Mesoporous Copper-Magnesium Oxide Hybrid Nanocatalyzed Synthesis of 3-Substituted Isocoumarins from 2-Iodobenzoic Acid and Terminal Alkyne under Green Conditions.

A 3-substituted isocoumarin scaffold has captivated extensive interest in synthetic and medicinal chemistry due to its presence in various natural products with diverse biological activities. Herein, we report a mesoporous CuO@MgO nanocomposite that was prepared via the sugar-blowing induced confined method with an E-factor of 12.2 and its catalytic potential in the facile synthesis of 3-substituted isocoumarin from 2-iodobenzoic acids and terminal alkynes. Powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller techniques were utilized for the characterization of the as-prepared nanocomposite. A broad substrate scope, mild reaction conditions, excellent yield in short reaction time, no usage of additives, and better green chemistry metrices such as a low E-factor (0.71), high reaction mass efficiency (58.28%), low process mass efficiency (1.71), and high turnover number (629) are the various advantages of the present synthetic route. The nanocatalyst was recycled and reused up to five runs without significant loss in its catalytic activity and a very low leaching of copper (3.20 ppm) and magnesium ions (0.72 ppm). Powder X-ray diffraction and high-resolution transmission electron microscopy techniques confirmed the structural integrity of the recycled CuO@MgO nanocomposite.