A Three‐Component Cycloaddition of Diazo Compounds, Nitrosobenzenes, and Alkenes for the Synthesis of Isoxazolidines Under Catalyst‐, Additive‐, and Base‐Free Conditions

A direct three‐component cycloaddition reaction, comprising diazo compounds, nitrosobenzenes, and alkenes, has been successfully established. This methodology exploits the reactivity of electron‐rich olefins and proceeds efficiently under synthetically appealing conditions that are entirely devoid of metals, additives, or bases. The transformation furnishes a diverse array of synthetically and biologically significant isoxazolidine derivatives in moderate to excellent yields. The strategic value of this protocol is underscored by its remarkable substrate scope, the utilization of commercially available and inexpensive starting materials, and its operational simplicity, thereby positioning it as a powerful and practical tool for the rapid assembly of complex heterocyclic scaffolds.