C-H functionalisation of aldehydes using light generated, non-stabilised diazo compounds in flow.

The difficulty in accessing and safely utilising non-stabilised diazo species has in the past limited the application of this class of compounds. Here we explore further the use of oxadiazolines, non-stabilised diazo precursors which are bench stable, in direct, non-catalytic, aldehyde C-H functionalisation reactions under UV photolysis in flow and free from additives. Commercially available aldehydes are coupled to afford unsymmetrical aryl-alkyl and alkyl-alkyl ketones while mild conditions and lack of transition metal catalysts allow for exceptional functional group tolerance. Examples are given on small scale and in a larger scale continuous production.

Visible-Light-Mediated Annulation of Electron-Rich Alkenes and Nitrogen-Centered Radicals from N-Sulfonylallylamines: Construction of Chloromethylated Pyrrolidine Derivatives.

A visible-light-mediated annulation of N-sulfonylallylamines and olefins is reported. Rapid access to highly functionalized chloromethylated pyrrolidines can be achieved using mild conditions for the generation of nitrogen-centered radicals. Both a transition-metal-based catalyst and an organic dye can be used as photosensitizers with 0.5 mol % loading. The reaction was found to be applicable to a large variety of electron-rich and electron-neutral olefins.