Unusual titanium-induced McMurry coupling of 4-oxo-4H-chromene-2-carbaldehydes enroute to bis-chromones

Abstract

Ti/Zn-mediated McMurry coupling of a series of 4-oxo-4H-chromene-2-carbaldehydes afforded unusual chemoselective CH₂–CH₂ tethered bis-chromones. Studying the reaction parameters and reagents further confirmed that the formation of unexpected coupled products is selective to 4-oxo-4H-chromene-2-carbaldehydes. This methodology demonstrated a simple and efficient route for the synthesis of bis-chromones.