An Efficient Heterogeneous Iron Catalyst for Click Reaction in Water: A Sustainable Alternative to Conventional CuAAC

Abstract A more sustainable iron based heterogeneous catalytic system, has been developed for the azide‐alkyne cycloaddition (AAC) reaction in water. The catalyst ( mPAN‐Fe ) is prepared in simple steps by immobilizing FeCl 3 over synthetically modified polyacrylonitrile ( mPAN ) and after characterisation it has been explored as an efficient catalyst for the click (AAC) reaction leading to the formation of 1,4‐disubstituted 1,2,3‐triazoles. The reaction proceeds in one pot via in situ formation of organic azide from benzyl bromides, followed by rapid cyclization with terminal alkynes in aqueous media, without any base or ligand. Under optimized reaction conditions, a variety of substituted terminal alkynes and benzyl bromides in presence of sodium azide afforded the corresponding triazoles in good to excellent yields. The simple preparation, ease of handling and recovery, excellent reusability, and stability of the prepared iron catalyst together with adopting three component AAC in water medium makes this protocol more sustainable and cost‐effective compared to the conventional CuAAC reaction.