Photoinduced Decarboxylative Dual Functional Group Transpositions

The remodelling of molecular frameworks provides entry to increased chemical value and complexity from simple starting materials, yet often relies on (hetero)cyclic scaffolds to template the reaction. Herein we describe a thermodynamic approach to dual functional group transposition which relies on radical sorting across linear alkyl frameworks, promoted by visible light irradiation and decarboxylation. Suitably primed β-thioether or β-boryl carboxylic acids, first activated as oxime esters, then irradiated in the presence of an energy transfer photosensitiser, undergo radical S,N- or B,N-reconfiguration to generate to 1,2-iminosulfides or 1,2-iminoboronic ester products. Divergent yet related mechanisms for these transposition processes were investigated using a combination of photophysical, structural and computational experiments. A suite of novel 1,2-iminofunctionalized compounds were accessible using this methodology amenable to further synthetic elaboration.