s, or keywords if they used Heck-type chemistry in their syntheses, because it became one of basic tools of organic preparations, a natural way to

http://aether.cmi.ua.ac.be/artikels/Artikels%20Gitte/Artikels/Reviews/Heck%20reactie%20Beletskaya%20%20Chem.%20Rev.%20003009.pdf

The heck reaction as a sharpening stone of palladium catalysis.

Catalytic dehydrogenative cross-coupling: forming carbon-carbon bonds by oxidizing two carbon-hydrogen bonds

/pdf/aryl-aryl-bond-formation-one-century-after-the-discovery-of-1jdyxlkwix.pdf

Aryl-aryl bond formation one century after the discovery of the Ullmann reaction.

The biaryl structural motif is a predominant feature in many pharmaceutically relevant and biologically active compounds. As a result, for over a century 1 organic chemists have sought to develop new and more efficient aryl -aryl bond-forming methods. Although there exist a variety of routes for the construction of aryl -aryl bonds, arguably the most common method is through the use of transition-metalmediated reactions. 2-4 While earlier reports focused on the use of stoichiometric quantities of a transition metal to carry out the desired transformation, modern methods of transitionmetal-catalyzed aryl -aryl coupling have focused on the development of high-yielding reactions achieved with excellent selectivity and high functional group tolerance under mild reaction conditions. Typically, these reactions involve either the coupling of an aryl halide or pseudohalide with an organometallic reagent (Scheme 1), or the homocoupling of two aryl halides or two organometallic reagents. Although a number of improvements have developed the former process into an industrially very useful and attractive method for the construction of aryl -aryl bonds, the need still exists for more efficient routes whereby the same outcome is accomplished, but with reduced waste and in fewer steps. In particular, the obligation to use coupling partners that are both activated is wasteful since it necessitates the installation and then subsequent disposal of stoichiometric activating agents. Furthermore, preparation of preactivated aryl substrates often requires several steps, which in itself can be a time-consuming and economically inefficient process.

http://aether.cmi.ua.ac.be/artikels/Artikels%20Gitte/Artikels/Reviews/Heck-Type-lautens.pdf

Aryl-aryl bond formation by transition-metal-catalyzed direct arylation.

N-Heterocyclic Carbenes in Late Transition Metal Catalysis

The first examples of assembling monodentate oxazoline donor and acceptor ligands by charge transfer interactions are described to mimic bidentate ligands in asymmetric catalysis. The corresponding copper(II) complexes were used in an enantioselective Diels–Alder reaction and showed very high efficiency, but only moderate stereoselectivity. These complexes were successfully recovered and reused after precipitation in pentane.

Assembly of chiral monodentate ligands to chelates by donor–acceptor interactions

Benzyloxycalix[8]arene supported catalysts bearing N-heterocyclic carbene palladium complexes on each subunit were readily synthesized Intermediates and catalysts were fully characterized, allowing for a fine control of their structure X-ray diffraction analysis confirmed the formation of a calix[8]arene bearing eight well-defined NHC palladium complexes The macrocyclic structure of calix[8]arenes allowed for a scalable and chromatography-free catalyst synthesis under homogeneous conditions, while the catalytic reaction proceeded under heterogeneous conditions, just by changing the nature of the solvent Indeed, when used as a suspension in ethanol, a high TON and TOF were obtained through a large panel of functionalized brominated substrates in C-C Suzuki-Miyaura couplings, with low metal contamination after simple filtration

Benzyloxycalix[8]arene: a new valuable support for NHC palladium complexes in C–C Suzuki–Miyaura couplings

Thiophene- and pyrrole-modified chiral cobalt–salen complexes were found to be efficient, enantioselective homogeneous catalysts for the dynamic hydrolytic kinetic resolution (HKR) of epibromohydrin. Their corresponding electrogenerated thiophene–salen–cobalt polymers were prepared by anodic oxidation and could be recovered as insoluble powders for heterogeneous catalysis. Their activity and selectivity were evaluated according to the polymerization conditions. A polymer that was formed from the direct oxidation of a CoII complex in a CH2Cl2/AcOH/nBu4NBF4 electrolytic mixture promoted the most-efficient synthesis of the expected bromoacetal (up to >99 % yield and 87 % ee). This heterogeneous catalyst was easily recovered, could be reused without the need for a reactivation step, and was highly stable, even after 11 consecutive catalytic runs. Moreover, this catalyst was engaged in a multi-substrate recovery procedure with various terminal epoxides, thereby demonstrating its usefulness for the transformation of diverse substrates.

Electrogenerated Polymers as Efficient and Robust Heterogeneous Catalysts for the Hydrolytic Kinetic Resolution of Terminal Epoxides

A new method for recycling chiral bis(oxazoline)-copper complexes is described based on the formation of charge-transfer complexes, their subsequent precipitation, and reuse after addition of new substrates. The conditions to perform this procedure were optimized in the presence of three bis(oxazoline)-based ligands. When associated with copper salts, these ligands efficiently catalyzed the Diels-Alder reaction between cyclopentadiene and alpha,beta-unsaturated acyloxazolidinones. These catalysts were successfully recycled up to ten times while maintaining their high activities and enantioselectivities.

Reusable catalysts for the asymmetric Diels-Alder reaction

Synthesis of Hoveyda-type ruthenium complexes, modified by pyrene tags on the NHC ligand and/or the benzylidene moiety, is described. Thanks to non-covalent π-π interactions these new complexes were immobilized on carbon supports [reduced graphene oxide (rGO) or graphene] and their activity and recoverability for metatheses reactions have been studied. A SIPr-based complex possessing the pyrene function on the benzylidene ligand ( C2 ) delivered the best results for the ring closing metathesis of diethyldiallyl malonate as benchmark reaction. The presence of additional pyrene-functionalized styrenyl-ether as ligand to the rGO-supported catalyst ( C2 / L @rGO) noticeably improved the recycling procedure allowing supplementary efficient catalytic runs. This may be due either to a facilitated boomerang effect or to a gradual release of the active species in solution. Finally, catalyst C2 / L @rGO was proven to be successfully used to promote metathesis reactions in a multisubstrate procedure, the same supported-catalyst batch being successively engaged to transform three different substrates, in diene and ene-yne RCM reactions.

/pdf/non-covalent-immobilization-of-pyrene-tagged-ruthenium-3i4ix6ulvj.pdf

Emmanuelle Schulz

Papers

Assembly of chiral monodentate ligands to chelates by donor–acceptor interactions

Benzyloxycalix[8]arene: a new valuable support for NHC palladium complexes in C–C Suzuki–Miyaura couplings

Electrogenerated Polymers as Efficient and Robust Heterogeneous Catalysts for the Hydrolytic Kinetic Resolution of Terminal Epoxides

Reusable catalysts for the asymmetric Diels-Alder reaction

Non covalent immobilization of pyrene-tagged ruthenium complexes onto graphene surfaces for recycling in olefin metathesis reactions