<i>Z</i>‐Selective Synthesis of α‐Sulfanyl Carbonyl Compounds from Internal Alkynes and Thiols via Photoredox Catalysis

Abstract A synthetically useful Z ‐selective cascade formal thiyl radical addition, 1,3‐double bond isomerization, oxygen trapping reaction, can be promoted by Eosin B under visible light, leading to the construction of 2‐aryl‐ and alkylthio enone derivatives in good yields. An accurate study on reactivity different thiols screening reaction conditions, allowed us extend this a large number substrates, showing functional groups tolerance while highlighting limitations procedure. Background experiments mechanistic studies were also. performed rationalize process. The usefulness methodology was finally demonstrated via transformation series α‐sulfanyl‐enone adducts through selected oxidation reactions, stereoselective synthesis cyclopropyl ketones, indanones, pyrazole compounds. magnified image