PEG-embedded KBr(3): A recyclable catalyst for multicomponent coupling reaction for the efficient synthesis of functionalized piperidines

PEG-embedded potassium tribromide ([K(+)PEG]Br(3)(−)) was found to be an efficient and recyclable catalyst for the synthesis of functionalized piperidines in high yields in a one step, three component coupling between aldehyde, amine and β-keto ester. At the end of the reaction the [K(+)PEG]Br(3)(−) was readily regenerated from the reaction mixture by treating the residue containing [K(+)PEG]Br(−) with molecular bromine.