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

A new water soluble palladium(II) complex (2) derived from N,N,N 0 ,N 0 -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 k 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.