Couple-close construction of polycyclic rings from diradicals.

Heteroarenes are ubiquitous motifs in bioactive molecules, conferring favourable physical properties when compared to their arene counterparts. In particular, semisaturated heteroarenes possess attractive solubility properties and a higher fraction of sp carbons, which can improve binding affinity and specificity. However, these desirable structures remain rare owing to limitations in current synthetic methods.

Selective Isomerization via Transient Thermodynamic Control: Dynamic Epimerization of to Diols.

Traditional approaches to stereoselective synthesis require high levels of enantio- and diastereocontrol in every step that forms a new stereocenter. Here, we report an alternative approach, in which the stereochemistry of organic substrates is selectively edited without further structural modification, a strategy with the potential to allow new classes of late-stage stereochemical manipulation and provide access to rare or valuable stereochemical configurations. In this work, we describe a selective epimerization of cyclic diols enabled by hydrogen atom transfer photocatalysis and boronic acid mediated transient thermodynamic control, selectively generating less stable products from the otherwise favored isomers.