1,3-Diynes synthesis by homo-coupling of terminal alkynes using a Pd(PPh3)4/Ag2O simple catalyst system

Amine- and copper salt-free palladium-catalyzed homo-coupling reaction of terminal alkynes proceeded efficiently in the presence of silver(I) oxide, which served as both activator and oxidant, in tetrahydrofuran at 60 °C to achieve satisfactory yields of 1,3-diyne compounds. It was demonstrated for the first time by means of XPS analysis that Pd(0) species can be oxidated to Pd(II) by silver(I) oxide.

Graphical abstractA simple palladium catalyst system was utilized for synthesis of 1,3-diynes, and the reaction conditions employed can tolerate ketone carbonyl group, hydroxy group, and an aldehyde group. The reaction mechanism was investigated through XPS analysis.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Developed an efficient method for the synthesis of 1,3-diynes. ► A variety of terminal alkynes can be employed to synthesize 1,3-diynes. ► The reaction conditions can tolerate carbonyl and hydroxy groups. ► It was demonstrated that Pd(0) species can be oxidated to Pd(II) by Ag2O.