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Montcada i Reixac, Spain

El-Faham A.,King Saud University | El-Faham A.,Alexandria University | El-Faham A.,Barcelona Institute for Research in Biomedicine | Subiros-Funosas R.,Barcelona Institute for Research in Biomedicine | And 4 more authors.
European Journal of Organic Chemistry | Year: 2010

A new family of uronium salts (HTMU, HMMU, and HDmPyMU) based on isonitroso Meldrum's acid (HONM) are reported as stand-alone coupling reagents. Amide bond formation with the use of these reagents occurred more quickly than that with other uronium salts as a result of the presence of a neighboring group effect with a cyclic structure. Thus, these novel onium salts were often more effective in the acylation of poor nucleophiles and in the control of optical purity than related Oxyma- and benzotriazole-based reagents. Among the HONM derivatives, HMMU showed the best performance in reducing racemization and assembling demanding sequences such as the Aib-ACP decapeptide or analogues of Leu-enkephalin pentapeptide, Furthermore, the scope and limitations of the use of HONM as an additive in combination with carbodiimides is discussed. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Custodio L.,University of Algarve | Ferreira A.C.,University of Algarve | Pereira H.,University of Algarve | Silvestre L.,University of Algarve | And 7 more authors.
Botanica Marina | Year: 2012

We report antioxidant, metal chelating and anticholinesterase activities of methanol extracts from two edible halophytes, Carpobrotus edulis and Arthrocnemum macrostachyum. We also report a preliminary chemical screening, total contents of phenolic compounds in the extracts and the fatty acid profiles of both species. Arthrocnemum macrostachyum is a potential source of metabolites with free radical scavenging, iron (Fe 3+ ) reducing and copper (Cu 2+ ) chelating activities; it had a high concentration of polyunsaturated fatty acids (46.5 % ), mainly α -linolenic and linoleic acids. Carpobrotus edulis had dual anti-cholinesterase activity against both acetylcholinesterase and butyrylcholinesterase. Both species had a high content of phenolic compounds. Arthrocnemum macrostachyum is a potential biological source of biochemicals counteracting free radical-induced oxidative damage and also degenerative diseases associated with metabolic stress, such as cancer and neurological disorders. Carpobrotus edulis is a candidate species for future studies on novel and alternative therapies for the treatment of neurological disorders associated with low levels of acetylcholine in the brain. © 2012 by Walter de Gruyter • Berlin • Boston. Source

Subiros-Funosas R.,Barcelona Institute for Research in Biomedicine | Subiros-Funosas R.,Networking Center on Bioengineering | Khattab S.N.,Alexandria University | Nieto-Rodriguez L.,Barcelona Institute for Research in Biomedicine | And 7 more authors.
Aldrichimica Acta | Year: 2013

The aim of this review is to cover recent advances in acylation chemistry (peptide, amide, and ester bond formation) in which ethyl 2-cyano-2-(hydroxyimino) acetate (Oxyma)-derived reagents are involved. The distinct applications of each class of Oxyma derivatives will be discussed and compared to the behavior of reputed standards in the field. Source

Garcia O.,University of Barcelona | Bofill J.M.,University of Barcelona | Nicolas E.,University of Barcelona | Albericio F.,University of Barcelona | And 2 more authors.
European Journal of Organic Chemistry | Year: 2010

The benzyl derivative of the Pbf group, which is the most commonly used side-chain protecting group for Arg, has been proposed for the protection of the side chains of Cys, Asp, and Glu. In the three cases, the new protecting group (Pbfm) was removed with a high concentration of TFA during the cleavage and global deprotection step. In addition, the Pbfm group can be removed from the Cys residue by using very dilute TFA solutions. Furthermore, when Cys is protected with the Pbfm group, it can be removed by oxidative treatment, thereby directly rendering the disulfide bridge on the solid phase. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Heras C.,University of Barcelona | Ramos-Tomillero I.,University of Barcelona | Ramos-Tomillero I.,Barcelona Institute for Research in Biomedicine | Caballero M.,University of Barcelona | And 8 more authors.
European Journal of Organic Chemistry | Year: 2015

The conventional electrophilic intramolecular aromatic substitution pathway proposed by Cresp et al. [J. Chem. Soc., Perkin Trans. 1 1973, 340-345] is confirmed by the observed products of phenolic formylation mediated by TiCl4. However, when the nucleophilic path is quenched by appropriate ligand modification, the initial equilibria between the possible neutral complexes of TiCl4 with 3,5-dimethoxyphenol and/or diethyl ether lead to different stable diradical intermediates induced by valence tautomerism that provide valuable activated reagents. Some of these species have been detected by EPR, characterized theoretically and captured by TEMPO, thus providing a consistent mechanism for the reaction with one or more equivalents of TEMPO per phenol. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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