Magnetically recoverable Fe₃O₄@chitosan@Ni₂B: a bio-based catalyst for one-pot green and efficient synthesis of tetrahydrobenzo[<i>b</i>]pyrans

This study investigates the development of a novel and environmentally friendly catalyst, Fe₃O₄@chitosan@Ni₂B nanocomposite, for multicomponent reactions (MCRs). Chitosan (CS), a biopolymer, is used because it is biocompatible, abundant, and has functional groups that can be complexed with metals. Nickel boride (Ni₂B) is used in hydrogenation reactions due to its catalytic properties. The magnetic properties of Fe₃O₄ nanoparticles enable easy separation. Herein, we describe the successful synthesis of the Fe₃O₄@CS@Ni₂B nanocomposite and its use in MCRs for the green synthesis of tetrahydrobenzo[<i>b</i>]pyran derivatives. These heterocyclic compounds impress with their diverse biological activities. The research has several advantages, including the implementation of environmentally friendly catalyst protocols, the simplification and cost-effectiveness of the synthesis process, the use of an easily accessible biopolymer, the successful performance of efficient one-pot reactions without additional waste generation, and the easy recycling of the catalyst. This research demonstrates the potential of Fe₃O₄@CS@Ni₂B as a promising catalyst for sustainable and selective MCRs.