Oxidative single-electron transfer-catalyzed tandem reactions consisting of a conjugate addition and a radical cyclization are reported, which incorporate the mandatory terminal oxidant as a functionality into the product.

A series of 3-substituted pyrazinium tetrafluoroborates was prepared as simple analogues of flavinium salts which are efficient organocatalysts for oxidations with hydrogen peroxide. It was shown that pyrazinium derivatives with an electronwithdrawing substituent catalyze mild oxidations of sulfides to sulfoxides and Baeyer-Villiger oxidations in a similar way to flavinium catalysts. The most reactive catalyst, 3-cyanopyrazinium tetrafluoroborate, was efficiently employed in preparative sulfoxidations of aromatic and aliphatic sulfides as well as in Baeyer-Villiger oxidations of cyclobutanones. A proposed mechanism for the catalysis is based on the formation of pyrazine hydroperoxide which is the agent oxidizing the substrate.

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Enantioselective syntheses of densely functionalized pyrrolidines deriving their chirality from (R)‐1‐(phenyl)ethylamine are reported. Allylic amines and β‐substituted‐α,β‐unsaturated esters are used as the building blocks in this one‐pot reaction. Single electron transfer (SET) oxidation served to merge the reactivities of anionic enolate and radical intermediates. Ferrocenium hexafluorophosphate, which is easy to prepare, store and handle, was applied as SET oxidant and persistent free radical TEMPO served as the oxygenating agent introducing a protected hydroxy function, which proved to be beneficial for further derivatization. Exclusive 2,3‐trans and up to 6:1 3,4‐cis/trans diastereoselectivities were achieved in the targeted tetrasubstituted pyrrolidines.