A series of spiro-pyran derivatives have been synthesised by a three-component reaction of ninhydrin or acenaphthenequinone, malononitrile and 1,3-dicarbonyl compounds such as cyclohexane-1,3-dione, dimedone and barbituaric acid in ethanol with NaHCO3as the catalyst. This method has the advantages of easy work-up, mild reaction condition, high yields and it is cheap.
In the absence of any solvent, a series of spiro-2-amino-4 H-pyrans derivatives were synthesised via the three component reaction of malononitrile and α-methylencarbonyl compounds/enol with 9,10-phenanthroquinone or ace-naphthenequinone using 1-butyl-3-methylimidazolium hydroxide ([bmim][OH]) as a basic ionic liquid catalyst. This method has some distinct advantages such as mild reaction conditions, short reaction time and is environmentally friendly.