Suzuki coupling reactions catalyst

Suzuki coupling reactions with aryl halides. Two as-prepared BaCei cPd c03. ( materials (x = 0.05 and 0.10) were successfully utihzed in several Suzuki coupling reactions. Both aryl iodides and aryl bromides react smoothly with 4-phenylboronic acid, eq 1, to yield the corresponding biatyls in high yields (> 95%). For both 4-bromoanisole and 4-iodoanisole, the biatyl yields reached nearly 100% in 3 min with BaCeo 95Pdoo503 5 as the catalyst, corresponding to an effective TON of ca. 2,000 and an effective TOF of nearly 50,000 h. Resnlts are smmnarized in Table 27.1. 

The biaiyl phenol (X) was the penultimate intermediate in the synthesis of this final drag substance. Thus after the Suzuki coupling reaction is performed to give the phenol, the levels of Pd have to be lowered to < 10 ppm. In the pharma industry this can be a significant problem. Additionally there is always batch to batch variability observed when catalysts like Pd2(dba)3 have been used in Suzuki couphng reactions. 

Baxendale IR, Griffiths-Jones CM, Ley SV, Tranmer GK (2006b) Microwave-assisted Suzuki coupling reactions with an encapsulated palladium catalyst for batch and continuous-flow transformations. Chem Eur J 12 4407-4416 Baxendale IR, Deeley J, Griffiths-Jones CM, Ley SV, Saaby S, Tranmer GK (2006c) A flow process for the multi-step synthesis of the alkaloid natural product oxomaritidine a new paradigm for molecular assembly. J Chem Soc Chem Commun 2566-2568... 

Kim, S.W. et al., Fabrication of hollow palladium spheres and their successful application to the recyclable heterogeneous catalyst for Suzuki coupling reactions, J. Am. Chem. Soc., 124, 7642, 2002. 

Baxendale IR, Griffiths-Jones CM, Ley S V, Tranmer GK. Microwave-assisted Suzuki coupling reactions with an encapsulated palladium catalyst for batch and continuous-flow transformations. ChemEur J 2006 12 4407-4416. 

Palladium catalysts have been found which are effective in the Suzuki coupling reaction of arylboronic acids with aryl chlorides carrying electron-withdrawing groups.73 Biaryls may also be synthesized by cross-coupling of arylboronic acids with arenediazonium salts.74,75 There has been a report of the polymer-bound palladium-catalysed Suzuki coupling of aryl triflates with organoboron compounds.76 Arylbor-onates may themselves be synthesized by the palladium-catalysed reactions of... 

The Suzuki coupling reaction is a powerful tool for carbon-carbon bond formation in combinatorial library production.23 Many different reaction conditions and catalyst systems have been reported for the cross-coupling of aryl triflates and aromatic halides with boronic acids in solution. After some experimentation, we found that the Suzuki cleavage of the resin-bound perfluoroalkylsulfonates proceeded smoothly by using [l,l -bis (diphenylphosphino)ferrocene]dichloropalladium(II), triethylamine, and boronic acids in dimethylformamide at 80° within 8 h afforded the desired biaryl compounds in good yields.24 The desired products are easily isolated by a simple two-phase extraction process and purified by preparative TLC to give the biaryl compounds in high purity, as determined by HPLC, GC-MS, and LC-MS analysis. 

Palladacycles [17] have been established as important class of catalysts, an unusual phosphine-free sulfur containing catalyst was introduced by Zim [18] et al. A phosphinite based palladacycle [19] proved to be very efficient in Suzuki coupling reactions. An N,P-Ligand type was synthesized by Kocovsky [20] et al. Tridentate pincer ligands [21] have been proved use-fill in the Heck reaction. Recent developments regarding Heck (22] and Suzuki [23] reactions have been reviewed by Fu and Littke. A new catalyst especially suitable for Heck couplings has been introduced by Beller [24] et al. 

Bicyclic complexes containing an azetidine ring and a palladium atom 525 have been shown to be effective catalysts in Suzuki coupling reactions with bromobenzenes and with the generally less reactive chlorobenzenes. The catalyst was stable in air for several months without loss of activity and the catalyst loading in the reaction could be lowered to 0.1% without a decrease of yield in the reactions studied <2005JOM2306>. 

Suzuki coupling reactions (solvent DMF, temp. 80 °C) and compared to the unsupported perfluoro-tagged catalyst at different catalyst concentrations. The yields using the perfluoro-tagged catalyst are significantly lower compared to the reactions were the supramolecular dendritic catalyst assembly... 

Zhang and Allen [97] have recently reported an easily prepared, air- and moisture-stable resin-bound palladium catalyst for the Suzuki coupling reaction. Commercially available resin-bound thiourea, Deloxan THP II [98], was used as the starting material. The resin-bound catalyst was prepared simply by treating the wet Deloxan resin with a solution of Pd(OAc)2 in methanol. Suzuki coupling reactions were then carried out using the resin at a... 

The so-called Suzuki coupling reaction [1] is considered one of the most important synthetic tools to make unsymmetrical biaryl building blocks [2]. It comprises the coupling of aryl- or vinyl halides with arylboronic acids according to eqs. (la) and (lb). Palladium compounds are the catalysts of choice. 

Wolfe, J. P., Singer, R. A., Yang, B. H., Buchwald, S. L. Highly Active Palladium Catalysts for Suzuki Coupling Reactions. J. Am. Chem. 

Phosphino)amines and their complexes have been shown to be efficient catalysts for the palladium-catalyzed Suzuki coupling reaction of chloroarenes,449 rhodium-catalyzed hydroformy-lations458 and asymmetric hydrogenations,463,466 allylic substitution reactions,47, 472 conversion of isocyanates to isocyanurates,478 and as ethylene polymerization catalysts.479... 

Suzuki coupling reaction of phenylboronic acids such as 74 with 4-bromopyridine [34]. Inada and Miyuara [35] have extended the method to 2-chloroquinoline 25. Therefore, the coupling between 25 and phenylboronic acid 74 led to 2-tolylquinoline 75 in 91% yield. The catalyst was recovered with ease and used in further coupling reactions. Not surprisingly, the couplings of phenylboronic acids with electron-rich chloroarenes were ineffective due to their slow oxidative addition to the palladium(O) complex. This reaction is an example where even quinolinyl chloride is a good substrate for the oxidative addition of Pd(0) if the chlorine atom is at the activated position (a or 8). 

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