PEG 400

Abstract

(A) Kouznetsov et al. had developed a simple and efficient one-pot method for the synthesis of novel 2,4-diaryl-1,2,3,4-tetrahydroquinolines using a three-component imino Diels-Alder cycloaddition between trans-isoeugenol or trans-anethole, anilines, and benzaldehyde in the presence of BF3·OEt2 in PEG 400.13 (B) Jorapur et al. reported the synthesis of dibenz[b,f]-1,4- oxazepine via intramolecular cyclization and revealed the utility PEG 400 as recyclable reaction medium.14 (C) Guchhait and Madaan reported the Ugi-type multicomponent reaction of heterocyclic amidines with aldehydes and isocyanides catalyzed by zirconium(IV) chloride in PEG 400. This protocol offers the rapid, environmentally friendly and regioselective synthesis of medicinally important N-fused 2- and 3-aminoimidazoles in good to high yields.15 (D) Reddy et al. developed a synthetic route to afford styrylfurans in good yields via 1,3-dipolar cycloaddition between isocyanides, dialkyl acetylenedicarboxylates, and α,β-unsaturated aldehydes in PEG 400.16 (E) Shitole et al. reported the synthesis of 2-amino-4H-chromenes by condensation of aromatic aldehyde, malononitrile, and α-naphthol. 17 (F) Zhang et al. disclosed the role of PEG 400 as an efficient catalyst to synthesize quinaoxalines via condensation of 1,2-diamines with 1,2-dicarbonyl compounds in excellent yields under mild reaction conditions.18 (G) Liang et al. reported a metal-free synthesis of amides by direct oxidative amidation of aldehydes with amines in a PEG 400/oxidant system in good to excellent yields.19 (H) Wang et al. reported a Hantzsch 1,4-dihydropyridines synthesis via a one-pot condensation of aldehydes, β-dicarbonyl compounds, and ammonium acetate in PEG 400. This method has the advantages of good yields, less pollution, and simple reaction conditions.20 (I) Bhosle et al. reported an efficient one-pot three-component cyclocondensation of 4-(p-tolyl sulfonoxy) benzaldehyde, aryl amines, and mercaptoacetic acid in PEG 400 to yield 2,3-disubstituted 4-thiazolidinones. 21 (J) Karnakar et al. developed a simple, efficient and eco-friendly synthetic protocol for the synthesis of pyrazolo[3,4-b]quinolines via a one-pot three-component reaction of aldehydes, amino pyrazole, and 1,3-cyclohexanediones using recyclable PEG 400 as reaction medium.22 © Georg Thieme Verlag KG Stuttgart · New York.