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Abstract
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An eco-friendly method for the synthesis of
hydroxyspiro[indoline-3,90-xanthene]triones as new
spiro[indoline-3,90-xanthene]trione derivatives is described.
These syntheses were accomplished via pseudo threecomponent
condensation reaction of dimedone and isatin
derivatives in the presence of silica-bonded n-propyltriethylenetetraminesulfamic
acid in refluxing ethanol. Most
of the acid catalysts gave spiro[indoline-3,90-xanthene]triones
as the final products. In the present method by using
different amounts of acid catalyst and controlling the
conditions, hydroxyspiro[indoline-3,90-xanthene]triones
were obtained as the only product. The advantages of our
method are practical simplicity, using reusable heterogeneous
catalyst, short reaction times, and good yields of the
products. The recycled catalyst could be reused fifth times
without appreciable loss in the catalytic activity. Two
compounds were found to display in vitro antioxidant and
cholinesterase inhibitory activities.
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