Abstract
We reported Chickpea leaf exudates (CLEs) as a Brønsted acid, naturally available biodegradable, eco-friendly, and reusable reaction medium for highly efficient and facile one-pot synthesis of pyran-annulated heterocyclic systems, like 7-aryl-benzopyrano[4,3-b]benzopyran-6,8- diones,tetrahydrobenzo[b]pyran, and dihydropyrano[c]chromenes scaffolds. The analogous products were obtained via tandem Knoevengel-Michael addition and cyclo condensation reaction in ethanol at room temperature with 90-96% yields in a short reaction time. Moreover, the reaction media containing Bronsted acids can be easily recovered and reused up to five times, slightly decreasing product yields.
Keywords: Brønsted acid, Chickpea leaf exudates, natural catalysts, pyran heterocycles, multicomponent reactions, Knoevengel- Michael cyclo condensation reaction.
Graphical Abstract
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