Synthesis of <i>C</i> -Allenyl <i>o</i> -Carboranes through Copper(I)-Catalyzed Coupling Reaction of Ethynyl <i>o</i> -Carboranes with <i>N</i> -Tosylhydrazones

A synthetic method for <i>C</i>-allenyl <i>o</i>-carboranes was demonstrated using the coupling reaction of ethynyl <i>o</i>-carboranes with <i>N</i>-tosylhydrazones under copper(I) catalysis. This approach is significant because it achieved high yields despite the incorporation of carboranes with various substituents. Moreover, this work is notable in that it successfully synthesized not only disubstituted allenes but also trisubstituted allenes.