Water-based reactions Suzuki-Miyaura reaction

A recent addition to this field is the polymer-supported di(2-pyridyl)-methylamine-palladium dichloride complex covalently attached to a styrene-alt-maleic acid anhydride copolymer. Turnover numbers as high as 105 were reported and a couple of microwave-heated Suzuki-Miyaura reactions could be performed in neat water [134], 2-Pyridinealdoxime-based Pd(II)-... 

The palladium-catalyzed Suzuki-Miyaura reaction is a cross-coupling reaction between aryl halides and horon derivatives (Scheme 19.40) [54]. Snznki received the Nobel Prize in 2010 [54h]. Reactions are performed under mild conditions and many functional gronps are tolerated. Water is not a problem and may be even beneficial (vide infra). The first reported reactions hy Suzuki in 1979 insisted about the presence of a base, even if no proton is exchanged [54a, b]. Various bases have been used EtO, MeO", OH", CO ", and F" associated with countercations such as Na, K% Cs+, LP, nBu N+, Ag+, or TP [54, 55]. The role of the base has led to many mechanistic interpretations involving among them anionic arylborates as reagents [54g, 56]. 

Some key developments in the methodology or conditions of the Suzuki-Miyaura reaction have been reported in recent years. In 2006, Liu et al. [137] reported a ligand-free Suzuki-Miyaura reaction. What was remarkable about this reaction was that without added ligand, the reaction could be carried out with 0.5 mol% Pd(OAc)2 and sodium carbonate as the base, at 35 °C in air, with water as cosolvent over 0.5-1 h, and give a plethora of compounds all in excellent yields. This methodology was also applied in consecutive multicoupling reactions to afford di- and tri-haloaromatics. 

To effect aqueous Suzuki-Miyaura reactions, water-soluble phosphine ligands have been explored. Miyaura and coworkers [122] reported that a palladium catalyst based on the water-soluble N-(4-diphenylphosphino)phenyl-methylgluconamide (GLCAphos, 40) was effective at low loadings for the Suzuld-Miyaura couphng of activated aryl chlorides in water (Scheme 6.26). 

The catalytic activity of benzothiazole-oxime-based Pd (Il)-complexes (xxxv) was evaluated in Suzuki-Miyaura and Heck-Mizoroki C-C cross coupling reactions of aryl bromides and chlorides with aryl boronic acid and olefins under microwave conditions in water was studied by Dawood [55]. 

Dawood KM (2007) Microwave-assisted Suzuki-Miyaura and Heck-Mizoroki crosscoupling reactions of aryl chlorides and bromides in water using stable benzothiazole-based palladium(ll) precatalysts. Tetrahedron 63 9642-9651... 

Since the discovery of the Suzuki-Miyaura cross-coupling reaction in 1979, the effect of various reaction parameters has been thoroughly studied, including bases, hgands, water, and various solvents [1, 2]. This section will outline new developments made over the past decades in further improving the Suzuki-Miyaura cross-coupling conditions. 

Yamada, and Suzuki laid the base for one of the most important and useful transformations for the construction of C-C bonds in the modem day organic chemistry. The Suzuki reaction becomes popular because of the ready availability of a wide range of functionally substituted boron derivatives and the mildness of the coupling reaction itself Suzuki reactions generally employ organic solvents such as tetra-hydrofliran and ethers as well as complex palladium catalysts, which are soluble in these solvents (Miyaura and Suzuki, 1995). The use of microwave heating is a convenient way to facilitate the Suzuki-type reactions in water (Leadbeater and Marco, 2002). 

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