Ethynylbenziodoxol(on)e (EBX) cyclic hypervalent iodine reagents are now established reagents for the alkynylation of radicals and nucleophiles, yet they presentl imited possibilities for further structure and reactivity modification. Herein, the first synthesis is reported for the corresponding ethynylbenziodazolone( EBZ) reagents, in which the oxygen atom in the iodoheterocycle is replaced by an itrogen atom. The substituent on the nitrogen enablesf ur-ther fine-tuningo ft he reagent structure and reactivity.E BZ reagents are obtained easily from the corresponding benzamides by using ao ne-step procedure, andd isplay reactivity comparable to that of EBX reagents. In particular, they are appliedi na na symmetricc opper-catalyzed oxyalkynylation of diazo compounds, which proceeds in high yield and enantioselectivity for ab road range of substituents on the diazo compounds and the alkyne.[a] Dr.