Cascade embedding triethyltryptophanium iodide ionic liquid (TrpEt₃⁺I⁻) on silicated titanomagnetite core (Fe_3‐xTi_xO₄‐SiO₂@TrpEt₃⁺I⁻): A novel nano organic–inorganic hybrid to prepare a library of 4‐substituted quinoline‐2‐carboxylates and 4,6‐disubstituted quinoline‐2‐carboxylates

Abstract

A library of substituted quinolone‐2‐carboxylates (4,6‐disubstituted quinolone‐2‐carboxylates, 6‐substituted quinoline dialkyl‐2,4‐dicarboxylates, and 6‐substituted 4‐[2‐methoxy‐2‐oxoethyl]quinoline‐2‐methylcarboxylates) was obtained through different scopes of one‐pot and one‐step MCRs such as (a) three‐component reaction of aromatic amines, dialkyl acetylenedicarboxylates, and terminal alkenes/ketones; (b) pseudo three‐component reaction of anilines and dialkyl acetylenedicarboxylates; and (c) pseudo three‐component reaction of anilines and methyl propiolate under solvent‐free conditions at 100°C. The promoter of these annulation processes is a novel inorganic–organic core–shell that was obtained from silicated titanomagnetite, tryptophan amino acid, and ethyl iodide. The tryptophan embedded on the silicated titanomagnetite core (Fe3‐xTixO4‐SiO2) followed by alkylation with ethyl iodide subsequently result in in situ preparation of triethyltryptophanium iodide ionic liquid (TrpEt3+I−). The final nanohybrid (Fe3‐xTixO4‐SiO2@TrpEt3+I−) was characterized by field‐emission scanning electron microscope, EDAX, FT‐IR, TGA/DTG, vibrating sample magnetometer, and X‐ray fluorescence techniques. The highlighted features of the protocol are as follows: (a) synthesis of a vast range of substituted quinolines through a straightforward method from simple substrates under solvent‐free conditions, (b) utilizing various scopes of functionalities as substrates, (c) simple separation of the nano promoter via an external magnet, (d) regioselectivity in the cascade annulation procedure, and (e) recovery and reusability of the nanocomposite within three runs without significant activity loss.

A pronounce approach on the catalytic performance of mesoporous natural silica toward esterification of acetic acid with iso‐amyl, benzyl, and cinnamyl alcohols

“…[32,39,41] In addition, the bands located at 781, 680, 489, and 451 cm À1 are attributed to the bending vibration of Si O Si link. [39,40,42,43] Moreover, no new bands were observed with the increase of annealing temperature, which again reflected the stability of α-SiO 2 .…”

Metal-bio functionalized bismuthmagnetite [Fe3−xBixO4/SiO2@l-ArgEt3+I−/Zn(ii)]: a novel bionanocomposite for the synthesis of 1,2,4,5-tetrahydro-2,4-dioxobenzo[b][1,4]diazepine malononitriles and malonamides at room temperature and under sonication

“… 32 Some catalytic systems also have been applied based on a titanomagnetite (Fe 3− x Ti x O 4 ) core to promote organic transformations. 33 The Walz group, in 2002, studied some characteristics of Fe 3− x M x O 4 (M = Ni, Mg, Co, Al, Ti, and Ga) via magnetic after-effect (MAE) spectroscopy. 34 However, although the investigations on Fe 3− x M x O 4 with different metals are comprehensive, in the literature, there are no reports on Fe 3− x Bi x O 4 .…”