Selectivity control in the reaction between 2-hydroxyarylaldehydes and 4-hydroxycoumarin. Antioxidant activities and computational studies of the formed products

A series of 6H,7H-7-(4-Hydroxy-3-coumarinyl)[1]benzopyrano[4,3-b][1]benzopyran-6-ones 4a-g and 3-(2-hydroxybenzoyl)-2H-chromen-2-ones 5a-g derivatives were synthesized by reaction of 4-hydroxycoumarin with 2-hydroxyarylaldehydes 2a-f or 2-hydroxynaphtaldehyde 2g using different solvents and acid/base catalysts. The approach relies on a regioselective cascade reaction involving one/two molar equiv of the 4-hydroxy coumarin iteratively acting as...