Silica-bonded N-propylpiperazine sodium n-propionate as recyclable catalyst for synthesis of 4H-pyran derivatives

Silica-bonded N-propylpiperazine sodium n-propionate (SBPPSP) was found to act as an efficient solid base for the preparation of a series of 4H-benzo[b]pyran derivatives. SBPPSP was used as a recyclable heterogeneous solid base catalyst for the synthesis of 3,4-dihydropyrano[c]chromenes, 2-amino-4H-pyrans, 1,4-dihydropyrano[2,3-c]pyrazoles, and 2-amino-4H-benzo[e]-chromenes via the condensation reaction of dimedone, ethyl acetoacetate, 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one, and α-naphthol, respectively, with aromatic aldehydes and malononitrile in refluxing aqueous ethanol. The heterogeneous solid base showed similar efficiency when reused in consecutive reactions.

Graphical AbstractSilica-bonded N-propylpiperazine sodium n-propionate is employed as a heterogeneous catalyst for the synthesis of pyran derivatives in refluxing aqueous ethanol.Figure optionsDownload full-size imageDownload as PowerPoint slide