Palladium catalysis Suzuki-Miyaura reactions

Application of the complexes 63 in the Mizoroki-Heck reaction did not reveal higher activity than the previously examined palladium(II) complexes. However, in the Suzuki-Miyaura reaction, a drastically increased activity was observed with complex 63. Catalysis starts without a measurable induction period at mild temperatures accompanied by an extraordinarily high turnover frequency (TOF) of 552 [mol product x mol Pd x h ] at the start of the reaction for the coupling of p-chlorotoluene and phenyl boronic acid [Eq. (48)]. ... 

Palladium nanoparticles and other heterogeneous catalysts are often invoked as catalysts in cross-coupling processes [194, 195). Direct evidence in support of an oxidative-addition-promoted leaching mechanism has been recently obtained in the Suzuki-Miyaura reactions with nanoparticle catalysts, suggesting that true surface catalysis remains largely unknown with these heterogeneous catalysts [196]. 

To conclude this part of this section, we include an interesting study that was reported in 2012 by Ikawa et al. [141], in which phenols treated with nonafluorobutenesulfonyl fluoride (where Nf=S02(CF2)3CF3) underwent the Suzuki-Miyaura reaction in moderate yields under palladium catalysis (Pd(OAc)2 or Pd2(dba)3), using SPhos as the ligand and a weak base. The reaction proceeds through nonaflation of the phenols, that is, via an activated nonafluorobutanesulfonyl intermediate. 

Sivudu, K.S., Reddy, N.M., Prasad, M.N., Raju, K.M., Mohan, Y.M., Yadav, J.S., Sabitha, G., Shailaja, D., 2008. Highly efficient and reusable hydrogel-supported nano-palladium catalyst evaluation for Suzuki—Miyaura reaction in water. Journal of Molecular Catalysis... 

Shylesh, S., Wang, L. and Thiel, W.R. (2010) Palladium(II)-phosphine complexes supported on magnetic nanoparticles filtration-free, recyclable catalysts for Suzuki-Miyaura crosscoupling reactions. Advanced Synthesis and Catalysis, 352 (2-3), 425-432. 

A tandem Suzuki-Miyaura coupling/nucleophilic aromatic substitution to carba-zoles was developed by St. Jean et al. (Scheme 51) [210]. Reaction of A -sulfonyl-protected 2-aminophenylboronates 216 with l-bromo-2-fluorobenzenes 217 under palladium(0)-catalysis provides the Af-sulfonyl-protected carbazoles 218. This annulation is compatible with a variety of electron-withdrawing groups (e.g., aldehydes, esters, and sulfones) and has been applied to an efficient synthesis of glycosinine (147) (four steps, 50% overall yield). 

The field of palladium catalysis is also progressing rapidly. The Tsuji-Trost and Mizoroki-Heck reactions have been mentioned earher, however other C-C coupling reactions (Miyaura-Suzuki, Sonogashira and Stille) are now extensively used in organic chemistry, and the search for non-polluting Sonogashira and Miyaura-Suzuki reactions is being actively pursued. 

Mixed phosphorus compounds, bearing at least two different tervalent phosphorus moieties have been developed and have found several applications in catalysis. Iri li described the synthesis of aminophosphine-phosphinite ligands 149 and 150, from the commercially available 3-piperidinemethanol and 3-(methylamino) pro-pan-l-ol. Their palladium and platinum complexes 151 and 152, containing metallocyclic rings, were obtained as air-stable compounds with high yields, and characterized by P, and NMR spectroscopy, FTIR spectroscopy and X-ray crystallography. The Pd complexes were effective catalysts on Suzuki-Miyaura cross-coupling reactions of various aryl chlorides and atyl bromides with phe-nylboronic acid. 

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