Description du projet
Des catalyseurs chiraux efficaces pour l’activation de substrats polyinsaturés
L’objectif du projet Foldmetcat, financé par l’UE, est de concevoir de nouveaux types de catalyseurs contenant des centres de métaux de transition électrophiles capables de simultanément replier et activer des substrats polyinsaturés et promouvoir des modes de cyclisation non inhérents. Ces cascades de cyclisation non conventionnelles remettent en question les recherches actuelles qui considèrent la réactivité intrinsèque du substrat comme le seul facteur déterminant la réactivité chimique des processus initiés par des carbocations. Elles permettent également d’accéder à de grands squelettes carbocycliques tels que ceux présents dans la synthèse énantiosélective du taxol et de l’ophioboline. Un autre objectif du projet consiste à mettre au point des catalyseurs électrophiles chiraux polyvalents et efficaces à base de métaux autres que l’or.
Objectif
Inspired by mimicking the characteristics of terpenoid cyclase enzymes, the goal of this proposal is to design new types of catalysts containing electrophilic transition metal centers that could simultaneously fold and activate polyunsaturated substrates promoting non-inherent cyclization modes. Our goal is unprecedented, although it is rooted on fundamental organometallic chemistry, in particular, on the known activation of polyunsaturated substrates by highly electrophilic transition metals. These unconventional cyclizations cascades challenge the paradigm that the intrinsic reactivity of the substrate is the relevant factor in carbocation-initiated processes and would provide access to large carbocyclic skeletons such as those present in taxol and ophiobolin enantioselectively in a single step under catalytic conditions. Although the initial work will be carried out with gold catalysts, a major goal of this research is to develop other general-purpose efficient chiral electrophilic catalysts based on zinc. To attain our goal, we will study more simple catalysts to delineate the factors that control the folding of polyenynes and polyenes. Thus, we will prepare new series of C2-chiral catalysts in which the stereogenic elements are close to the reaction site. Related C2-chiral systems will be generated by supramolecular hydrogen-bond pairing. A similar chiral arrangement could also be achieved by an intramolecular chiral anion translocation from the metal to a distant hydrogen-bond donor site. In addition, we will explore larger systems based on structurally well-defined metallic clusters to generate highly electrophilic chiral reactive sites. The folding and activation of polyunsaturated substrates will be studied first with a series of catalytic prototypes based on digold or heterobimetallic complexes with N-heterocyclic carbenes, diphosphines, mixed ligands of these types, as well as resorcinarene-phosphonite cavitant ligands.
Champ scientifique
Programme(s)
Thème(s)
Régime de financement
ERC-ADG - Advanced GrantInstitution d’accueil
43007 Tarragona
Espagne