In water medium, environmentally benign, facile, and efficient synthesis of pyrans was achieved in good yields by the reactions of a variety of cyclic 1, 3-dicarbonyls with several α, β-unsaturated aldehydes. The key strategy was a formal [3+ 3] cycloaddition by domino Knoevenagel/6π-electrocyclization. This methodology was applied to the synthesis of biologically interesting pyranocoumarin, pyranoquinolinone, and pyranonaphthoquinone ...
![2-methyl-2-(4-methylpent-3-enyl)benzo[g]chromene-5,10-dione Structure](https://image.chemsrc.com/caspic/325/77566-45-1.png)
