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Multicomponent reactions (MCRs) are fundamentally different from two-component reactions in several aspects. Among the MCRs, those with isocyanides have developed into popular organic-chemical reactions in the pharmaceutical industry for the preparation of compound libraries of low-molecular druglike compounds. With a small set of starting materials, very large libraries can be built up within a short time, which can then be used for research on medicinal substances. Due to the intensive research of the last few years, many new backbone types have become accessible. MCRs are also increasingly being employed in the total synthesis of natural products. MCRs and especially MCRs with isocyanides offer many opportunities to attain new reactions and basic structures. However, this requires that the chemist learns the “language” of MCRs, something that this review wishes to stimulate.

Multicomponent Reactions with Isocyanides.

Pick your Pd partners: A number of catalytic systems have been developed for palladium-catalyzed CH activation/CC bond formation. Recent studies concerning the palladium(II)-catalyzed coupling of CH bonds with organometallic reagents through a PdII/Pd0 catalytic cycle are discussed (see scheme), and the versatility and practicality of this new mode of catalysis are presented. Unaddressed questions and the potential for development in the field are also addressed.

In the past decade, palladium-catalyzed CH activation/CC bond-forming reactions have emerged as promising new catalytic transformations; however, development in this field is still at an early stage compared to the state of the art in cross-coupling reactions using aryl and alkyl halides. This Review begins with a brief introduction of four extensively investigated modes of catalysis for forming CC bonds from CH bonds: PdII/Pd0, PdII/PdIV, Pd0/PdII/PdIV, and Pd0/PdII catalysis. A more detailed discussion is then directed towards the recent development of palladium(II)-catalyzed coupling of CH bonds with organometallic reagents through a PdII/Pd0 catalytic cycle. Despite the progress made to date, improving the versatility and practicality of this new reaction remains a tremendous challenge.

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Palladium(II)-catalyzed C-H activation/C-C cross-coupling reactions: versatility and practicality.

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.

/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.

Anion-Accelerated Palladium-Catalyzed Intramolecular Coupling of Phenols with Aryl Halides.

Strychnine has been synthesized by a short, highly stereocontrolled route that involves the efficient transformation of commercially available 2-nitrophenylacetonitrile into isostrychnine, a known precursor to strychnine

A Short, Stereocontrolled Synthesis of Strychnine

ConspectusThe transition-metal-catalyzed asymmetric cyclopropanation of olefins with diazoacetates has become one of the most important methods for the synthesis of optically active cyclopropane derivatives, which are key pharmaceutical building blocks and present in a large number of natural products. To date, significant progress has been made in this area of research, and efficient stereocontrolled synthetic approaches to cyclopropane derivatives have been developed using rhodium, ruthenium, copper, and cobalt catalysts. However, the vast majority of these strategies are limited to electron-rich olefins, such as styrene derivatives, due to the electrophilicity of the metal–carbene intermediates generated from the reaction of the metal with the diazo compound. Recently, the D2-symmetric Co(II)–phophyrin complexes developed by Zhang et al. were shown to be the most efficient catalysts for the asymmetric cyclopropanation of electron-deficient olefins. This catalytic system is mechanistically distinct from...

Enantioselective Cyclopropanation of a Wide Variety of Olefins Catalyzed by Ru(II)-Pheox Complexes.

Highly enantioselective chlorination of β-oxo esters and subsequent stereospecific substitution of tertiary chlorides are described. Enantioselective chlorination of β-keto esters and malonates was performed using a chiral Lewis acid catalyst prepared from Cu(OTf)(2) and the newly developed spirooxazoline ligand 2 to yield the desired α-chlorinated products with high enantioselectivity (up to 98% ee). Nucleophilic substitution of the resulting chlorides proceeded smoothly to afford a variety of chiral molecules such as α-amino, α-alkylthio, and α-fluoro esters, without loss of enantiopurity. The results of X-ray crystallographic analysis proved that Walden inversion occurs at the chlorinated tertiary carbon center. These results supported the fact that the substitution proceeds via an S(N)2 mechanism.

Highly enantioselective chlorination of β-keto esters and subsequent S(N)2 displacement of tertiary chlorides: a flexible method for the construction of quaternary stereogenic centers.

relatively low to moderate yields have so far been achieved.After an extensive literature survey, we concluded that all ofthe previously reported PSCCs depended on the polymeri-zation of a monomeric chiral ligand or the grafting of a chiralligand onto a polymeric support and subsequent complex-ation with a metal.

Asymmetric inter- and intramolecular cyclopropanation reactions catalyzed by a reusable macroporous-polymer-supported chiral ruthenium(II)/phenyloxazoline complex.

Seiji Iwasa

Papers

Anion-Accelerated Palladium-Catalyzed Intramolecular Coupling of Phenols with Aryl Halides.

A Short, Stereocontrolled Synthesis of Strychnine

Enantioselective Cyclopropanation of a Wide Variety of Olefins Catalyzed by Ru(II)-Pheox Complexes.

Highly enantioselective chlorination of β-keto esters and subsequent S(N)2 displacement of tertiary chlorides: a flexible method for the construction of quaternary stereogenic centers.

Asymmetric inter- and intramolecular cyclopropanation reactions catalyzed by a reusable macroporous-polymer-supported chiral ruthenium(II)/phenyloxazoline complex.