Abstract
Imidazole derivatives represent a privileged class of nitrogen-containing heterocycles that continue to attract considerable attention owing to their structural versatility, synthetic accessibility, and wide range of applications in medicinal chemistry, materials science, catalysxis, and corrosion inhibition. In recent years, significant efforts have been directed towards the development of efficient, sustainable, and experimentally simple synthetic methodologies for substituted imidazoles. This review summarizes and critically evaluates recent advances (mainly from 2021 onward) in the synthesis of imidazole derivatives, with particular emphasis on multicomponent reactions, especially the Debus-Radziszewski condensation. Catalyst-free protocols, organocatalysts, metal-based catalysts, nanocatalysts, and ionic liquids are systematically discussed and compared. In addition, alternative two- and three-component strategies that enable access to nonclassical substitution patterns are reviewed. The advantages and limitations of each approach are highlighted with respect to reaction efficiency, substrate scope, sustainability, and practical applicability. This review aims to serve as a comprehensive reference for synthetic chemists seeking rational strategies for the preparation of structurally diverse imidazole derivatives.