Facile and Chemically Sustainable Catalyst‐Free Synthesis of Diverse 2‐Aryl‐4‐Alkyl/Aryl‐Pyrano[3,2‐ c ]chromen‐5(4 H )‐Ones by One‐Pot Multicomponent Reactions at Room Temperature

A simple, catalyst‐free, straightforward and highly efficient one‐pot synthesis of pharmaceutically‐interesting diverse kind of functionalized 2‐aryl‐4‐alkyl/aryl‐pyrano[3,2‐ c ]chromen‐5(4 H )‐ones ( 4 a‐4 z′′ ) and 3‐/4‐(5‐oxo‐2‐aryl‐4,5‐dihydropyrano[3,2‐ c ]chromen‐4‐yl)benzaldehydes ( 4′a ‐ 4′j ) has been developed based on a multicomponent reaction between alkyl/aryl aldehydes ( 1 / 1′ ), acetophenones ( 2 ) and 4‐hydroxycoumarin ( 3 ) in aqueous ethanol at room temperature (25‐30 °C). The salient features of this protocol are mild reaction conditions, use of no catalyst, good to excellent yields, high atom‐economy, eco‐friendliness, easy isolation of products, and reusability of reaction media.