Potassium N-Borylisocyanamide: Synthesis, Structure, and Its Utilization as an Amino and Cyano Transfer Reagent

Substituted diazomethanides are important reagents and intermediates in organic synthesis and organometallic chemistry. Herein, we demonstrate that KOtBu-mediated desilylation of α-boryl(trimethylsilyl)diazomethane delivers the isomeric potassium N-borylisocyanamide, [R₂B═N-N≡C][K], rather than boryldiazomethanide. Its structure was unambiguously elucidated by single-crystal X-ray diffraction and supported by DFT calculations. The potassium borylisocyanamide exhibits dual reactivity: it acts as a 1,3-dipole toward aryl nitriles via the BN₂C unit and it undergoes ring-open cycloaddition with propene oxide via the nucleophilic B═N functionality. Remarkably, the [3 + 2] cycloadduct with nitriles undergoes unprecedented N-N bond cleavage-induced ring-opening, enabling the development of a one-pot amino and cyano group transfer reaction from boryl(trimethylsilyl)diazomethane. This transformation provides efficient access to a range of N-cyanoformamidines, valuable precursors for the synthesis of triazines─key components in organic light-emitting diodes (OLEDs).