Zr(HSO 4 ) 4 ‐catalyzed one‐pot three‐component synthesis of 7‐alkyl‐6 H ,7 H ‐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‐6 H ,7 H ‐naphtho[1′,2′:5,6]pyrano[3,2‐ c ]chromen‐6‐ones by condensation of β‐naphthol, aromatic aldehydes, and 4‐hydroxycoumarin using Zr(HSO 4 ) 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).