Tetrahydropyridines: a recent update for their multicomponent synthesis.

Tetrahydropyridines (THPs) are important nitrogen-based ring compounds found in many natural and synthetic molecules with wide biological importance. Their simple structure and chemical flexibility make them valuable in drug design and organic synthesis. Among different synthetic methods, multicomponent reactions (MCRs) have become a fast, efficient, and eco-friendly approach for preparing a large variety of THP derivatives in a single step. This review focuses on recent developments in the synthesis of tetrahydropyridines using MCRs with different nitrogen sources such as amines, enamines, imines, ammonia, ammonium acetate, etc. It also highlights green and sustainable methods like solvent-free, microwave-assisted, photoinduced, and catalyst-free reactions. Overall, this review explains how multicomponent reactions provide an easy, economical, and environmentally friendly route for building diverse tetrahydropyridine structures useful in chemical and medicinal research.