Cinquima

Instituto Universitario

Recent advances in the discovery and development of new nickel-catalyzed processes will be described. Illustrations in the reductive coupling of unsaturated components and in the development of new transformations of easily accessible phenol derivatives will be provided. In these areas, our recent efforts have focused on the design of regiodivergent processes and on the development of strategies to enable regioselectivity and enantioselectivity to be simultaneously addressed in catalytic transformations. Mechanistic studies are providing considerable insight into the origins of selectivity and reactivity in the processes under development. In addition to the focus on catalysis by nickel-NHC complexes, the lecture will also describe recent collaborative work in biocatalysis using cytochrome P450 enzymes as an enabling tool for organic synthesis.

John Montgomery was born in 1965 in Concord, N.C. He studied chemistry at the University of North Carolina in 1987 under the direction of Profs. Joe Templeton and Maurice Brookhart where his undergraduate research experience sparked his interest in organometallic chemistry. He received his Ph.D. at Colorado State University in 1991 under the direction of Prof. Louis Hegedus, and he was an American Cancer Society Postdoctoral Fellow at the University of California at Irvine from 1991 – 1993 with Prof. Larry Overman. In 1993, he began his independent career at Wayne State University, and he moved to the University of Michigan at Ann Arbor in 2005, and in 2013 he was appointed as the Margaret and Herman Sokol Professor of Synthetic or Medicinal Chemistry. He current serves as the Director of the Michigan Chemistry-Biology Interface Training Program funded by NIGMS.

He has received a number of awards including a Pfizer Michigan Green Chemistry Award (2007), American Chemical Society Arthur C. Cope Scholar Award (2001), Johnson and Johnson Focused Giving Grant (2001), Camille Dreyfus Teacher Scholar Award (1998), National Science Foundation CAREER Award (1996), 3M Corporation New Faculty Award (1996), and he was recently elected as a Fellow of the American Association for the Advancement of Science (2011). He has coauthored over 90 research publications and presented over 220 invited lectures at various symposia, meetings, academic institutions, and pharmaceutical and biotechnology companies.

John’s independent career has focused on the use of transition metals in reaction discovery, synthetic methodology development, mechanistic chemistry, and complex molecule synthesis. A number of new nickel-catalyzed reactions have been discovered in his laboratory involving the reductive coupling of two π-components with a reducing agent. Among these, the reductive coupling of aldehydes and alkynes, enones and alkynes, and aldehydes and allenes have been most extensively developed. Total or formal syntheses completed by the Montgomery group using nickel-catalyzed reductive couplings as key steps include several members of the allopumiliotoxin, kainic acid, and domoic acid families of natural products as well as testudinariol A, isogeissoschizine, aigialomycin D, and methymycin. Other new catalytic reactions developed include the reductive cycloaddition of enals and alkynes, the [4+2+1] cycloaddition of dienes, alkynes, and diazoalkanes, the crossed cycloaddition of cyclopropyl ketones and enones, the three-component coupling of enoates, aryl iodides, and aldehydes, and several coupling processes involving redox isomerization. Other current interests include the discovery of new glycosylation methods and the use of biocatalytic transformations in organic synthesis.

Abstract:

Radicals are intrinsically reactive, and were long believed to be “too reactive to be selective”. However, in the coordination sphere of transition metals highly selective radical-type processes are certainly possible. In fact, radical-type reactions are tremendously important in several bio-synthetic pathways mediated by metallo-enzymes. Nature solves its most difficult and most interesting bio-synthetic problems with radical-reactivity. Yet, despite their radical-nature, these reactions proceed with ultrahigh precision and selectivity.

Inspired by such intriguing catalytic radical-type transformations mediated by metallo-enzymes, we are investigating new catalytic radical-type transformations mediated by synthetic (open-shell) organometallic catalysts. This presentation is focused on the diverse radical-type reactivity of cobalt-carbene (and nitrene) complexes, in which the transient reactive moieties act as redox active ligands producing discrete carbene (and nitrene) radicals. Such species provide unique opportunities in developing new catalytic ring-closure protocols. Here we report on their diverse radical-type pathways, revealing both convergent pathways and unique divergent routes to a variety of desirable organic ring products.

Bas de Bruin studied chemistry at the University of Nijmegen from 1989-1994. He obtained his Ph. D. (April 20, 1999) from the same university (Rh Mediated Olefin Oxygenation). He did his postdoc in the group of Wieghardt at the Max-Planck Institut für Bioanorganische Chemie (Mülheim a/d Ruhr, Germany, April 1999-April 2000) for which he obtained an Alexander-von-Humboldt fellowship in 1999. After his postdoc he returned to the University of Nijmegen as an assistant professor in Inorganic Chemistry (Metal-Organic Chemistry), where he was involved in several research activities ranging from olefin oxygenation, radical organometallic chemistry, EPR spectroscopy, catalysis, light-switchable redox bistable molecules, DFT calculations, and (catalytic) synthesis of new materials. September 2005, Bas de Bruin obtained an NWO-VIDI grant to uncover new catalytic reactions. November 2005 he moved to the University of Amsterdam (UvA, group Reek, Homogeneous and Supramolecular Catalysis), where he was promoted to Associate Professor (UHD, October 2008). January 2013 he was promoted to Full Professor (chair) at the same university.

Bas de Bruin presently focuses at the development of new tools in homogeneous catalysis, using metals in unconventional oxidation states and unconventional ligands, specifically aiming at the development of new catalytic reactions. In 2008 he obtained a prestigious ERC Starting Grant (first round of the EU 7th framework Ideas Program; ERC = European Research Council). In 2012 he obtained a prestigious NWO-VICI grant to investigate new controlled (catalytic) radical-type transformations. Bas de Bruin is involved in teaching Inorganic Chemistry, Thermodynamics, Organometallic Chemistry, Bioinorganic Chemistry, Homogeneous Catalysis and (Catalytic) Reaction Mechanisms.

25 marzo, 2015
por cinquima
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Defensa de la Tesis Doctoral de Mercedes Calvillo

El viernes 27 de marzo tendrá lugar la defensa de la tesis doctoral de Mercedes Calvillo titulada: “Adición Enantioselectiva de Derivados Dialquilzinc a Cetonas Catalizada por Diaminas Quirales Voluminosas: Síntesis de Alcoholes Trifluorometilados Quirales y Estudios Mecanísticos” dirigida por Pablo Espinet, Jesús Mª … Continuar leyendo