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

Descripción del proyecto

Nuevas vías en la química radical

Las moléculas alifáticas son esenciales en muchos procesos químicos, pero crearlas puede ser difícil debido al comportamiento de los radicales alquílicos. Estos radicales suelen ser nucleófilos, lo que significa que no reaccionan bien con compuestos ricos en electrones, como los aromáticos y las olefinas. Por otro lado, los radicales electrofílicos reaccionan fuertemente con estos compuestos, pero no son muy útiles en la química sintética. Con el apoyo de las Acciones Marie Skłodowska-Curie, el equipo del proyecto BRAT desarrollará un método nuevo para invertir el comportamiento de estos radicales. Combinando la catálisis fotorreductora con la transferencia de átomos de hidrógeno mediada por radicales borilo, en el proyecto se generarán nuevos radicales capaces de reaccionar con los compuestos ricos en electrones. Esto facilitará la creación de productos alifáticos de alto valor y ampliará las posibilidades de la química radical.

Objetivo

"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.
"