The Choice Is Yours: Using Liquid-Assisted Grinding To Choose between Products in the Palladium-Catalyzed Dimerization of Terminal Alkynes

Herein, we report on the dimerization of terminal alkynes using various palladium catalysts under solvent-free mechanochemical conditions. When tetrakis(triphenylphosphine)palladium(0) was employed as the catalyst, we observed the 1,3-butadiyne as the major product. However, when we employed bis(triphenylphosphine)palladium(II) dichloride as the catalyst, we observed the trans-enyne as the major product. When we used a polymer-supported bis(triphenylphosphine)palladium(II) dichloride catalyst under liquid-assisted grinding conditions, we discovered the ability to tune the catalyst to generate either the diyne or trans-enyne as the major product, depending on the grinding medium.