Asymmetric 1, 3-dipolar cycloaddition reactions between methacrylonitrile and nitrones catalysed by well-defined M(diphosphane) (M=Rh, Ir) complexes

The cationic half-sandwich aqua-complexes (¿ 5-C5Me5)M(PP*)(H2O)]SbF6]2 M=Rh, Ir; PP* =(R)-Benphos, (R)-Cyphos, (2R, 4R)-Norphos] catalyse the 1, 3-dipolar cycloaddition reaction of nitrones with methacrylonitrile with perfect regioselectivity, low-to-perfect endo-selectivity and low-to-moderate enantioselectivity. The active species involved in the catalytic process, (¿ 5-C5Me5)M(PP*)(methacrylonitrile)]SbF6]2, have been isolated and characterised as mixtures of the (S)- and (R)-at-metal epimers. NMR measurements of these mixtures indicated that the (R M)-isomers epimerise to the corresponding (S M) counterparts. The molecular structure of the rhodium complex (S Rh, R C)-(¿ 5-C5Me5)Rh((R)-Benphos)(methacrylonitrile)]SbF6]2 has been determined by X-ray diffraction methods. Diastereomerically pure (S Rh, R C)-(¿ 5-C5Me5)Rh(PP*)(methacrylonitrile)]SbF6]2 compounds catalyse stoichiometrically the above mentioned dipolar cycloaddition reaction with up to 90% enantiomeric excess, thus indicating the influence of the metal handedness on the catalytic stereochemical outcome. Catalysts can be recycled up to three times without a significant loss of either activity or selectivity

Synthesis and catalytic activity of well-defined Co(i) complexes based on NHC–phosphane pincer ligands

A new methodology for the preparation of Co(I)–NHC (NHC = N-heterocyclic carbene) complexes, namely, [Co(PCNHCP)(CO)2][Co(CO)4] (1) and [Co(PCNHCP)(CO)2]BF4 (2), has been developed (PCNHCP = 1,3-bis(2-(diphenylphosphanyl)ethyl)-imidazol-2-ylidene). Both complexes can be straightforwardly prepared by direct reaction of their parent imidazolium salts with the Co(0) complex Co2(CO)8. Complex 1 efficiently catalyses the reductive amination of furfural and levulinic acid employing silanes as reducing agents under mild conditions. Furfural has been converted into a variety of secondary and tertiary amines employing dimethyl carbonate as the solvent, while levulinic acid has been converted into pyrrolidines under solventless conditions. Dehydrocoupling of the silane to give polysilanes has been observed to occur as a side reaction of the hydrosilylation process

Molecular hydrogen and water activation by transition metal frustrated Lewis pairs containing ruthenium or osmium components: catalytic hydrogenation assays

The transition metal frustrated Lewis pair compounds [(Cym)M(κ3S,P,N-HL1)][SbF6] (Cym = η6-p-MeC6H4iPr; H2L1 = N-(p-tolyl)-N′-(2-diphenylphosphanoethyl)thiourea; M = Ru (5), Os (6)) have been prepared from the corresponding dimer [{(Cym)MCl}2(μ-Cl)2] and H2L1 by successive chloride abstraction with NaSbF6 and AgSbF6 and NH deprotonation with NaHCO3. Complexes 5 and 6 and the previously reported phosphano–guanidino compounds [(Cym)M(κ3P,N,N′-HL2)][SbF6] [H2L2 = N,N′-bis(p-tolyl)-N′′-(2-diphenylphosphanoethyl) guanidine; M = Ru (7), Os (8)] and pyridinyl–guanidino compounds [(Cym)M(κ3N,N′,N′′-HL3)][SbF6] [H2L3 = N,N′-bis(p-tolyl)-N′′-(2-pyridinylmethyl) guanidine; M = Ru (9), Os (10)] heterolytically activate H2 in a reversible manner affording the hydrido complexes [(Cym)MH(H2L)][SbF6] (H2L = H2L1; M = Ru (11), Os (12); H2L = H2L2; M = Ru (13), Os (14); H2L = H2L3; M = Ru (15), Os (16)). DFT calculations carried out on the hydrogenation of complex 7 support an FLP mechanism for the process. Heating 9 and 10 in methanol yields the orthometalated complexes [(Cym)M(κ3N,N′,C-H2L3-H)][SbF6] (M = Ru (17), Os (18)). The phosphano–guanidino complex 7 activates deuterated water in a reversible fashion, resulting in the gradual deuteration of the three cymene methyl protons through sequential C(sp3)–H bond activation. From DFT calculations, a metal–ligand cooperative reversible mechanism that involves the O–H bond activation and the formation of an intermediate methylene cyclohexenyl complex has been proposed. Complexes 5–10 catalyse the hydrogenation of the C[double bond, length as m-dash]C double bond of styrene and a range of acrylates, the C[double bond, length as m-dash]O bond of acetophenone and the C[double bond, length as m-dash]N bond of N-benzylideneaniline and quinoline. The C[double bond, length as m-dash]C double bond of methyl acrylate adds to catalyst 9, affording complex 19 in which a new ligand exhibiting a fac κ3N,N′,C coordination mode has been incorporated

