Multi-Component Syntheses of Spiro[furan-2,3′-indoline]-3-carboxylate Derivatives Using Ionic Liquid Catalysts

Two previously described Brønsted acidic ionic liquids, 3,3′-(1,6-hexanediyl)bis(1-methyl)-1H-imidazolium hydrogen sulfate (Cat1) and 1,1′-(1,6-hexanediyl)bis(pyridinium) hydrogen sulfate (Cat2), were used as catalysts for the preparation of spiro[furan-2,3′-indoline]-3-carboxylate derivatives via a...

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Bibliographic Details
Published in:Molecules (Basel, Switzerland) Vol. 29; no. 6; p. 1223
Main Authors: Khalaj, Mehdi, Zarandi, Maryam, Samadi Kazemi, Malihe, Musavi, Seyed Mahmoud, Hohnsen, Johannes, Klein, Axel
Format: Journal Article
Language:English
Published: Switzerland MDPI AG 01.03.2024
MDPI
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ISSN:1420-3049, 1420-3049
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Summary:Two previously described Brønsted acidic ionic liquids, 3,3′-(1,6-hexanediyl)bis(1-methyl)-1H-imidazolium hydrogen sulfate (Cat1) and 1,1′-(1,6-hexanediyl)bis(pyridinium) hydrogen sulfate (Cat2), were used as catalysts for the preparation of spiro[furan-2,3′-indoline]-3-carboxylate derivatives via a three-component reaction of anilines, isatins (N-alkyl-indoline-2,3-diones), and diethyl acetylenedicarboxylate, in high yields. The use of ultrasonic (US) irradiation led to the targeted products (1a–15a) in high yields ranging from 80% to 98%. Under the same conditions, the use of sulfuric acid and acetic acid as a Brønstedt catalyst did not yield the desired benchmark product 1a.
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ISSN:1420-3049
1420-3049
DOI:10.3390/molecules29061223