Zr(HSO4)4‐catalyzed one‐pot three‐component synthesis of 7‐alkyl‐6H,7H‐naphtho[1′,2′:5,6]pyrano[3,2‐c]chromen‐6‐ones

A new, one‐pot, simple thermally efficient and solvent‐free method for the preparation of 7‐alkyl‐6H,7H‐naphtho1′,2′:5,6]pyrano3,2‐c]chromen‐6‐ones by condensation of β‐naphthol, aromatic aldehydes, and 4‐hydroxycoumarin using Zr(HSO₄)₄ as a safe and efficient catalyst is described. This method has the advantages of high yields, a cleaner reaction, simple methodology, short reaction times, easy workup, and greener conditions. J. Heterocyclic Chem., (2011).