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NMR and DFT Insight into the Synergistic Role of Bovine Serum Albumin–Ionic Liquid for Multicomponent Cascade Aldol/Knoevenagel–thia‐Michael/Michael Reactions in One Pot
Author(s) -
Thopate Yogesh,
Singh Richa,
Sinha Arun K.,
Kumar Vikash,
Siddiqi Mohammad Imran
Publication year - 2016
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201600637
Subject(s) - knoevenagel condensation , michael reaction , chemistry , ionic liquid , aldol reaction , catalysis , bromide , aldol condensation , combinatorial chemistry , bovine serum albumin , pyridine , organic chemistry , biochemistry
The synergistic combination of two catalysts is an emerging strategy towards the formation of unprecedented complex molecules, and herein bovine serum albumin (BSA) and the neutral ionic liquid 1‐butyl‐3‐methylimidazolium bromide ([bmim]Br) are used together for the first time towards multiple C−C and C−S bond‐formation reactions in one pot under metal‐free, acid‐free, and base‐free conditions by merging two classical named reactions, that is, aldol condensation (AC) and thia‐Michael addition (TMA) for the cascade chemoselective generation of β‐aryl‐β‐sulfido carbonyl compounds from aliphatic ketones, aromatic aldehydes, and thiols. NMR spectroscopy and DFT calculations studies provided insight into the synergism, progress, and mechanism of the reaction, and control experiments highlighted that the single catalysts (BSA or IL) alone did not allow even the first AC step to proceed. Moreover this synergistic BSA–[bmim]Br catalytic system offers the step‐economical synthesis of the anticoagulant warfarin through sequential aldol–Michael addition reactions and potent pyridine analogues through a Knoevenagel–Michael route. Besides, the recyclability of the catalytic system (up to 5 times) with the generation of water as a byproduct makes our one‐pot protocol more economically efficient and synthetically attractive than traditional methods.