Synthesis and Application of Heterogeneous Zinc Catalysts for Decarboxylative Coupling

The coupling of aldehyde, amine, and alkyne (known as A³-coupling) is a versatile strategy for the synthesis of propargylamines which are important precursors for the biologically active molecules. Recently, phenylglyoxylic acid as a surrogate of aldehyde has gained importance in the above reaction via decarboxylative coupling. Transition metal catalysts of Cu and Au have been reported for this reaction. However, metal waste and their disposal is the major challenge faced by chemical industries. In this work, we have explored chitosan-supported zinc catalysts for the decarboxylative coupling of phenylglyoxylic acid with amine and alkyne. We found that this reaction gives the best yield under solvent-less condition. For comparison purpose, the catalytic activity of synthesized catalysts in various molecular solvents has also been explored.