Isatogens and Their Reactivity Landscape

Isatogen (indol‐3‐one N ‐oxide) has attracted renewed attention in synthetic chemistry in recent years. First discovered by Adolf von Baeyer in 1881–1882, its potential as a bioactive scaffold and as a versatile synthetic intermediate remained sporadically explored for much of its history. The recent expansion of the literature has highlighted the distinctive features of the isatogen framework, notably the oxidized nitrogen center embedded within an aromatic system, which confer unusual and exploitable reactivity. This Review provides an up‐to‐date and comprehensive account of isatogen chemistry, encompassing both methods for its preparation and its synthetic applications. Recent advances are integrated with earlier work to present a coherent picture of isatogen reactivity across electrophilic activation, redox processes, cyclizations, and functionalization reactions. The Review is organized to cover historical background, reported bioactivities, and synthetic chemistry, with emphasis on preparative strategies and downstream transformations. By consolidating and critically assessing contemporary developments, this Review clarifies established reactivity patterns, underscores their practical relevance, and aims to stimulate further exploration of isatogens as dynamic scaffolds for modern synthetic strategy development.