10.1021/acs.orglett.7b03783.s001 Huan Liu Huan Liu Yi Fang Yi Fang Shun-Yi Wang Shun-Yi Wang Shun-Jun Ji Shun-Jun Ji TEMPO-Catalyzed Aerobic Oxidative Selenium Insertion Reaction: Synthesis of 3‑Selenylindole Derivatives by Multicomponent Reaction of Isocyanides, Selenium Powder, Amines, and Indoles under Transition-Metal-Free Conditions American Chemical Society 2018 reaction conditions Selenium Powder nitrogen-centered radicals selenium functionalization electron spin-resonance selenium radicals Transition-Metal-Free Conditions approach selenium powder O 2 3- selenylindole derivatives TEMPO-Catalyzed Aerobic Oxidative Selenium Insertion Reaction ESR Multicomponent Reaction selenium source 2018-02-01 22:32:10 Journal contribution https://acs.figshare.com/articles/journal_contribution/TEMPO-Catalyzed_Aerobic_Oxidative_Selenium_Insertion_Reaction_Synthesis_of_3_Selenylindole_Derivatives_by_Multicomponent_Reaction_of_Isocyanides_Selenium_Powder_Amines_and_Indoles_under_Transition-Metal-Free_Conditions/5848011 A novel and efficient approach for the selenium functionalization of indoles was developed with selenium powder as the selenium source, catalyzed by 2,2,6,6-tetramethyl­piperidinooxy (TEMPO) and employing O<sub>2</sub> as the green oxidant. This protocol provides a practical route for the synthesis of 3-selenylindole derivatives and has the advantages of readily available starting materials, mild reaction conditions, and a wide scope of substrates. Electron spin-resonance (ESR) studies reveal that the approach involves the formation of nitrogen-centered radicals and selenium radicals via oxidation of <i>in situ</i> generated selenoates.