Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: El acceso a la versión del editor puede requerir la suscripción del recurso Access to the published version may require subscription High-fidelity Noncovalent Synthesis of Hydrogen-bonded Macrocyclic AssembliesCarlos Montoro-García, Jorge Camacho-García, Ana M. López-Pérez, Nerea Bilbao, Sonia RomeroPérez, María J. Mayoral and David González-Rodríguez* Abstract: A hydrogen-bonded cyclic tetramer is assembled with remarkably high effective molarities from a properly designed dinucleoside monomer. This self-assembled species exhibits an impressive thermodynamic and kinetic stability and is formed with high fidelities within a broad concentration range.

Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: A series of lipophilic nucleosides comprising natural and non-natural bases that are -conjugated to a short oligophenylene-ethynylene fragment has been synthesized. These bases comprise guanosine, isoguanosine, 2-aminoadenosine as purine heterocycles, and cytidine, isocytosine and uridine as complementary pyrimidine bases. The hydrogen-bonding dimerization and association processes between complementary bases were as well studied by 1 H NMR and absorption spectroscopies in order to obtain the relevant association constants.

Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: Copyright: © 2016 Wiley VCH VerlagEl acceso a la versión del editor puede requerir la suscripción del recurso Access to the published version may require subscription The Role of Multipoint Hydrogen-bond Symmetry on Chelate Cooperativity in Supramolecular MacrocyclizationsCarlos Montoro-García, [a] Jorge Camacho-García, [a] Ana M. López-Pérez, [a] María J. Mayoral, [a] Nerea Bilbao, [a] and David González-Rodríguez [a] *Abstract: Here, we analyze the intrinsic chelate effect that multipoint H-bonding patterns exert in the overall energy of dinucleoside cyclic systems. Our results indicate that the magnitude of EM is regulated by the symmetry of the H-bonding pattern, which is reduced by about 3 orders of magnitude when going from the unsymmetric ADD-DAA or DDA-AAD patterns to the symmetric DAD-ADA pattern.The supramolecular synthesis [1] of complex nanostructures with a precision analogous to that found in the natural world requires not only an understanding of the noncovalent interactions involved, [2] but also of cooperative and multivalent phenomena that may arise between the individual constituents, since the control of structure and monodispersity depends largely on this issue. [3] A molecule with more than one binding site may assemble into linear (open) or cyclic (closed) structures. Although the size of linear oligomers can be sometimes limited within a certain range, the supramolecular product is commonly a statistical distribution of chain lengths.[4]Therefore, the synthesis of discrete supramolecular structures has normally been focused on closed (multi)macrocyclic systems, where size and structure are dictated by the geometric requirements of the monomer and the binding interaction. [5] The effect that causes the quantitative formation of a particular ring-closed species is defined as chelate cooperativity, and stems from the fact that an intramolecular interaction is favored over an intermolecular one, providing a series of conditions of enthalpic and entropic origin are met. [3] The increased in stability when comparing a linear and a cyclic oligomer of a certain length is given by the product K inter ·EM, where K inter is the intermolecular binding constant and considers the additional association to form the cycle, whereas EM, the key parameter quantifying chelate cooperativity, stands for effective molarity and takes into account that this last binding event is intramolecular (EM = K intra /K inter ). [6] In this context, multipoint H-bonding motifs, constituted by an array of vicinal H-bonding donor (D) and acceptor (A) groups, arise as a relevant noncovalent interaction increasingly used to produce not only discrete cyclic assemblies, but also supramolecular polymers and functional materials.[7] A relevant example is represented by the nucleobases [8] and DNA itself, constituted by combinations of unsymmetric ADD-DAA guaninecytosine and symmetric DA-AD adenine...

A mild palladium-catalyzed Kumada-Corriu reaction of secondary benzylic bromides with aryl and alkenyl Grignard reagents has been developed. In the presence of the Xantphos ligand, the undesired beta-elimination pathway is minimized, affording the corresponding cross-coupling products in acceptable to good yields. The reaction proceeds with inversion of the configuration.

Enantioenriched 3-pyrrolines have been synthesized by highly enantioselective Fesulphos-Cu-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with trans-1,2-bisphenylsulfonyl ethylene, followed by reductive sulfonyl elimination. High levels of reactivity, exoselectivity, and enantioselectivity have been accomplished for a variety of substituted azomethine ylides. This cycloaddition-desulfonylation strategy has been applied as a key step in the enantioselective synthesis of a biologically active C-azanucleoside.