Efficient One-Pot Syntheses of 7-Alkyl-6H,7H-naphtho[1,2:5,6]pyrano-[3,2-c]chromen-6-ones by 1-Methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium Chloride

An efficient synthesis of 7-alkyl-6H,7H-naphtho-[10,20:5,6]pyrano[3,2-c]chromen-6-ones by three-component condensation reaction of β-naphthol, aromatic aldehydes, and 4-hydroxycoumarin catalyzed by 1-methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium chloride is reported in good to excellent yields and short reaction times.