Nickel Catalysis in a High Speed Ball Mill: A Recyclable Mechanochemical Method for Producing Substituted Cyclooctatetraene Compounds

A solvent-free, nickel-catalyzed [2 + 2+2 + 2] cycloaddition of alkynes to synthesize substituted cyclooctatetraene (COT) derivatives has been developed. This mechanochemical approach takes advantage of the frictional energy created by reusable nickel pellets, which also act as the catalyst. In contrast to solution chemistry, the major products are cyclooctatetraene isomers rather than substituted benzenes.