Solvent-free and efficient heterogeneous Biginelli reactions catalyzed by copper (II)-incorporated iminophenol-based porous organic polymer

The copper (II)-incorporated iminophenol containing porous polymer (Cu-TAzo-TAPB), which was reported to be a recyclable catalyst for click reactions, is now exploited as an efficient catalyst in the solvent-free one-pot process to make 3,4-dihydropyrimidinone derivatives (DHPMs) by a three-component condensation reaction of urea/thiourea, aldehydes, and active methylene compounds. Usually, these reactions are complicated to carry out in a neutral medium. We describe here an eco-friendly method to produce Biginelli products with 5 mol% catalyst loading with a simple isolation technique. The high product yields show the effective Biginelli reaction technique. The catalyst is highly stable and easily recoverable for reuse without significant loss of catalytic efficiency.