N,N,N ',N '-Tetrakis(2-hydroxyethyl)ethylenediamine palladium(II) complex as efficient catalyst for the Suzuki/Miyaura reaction in water

Abstract

A new water soluble palladium(II) complex (2) derived from N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine (edteH(4)) (1) was synthesized in high yield and characterized by (1)H, (13)C, HMQC and COSY NMR spectroscopy. X-ray diffraction studies on a single crystal of 2 confirmed the cis square planar geometry; the edteH(4) ligand (1) is kappa(2) (N,N)-coordinated with four pendant CH(2)CH(2)OH groups. This new complex [PdCl(2)(edteH(4))] (2) and the previously synthesized triethanolamine complex [Pd(OCH(2)CH(2)N (CH(2)CH(2)OH)(2))(2)] (3) were tested as catalysts for the Suzuki/Miyaura cross-coupling reaction of various aryl bromides with phenylboronic acid in water. Electronically activated aryl bromides, such as 4-bromoacetophenone and 4-bromobenzaldehyde undergo the cross-coupling with extremely high turnover numbers (TON) of up to 1,00,000 without organic solvent