A simple route for the synthesis of 3,3,3′,3′-tetramethyl-2,3,3′,4′-tetrahydro-1H,1′H-[4,9′-bixanthene]-1,1′(2′H,9′H)-dione and its derivatives catalyzed by Mn2+ and other transition metal cations

A simple and efficient unusual coupling reaction of 9-(2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-en-1-yl)-3,3-dimethyl-2,3,4,9-tetrahydro-1H-xanthen-1-one and its derivatives was accomplished in the presence of Mn2+, Cu2+, Cd2+, Hg2+, Fe3, or La3+. The structure elucidation was accomplished by IR, 1H NMR, 13C NMR, X-ray crystallography, UV–Visible and elemental analysis. A reaction mechanism is proposed.