Frustrated Lewis Pair‐Enabled Strategies for Heterocycle Synthesis

Frustrated Lewis pairs (FLPs) are composed of Lewis acids and Lewis bases that are prevented from adduct formation by steric and/or electronic effects, thereby maintaining their individual reactivity and enabling the cooperative activation of small molecules. In recent years, the unique chemical properties of FLPs have received increasing attention from chemists, especially in heterocyclic synthesis. This review focuses on the growing application of FLPs in heterocycle synthesis. We outline a wide range of FLP- and borane-enabled heterocycle-forming methods reported from 2012 to 2025, differentiating the mechanistic relationships among genuine FLP cooperativity, single-center borane catalysis, and reactions mediated by borane-derived Brønsted acids. This mechanistic perspective highlights key considerations for catalyst design, reaction selectivity, and the future development of heterocycle-forming methodologies.