Transition metal catalysis coupling reactions

Metal Enolates. In parallel with additives, transition metals may be added to enolates to give transmetallated species which can undergo cross-coupling chemistry. Perhaps the earliest example of metal-catalyzed enolate reactions is the Reformatsky reaction. Transition metal-catalyzed enolate chemistry has been recently revived in the literature, particularly in the field of asymmetric catalysis. The transition metal-catalyzed coupling reactions of aryl halides, allyl epoxides, and allylic esters with alkyl enolates have been recently investigated. Generally the choice of base employed depends on the substrate and on the reaction performed. For enolate arylation, KHMDS seems to be the most... 

Nanostructured Carbon Materials for Catalysis 24 Heterocycles from Double-Functionalized Arenes Transition Metal Catalyzed Coupling Reactions 25 Asymmetric Functionalization of C—H Bonds... 

Pd-catalyzed site-selective cross-coupling reactions demonstrate the influential role of ligands in transition metal catalysis. The reactions described in this review discuss efficient approaches to introduce various substituents at specific halo-substituted posititMis (Ml (hetero)aromatic compounds. The commercial availability of a variety of dihalo-substituted starting materials makes site-selective crosscoupling reactions practical for the rapid production of diverse (hetero)arenes with multiple substituents. In all examples described here, the reactions proceeded successfully only on substrates containing hetero atoms, and this field of chemistry aims to include substrates without hetero atoms in the substrate scope. 

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. 

The enantiopure l-chloro-2,5-dimethylphospholane 2 is now available from the corresponding 1-trimethylsilylphospholane 1. The new phospholane 2 was used as an electrophilic building block in a wide range of coupling reactions giving rise to new phospholanes. These proved to be valuable as chiral ligands in transition metals catalysis with Rh, Ir or Ru complexes. 

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

Using established principles of late-transition metal catalysis, several research groups have engineered multi-component coupling reactions from the basis set of known Group 9 metal vinylidene-mediated reactions. In 2004, Jun and coworkers described a new method for the synthesis of enones via rhodium vinylidene-mediated hydrative dimerization of alkynes (Table 9.12) [24]. 

Transition Metal Catalysis in tonic Liquids 241 5.2.4.4 Heck, Suzuki, Stille, and Negishi coupling reactions... 

Low reactive aryl chlorides are converted to the respective organomagnesium species in excellent yields through transition metal catalysis using 2 mol% FeCU (4-6, equation 3). Alternatively, a safe and reproducible method for activation of aryl chlorides or bromides 7 uses microwave irradiation (equation 4). In a synthesis of a novel HIV-1 protease inhibitor, microwave irradiation was essential to generate the starting arylmagnesium halide as well as to promote the subsequent Kumada coupling reaction. ... 

Biaryls have also been prepared by coupling support-bound aryl halides with aryl-zinc compounds (Figure 5.20) or with aryl(fluoro)silanes [203]. As with Suzuki or Stille couplings, these reactions also require transition metal catalysis. An additional strategy for coupling arenes on solid phase is the oxidative dimerization of phenols (Figure 5.20). 

Negishi, E., Van Horn, D. E. Selective carbon-carbon bond formation via transition metal catalysis. 4. A novel approach to cross-coupling exemplified by the nickel-catalyzed reaction of alkenylzirconium derivatives with aryl halides. J. Am. Chem. Soc. 1977, 99, 3168-3170. 

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