Engineering iodine decorated azo-bridged porous organic polymer: A brilliant catalyst for the preparation of 2,4,6-trisubstituted pyridines

Abstract

Iodine catalysis in organic transformations affords detailed coverage of recent advances in iodine chemistry. In this direction, the azo-bridged porous organic polymer bearing triazine and phloroglucinol moieties (Azo-POP1) was constructed via interfacial azo-coupling polymerization in water at room temperature. Considering its high specific surface area (153 m².g^-1) and pore size of 2.2 nm, karyotype-like morphology and considerable surface wettability, Azo-POP1 was successfully used as an adsorbent of I₂. The adsorption kinetics studies show that the adsorption reaches equilibrium within one hour and increases with temperature. To our delight, this system (I₂@Azo-POP1) was used as an irreplaceable heterogeneous catalyst for the synthesis of 2,4,6-trisubstituted pyridines via condensation reaction of diverse ketones with benzylamine and the following cyclization and cooperative vinylogous anomeric based oxidation. All the products were prepared in good yields under mild reaction conditions. Also, this attitude benefits from the environmentally friendly and recyclability of described catalyst.