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Abstract
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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 ??naphthol, respectively, with aromatic aldehydes and malononitrile in refluxing aqueous
ethanol. The heterogeneous solid base showed similar efficiency when reused in consecutive reactions.
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