Palladium(II) Complexes of a Neutral CCC-Tris(N-heterocyclic carbene) Pincer Ligand: Synthesis and Catalytic Applications

An indole-amide-based phosphine ligand enabling a general palladium-catalyzed sterically hindered Suzuki-Miyaura cross-coupling reaction

A novel family of indole-amide-based phosphine ligands was designed and synthesized. The Pd/InAm-phos (L1) catalytic system exhibited excellent efficiency in the Suzuki-Miyaura cross-coupling of sterically hindered (hetero)aryl chlorides to synthesize tri-ortho-substituted biaryls. Excellent product yields were obtained in a short reaction time (e.g., 10 min), and a Pd catalyst loading down to 50 ppm was also achieved. The oxidative addition adduct of Pd-L1 with 2-chlorotoluene was also well-characterized by single-crystal X-ray crystallography and showed a κ²-P,O-coordination of L1 with palladium.