Proline confined FAU zeolite: heterogeneous hybrid catalyst for the synthesis of spiroheterocycles via a Mannich type reaction

A novel L-proline confined FAU zeolite catalyst system has been developed by confinement of L-proline in faujasite zeolite and its catalytic activity has been tested in the aqueous mediated synthesis of novel 1′,3′-di-(4-methylphenyl)-2′,3′,4′,6′-tetrahydro-1′H-spiro[indoline-3,5′-pyrimidin]-2-one (4a) and 1′,3′-di-(4-methylphenyl)-2′,3′,4′,6′-tetrahydro-1′H-spiro[indene-2,5′-pyrimidin]-1(3H)-one (4d) for the first time via the one-pot three-component condensation of lactams/cyclic ketones, amines and aqueous formaldehyde. The recyclability of the novel catalyst system was studied, which resulted in no loss of catalytic activity up to five cycles.