Efficient [(NHC)Au(NTf₂)]-catalyzed hydrohydrazidation of terminal and internal alkynes

Abstract

The efficient hydrohydrazidation of terminal (6a–r, 18 examples, 0.1–0.2 mol % [(NHC)Au(NTf2)], T = 60 °C) and internal alkynes (7a–j, 10 examples, 0.2–0.5 mol % [(NHC)Au(NTf2)], T = 60–80 °C) utilizing a complex with a sterically demanding bispentiptycenyl-substituted NHC ligand and the benign reaction solvent anisole, is reported.

Facile Synthesis of Triptycene‐Azolium Salts and NHC‐Metal Complexes

“…Bis‐Pentiptycene‐NHC ligands (type A in Scheme 1) are sterically very demanding and metal ions coordinated by such ligands are located in a deep pocket shielded from the environment [2] . The corresponding NHC‐gold complexes have been successfully employed in the efficient gold‐catalyzed alkyne hydration [3] and in the gold‐catalyzed hydrohydrazidation of alkynes [4] . A nickel complex of the closely related pentiptycene‐diimines was shown to be a highly efficient catalyst for the homopolymerization of ethene as well as for the copolymerization of ethene with polar monomers, [5] which is mainly attributed to the steric shielding of the transition metal.…”