Fast and efficient synthesis of chromeno[d]pyrimidinediones catalysed by a TiO2–SiO2 nanocomposite in aqueous media

A 1:1 TiO2–SiO2 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.