Polymer-supported benzimidazolium based ionic liquid: an efficient and reusable Brønsted acid catalyst for Biginelli reaction

Abstract

A polymer-supported benzimidazolium based ionic liquid (PSBIL) was synthesized by reaction of poly(vinylbenzyl chloride) and benzimidazole followed by ring opening of 1,4-butane sultone and acidification with sulphuric acid.

Efficient Rapid Access to Biginelli for the Multicomponent Synthesis of 1,2,3,4-Tetrahydropyrimidines in Room-Temperature Diisopropyl Ethyl Ammonium Acetate

“…Even though various modes have been reported in the literature, the Biginelli MCR is moderately versatile because it can be implemented with numerous chemical takes in all three key components (i.e., aldehyde, β-ketoester, and thiourea or urea) paramount to a manifold of thiones/dihydropyrimidinones. 27 These reactions can be accomplished under a variability of tentative conditions, and several improvements have been reported in recent years, such as p -TsOH·H 2 O, 28 H 3 BO 3 , 29 [Al(H 2 O) 6 ](BF 4 ) 3 , 30 thiamine hydrochloride, 31 imidazole-1-yl-acetic acid, 32 l-(+)-tartaric acid-dimethylurea, 32 HClO 4 –SiO 2 , 33,34 SnCl 2 ·2H 2 O, 35 polymer-supported benzimidazolium-based ionic liquid, 36 basic IL, 37 Al-plante MCM-41, 38 (NH 4 ) 2 CO 3 , 39 CeCl 3 ·7H 2 O, 40 CaCl 2 , 39 Ce(NH 4 ) 2 (NO 3 ) 6 polyvinylsulfonic acid, 34 and Fe(OTs) 3 ·6H 2 O. 41 However, numerous of these testified methods become infected with several disadvantages such as strong acidic conditions, use of hazardous or costly reagents, long reaction times, low yields of products, and sophisticated treatment.…”

Biginelli Reaction: Polymer Supported Catalytic Approaches

“…In 2016, Khiratkar et al synthesized polymer-supported benzimidazolium based ionic liquid (PSBIL, Figure 1G) as a Bronsted-acidic, heterogeneous organocatalyst for the Biginelli reaction (Table 1). 45 The catalyst was prepared by reaction of poly(vinylbenzyl chloride) and benzimidazole, followed by ring opening of 1,4-butane sultone and acidification with sulfuric acid. Among various polar solvents, ethanol was found effective with the PSBIL catalyst.…”

Expanding the Chemical Space of Benzimidazole Dicationic Ionic Liquids

“…Starting from the first report by Katritzky et al [45], BILs were investigated in fields that comprise CO 2 capture and conversion [46,47], electronics [48][49][50], dye solar cells [51], anticancer and antibacterial agents [52,53], bioremediation technologies [54,55], fuel desulfurization [56], extraction [57], lignin conversion [58], and fuel cell [59,60]. On the other hand, an area in which BILs were heavily studied is organic synthesis, where they were successfully used as catalysts in several reaction classes such as the Biginelli reaction [61], the Micheal reaction [62,63], condensations [64][65][66][67], alkylations [68], amine formylation [69], coupling [70], and esterifications [71]. Furthermore, the use of BILs as catalysts has also been reported in the preparation of natural-derived building blocks: in the transesterification of castor oil with methanol [72], in the production of ethyl levulinate [73] and in the preparation of 5-hydroxymethyl furfural starting from chitosan [74].…”