PPh3/Isocyanide and N2/Isocyanide Exchange: Pathways to Isolable Alkali Metal Keteniminyl Anions

Keteniminyl anions hold significant promise for advancing ketenimine chemistry, yet their isolation has remained elusive until now. Drawing inspiration from recent advances in ligand exchange reactions at carbon, we report the successful synthesis of isolable keteniminyl anions through the substitution of the phosphine ligand in a metalated ylide and the N₂ ligand in a diazomethanide with isocyanides. The resulting keteniminyl anions exhibit bent geometries, which can be attributed to a dative interaction with the isocyanide, giving rise to a carbone-like structure. Electron-withdrawing substituents on the nitrogen enhance backbonding, leading to larger bending angles. The keteniminyl anions react efficiently with unsaturated compounds to form a diverse array of heterocycles, highlighting their potential as versatile building blocks in synthetic chemistry.