Sodium alginate: An efficient biopolymeric catalyst for green synthesis of 2-amino-4H-pyran derivatives

•4H-pyran derivatives have various biological and pharmacological activities.•Sodium alginate, as a natural bioploymeric macromolecule, without any postmodification was found to be an efficient and bifunctional heterogeneous catalyst for green synthesis of 4H-pyran derivatives.•4H-pyran derivatives were obtained in short reaction times and high to excellent yields in EtOH through a green method.•Sodium alginate can be recovered and reused at least for five times for green synthesis of 4H-pyran derivatives.

Sodium alginate, a naturally occurring macromolecule, in its granular form and without any post-modification was found to be an efficient and recoverable bifunctional heterogeneous organocatalyst for the domino synthesis of various 2-amino-3-cyano-4H-pyran annulated derivatives through three-component condensation of different aldehydes, malononitrile and diverse 1,3-dicarbonyl compounds under mild conditions. Corresponding 4H-pyran derivatives were obtained in high to excellent yields after 25–150 min stirring in 2 mL EtOH under reflux conditions in the presence of 10 mol% of sodium alginate, equimolar amounts of aldehydes, malononitrile and 1,3-dicarbonyl compounds. The catalyst was easily separated from the reaction mixture to obtain desired products in excellent purity as shown by FTIR and 1H NMR spectroscopic methods. Avoiding the use of any transition metal, one-pot and multi-component procedure catalyzed by a renewable biopolymer, the reusability of the catalyst, broad substrate scope and operational simplicity are important features of this methodology for preparation of medicinally important compounds.

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