Scanning nitrogen in sp ³ -rich scaffolds enabled by carbonyl-to-nitrogen atom swap

Medicinal chemistry campaigns routinely require access to series of saturated nitrogen heterocycle (SNH)–based analogs that place nitrogen at different positions to probe structure-activity relationships. However, systematic preparation of N -positional variants remains synthetically burdensome. In this work, we report a strategy for nitrogen scanning in sp 3 -rich scaffolds enabled by the exchange of a carbonyl group with an amine moiety, formally achieving a carbonyl-to-nitrogen (CO-to-N) atom swap. Because ketone positional isomers can be readily obtained through carbonyl transposition or carbon-hydrogen oxidation from a common carbocyclic precursor, the CO-to-N atom swap greatly streamlines the preparation of SNH positional analogs and obviates the need for multiple de novo syntheses. The CO-to-N reaction exhibits exceptional functional group compatibility and generality, which makes it well suited for late-stage modification of complex bioactive molecules and for isotopic labeling.