOI:10.1039/c4gc01822b
日期:——
A catalytic amount of a nitrogen bicyclic base, i.e., DABCO, DBU or TBD, is effective for the one-pot synthesis of heterocycles from 1,4-, 1,5-diols and 1,4-bifunctional compounds via dimethyl carbonate chemistry under neat conditions. Nitrogen bicyclicbases that were previously shown to have enhanced the reactivity of DMC in methoxycarbonylation reaction by a BAc2 mechanism are herein used for the
氮双环碱,催化量的即,DABCO,DBU或TBD,有效用于从所述1,4-一锅合成杂环的,1,5-二醇和1,4-双官能化合物通过下碳酸二甲酯化学整洁的条件。先前显示通过B Ac 2机理增强了DMC在甲氧基羰基化反应中的反应性的氮双环碱在本文中首次用作涵盖B Ac 2和B Al 2途径的环化反应的有效催化剂。从D-山梨糖醇和D开始,该合成方法也适用于环糖,异山梨醇和异甘露糖苷的大规模合成。-甘露醇。得到的无水糖醇为纯净的结晶化合物,不需要任何进一步的纯化或结晶。
Synthesis of Five-Membered Cyclic Ethers by Reaction of 1,4-Diols with Dimethyl Carbonate
The reaction of 1,4‐diols with dimethyl carbonate in the presence of a base led to selective and high‐yielding syntheses of related five‐membered cyclicethers. This synthetic pathway has the potential for a wide range of applications. Distinctive cyclicethers and industrially relevant compounds were synthesized in quantitative yield. The reaction mechanism for the cyclization was investigated. Notably