Aqueous conditions Suzuki-Miyaura reaction

Heterogeneous Pd catalysts can activate the C-Cl bond in aryl chlorides for the Suzuki-Miyaura reaction, presumably due to a synergistic anchimeric and electronic effect that occurs between the Pd surface and the aryl chlorides. Pd on carbon has been found to be a very effective pre-catalyst for a variety of substrates even under very mild reaction conditions and aqueous solvent mixtures.In 2001, Kabalka and co-workers described that Pd powder and KF as base were useful to couple aryl iodides with arylboronic acids in methanol." At the conclusion of the reaction, Pd metal could be recovered by simple decantation. The use of microwave irradiation accelerates the reaction by... 

The development of catalytic systems using neat water as solvent is of high importance to industrial and environmentally friendly applications. In this respect, water is perhaps the ultimate solvent because of its lack of toxicity and ready availability. Leadbeater has published several papers where the Suzuki-Miyaura reaction has been optimized for aqueous conditions [9,120]. Aryl bromides and iodides were coupled and the corresponding products isolated in good yields with an attractive ligandless protocol. Some reactions gave increased yields with the addition of tetrabutylammonium bromide (TBAB) [121], Recently, an application for a scaled-up Suzuki-Miyaura synthesis in water using an automated batch stop-flow apparatus was also published (Scheme 46) [89]. 

Kostas, I.D., Coutsolelos, A.G., Charalambidis, G. and Skondra, A. (2007) The first use of porphyrins as catalysts in cross-couphng reactions a water-soluble palladium complex with a porphyrin ligand as an efficient catalyst precursor for the Suzuki-Miyaura reaction in aqueous media under aerobic conditions. Tetrahedron Lett., 48, 6688-91. 

Organoboron compounds cannot react without proper activation. The use of oxygen bases is inherent in the standard Suzuki-Miyaura cross-coupling method. Fluorides (usually CsF) can be used as alternative activating agents, which is particularly useful in cases when the reagents are incompatible with oxygen bases for the reactions run under anhydrous conditions,24 (66) 241 Fluoride activation can be effective, however, even under aqueous phase-transfer conditions (67) 242... 

Chem 663 46 2002] obtained high turnover numbers and turnover frequencies in Suzuki-Miyaura cross-coupling reactions at room temperature conditions with this catalyst. Botella Najera [J Org Chem 70 4360 2005] also studied this catalyst for Mirozoki-Heck couplings in aqueous A. iV-dimethylacetamide in air using N-methyldicyclohexylamine (see [7560-83-0]) as base with or without Bu4NBr. 

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