C(sp2)‐C(sp) and C(sp)‐C(sp) Coupling Reactions Catalyzed by Oxime‐Derived Palladacycles

Oxime‐derived chloro‐bridged palladacycle 8a, derived from 4,4′‐dichlorobenzophenone, is an efficient pre‐catalyst for the copper‐ and amine‐free Sonogashira coupling between terminal acetylenes and aryl iodides and aryl and vinyl bromides achieving turnover numbers (TON) of up to 72000. Catalyst 8a has also been shown as a effective promoter for the sila‐Sonogashira coupling between 1‐(trimethylsilyl)alkynes and aryl iodides and bromides in the presence of CuI or Bu4NBr as co‐catalysts. This complex also catalyzes efficiently the homocoupling reaction (Glaser‐type coupling) between 1‐alkynes in NMP at room temperature with TONs of up to 1000. All the reactions can be performed under air and employing reagent‐grade chemicals under very low loading conditions, which demonstrates the versatility and high activity of oxime‐derived palladacycles.