Palladium C–N bond formation catalysed by air-stable robust polydentate ferrocenylphosphines: a comparative study for the efficient and selective coupling of aniline derivatives to dichloroarene

Abstract

The arylation of aniline derivatives with dichloroarenes under a low palladium content (below the currently used 5 to 10 mol%) was studied using nine different ferrocenylphosphine ligands, including the easily accessible 1,1′-bis(diphenylphosphino)ferrocene, DPPF. The electron-enriched air-stable tridentate ferrocenylpolyphosphine 1,2-bis(diphenylphosphino)-1′-(diisopropylphosphino)-4-tert-butylferrocene, L5, employed in 2 mol% in combination with 1 mol% [PdCl(η³-C₃H₅)]₂ allows an efficient and selective coupling, while such demanding substrates currently induce chloroarene homocoupling and/or dehalogenation processes. The scope and limitation of the optimized system are explored, with a focus on electron-poor fluoroanilines (deactivated nucleophiles) and electron-rich methylated and methoxylated dichlorobenzenes (deactivated electrophiles).