Visible Light-Mediated Truce-Smiles Rearrangements

Abstract

The radical Truce-Smiles rearrangement is an intramolecular aryl migration reaction that allows for the conversion of sulfonamide or sulfonate starting materials into higher value organic products, usually using the extrusion of sulfur dioxide as an entropic driving force for the reaction. Presented herein are three transformations using modern photochemical techniques for the mild generation of radical species. Firstly, an allylamine-based starting material is transformed into an arylsulfonylacetamide starting material. Difluroalkyl radicals could undergo intermolecular addition to this unactivated alkene, triggering a Truce-Smiles rearrangement, giving a carboarylated product. The reactions proceeds under metal-free conditions, with a postulated EDA complex mechanism, using N,N,N′,N′-tetramethylethylenediamine (TMEDA) as the stoichiometric electron donor. Building on these results, a decarboxylative, desulfonylative Truce-Smiles rearrangements was developed. To achieve this, a β-amino acid starting material was converted into a sulfonamide starting material and an energy-transfer mechanism was employed for the radical decarboxylation. This methodology was used to synthesise a range of arylethylamine products, relevant to the pharmaceutical industry. Finally a strained 3-aminocyclobutanone starting material was used to realise the first Truce-Smiles rearrangement by strain release using an Eosin Y dye under visible light irradiation at room temperature. The arylated β-amino nitrile products were precursors to arylated 1,3-diamines or β-amino acids.

Date of Award	31 Dec 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	David Procter (Supervisor) & Michael Greaney (Supervisor)