Catch and Release Catalysis

Abstract

Catch and Release Catalysis is a system developed by PhosphonicS for the reuse of palladium in cross-coupling reactions. The drive for a greener, more sustainable chemical industry means that the development of systems for the reuse of finite resources is required. Therefore, this body of work investigates the development and application of the Catch and Release system in a range of cross-coupling reactions.

The Catch and Release system centres around the formation of a Pd(II) oxidative addition complex supported onto silica that can act as a pre-catalyst for reactions. The use of pre-catalysts is common to counteract issues that arise with Pd/L systems and a review of the literature surrounding this topic was conducted (Chapter 1). The individual steps of the system were investigated before being combined and applied to Suzuki-Miyaura reactions.

Firstly, optimisation of the formation of the Pd(II) oxidative addition complex (‘Catch’) using both the functionalised silica developed by PhosphonicS and a backbone model was undertaken before these conditions were applied to other aryl halides (Chapter 2). Studies into the stability of the formed Pd(II) complexes when subjected to common reaction conditions were also carried out.
The release of the supported Pd(II) into solution to form active Pd(0) (‘Release’) was investigated using a range of common nucleophiles (Chapter 3). Application of both the silica supported Pd(II) complex and the backbone model Pd(II) complex as pre-catalysts for Buchwald-Hartwig, Sonogashira, and Suzuki-Miyaura cross-couplings was successfully undertaken.

Finally, the Catch and Release system was applied to both Buchwald-Hartwig and Suzuki-Miyaura cross-couplings for the reuse of palladium (Chapter 4). The steps required to link the Catch and the Release portions underwent further investigation (‘Reaction – Catch’, ‘Release – Reaction’, ‘Reaction – Catch – Reaction’). The full Catch and Release system was demonstrated to allow the reuse of a single palladium precursor in four Suzuki-Miyaura cross-coupling reactions.

Date of Award	11 Dec 2024
Original language	English
Awarding Institution	University of Bath
Supervisor	Christopher Frost (Supervisor), James Taylor (Supervisor), Hannah Leese (Supervisor), Paul Murray (Advisor) & Nicholas Taylor (Advisor)