1‑Iodobuta-1,3-diynes in Copper-Catalyzed Azide–Alkyne Cycloaddition: A One-Step Route to 4‑Ethynyl-5-iodo-1,2,3-triazoles

Cu-catalyzed 1,3-dipolar cycloaddition
of iododiacetylenes with
organic azides using iodotris­(tri­phenyl­phos­phine)­copper­(I)
as a catalyst was found to be an efficient one-step synthetic route
to 5-iodo-4-ethynyltriazoles. The reaction is tolerant to various
functional groups in both butadiyne and azide moieties. The synthetic
application of 5-iodo-4-ethynyl triazoles obtained was also evaluated:
the Sonogashira coupling with alkynes resulted in unsymmetrically
substituted triazole-fused enediyne systems, while the Suzuki reaction
yielded the corresponding 5-aryl-4-ethynyl triazoles.