biostudies-literatureKhalaj MUniversity of Cologne1223https://www.ebi.ac.uk/biostudies/studies/S-EPMC10976190biostudies-literatureUnknown29(6)Two previously described Brønsted acidic ionic liquids, 3,3'-(1,6-hexanediyl)bis(1-methyl)-1<i>H</i>-imidazolium hydrogen sulfate (<b>Cat1</b>) and 1,1'-(1,6-hexanediyl)bis(pyridinium) hydrogen sulfate (<b>Cat2</b>), were used as catalysts for the preparation of spiro[furan-2,3'-indoline]-3-carboxylate derivatives via a three-component reaction of anilines, isatins (<i>N</i>-alkyl-indoline-2,3-diones), and diethyl acetylenedicarboxylate, in high yields. The use of ultrasonic (US) irradiation led to the targeted products (<b>1a</b>-<b>15a</b>) 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 <b>1a</b>.Molecules (Basel, Switzerland)Multi-Component Syntheses of Spiro[furan-2,3'-indoline]-3-carboxylate Derivatives Using Ionic Liquid Catalysts.PMC10976190Axel KleinZarandi MMusavi SMKlein AKhalaj MHohnsen JSamadi Kazemi MfalseMulti-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)-1<i>H</i>-imidazolium hydrogen sulfate (<b>Cat1</b>) and 1,1'-(1,6-hexanediyl)bis(pyridinium) hydrogen sulfate (<b>Cat2</b>), were used as catalysts for the preparation of spiro[furan-2,3'-indoline]-3-carboxylate derivatives via a three-component reaction of anilines, isatins (<i>N</i>-alkyl-indoline-2,3-diones), and diethyl acetylenedicarboxylate, in high yields. The use of ultrasonic (US) irradiation led to the targeted products (<b>1a</b>-<b>15a</b>) 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 <b>1a</b>.2024-01-01T00:00:00Z2024 Mar2025-04-26T11:22:26.313Z2025-04-06T13:39:03.125ZS-EPMC109761903854286010.3390/molecules29061223