Phosphine-Free Palladium Acetate Catalyzed Suzuki Reaction in Water

Abstract

Pd(OAc)(2) in a mixture of water and poly(ethylene glycol) (PEG) is shown to be an extremely active catalyst for the Suzuki reaction of aryl iodides and bromides. The reaction can be conducted under mild conditions (50 degrees C) without the use of a microwave or phosphine ligand in high yields. The isolation of the products is readily performed by the extraction of diethyl ether, and the Pd(OAc)(2)-PEG can be reused without significant loss in activity.

Speciation of Pd(OAc)2in ligandless Suzuki–Miyaura reactions

“…The process can be dependent upon the reaction medium, oxygen, moisture and additives/ stabilizers. A plethora of additives/stabilizers has been reported for 'ligandless' SM reactions, 21,23,[25][26][27][28] but this is not always necessary; we 29 and others 17,24 have shown that Pd(OAc) 2 alone is sufficient for high turnovers. Notably, these reactions occur in protic solvents such as alcohols, ethylene glycol derivatives, or mixtures of water with organic solvents.…”

“On-water” Hiyama coupling catalyzed by CNC pincer complexes of Pd(II)

“…The resulting residue was redissolved in CDCl 3 and the yield was calculated by 1 H-NMR using diethylene glycol dimethyl ether as internal standard. Following this procedure the following products were prepared: 1-Biphenyl-4-yl-ethanone (5ª) 13 (>99%, chromatographically pure, 99% isolated yield) 4-Methoxybiphenyl (5d) 13 (60%) 3-Methoxybiphenyl (5e) 14 (11%). 13 (6%) generous donation of hexane.…”

“…Following this procedure the following products were prepared: 1-Biphenyl-4-yl-ethanone (5ª) 13 (>99%, chromatographically pure, 99% isolated yield) 4-Methoxybiphenyl (5d) 13 (60%) 3-Methoxybiphenyl (5e) 14 (11%). 13 (6%) generous donation of hexane. Finally, technical and human support provided by SGIker (UPV/EHU, MICINN, GV/EJ, ESF) is acknowledged.…”

“…Purification by Flash column chromatography using 10% ethyl acetate/hexane as eluent was performed when indicated. Following this procedure the following products were prepared: 1-Biphenyl-4-yl-ethanone (5a) 13 (>99%, chromatographically pure, 99% isolated yield). …”

Ligandless palladium supported on SiO2–TiO2 as effective catalyst for Suzuki reaction

“…However, there are still several problems with these complexes heterogeneous catalysis systems, including the expatiatory synthetic route and high cost [16,17]. Consequently, there is a strong interest in developing 'ligandless' Pd catalysts [18][19][20], and some ligandless supported catalysts have been developed in Suzuki reaction [21,22]. The choice of the support is critical to formulate an effective immobilization strategy because of the support influences the catalytic behavior of immobilized catalysts obviously [23].…”