Browsing by Subject "Paladio"
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- PublicationOpen AccessEight-membered Palladacycles Derived from the Insertion of Olefines into the Pd–C Bond of Ortho-palladated Pharmaceuticals Phenethylamine and Phentermine. Synthesis of Stable Heck-type Intermediates Containing Accessible β-Hydrogens and its Use in the Synthesis of 2-Styryl-phenethylamines, Tetrahydroisoquinolines and Eight-membered Cyclic Amidines(ACS, 2010-09-13) Vicente, José; Saura-Llamas, Isabel; García-López, José-Antonio; Bautista, Delia; Vicente, José; Química InorgánicaThe ortho-metalated complexes derived from phenethylamine and phentermine [Pd(C,N-C6H4CH2CR2NH2-2)(μ-X)]2 (R = H, X = Br (A); R = Me, X = Cl (B)) react with olefins giving (1) the product of its insertion into the Pd–C bond, [Pd{C,NCH( R’)CH2C6H4CH2CR2NH2-2}(μ-X)]2 (olefin = CH2=CHR’; R = H, X = Cl, R’ = C(O)Me (1a), CO2Et (1c); R = Me, X = Cl, R’ = C(O)Me (1b), CO2Et (1d)), [Pd{C,NCH( C5H8)CHC6H4(CH2CMe2NH2)-2}(μ-Cl)]2 (olefin = norbornene, C5H8; 1e) or (2) the decomposition products of 1, i.e., Pd(0) and the complexes containing the arylated olefin, trans-[PdX2(NH2CR2CH2C6H4CH=CHPh-2)2] (olefin = styrene; R = H, X = Cl (3f); R = Me, X = Br (3g)). While complexes 1c and 1d can be isolated but decompose in solution to afford Pd(0) and the corresponding complexes 3 (R = H, X = Cl (3c); R = Me, X = Br (3d)), the others are surprisingly stable. Neutral ligands L cleave the bridge of complexes 1 to afford [Pd(C^N)X(L)] (2) (L = 4-methyl-pyridine (pic), NH3, NHEt2, PPh3, tBuNC, XyNC). Complexes 3 react with 1,10-phenanthroline (phen) to give [PdX2(phen)] and the orthovinylated arylalkylamine RCH=CHC6H4CH2CR2NH2-2 (R = H (4f), Me (4g)), which in the case of 3c or 3d can not be isolated as it undergoes an intramolecular hydroamination process to afford the tetrahydroisoquinoline 5c or 5d, respectively. To prepare the tetrahydroisoquinoline 5b, it is necessary to heat a mixture of complex 1b with one equiv of TlOTf. The eight-membered cyclic amidine 7d is obtained from thermal decomposition of complex cis-[Pd{C,N-CH(CO2Et)CH2C6H4CH2CR2NH2-2}(CNXy)2]OTf (8d), prepared by reaction of 2d-5 with TlOTf and XyNC. The amidinium salt 7e-HOTf is formed by refluxing in toluene a mixture of 2e-4 and TlOTf. The crystal structures of compounds 2a·CHCl3, 2b-1, 3 2d-3·1/3CH2Cl2, 2e-4·1/2CHCl3, 3d, 3g, 6 and 7e-HOTf have been determined by X-ray diffraction studies.
- PublicationOpen AccessExploring the mechanism of the Pd-catalyzed spirocyclization reaction: a combined DFT and experimental study(RSC, 2018-01) Franzoni, Ivan; Yoon, Hyung; García-López, José-Antonio; Poblador-Bahamonde, Amalia Isabel; Lautens, Mark; Química Inorgánica
- PublicationOpen AccessInsertion of benzyne into the Pd–C bond. Synthesis of unnatural amino acid derivatives by sequential insertion of benzyne and CO: 2,2’-functionalized biaryls containing alkylamino and carboxymethyl substituents. Isolation of stable carbopalladated-benzyne intermediates(RSC, 2012-05-16) García-López, José-Antonio; Oliva-Madrid, María-José; Saura-Llamas, Isabel; Bautista, Delia; Vicente, José; Vicente, José; Química InorgánicaReaction of ortho-palladated derivatives of phentermine and homoveratrylamine with benzyne allows the synthesis of enlarged eight-membered palladacycles resulting from the insertion of the aryne into the Pd–C bond, which subsequently react with CO, to render unnatural amino acid derivatives.
- PublicationOpen AccessInsertion of Isocyanides, Isothiocyanates and Carbon Monoxide into the Pd–C Bond of Cyclopalladated Complexes Containing Primary Aryl-Alkylamines of Biological and Pharmaceutical Significance. Synthesis of Lactams and Cyclic Amidinium Salts Related to the Isoquinoline, Benzo[g]isoquinoline and b-Carboline Nuclei(ACS, 2008-12) Vicente, José; Saura-Llamas, Isabel; García-López, José-Antonio; Química Inorgánica
- PublicationOpen AccessOrtho-Palladation and Functionalization of L-Phenylalanine Methyl Ester(2007-04) Vicente, José; Saura-LLamas, Isabel; García-López, José-Antonio; Calmuschi-Cula, Beatrice; Química Inorgánica
- PublicationOpen AccessOxidaciones de leucocolorantes derivados del trifenil metano con cloramina T, catalizadas por el ioduro. Determinaciones de ioduro, plata, m-ercurio y paladio(Murcia: Universidad de Murcia, Servicio de Publicaciones, 1984) Pérez Ruiz, Tomás; Martínez Lozano, C.; Hernández Lozano, Manuel; Facultad de BiologíaLa oxidación del leucovioleta cristal y leucoverde malaquita por la cloramina T es catalizada por el ioduro. Basados en este efecto se proponen dos m6todos para la determinación de ioduro sensibles, exactos, seIectivos y rápidos. En condiciones adecuadas 10s. iones Ag(I), HgCII) y Pd(I1) inhiben la acción cataIitica del ioduro sobre la oxidacidn de las formas reducidas de ambos colorantes por la cloramina T. Las determinaciones cinéticas de estos iones metálicos son aplicables en rangos de concentración a niveles de trazas.
