Catalysis Suzuki-Miyaura coupling

Phan NTS, Van Der Sluys M, Jones CW (2006) On the nature of the active species in palladium catalyzed Mizoroki-Heck and Suzuki-Miyaura couplings - homogeneous or heterogeneous catalysis, a critical review. Adv Synth Catal 348 609-679... 

Since Suzuki-Miyaura coupling reactions are easy to perform, functionalised carbenes have often been tested in this catalysis, but with mediocre to poor results [89-91]. In retrospect, this is easily understood, since the best results are obtained for bulky trans-biscarbene complexes and functionalised NHC usually provide cix-chelate complexes [92]. However, the Suzuki-Miyaura reaction was used to evaluate the electronic properties of annulated carbenes [93,94]. 

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). 

In the field of catalysis, Au NPs appear to be particularly important as an efficient catalyst in organic reactions it can offer the most favourable combination of activity and selectivity in various catalytic reactions such as electrocatalysis, redox catalysis, carbon-carbon bond formation, and photocatalytic reactions. Moreover, recent literature reported that the Au NPs-graphene composites exhibit unprecedented catalytic activity for CO oxidation, reduction of nitro-aniline and Suzuki-Miyaura coupling reaction of chlorobenzene with arylboronic acid. 

An imine-based COF can uptake Pd ions into its pores by coordinating them via nitrogen atoms. These Pd ions on the COF walls show catalytic activity in heterogeneous catalysis as they are accessible for both the substrate and the reactant. One effective catalytic reaction by Pd/COF is the Suzuki-Miyaura coupling reaction, in which the catalyst shows tremendous activity with great recyclability. ... 

The most active NHCP system developed for Suzuki-Miyaura coupling so far was introduced by Shi et al. They investigated the chiral ferrocenyl NHCP system R-8, which was developed by Chung and coworkers for asymmetric hydrogenation (see Section 10.3), because of its resemblance to the famous Josiphos ligand, which, next to its performance in asymmetric catalysis, is also known for... 

M. Van der Sluys, C.W. Jones - On the Nature of the Active Species in Palladium Catalyzed Mizoroki-Heck and Suzuki-Miyaura Couplings- Homogeneous or Heterogeneous Catalysis, A Critical Review, Adv. Syn. Catal. 348,609, 2006. 

The same year, Gandon et al. reported the synthesis of fused arylboronic esters 36 via cobalt(0)-mediated cycloaddition of alkynylboronates 33 with diynes 35 (Scheme 1.11) [22], The boronate is first reacted with Co2(CO)g at room temperature for 4 h to generate the corresponding dicobaltatetrahedrane 34. The diyne is then added and the mixture is refluxed for 2 h. To show the utility of the products, one of them was treated with phenyl iodide under Pd catalysis to give 37. Complementary to these investigations, Ru-catalyzed [2 - - 2 - - 2] cycloaddition of tethered alkynyl-boronic esters with alkynes was reported [23]. In this case, the borylated arene could not be isolated but was converted directly in situ by Suzuki-Miyaura coupling. 

The Suzuki-Miyaura synthesis is one of the most commonly used methods for the formation of carbon-to-carbon bonds [7]. As a palladium catalyst typically tetrakis(triphenylphosphine)palladium(0) has been used, giving yields of44—78%. Recently, Suzuki coupling between aryl halides and phenylboronic acid with efficient catalysis by palladacycles was reported to give yields of 83%. 

Transition metal-catalysed reactions have emerged as powerful tools for carbon-carbon (C-C) bond formation [1], Cross-coupling reactions (Suzuki-Miyaura, Mizoroki-Heck, Stille, etc.) are recognised to be extremely reliable, robust and versatile. However, some other catalysed arylation reactions have been studied and have been reported to be very efficient [2]. In recent years, A -heterocyclic carbenes (NHC) have been extensively studied and their use as ligands for transition-metal catalysis has allowed for the significant improvement of many reactions [3]. This chapter highlights the use of NHC-bearing complexes in those arylation 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)]. ... 

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