A Click Reaction Enabled by Phosphorus‐Oxygen Bond for Synthesis of Triazoles

Synthesis of various N−H triazoles via azidyl radical was achieved using diphenyl phosphoryl azide (DPPA) and internal alkynes containing carbonyl group in wet‐DMSO at 90 °C in excellent yield. Mechanistic investigations revealed that an azidyl radical was generated in the reaction medium. The driving force was probably due to the presence of the C=O group of ester or ketone in conjugation with the triple bond of the substrate. This resulted in cleavage of the phosphorus nitrogen (P−N) bond of DPPA by forming an allenic intermediate. The C=O group of the ester or ketone is a determinant factor that results in triazole as the outcome. The formation of the phosphorus oxygen bond resulted in cleavage of a strong P−N bond (617.1±20.9 kJ mol −1 ) of phosphoryl azidate in an additive free Click reaction of internal alkynes. Overall, good to excellent yield of N 1 ‐H triazole scaffolds were synthesized following the protocol.