Ultrasound assisted synthesis of pyrano[3,2-b]pyran and 7-tosyl-4,7-dihydropyrano[2,3-e]indole scaffolds using barium titanate nanoparticles

Barium titanate nanoparticles (BaTiO 3 NPs) were synthesized under sonochemical conditions. The synthesized BaTiO 3 NPs was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry analysis (TGA), Brunauer–Emmett–Teller (BET), Field emission scanning electron microscopy (FE-SEM) and Transmission electron microscopy (TEM). Morphological study reveals that BaTiO 3 NPs have spherical shape with particle size ranging between of 60 and 80 nm. BaTiO 3 NPs were further utilized as an efficient and reusable heterogeneous catalyst for ultrasound assisted synthesis of pyrano[3,2- b ]pyran. In addition, novel 7-tosyl-4,7-dihydropyrano[2,3- e ]indole derivatives were also synthesized using ultrasonication. This new catalytic method displays several notable features such as simplicity, short reaction time, easy work up, easy purification, increased yield and green reaction conditions. The nanocatalyst was reusable up to five runs with marginal loss in its catalytic activity.