- PublicationOpen AccessPd-catalyzed formal [2+2]-retrocyclization of cyclobutanols via two-fold Csp3–Csp3 bond cleavage(ACS, 2024-01-04) Parra-García, Sergio; Ballester-Ibáñez, Marina; García-López, José-Antonio; Química InorgánicaIn this work we describe the unexpected two-fold Csp3–Csp3 bond cleavage suffered by cyclobutanols in the presence of a catalytic amount of Pd(OAc)2 and promoted by the bulky biaryl JohnPhos ligand. Overall, the sequential cleavage of a strained and an unstrained Csp3–Csp3 bond leads to the formal [2+2]-retrocyclization products, namely, styrene and ace- tophenone derivatives. This procedure might enable the use of cyclobutanols as masked acetyl groups resisting harsh condi- tions in organic synthesis.
- PublicationOpen AccessPd-Catalyzed Ring-Opening Polymerization of Cyclobutanols through C(sp3)–C(sp3) Bond Cleavage(ACS, 2024-07-09) Parra-García, Sergio; Saura-Llamas, Isabel; Bautista, Delia; Gil-Rubio, Juan; García-López, José-Antonio; Química InorgánicaA new approach to ring-opening polymerization (ROP) based on C(sp3)–C(sp3) bond cleavage is reported. This process is based on the ability of Pd to promote both, the b-carbon elimination of a bifunctional cyclobutanol precursor and the C–C coupling process with the resulting Pd-alkyl intermediate. Consequently, novel polyketone materials are obtained. Owing to the modular synthesis of the used cyclobutanol monomers, the present ROP reaction allows the introduction of substitution patterns in the polymeric chain which are not accessible by current polyketone synthesis methodologies. We have explored in detail the initiation, propagation and termination steps of this new polymerization process.
- PublicationOpen AccessReactivity toward CO of Eight-Membered Palladacycles Derived from the Insertion of Alkenes into the Pd–C Bond of Cyclopalladated Primary Arylalkylamines of Pharmaceutical Interest. Synthesis of Tetrahydrobenzazocinones, Ortho-Functionalized Phenethylamines, Ureas, and an Isocyanate(ACS, 2012-08-16) García-López, José-Antonio; Oliva-Madrid, María-José; Saura-Llamas, Isabel; Bautista, Delia; Vicente, José; Vicente, José; Química InorgánicaThe ortho-metalated complex [Pd{C,N-C6H2CH2CH2NH2-2,(OMe)2-4,5}(μ-Br)]2 (1a) derived from homoveratrylamine reacts with ethyl acrylate, methyl vinyl ketone or 2-norbornene to give the dimeric complex arising from the insertion of the alkene into the Pd–C bond, [Pd{C,N-CH(R)CH2C6H2CH2CH2NH2-2,(OMe)2-4,5}(μ-Br)]2 (R = CO2Et (2a1), C(O)Me (2a2)) or [Pd{C,N-CH(C5H8)CHC6H2CH2CH2NH2-2,(OMe)2-4,5}(μ-Br)]2 (2a3). Complexes 2a and the phentermine homologues 2b react with CO to afford Pd(0) and (1) tetrahydrobenzazocinones, the heterocycles resulting from CO insertion into the Pd–C bond and C–N coupling, (2) unnatural aminoacid derivatives resulting from CO insertion and the reaction of the obtained acyl complex with the solvent (MeOH), or the product of protonolysis of the Pd–C bond, depending on the nature of the initial cyclopalladated compound or (3) ureas, alone or mixed with an isocyanate, in the presence of a base. Phentermine derivatives 2b react with HCl to give a dinuclear palladium complex [PdCl(μ- Cl)(L)], where L is the amine arising from the protonolysis of the Pd–C bond or the alkyl group resulting from Pd–N bond protonolysis, depending on the nature of the inserted alkene. The crystal structures of some palladium complexes and organic compounds have been determined by X-ray diffraction studies.
- PublicationOpen AccessSynthesis of Benzofused O- and N‐Heterocycles through Cascade Carbopalladation/Cross-Alkylation of Alkynes Involving the C−C Cleavage of Cyclobutanols(American Chemical Society, 2022-03-03) Pérez-Gómez, Marta; Herrera-Ramírez, Piedad; Bautista, Delia; Saura-LLamas, Isabel; García-López, José Antonio; Química InorgánicaWe report a Pd-catalyzed route to heterocycles bearing a tetrasubstituted alkene fragment. Our approach merges the intramolecular carbopalladation of tethered alkynes with an alkylation step produced by the C–C cleavage of cyclobutanol derivatives. An alkenyl-Pd(II) intermediate has been isolated and characterized by X-ray diffraction studies. Interestingly, the nature of the tethering alkynyl chain influences the E/Z stereochemistry of the alkenyl fragment in the functionalized heterocycles
- PublicationOpen AccessUse of 2‐Bromophenylboronic Esters as Benzyne Precursors in the Pd-Catalyzed Synthesis of Triphenylenes(ACS, 2014-04) García-López, José-Antonio; Greaney, Michael; Greaney, Michael; Química Inorgánica