Ligand-Accelerated Gold-Catalyzed Addition of in Situ Generated Hydrazoic Acid to Alkynes under Neat Conditions

The direct addition of in situ generated hydrazoic acid to alkynes is realized without solvent by using a gold catalyst derived from a recently designed remotely functionalized biaryl-2-ylphosphine ligand (i.e., WangPhos). With terminal alkynes, the additions are mostly realized with 0.1 mol% catalyst loadings and at 40 degrees C. With more challenging internal alkynes devoid of direct EWG substitution, the one-step transformation is realized for the first time, with generally high efficiency at ambient temperature.