Recyclable Bi2WO6-nanoparticle mediated one-pot multicomponent reactions in aqueous medium at room temperature

Different types of multicomponent reactions (MCRs) are reported using Bi<inf>2</inf>O<inf>3</inf>, BiVO<inf>4</inf>, and Bi<inf>2</inf>WO<inf>6</inf> (nanoparticle) as heterogeneous catalysts. Among these, Bi<inf>2</inf>WO<inf>6</inf> nanoparticles showed excellent reactivity for the synthesis of functionalized dihydropyridine, polyhydroquinoline, 4H-chromene and 2-amino-4H-benzo[b]pyran derivatives at ambient temperature in aqueous medium. All the reactions gave good to excellent yields in 10-45 minutes in the presence of 5 mol% (optimized) of the catalyst. The catalyst was regenerated and reused up to 5 times without losing catalytic activity. The gram scale synthesis of dihydropyridine gave the desired product in 82% yield in 2 h. This journal is