Dinuclear Pyridine-4-thiolate-bridged rhodium and iridium complexes as ditopic building blocks in molecular architecture

A series of dinuclear pyridine-4-thiolate rhodium and iridium compounds [M(μ-4-Spy)(diolef)]2 (diolef = 1,5-cyclooctadiene, cod; M = Rh (1), Ir (2); 2,5-norbornadiene, nbd; M = Rh (3)) have been prepared by reaction of Li(4-Spy) with the appropriate compound [M(μ-Cl)(diolef)]2 (M = Rh, Ir). The dinuclear compound [Rh(μ-4-Spy)(CO)(PPh3)]2 (4) has been obtained by reaction of [Rh(acac)(CO)(PPh3] with 4-pySH. Compounds 1-4 have been assessed as metalloligands in self-assembly reactions with the cis-blocked [M(cod)(NCCH3)2](BF4) (M = Rh (a) and M = Ir (b)) and [M(H2O)2(dppp)](OTf)2 (M = Pd (c), Pt (d)) (dppp = 1,3-bis(diphenylphosphino)propane) acceptors. Homo [{M2(μ-4-Spy)2(cod)2}2{M(cod)}2](BF4)2 (M = Rh (1a)2, and M = Ir (2b)2), and hetero [{Rh2(μ-4-Spy)2(cod)2}2{Ir(cod)}2](BF4)2 (1b)2, [{Rh2(μ-4-Spy)2(cod)2}2{M'(dppp)}2](OTf)4 ( M' = Pd (1c)2 and M'= Pt (1d)2) and [{Ir2(μ-4-Spy)2(cod)2}2{M'(dppp)}2](OTf)4 ( M' = Pd (2c)2 and M'= Pt (2d)2) hexanuclear metallomacrocycles have been obtained. NMR spectroscopy, in combination with ESI mass spectrometry has been used to elucidate the nature of the metalloligands and their respective supramolecular assemblies. Most of synthesized species have shown to be non-rigid in solution and their fluxional behavior has been studied by VT 1H NMR spectroscopy. An X-ray diffraction study on the assemblies (1a)2 and (1d)2 revealed the formation of rectangular (9.6 x 6.6 Å) hexanuclear metallomacrocycles with alternating dinuclear (Rh2) and mononuclear (Rh or Pt) corners. The hexanuclear core is supported by four pyridine-4-thiolate linkers, which are bonded through the thiolate moiety to the dinuclear rhodium units, exhibiting a bent-anti arrangement, and through the peripheral pyridinic nitrogen atoms to the mononuclear corners

Iridium-(K2-NSi) catalyzed dehydrogenation of formic acid: effect of auxiliary ligands on the catalytic performance

