Fig. 2: Substrate scope study.

^aCuBr (15 mol%) and L5 (18 mol%) were used. ^bDue to the difficulty of separating the two regioisomers, the yield value refers to the isolated yield of a mixture of alkyne and allene; the regioselectivity was determined by ¹H NMR analysis. ^cThe reaction was conducted in 10 mL CH₃CN.