A novel and environment-friendly method for preparing dihydropyrano[2,3-c]pyrazoles in water under ultrasound irradiation

► Ultrasonic-assisted synthesis of dihydropyrano[2,3-c]pyrazoles via four-component reaction in water was investigated. ► Ultrasound was found to have beneficial effect on the synthesis of dihydropyrano[2,3-c] pyrazoles. ► The role and acceleration mechanism of sonication in this heterogeneous system was discussed. ► Mechanistic study of ultrasonic-assisted dihydropyrano[2,3-c]pyrazoles derivatives synthesis.