One-Pot (3 + 2) Cycloaddition-Isomerization-Oxidation of 2,2,2-Trifluorodiazoethane and Styryl Derivatives.
1. Universidad de Alcalá, Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química "Andrés M. del Río" (IQAR), 28805, Alcala de Henares, Madrid, Spain. 2. Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS) 28034, Madrid, Spain.
A facile access to 5-aryl-3-trifluoromethylpyrazoles has been developed by a one-pot (3 %@2B 2) cycloaddition-isomerization-oxidation sequence employing 2,2,2-trifluorodiazoethane and styryl derivatives. A broad variety of functional groups and good yields are achieved under mild conditions. Additionally, the functionalization of 3-trifluoromethylpyrazoles was studied. DFT calculations of the cycloaddition transition state energies are consistent with the experimentally observed reactivity.
Hyper-Cross-Linked Porous Polymer Featuring B-N Covalent Bonds (HCP-BNs): A Stable and Efficient Metal-Free Heterogeneous Photocatalyst.
1. Department of Frontiers in Materials Chemistry, Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Sor Juana Inés de la Cruz, 3, Cantoblanco, Madrid 28049, Spain. 2. Universidad de Alcalá (IRYCIS), Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química "Andrés M. del Río" (IQAR), Campus Científico-Tecnológico, Facultad de Farmacia, Autovía A-II, Km 33.1, 28805-Alcalá de Henares, Madrid, Spain.
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 S(BET) of 612 m(2)/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.
Visible-Light-Mediated Regioselective Chlorosulfonylation of Acrylamides.
acrylamides; difunctionalization of alkenes; photocatalysis; chlorosulfonylation; α-chlorosulfones
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.
1. Universidad de Alcalá (IRYCIS), Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química "Andrés M. del Río" (IQAR), Campus Científico-Tecnológico, Facultad de Farmacia, Autovía A-II, Km 33.1, 28805-Alcalá de Henares, Madrid, Spain. 2. Departamento de Química Orgánica e Inorgánica, Instituto Universitario de Química Organometálica "Enrique Moles", Universidad de Oviedo, C/Julián Clavería, 8, 33006 Oviedo, Spain.
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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.
Synthesis of Five-Membered Organoborate Heterocycles via a Metal-Free Carboboration and Their Use in Cross-Coupling Reactions.
metal-free carboboration; organoboron compounds; organoborate heterocycles; cross-coupling reactions; boron chemistry
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.