Synthetic Advances of Five‐Membered N‐Heterocycles via Amino‐Based Organocatalysis

Nitrogen heterocycles are among the most significant structural components, not only because of their natural abundance, but also because of their chemical, pharmaceutical, biological and other significances. They serve as the building blocks for innumerable natural and non‐natural products, pharmaceuticals, agrochemicals, functional materials, and biologically active compounds. Over the past decades, organocatalysis and a synergistic approach to metal‐based catalysis have emerged as highly effective for the synthesis of these molecules. The application of organocatalysis to heterocyclic synthesis has considerably expanded the scope of synthetic strategies available to organic chemists. Numerous heterocyclic scaffolds, such as pyrroles, pyrazoles, imidazoles, 1,2,3‐triazoles, 1,2,4‐triazoles, and tetrazoles, have been efficiently synthesised using organocatalytic approaches under mild reaction conditions, often in one‐pot or multi‐component reactions with high levels of regio‐ and stereo‐selectivity. These catalytic approaches offer several advantages, including low toxicity, operational simplicity, moisture and air tolerance, ease of handling, and minimal environmental impacts. In this review, we explore amine‐based organocatalytic strategies for the synthesis of N‐containing five‐membered heterocycles, focusing on efficient, sustainable, and selective methodologies and understanding the reaction mechanisms for five‐member N‐heterocyclic compounds over the last 15 years. The review will be useful to scientists in the research fields of organic synthesis, medicinal chemistry, and pharmacology.