A Modular Approach for Accessing 3D Heterocycles <i>via</i> 1,2‐Dicyanation of Planar <i>N</i>‐Heteroarenes

The rapid construction of three-dimensional (3D) heterocyclic frameworks is a key challenge in contemporary medicinal chemistry. The molecules with three-dimensional complexity hold a greater probability to improve clinical outcomes, solubility, selectivity for target proteins, and metabolic stability. However, the prevalence of flat molecules persists among new drug candidates, primarily owing to the multitude of chemical methods available for their synthesis. In principle, the dearomative functionalization of N-heteroarene allows for the conversion of readily available planar molecules into partially or fully saturated nitrogen heterocycles, which are most significant structural motifs of pharmaceuticals and natural products. Unfortunately, these reactions are very rare because of the inherent challenge imposed by heteroarenes' poor reactivity, rendering the process thermodynamically unfavorable. Herein, we report a modular approach for accessing 3D chemical space in translating planar heteroarenes into valuable 3D heterocycles via the installation of a highly versatile cyano group as a new vector. This approach is enabled by the in situ generation of reactive, non-symmetric iodane by combining cyanide anion and bench-stable PhI(OAc)₂. This reaction represents a rare example of 1,2-dicyanation of N-heteroarenes that meets the numerous requirements for broad implementation in drug and agrochemical discovery. The transformation is highly selective and amenable to a wide range of N-heteroarenes and late-stage partial saturation of drugs and agrochemicals.