Chitosan synergistically enhanced by successive Fe3O4 and silver nanoparticles as a novel green catalyst in one-pot, three-component synthesis of tetrahydrobenzo[α]xanthene-11-ones

Synthesis and Characterization of Fe3O4@SiO2 NPs as an Effective Catalyst for the Synthesis of Tetrahydrobenzo[a]xanthen-11-ones

“…Three-component condensation of aldehydes, 2-naphthol and cyclic 1, 3- 45 In the context of our interest on sustainable approaches in the preparation of heterocyclic compounds and in continuation of our interest towards the advancement of effective and environmentally friendly nanocatalysts in organic synthesis, [46][47][48][49][50][51][52] we now wish to report a green and efficient method for the preparation of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones by MCRs using Fe 3 O 4 @SiO 2 core-shell nanoparticles as robust, environmentally benign and resuabale catalyst with acidic properties.…”

Co(II) anchored glutaraldehyde crosslinked magnetic chitosan nanoparticles (MCS) for synthesis of 2,4,5‐trisubstituted and 1,2,4,5‐tetrasubstituted imidazoles

“…These magnetic nanoparticles were then dried in an oven at 60°C. [45] Then, 0.5 g of as-prepared MCS-GT nanoparticles were dispersed in distilled water using sonication. An amount of 0.3 g of Co(CH 3 COO) 2 salt was dissolved in 5 ml of water.…”

“…The contents were stirred overnight and the MCS-GT@Co(II) nanoparticles (Scheme 1c) were washed with distilled water and dried in an oven. [45] 2.3 | General procedure for synthesis of 2,4,5-Trisubstituted Imidazoles (Scheme 2)…”

“…The weight loss of bare Fe 3 O 4 nanoparticles in the range 100-550°C was about 20%, which might be due to the loss of remaining water from the surface [52] ( Figure 7a). Pure chitosan shows a weight loss of 5-10% at 110°C, which could be attributed due to the loss of moisture from its surface and another fall was observed near 320°C due to the degradation of chitosan chain [45] ( Figure 7b). The weight losses for Fe 3 O 4 , chitosan, MCS-GT and MCS-GT@Co(II) at 550°C were 20, 96, 81 and 74%, respectively as shown in Figure 7(a-d).…”

“…), which can further enhance its use in industry, pharmaceuticals, biomedicine, food processing, metal chelating, etc. [45,46] Further, this catalyst was used in the one-pot three-component reaction for the formation of 2,4,5-trisubstituted imidazoles by the condensation of benzil, aldehyde and ammonium acetate and in the one-pot four-component reaction for the formation of 1,2,4,5-tetrasubsituted imidazole by the condensation of benzil, aldehyde, ammonium acetate and various substituted aromatic amines under refluxing conditions using EtOH. Finally, as our catalyst is based on magnetic nanoparticles, it can be easily recovered using an external magnet and reused, so the protocol is environmentally benign.…”