Recent Advances in Catalytic 5 + 3 Cycloadditions

Higher‐order cycloadditions (HOCs) offer a robust and convergent strategy for the rapid assembly of complex molecular architectures. These transformations enable direct access to ring systems that are otherwise challenging to construct. Among them, the 5 + 3 cycloaddition has emerged as a versatile platform for the synthesis of eight‐membered carbo‐ and heterocycles, which are widely represented in bioactive natural products, pharmaceuticals, and functional materials. This review provides a comprehensive overview of developments in catalytic 5 + 3 cycloadditions from 2003 to the present, encompassing both transition metals and organocatalytic systems. Emphasis is placed on catalyst class, ligand design, activation mode, and substrate scope, as well as their influence on chemo‐, regio‐, and stereoselectivity, together with comparative performance data. Representative mechanistic proposals reported in the literature are discussed where relevant. Although most catalytic 5 + 3 processes proceed through stepwise pathways and are therefore best described as formal 5 + 3 cycloadditions, true pericyclic 5 π + 3 π cycloadditions are comparatively rare. Where applicable, this mechanistic distinction is clearly indicated in the corresponding sections.