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Brönsted Acidic Ionic Liquids Catalysed Sequential Michael‐Like Addition of Indole with Chalcones via Claisen‐Schmidt Condensation
Author(s) -
Das Sukanya,
Porashar Bikoshita,
Saikia Susmita,
Borah Ruli
Publication year - 2020
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201904851
Subject(s) - ionic liquid , chemistry , acetophenone , michael reaction , catalysis , condensation , solvent , condensation reaction , organic chemistry , indole test , ionic bonding , medicinal chemistry , physics , thermodynamics , ion
A sequential acidic ionic liquid catalyzed one pot approach was conducted for preparation of 3‐substituted indoles starting from in situ generated chalcones involving Claisen‐Schmidt condensation of substituted aromatic aldehydes with acetophenone followed by Michael‐like addition of indoles to these chalcones under solvent‐free thermal reactions. For this purpose, some new and some reported Brönsted acidic ionic liquids, 2‐alkyl‐1, 3‐disulfoimidazolium carboxylate [RDSIM][X] (where R=Me & Et and X=CH 3 COO − , CCl 3 COO − , CF 3 COO − ), were analyzed to compare their Brönsted acidic strength and thermal stabilities. From this investigation, 2‐methyl‐1, 3‐disulfoimidazolium trifluoroacetate [MDSIM][CF 3 COO] and 2‐ethyl‐1,3‐disulfoimidazolium trifluoroacetate [EDSIM][CF 3 COO] were determined as efficient ionic liquid catalysts for study of the two‐step one pot synthesis of 3‐substituted indoles.