IThe iridium(III) complexes [Ir(H)(Cl)(κ2-NSitBu2)(κ2-bipyMe2)] (2) and [Ir(H)(OTf)(κ2-NSitBu2)(κ2-bipyMe2)] (3) (NSitBu2 = {4-methylpyridine-2-yloxy}ditertbutylsilyl) have been synthesized and characterized including X-ray studies of 3. A comparative study of the catalytic activity of complexes 2, 3, [Ir(H)(OTf)(κ2-NSitBu2)(coe)] (4), and [Ir(H)(OTf)(κ2-NSitBu2)(PCy3)] (5) (0.1 mol%) as catalysts precursors for the solventless formic acid dehydrogenation (FADH) in the presence of Et3N (40 mol%) at 353 K has been performed. The highest activity (TOF5 min ≈ 3260 h−1) has been obtained with 3 at 373 K. However, at that temperature the FTIR spectra show traces of CO together with the desired products (H2 and CO2). Thus, the best performance was achieved at 353 K (TOF5 min ≈ 1210 h−1 and no observable CO). Kinetic studies at variable temperature show that the activation energy of the 3-catalyzed FADH process is 16.76 kcal mol−1. Kinetic isotopic effect (5 min) values of 1.6, 4.5, and 4.2 were obtained for the 3-catalyzed dehydrogenation of HCOOD, DCOOH, and DCOOD, respectively, at 353 K. The strong KIE found for DCOOH and DCOOD evidenced that the hydride transfer from the C–H bond of formic acid to the metal is the rate-determining step of the process

Phase II randomized trial of capecitabine with bevacizumab and external beam radiation therapy as preoperative treatment for patients with resectable locally advanced rectal adenocarcinoma: long term results

Background: Preoperative chemoradiotherapy with capecitabine is considered as a standard of care for locally advanced rectal cancer. The “Tratamiento de Tumores Digestivos” group (TTD) previously reported in a randomized Ph II study that the addition of Bevacizumab to capecitabine-RT conferred no differences in the pre-defined efficacy endpoint (pathological complete response). We present the follow-up results of progression-free survival, distant relapse-free survival, and overall survival data at 3 and 5 years. Methods: Patients (pts) were randomized to receive 5 weeks of radiotherapy (45 Gy/25 fractions) with concurrent Capecitabine 825 mg/m2 twice daily, 5 days per week with (arm A) or without (arm b) bevacizumab (5 mg/kg once every 2 weeks). Results: In our study, the addition of bevacizumab to capecitabine and radiotherapy in the neoadjuvant setting shows no differences in pathological complete response (15.9% vs 10.9%), distant relapse-free survival (81.0 vs 80.4 and 76.2% vs 78.2% at 3 and 5 years respectively), disease-free survival (75% vs 71.7 and 68.1% vs 69.57% at 3 and 5 years respectively) nor overall survival at 5-years of follow-up (81.8% vs 86.9%). Conclusions: the addition of bevacizumab to capecitabine plus radiotherapy does not confer statistically significant advantages neither in distant relapse-free survival nor in disease-free survival nor in Overall Survival in the short or long term

VITAL phase 2 study: Upfront 5-fluorouracil, mitomycin-C, panitumumab and radiotherapy treatment in nonmetastatic squamous cell carcinomas of the anal canal (GEMCAD 09-02)

Aim: VITAL, a phase II single-arm study, aimed to evaluate efficacy and safety of panitumumab addition to 5-fluorouracil (5-FU), mitomycin-C (MMC) and radiotherapy (RT) in patients with localized squamous cell carcinoma of the anal canal (SCCAC). Methods: Adult, treatment-naïve SCCAC patients (Stage T2-T4, any N, M0) and ECOG-PS ≤2, received panitumumab (6 mg/kg, day 1 and Q2W; 8 weeks), 5-FU (1000 mg/m2/d, days 1-4 and 29-32), MMC (10 mg/m2, days 1 and 29) and RT 45 Gy (1.8 Gy/fraction) to the primary tumor and mesorectal, iliac and inguinal lymph nodes, plus 10-15 Gy boost dose to the primary tumor and affected lymph nodes. The primary objective was disease free survival rate (DFS) at 3-years (expected 3-year DFS rate: 73.7 ± 12%). Results: Fifty-eight patients (31 women; median age: 59 years; ECOG-PS 0-1:98%; TNM II [29%] (T2 or T3/N0/M0)/IIIA (T1-T3/N1/M0 or T4/N0/M0) [21%]/IIIB (T4/N1/M0 or any T/N2 or N3/M0) [47%]/nonevaluable [4%]) were included. The median follow-up was 45 months. The 3-year DFS rate was 61.1% (95% CI: 47.1, 72.4). The 3-year overall survival rate was 78.4% (95% CI: 65.1, 87.1). Eighteen patients (31.0%) required a colostomy within 2 years posttreatment. Grade 3-4 toxicities were experienced by 53 (91%) patients. Most common grade 3-4 treatment-related events were radiation skin injury (40%) and neutropenia (24%). No toxic deaths occurred. Improved efficacy in colostomy-free survival and complete response rate was observed in human papilloma virus positive patients. Conclusions: Panitumumab addition to MMC-5FU regimen in SCCAC patients increases toxicity and does not improve patients’ outcomes. RT plus MMC-5FU remains the standard of care for localized SCCAC patients.This work was supported by Amgen S.A

