Efficient P, O chelate palladium(II)/AgNO₃ cocatalyzed homocoupling of aromatic terminal alkynes in aqueous media under ambient atmosphere

A new and efficient protocol for the P, O chelate Pd(II)/AgNO₃ cocatalyzed oxidative homocoupling reaction of aromatic terminal alkynes in the synthesis of symmetrical 1,4-disubstituted-1,3-diynes was described in aqueous media under ambient atmosphere. The results showed that both NEt₃ and THF/H₂O (in 4:1 proportion) played crucial roles in the reaction. In contrast, this protocol employs a low palladium(II) complex loading and AgNO₃ as cocatalyst to obtain the homocoupled products in moderate to good yields.