Microwave–Assisted and Green Catalytic Synthesis of Dihydroquinazoline Derivatives: Recent Advances and Pharmacological Significance

Quinazolines, dihydroquinazolines, and quinazolinones represent a significant class of nitrogen-containing heterocyclic compounds, widely distributed in natural sources such as plants, microorganisms, and animals. Among these, dihydroquinazolines, characterized by the quinazolin-4-(3H)-one core, exhibit a broad spectrum of pharmacological and biological activities, including anticancer, antimicrobial, anti-inflammatory, antiviral, and antitubercular properties. Due to their diverse therapeutic potential, the synthesis of these heterocycles has garnered considerable attention from medicinal and synthetic chemists. Traditional synthetic methods, however, often involve harsh reaction conditions, toxic solvents, and expensive catalysts, prompting the need for more sustainable and efficient approaches. Recent advancements in green chemistry have introduced microwave-assisted synthesis as a powerful tool for the rapid, energy-efficient, and environmentally benign preparation of dihydroquinazoline derivatives. Microwave irradiation facilitates faster reaction rates, higher yields, and reduced energy consumption compared to conventional heating methods. Additionally, the use of green catalysts, such as ionic liquids, nanocatalysts, and biodegradable polymers, further enhances the sustainability of these synthetic protocols. This review comprehensively summarizes the latest developments in microwave-assisted and green catalytic strategies for the synthesis of dihydroquinazoline derivatives over the past decade. Special emphasis is placed on solvent-free conditions, catalyst recyclability, and one-pot multicomponent reactions. By highlighting these eco-friendly methodologies, this review aims to guide researchers in designing more efficient and sustainable synthetic routes for pharmacologically relevant dihydroquinazoline scaffolds.