Precariedad, exclusión social y diversidad funcional (discapacidad): lógicas y efectos subjetivos del sufrimiento social contemporáneo (II). Innovación docente en Filosofía

El PIMCD "Precariedad, exclusión social y diversidad funcional (discapacidad): lógicas y efectos subjetivos del sufrimiento social contemporáneo (II). Innovación docente en Filosofía" se ocupa de conceptos generalmente eludidos por la tradición teórica (contando como núcleos aglutinantes los de la precariedad laboral, la exclusión social y diversidad funcional o discapacidad), cuyo análisis propicia nuevas prácticas en la enseñanza universitaria de filosofía, adoptando como meta principal el aprendizaje centrado en el estudiantado, el diseño de nuevas herramientas de enseñanza y el fomento de una universidad inclusiva. El proyecto cuenta con 26 docentes de la UCM y otros 28 docentes de otras 17 universidades españolas (UV, UNED, UGR, UNIZAR, UAH, UC3M, UCA, UNIOVI, ULL, EHU/UPV, UA, UAM, Deusto, IFS/CSIC, UCJC, URJC y Univ. Pontificia de Comillas), que permitirán dotar a las actividades programadas de un alcance idóneo para consolidar la adquisición de competencias argumentativas y dialécticas por parte de lxs estudiantes implicados en el marco de los seminarios previstos. Se integrarán en el PIMCD, aparte de PDI, al menos 26 estudiantes de máster y doctorado de la Facultad de Filosofía, a lxs que acompañarán durante el desarrollo del PIMCD 4 Alumni de la Facultad de Filosofía de la UCM, actualmente investigadores post-doc y profesorxs de IES, cuya experiencia será beneficiosa para su introducción en la investigación. Asimismo, el equipo cuenta con el apoyo de varixs profesorxs asociadxs, que en algunos casos son también profesores de IES. Varixs docentes externos a la UCM participantes en el PIMCD poseen una dilatada experiencia en la coordinación de proyectos de innovación de otras universidades, lo que redundará en beneficio de las actividades a desarrollar. La coordinadora y otrxs miembros del PIMCD pertenecen a la Red de Innovación Docente en Filosofia (RIEF), puesta en marcha desde la Universitat de València (http://rief.blogs.uv.es/encuentros-de-la-rief/), a la que mantendremos informada de las actividades realizadas en el proyecto. Asimismo, lxs 6 miembros del PAS permitirán difundir debidamente las actividades realizadas en el PIMCD entre lxs estudiantes Erasmus IN del curso 2019/20 en la Facultad de Filosofía, de la misma manera que orientar en las tareas de maquetación y edición que puedan ser necesarias de cara a la publicación de lxs resultados del PIMCD y en las tareas de pesquisa bibliográfica necesarias para el desarrollo de los objetivos propuestos. Han manifestado su interés en los resultados derivados del PIMCD editoriales especializadas en la difusión de investigaciones predoctorales como Ápeiron y CTK E-Books

