Cross-coupling reaction catalysis

Keywords Palladium N-heterocyclic carbene Cross-coupling reaction Catalysis... 

Tamao K, Miyaura N (2002) Introduction to Cross-Coupling Reactions. 219 1-9 Tanaka M (2003) Homogeneous Catalysis for H-P Bond Addition Reactions. 232 25-54 Tanner PA (2004) Spectra, Energy Levels and Energy Transfer in High Symmetry Lanthanide Compounds. 241 167-278 ten Cate MGJ, see Crego-Calama M (2005) 249 in press ten Holte P,see Zwanenburg B (2001) 216 93-124 Thiem J,see Werschkun B (2001) 215 293-325... 

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. 

During the past decade, NHCs have been coordinated to virtually all transition metals (TM) and studied in numerous catalytic transformations, pushing back the frontiers of catalysis. In this regard, the most salient examples are found in olefin metathesis and cross coupling reactions, and more recently in organocatalysis. 

In summary, these results demonstrate that air-stable POPd, POPdl and POPd2 complexes can be directly employed to mediate the rate-limiting oxidative addition of unactivated aryl chlorides in the presence of bases, and that such processes can be incorporated into efficient catalytic cycles for a variety of cross-coupling reactions. Noteworthy are the efficiency for unactivated aryl chlorides simplicity of use, low cost, air- and moisture-stability, and ready accessibility of these complexes. Additional applications of these air-stable palladium complexes for catalysis are currently under investigation. 

Aryl-aryl or Aryl-heteroaryl cross-coupling reactions can be performed with either Ni- or Pd-based catalysis. Due to the low reaction temperatures, substrates containing some additional functional groups are tolerated (26).138... 

The ideal ligand for the cross-coupling reactions should satisfy the requirements of all stages of the catalytic cycle. In practice this is unlikely, as these requirements are not parallel. A careful compromise between various factors is necessary for any particular realization of cross-coupling chemistry. The path of reasoning should be similar for both Pd- and Ni-catalyzed processes however, since very little information is available concerning Ni catalysis, only Pd catalysis will be discussed here. 

Commercially available Pd(PtBu3)2 is a unique, air-stable 14e Pd° complex, an excellent catalyst for cross-coupling reactions of aryl chlorides. The ability of P Bu3 to stabilize such a coordin-atively unsaturated, extremely reactive, and yet easily manageable form of Pd° is one of the most amazing and fruitful recent findings in Pd-based catalysis. The cross-coupling of arylzinc reagents with aryl or vinyl chlorides can be readily accomplished with as little as 0.03% of this catalyst. Both electron-rich and sterically hindered substrates are welcome in this protocol.404... 

Direct C-Harylation of purines in position 8 by diverse aryl iodides has been achieved with Pd catalysis in the presence of Cul and CS2CO3. The methodology is general and efficient and was applied in the consecutive regioselective synthesis of 2,6,8-trisubstituted purines bearing three different C-substituents in combination with two cross-coupling reactions... 

The cross-coupling reaction of unactivated allenes and 1-alkynes has been efficiently achieved by making use of catalysis with HRh(CO)(PPh3)3 and Et3P, giving endo-(E)-enynes in high yields and selectivities (Scheme 16.95) [101],... 

Siamaki, A.R., et ah, Microwave-assisted synthesis of palladium nanoparticles supported on graphene A highly active and recyclable catalyst for carbon-carbon cross-coupling reactions. Journal of Catalysis, 2011. 279(1) p. 1-11. 

Cross-coupling reactions of alkynes with (Z)-vinylic tellurides under PdCyCuI catalysis gives rise to the corresponding enynes and enediynes with retention of the configuration."... 

Carbon-carbon bond-forming reactions are one of the most basic, but important, transformations in organic chemistry. In addition to conventional organic reactions, the use of transition metal-catalyzed reactions to construct new carbon-carbon bonds has also been a topic of great interest. Such transformations to create chiral molecules enantioselectively is therefore very valuable. While various carbon-carbon bond-forming asymmetric catalyses have been described in the literature, this chapter focuses mainly on the asymmetric 1,4-addition reactions under copper or rhodium catalysis and on the asymmetric cross-coupling reactions catalyzed by nickel or palladium complexes. 

Keywords Carbon-carbon bond formation Cross-coupling reaction Organobismuth compounds Transition-metal catalysis... 

Cross-coupling reaction of alkenyl iodides with Ar3Bi were efficient under Pd catalysis [59] (Schemes 41 —4-3). Various alkenyl iodides furnished cross-coupling products in good yields in short reaction times under mild conditions. A bromine substituent did not affect the reaction and afforded the corresponding bromine-substituted products. 

Functionalized isoflavones can be easily obtained from the cross-coupling reaction of 3-iodochromones with Ar3Bi under Pd catalysis (Scheme 44). The coupling reaction of a variety of substituted 3-iodochromones and Ar3Bi afforded substituted isoflavones in high yields [60]. 

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