A rapid and eco-friendly synthesis of novel and known benzopyrazines using silica tungstic acid (STA) as a new and recyclable catalyst

A novel silica tungstic acid (STA) as a green catalyst has been prepared and employed for the solvent-free synthesis of novel benzopyrazines. Catalyst loadings as low as 2 mol% could be used leading to high yields of pure products. The STA was characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), inductively coupled plasma (ICP-OES) and Fourier transform infrared spectroscopy (FT-IR).