5,6‐ and 6,6‐Membered Palladium(II) Pincer Complexes Based on Functionalized Carboxamides with Ancillary Sulfur and Nitrogen Donors

Abstract

New multidentate ligands have been synthesized by the condensation of 2‐(methylsulfanyl)benzoyl chloride with a range of amines bearing ancillary N or S donors. In reactions with PdCl2(NCPh)2, the ligands smoothly underwent direct cyclopalladation to give pincer complexes with 5,6‐ or 6,6‐membered fused metallocycles. The oxidation of the sulfide ligands with H2O2 afforded the corresponding sulfoxide derivatives, which readily formed analogous pincer complexes with the PdII ions. The realization of κ3‐S,N,X coordination (X = N or S) was confirmed by multinuclear NMR and IR spectroscopic data and, in some cases, X‐ray crystallography. An unusual dynamic behavior of the 6,6‐membered S,N,S complex with an organophosphorus ligand was additionally studied by the ROESY technique. All of the palladocycles obtained were tested as precatalysts for the Suzuki cross‐coupling of aryl bromides with arylboronic acids, which allowed us to evaluate the main structure–activity relationships.

Heteroleptic Palladium(II) Complexes of Thiazolinyl‐picolinamide Derived N∩N∩N Pincer Ligand: An Efficient Catalyst for Acylative Suzuki Coupling Reactions

“…[13,33] However, late transition metal amido complexes have been found to be potential catalysts for many organic transformations including transfer hydrogenation to an unsaturated substrate and coupling reactions (Figure 1). [34][35][36][37][38][39][40][41][42][43][44][45][46] The intrinsic structure of the pincer ligands allows the development of late transition metal amido complexes and to explore their catalytic activities. [47,48] Palladium-catalyzed cross-coupling reactions are important and pioneering methodology for producing the C sp 2 À C sp 2 , C sp 2 À N and C sp 2 À O in the synthesis of industrially important valueadded molecules and other natural products, bioactive compounds, polymers, and materials.…”