Synthesis of Coumarin 3‐aldehyde Derivatives via Photocatalytic Cascade Radical Cyclization‐Hydrolysis

Abstract New synthetic method of coumarins 3‐aldehyde via visible light stimulation and oxidation promotion cascade radical cyclization/hydrolysis process is reported. this reaction involves a two‐step procedure, the 1,3‐dioxolane radical is initiated in situ from 1,3‐dioxolane via the excited Ru(bpy) 3 Cl 2 and oxidant TBHP, subsequently an addition to triple bond of various alkynes produces vinyl radicals, the radical intermediates can smoothly convert to coumarin 3‐aldehyde via tandem cyclization/acidic hydrolysis process in good to excellent yields. Furthermore, the synthetic application valuable of coumarin 3‐aldehyde is also evaluated in this work.