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Francos J.,University of Santiago de Compostela | Grande-Carmona F.,Institute Investigaciones Quimicas CSIC USE | Faustino H.,University of Santiago de Compostela | Iglesias-Siguenza J.,University of Seville | And 6 more authors.
Journal of the American Chemical Society | Year: 2012

The first highly enantioselective intermolecular (4 + 2) cycloaddition between allenes and dienes is reported. The reaction provides good yields of optically active cyclohexenes featuring diverse substitution patterns and up to three stereocenters. Key to the success of the process is the use of newly designed axially chiral N-heterocyclic carbene-gold catalysts. © 2012 American Chemical Society. Source

Romero-Estudillo I.,CSIC - Institute of Natural Products and Agrobiology | Saavedra C.,CSIC - Institute of Natural Products and Agrobiology | Boto A.,CSIC - Institute of Natural Products and Agrobiology | Alvarez E.,Institute Investigaciones Quimicas CSIC USE
Biopolymers | Year: 2015

The creation of peptide libraries by site-selective modification of a few peptide substrates would increase the efficiency of discovery processes, but still is a real synthetic challenge. The site-selective modification of small peptides at serine or threonine residues, by using a short scission-addition procedure, allows the preparation of peptides with unnatural α-aryl glycines. In a similar way, the scission of hydroxyproline residues is the key step in the production of optically pure α-alkyl glycines which are precursors or components of branched peptides. With these versatile processes, a single peptide can be transformed into a variety of peptide derivatives. The process takes place under mild conditions, and good global yields are obtained. © 2015 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 104: 650-662, 2015. © 2015 Wiley Periodicals, Inc. Source

Boto A.,CSIC - Institute of Natural Products and Agrobiology | Gallardo J.A.,CSIC - Institute of Natural Products and Agrobiology | Alvarez E.,Institute Investigaciones Quimicas CSIC USE
European Journal of Organic Chemistry | Year: 2012

A one-pot process for the transformation of relatively inexpensive serine derivatives into oxazine derivatives of γ-aryl-γ-hydroxy-α- amino acids is described. The reaction preferentially afforded 4,6-cis oxazines. The method can also be applied to the transformation of amino sugars into highly functionalized oxazines, which are precursors of chiral amines. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Grande-Carmona F.,University of Seville | Iglesias-Siguenza J.,University of Seville | Alvarez E.,Institute Investigaciones Quimicas CSIC USE | Diez E.,University of Seville | And 2 more authors.
Organometallics | Year: 2015

The selective Suzuki cross-coupling of 1,3-dichloroisoquinoline with 2-substituted 1-naphthylboronic acids/esters followed by construction of the imidazo[1,5-b]isoquinoline ring and alkylation constitutes a straightforward route to imidazolium salts fused into an axially chiral biaryl skeleton. Metalation of these azolium salts afforded the corresponding NHC silver complexes, which were used as carbene transfer agents for the synthesis of Au(I) derivatives. © 2015 American Chemical Society. Source

Magriz A.,Institute Investigaciones Quimicas CSIC USE | Gomez-Bujedo S.,University of Seville | Alvarez E.,Institute Investigaciones Quimicas CSIC USE | Fernandez R.,University of Seville | Lassaletta J.M.,Institute Investigaciones Quimicas CSIC USE
Organometallics | Year: 2010

The direct metalation of phthalazinium halides with [Rh( tBuO)(COD)]2 or [Ir(tBuO)(COD)]2 led to the isolation of stable [MCl(phthalazin-2-ylidene)X(COD)] (M = Rh, Ir) as a new family of cyclic amino aryl carbene transition metal complexes. The X-ray diffraction analysis of several representatives systematically revealed a relatively short C(aryl)-C(carbene) bond distance of 1.44-1.46 Å, shorter than the typical C(sp2)-C(sp2) single bond, indicating some electron density delocalization from the π system of the aryl ring over the vacant carbene orbital. © 2010 American Chemical Society. Source

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