One-Pot Synthesis of Biologically Important Spiro-2-amino-4H-pyrans,Spiroacenaphthylenes, and Spirooxindoles Using DBU as a Green and Recyclable Catalyst in Aqueous Medium

We have reported DBU-catalyzed one-pot synthesis of biologically and pharmacologically important spiropyrans from condensation of malononitrile/ethyl cyanoacetate, 1,3-dicarbonyl compounds, and ninhydrin/acenaphthequinone/istain in good yields. This new protocol employing DBU, which is a green, recyclable, and inexpensive catalyst, offers advantages such as mild reaction conditions, short reaction times, and easy isolation of products. The structures have been confirmed by x-ray analysis.

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