One-Pot Synthesis of 2H-Pyrans by Indium(III) Chloride-Catalyzed Reactions.Efficient Synthesis of Pyranocoumarins, Pyranophenalenones, and Pyranoquinolinones

An efficient synthesis of 2H-pyrans is achieved by indium (III) chloride-catalyzed reactions of 1,3-dicarbonyl compounds with a variety of <TEX>αβ-unsaturated</TEX>, aldehydes in moderate yields. This method has been applied to the synthesis of pyranocoumar ins, pyranophenalenones, and pyranoquinolinone alkaloids.