Recent Advances in the Synthesis of Nitrogen‐Containing Heterocycles from o ‐Aminobenzamides: Reactions and Mechanism

Nitrogen‐containing heterocycles constitute a pivotal class of core structural scaffolds, notable for their significant biological activities and functional versatility. Consequently, the development of efficient, green, and atom‐economical methodologies for the construction of N ‐heterocycles represents a central pursuit in modern synthetic chemistry. o ‐Aminobenzamides have emerged as versatile platform molecules in this context. Their molecular architecture, featuring a nucleophilic amino group, an electrophilic amide carbonyl, and a readily modifiable aromatic ring, enables efficient construction of CN and NN bonds via condensation and cyclization reactions, rendering them key starting materials for accessing diverse N ‐heterocycles. This review systematically summarizes research advances from the past decade (2015–2025) on the synthesis of N ‐heterocyclic systems including quinazolinones, quinazoline diones, benzodiazepinediones, acridones, and benzotriazinones from o ‐aminobenzamides with various “C1 sources” (e.g., aldehydes, alcohols, ketones, carboxylic acids, esters), “N1 sources” (e.g., nitromethane, tert ‐butyl nitrite, nitrates), and other functional reagents. The discussion focuses on the design strategies of reaction pathways and the mechanisms underpinning key cyclization steps, such as intramolecular nucleophilic attack, oxidative cyclization, and radical processes. A comparative analysis is provided on the advantages and limitations of different catalytic systems, including transition‐metal catalysis, catalyst‐free conditions, photocatalysis, electrochemical synthesis, and heterogeneous catalysis, with respect to reaction efficiency, regioselectivity, and functional group tolerance. These methodological advances not only expand the synthetic toolkit for N ‐heterocycle construction but also offer robust support for the rapid discovery and structural optimization of drug leads.