Preparation of benzo[4,5]thiazolo[3,2-a]chromeno[4,3-d]pyrimidin-6-one derivatives using MgO-MgAl2O4 composite nano-powder

MgO-MgAl2O4 nanocomposite was prepared from the co-precipitation of Mg(NO3)(2) and Al(NO3)(3) salts, characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and fourier transform infrared spectroscopy (FTIR) techniques and evaluated in the synthesis of thirty five derivatives of benzo[4,5]thiazolo[3,2-a]chromeno[4,3-d]pyrimidin-6-ones (d(1)-d(34)) via the multi-component reaction of 4-hydroxycoumarins, aldehydes, and 2-aminobenzothiazole derivatives under solvent free condition. The catalytic activity of MgO-MgAl2O4 nanocomposite and the synthesis of the above mentioned compounds were investigated under thermal solvent free (times: 1.4-3 h; yields: 75-95%), ultrasonic irradiation (US) conditions (times: 1-2.5 h; yields: 69-97%) and using high-speed ball milling (HSBM) technique (times: 0.7-2.5 h; yields: 67-97%). In all cases, the products were obtained in excellent yields. Nuclear Magnetic Resonance (NMR) and MASS spectroscopy were used to characterize the structure of the desired product. The mechanism for the preparation of compounds d(1)-d(34) was proposed and confirmed by H-1 NMR investigations. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of King Saud University.