Air-stable palladium(0) phosphine sulfide catalysts for Ullmann-type C–N and C–O coupling reactions

• Two air stable phosphine sulphide ligands and their corresponding Pd(0) complexes were synthesized.
• We report N-arylation and O-arylation of aryl halides by Ullmann-type cross coupling reaction.
• C–N & C–O coupling reactions took place without using inert condition in a short reaction time.
• These catalysts could be recycled up to 5 cycles without significant loss in yield.

This paper describes an efficient procedure for palladium(0)-catalyzed N-arylation and O-arylation of aryl halides by Ullmann-type cross coupling reaction under mild reaction conditions in a short reaction time. Two phosphine sulphide ligands and their corresponding Pd(0) complexes namely [Pd(p2S2)(dba)] and [Pd(pp3S4)(dba)], were synthesized, where p2S2 is 1,2-bis(diphenylphosphino)ethane disulfide, pp3S4 is tris[2-(diphenylphosphino)ethyl]phosphine tetrasulfide and dba is dibenzylideneacetone. Optimal reaction conditions were determined for the arylation reactions using iodobenzene and benzimidazole by varying temperature, solvent, base and catalyst loading. The cross coupling reactions were carried out taking iodobenzenes/bromobenzenes and a wide variety of substituted aryl amines/phenols/alcohols with different steric and electronic properties to afford the desired N-aryl amines/diaryl ethers/alkyl aryl ethers in good to excellent yield (70–94%).

The Ullmann-type cross coupling of aryl halides (iodobenzene and bromobenzene) with N-aryl amines/phenols/alcohols were carried out using palladium(0)-catalysts in an open atmosphere. Effects of temperature, solvent, base and catalyst loading on the reaction systems were studied. A wide range of N-arylamines/ethers were synthesized in good to excellent yields.Figure optionsDownload as PowerPoint slide