Development of a boryl radical-mediated H-atom transfer umpolung blueprint to make nucleophilic radicals behave as electrophilic species

Description du projet

De nouvelles voies dans la chimie des radicaux

Les molécules aliphatiques sont essentielles dans de nombreux processus chimiques, mais leur création peut s’avérer difficile en raison du comportement des radicaux alkyles. Ces radicaux sont généralement nucléophiles, ce qui signifie qu’ils ne réagissent pas bien avec les composés riches en électrons tels que les aromatiques et les oléfines. En revanche, les radicaux électrophiles réagissent fortement avec ces composés, mais ne sont pas très utiles en chimie de synthèse. Soutenu par le programme Actions Marie Skłodowska-Curie, le projet BRAT concevra une nouvelle méthode pour inverser le comportement de ces radicaux. En combinant la catalyse photoredox avec le transfert d’atomes d’H médié par le radical boryle, le projet générera de nouveaux radicaux capables de réagir avec des composés riches en électrons. Il facilitera la création de produits aliphatiques de grande valeur et élargira les possibilités de la chimie des radicaux.

Objectif

"Aliphatic molecules are integral to every aspect of chemistry and radical chemistry has strong impact in their preparation. However, radical reactions are heavily influenced by the polarity of these species, which ultimately controls their reactivty profile.Most notably, standard alkyl radicals are nucleophilic and therefore do not react with electron rich aromatics and olefins. Electrophilic radicals display strong reactivity with these species but they are of limited synthetic value.

This project seeks to address this challenge by developing an innovative approach for radical ""umpolung"". In particular, we will demonstrate the integration of photoredox catalysis and boryl radical-mediated H-atom transfer catalysis, as a unique blueprint for the activation of alpha,alpha-diborylated alkalnes. This will generate alpha,alpha-diborylated radicals that, owing to their strong electrophilic character, will (i) react with electron rich aromatics and olefins and then (ii) enable diverge functionalization. In this way we will overcome the fundamental issue that nucleophilic alkyl radicals do not react with electron rich olefins/aromatics. This reactivity will streamline the preparation of many high-value but difficult to make aliphatic products, will be used in late-stage functionalizations and will substantially expand the fields of photoredox catalysis and boryl radical chemistry.

This research capitalizes on recent developments of the Leonori group that has experience in the design of methodologies based on both H-atom transfer and boryl radical reactivity.

The completion of such an innovative and ambitious project at RWTH Aachen University will be facilitated by generating, transferring, sharing and disseminating knowledge, and will enhance my future career following the training plan envisioned.
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