Asymmetric 1,3-dipolar cycloaddition reactions between methacrylonitrile and nitrones catalysed by well-defined M(diphosphane) (M = Rh, Ir) complexes

The cationic half-sandwich aqua-complexes [(η-CMe)M(PP∗)(HO)][SbF] [M = Rh, Ir; PP∗ = (R)-Benphos, (R)-Cyphos, (2R,4R)-Norphos] catalyse the 1,3-dipolar cycloaddition reaction of nitrones with methacrylonitrile with perfect regioselectivity, low-to-perfect endo-selectivity and low-to-moderate enantioselectivity. The active species involved in the catalytic process, [(η-CMe)M(PP∗)(methacrylonitrile)][SbF], have been isolated and characterised as mixtures of the (S)- and (R)-at-metal epimers. NMR measurements of these mixtures indicated that the (R)-isomers epimerise to the corresponding (S) counterparts. The molecular structure of the rhodium complex (S,R)-[(η-CMe)Rh{(R)-Benphos}(methacrylonitrile)][SbF] has been determined by X-ray diffraction methods. Diastereomerically pure (S,R)-[(η-CMe)Rh(PP∗)(methacrylonitrile)][SbF] compounds catalyse stoichiometrically the above mentioned dipolar cycloaddition reaction with up to 90% enantiomeric excess, thus indicating the influence of the metal handedness on the catalytic stereochemical outcome. Catalysts can be recycled up to three times without a significant loss of either activity or selectivity.We thank the Ministerio de Economía y Competitividad, Spain and European Social Fund (Grants CTQ2012-32095, CTQ2015-66079-P and CONSOLIDER INGENIO-2010 CSD2006-0015), European Union and Gobierno de Aragón and European Social Fund (Grupo Consolidado: Catalizadores Organometálicos Enantioselectivos), European Union for financial support. A.A. thanks the IUCH for a grant.Peer Reviewe

Síntesis y reactividad del complejo [{Ir(μ-Cl)(C7H8)3}2] frente a ligandos N-, P- y C- dadores

Resumen del trabajo presentado a la 6ª Jornada de Jóvenes Investigadores en Física y Química de Aragón celebrada en Zaragoza el 20 de noviembre de 2014.El fácil acceso sintético a complejos dinucleares de rodio e iridio del tipo [{Ir(μ-Cl)(diolefina)}2] (diolefina = 1,5-ciclooctadieno (COD), tetrafluorobenzobarreleno (TFB)) ha permitido el desarrollo de una química organometálica muy extensa. En este contexto las diferencias estructurales, de origen tanto estérico como electrónico, entre estas dos diolefinas inducen una reactividad diferente a los complejos correspondientes. Otra diolefina disponible comercialmente íntimamente relacionada es 2,5-norbornadieno (NBD), que posee un ángulo de mordedura más pequeño. Aunque la química de rodio con este dieno es conocida, en el caso de iridio esta química está mucho menos desarrollada. En este trabajo de investigación se explora el comportamiento químico de complejos de iridio con la diolefina NBD. La reacción de sustitución del dieno COD por el dieno NBD en el complejo dinuclear [{Ir(μ-Cl)(COD)}2] da lugar a un complejo dinuclear de fórmula [{Ir(μ-Cl)(C7H8)3}2],2 en el que formalmente hay tres diolefinas por átomo de iridio. Mediante difracción de rayos X se puede comprobar como dos de estas unidades de NBD han experimentado un acoplamiento carbono–carbono inducido por el metal formando un metalaciclo de cinco miembros, mientras que una de las diolefinas está coordinada en su modo natural η4-C=C. Este complejo es insoluble; sin embargo su interacción con ligandos N-, P- y C- dadores da lugar a la formación de aductos mononucleares solubles que se han caracterizado mediante técnicas de RMN y de rayos X. En algunos casos, dependiendo de la naturaleza del ligando, se observan fenómenos de inserción del metalaciclo en enlaces Ir–CO e incluso el acoplamiento C–C de una tercera molécula de NBD formando un metalaciclo de 7 miembros.Proyecto CTQ2012-35665 y Programa CONSOLIDER INGENIO- 2010.Peer reviewe