The first example of a porous polymer containing B–N covalent bonds, prepared from a tetraphene B–N monomer and biphenyl as a comonomer, is reported. It was prepared using the solvent knitting strategy, which allows the connection between the aromatic rings of the two monomers through methylene groups provided by an external cross-linking agent. The new polymer exhibited micromeso porosity with an SBET of 612 m2/g, high thermal stability, and potential properties as a heterogeneous photocatalyst, since it is very active in the aza-Henry coupling reaction (>98% of conversion and selectivity). After the first run, the catalyst improves its photocatalytic activity, shortening the reaction time to only 2 h and maintaining this activity in successive runs. The presence of a radical in this structure that remains stable with successive runs makes it a new type of material with potential applications as a highly stable and efficient photocatalyst.
Dra. Rosa López Álvarez, Senior Researcher, Universidad del País Vasco (Campus de San Sebastián) Challenges in Brønsted Base Catalysis: An Opportunity for Structure Design
Sala de Grados, Edificio de Farmacia, UAH. June 14th, 12.00.
Mizoroki-Heck macrocyclization reactions are carried out at 1M concentration with ligand-free Pd cluster catalysts either in solution or supported on solids. Mechanistic studies unveil the essential role of the fluxional Pd cluster to accommodate, at the same time, the reacting groups, to give the intramolecular vs the intermolecular coupling reaction at this high concentration, enabling (in-flow) solid-catalyzed macrocyclization reactions.
Visible-Light-Mediated Regioselective Chlorosulfonylation of Acrylamides
Mercedes Zurro, Sergio Torres-Oya, Guillermo G. Otárola, Juan José Vaquero, Estíbaliz Merino*
Synthesis 2023, Special Issue dedicated to Prof. Cristina Nevado, recipient of the 2021 Dr. Margaret Faul Women in Chemistry Award
DOI: 10.1055/s-0042-1751424
A one-step chlorosulfonylation of acrylamides via a photocatalytic redox process is described. This reaction provides α-chlorosulfonylamides with a quaternary center with high regioselectivity via radical process. It is amenable to a broad range of substrates and the products are obtained in moderate to good yields.
Gold-catalyzed endo-selective cyclization of alkynylcyclobutanecarboxamides: synthesis of cyclobutane-fused dihydropyridones
M. Soledad Garre, Guillermo G. Otárola, Estíbaliz Merino, David Sucunza, Enrique Aguilar, M. Teresa Quirós, Juan J. Vaquero* and Patricia García-García*
Cyclobutane-fused dihydropyridones can be efficiently synthesized by a completely endo-selective gold-catalyzed cyclization of alkynylcyclobutanes bearing an appended amide, which proceeds under mild conditions. The observed selectivity, which is reversed from that previously observed for the cyclization of related alcohols and acids, is supported by DFT calculations.
XVIII Simposio de Jóvenes Investigadores Químicos de la RSEQ
Sevilla, 21 – 28 November
– Oral: · Metal-free synthesis of 3-trifluoromethypyrazoles: [3+2] cyclization of styrenes and 2,2,2-trifluorodiazoethane Julia Altarejos, David Sucunza, Juan J. Vaquero, Estíbaliz Merino, and Javier Carreras
– Póster: · Visible-light mediated synthesis of indazoles Clara Mañas, Estíbaliz Merino
– Póster: · Synthesis of novel five membered organoborate heterocycles and their use in cross-coupling reactions Isabel Valencia, Patricia Garcia-Garcia, David Sucunza, Adrián Pérez-Redondo, Juan J. Vaquero
Treatment of various vinylbenzopyridines with allyl(dichloro)borane affords five-membered organoborate heterocycles via a metal-free carboboration. The reaction between these organoborates and Grignard reagents increases the number of derivatives belonging to this novel family of four-coordinate organoboron compounds. Some of them were used as reagents in phenylations and methylations in moderate to high yields under standard palladium-catalyzed cross-coupling reaction conditions.
Gold(I)-catalyzed cyclization of o-alkenyl-o’-alkynylbiaryls in the presence of external or internal nucleophiles provides a straightforward access to phenanthrene-based polycycles, which are of considerable interest in materials science. Thus, their reactions with alcohols yield functionalized dihydrophenanthrenes, in a process that can also be carried out intramolecularly to provide phenanthrene-derived heteropolycyclic compounds. Moreover, benzo[b]triphenylenes can be synthesized from o-methoxyvinyl-o’-alkynylbiaryls, in a reaction in which an (hetero)aryl substituent at the triple bond acts as an internal nucleophile.
Highly efficient unbridged D-A+(D) chromophores based on the quinolizinium cation for nonlinear optical (NLO) applications
Esmeralda Sánchez-Pavón, Javier Recio, Marco Antonio Ramirez, Belen Batanero, Koen Clays, Francisco Mendicuti, Gema Marcelo, Thais Carmona, Obis Castaño, Silvia Angelova, Jose L. Andres, Juan J. Vaquero, Ana M. Cuadro*
Novel charged D-A+ chromophores based on quinolizinium cations as acceptor unit have been prepared by treating haloquinolizinium salts with N-heteroarylstannanes under Stille reaction conditions. This approach provides an easy access to potential one-dimensional D-A+ and two-dimensional D-A+-D chromophores in which the acceptor moiety (A+) is the simple azonia cation and the donors are different π-rich N-heterocycles. The first hyperpolarizabilities (β) were measured by hyper-Rayleigh scattering experiments and the experimental data confirmed that the inherent polarization between donor and acceptor fragments modulates the NLO properties. The electronic structures and properties (including both the linear and nonlinear optical properties) of the quinolizinium chromophores were examined by theoretical (DFT, HF and MP2) calculations. A promising strategy for the rational design of D-A building blocks to create new organic-based NLO materials is proposed.
