Transition Metal-Catalyzed Nitrogen Atom Insertion into Carbocycles.

Summary: Imagine trying to renovate a circular brick tower by inserting a new window without knocking the whole structure down. In chemistry, "carbocycles" are rings made entirely of carbon atoms, but many life-saving medicines require "heterocycles"—rings that contain a nitrogen atom. Traditionally, chemists had to build these nitrogen rings from scratch. This paper reviews a cutting-edge technique called "skeletal editing," where transition metal catalysts act like molecular surgeons. They precisely cut into existing carbon rings and insert a nitrogen atom, transforming simple chemicals into complex drug scaffolds efficiently and directly.