Fast and efficient synthesis of chromeno[ d ]pyrimidinediones catalysed by a TiO 2 –SiO 2 nanocomposite in aqueous media

A 1:1 TiO 2 –SiO 2 nanocomposite was used as an efficient and green recyclable catalyst for the synthesis in water of 11 chromeno[ d]pyrimidinediones, six of which are new. All reactions were carried out under very mild conditions to afford the corresponding products in excellent yields.