3.7. Palladium Nanoparticles as Catalysts 888 3.8. Other Transition-Metal Complexes 888 3.9. Transition-Metal-Free Reactions 889 4. Applications 889 4.1. Alkynylation of Arenes 889 4.2. Alkynylation of Heterocycles 891 4.3. Synthesis of Enynes and Enediynes 894 4.4. Synthesis of Ynones 896 4.5. Synthesis of Carbocyclic Systems 897 4.6. Synthesis of Heterocyclic Systems 898 4.7. Synthesis of Natural Products 903 4.8. Synthesis of Electronic and Electrooptical Molecules 906

https://www.chem.ccu.edu.tw/~joyce/referance/ericyang/Chem.%20Rev/Chem.%20Rev.%202007,%20107,%20874-922.pdf

The Sonogashira Reaction: A Booming Methodology in Synthetic Organic Chemistry†

ion. The oxidative addition mechanism was originally proposed22i because of the lack of a strong rate dependence on polar factors and on the acidity of the medium. Later, however, the electrophilic substitution mechanism also was proposed. Recently, the oxidative addition mechanism was confirmed by investigations into the decomposition and protonolysis of alkylplatinum complexes, which are the reverse of alkane activation. There are two routes which operate in the decomposition of the dimethylplatinum(IV) complex Cs2Pt(CH3)2Cl4. The first route leads to chloride-induced reductive elimination and produces methyl chloride and methane. The second route leads to the formation of ethane. There is strong kinetic evidence that the ethane is produced by the decomposition of an ethylhydridoplatinum(IV) complex formed from the initial dimethylplatinum(IV) complex. In D2O-DCl, the ethane which is formed contains several D atoms and has practically the same multiple exchange parameter and distribution as does an ethane which has undergone platinum(II)-catalyzed H-D exchange with D2O. Moreover, ethyl chloride is formed competitively with H-D exchange in the presence of platinum(IV). From the principle of microscopic reversibility it follows that the same ethylhydridoplatinum(IV) complex is the intermediate in the reaction of ethane with platinum(II). Important results were obtained by Labinger and Bercaw62c in the investigation of the protonolysis mechanism of several alkylplatinum(II) complexes at low temperatures. These reactions are important because they could model the microscopic reverse of C-H activation by platinum(II) complexes. Alkylhydridoplatinum(IV) complexes were observed as intermediates in certain cases, such as when the complex (tmeda)Pt(CH2Ph)Cl or (tmeda)PtMe2 (tmeda ) N,N,N′,N′-tetramethylenediamine) was treated with HCl in CD2Cl2 or CD3OD, respectively. In some cases H-D exchange took place between the methyl groups on platinum and the, CD3OD prior to methane loss. On the basis of the kinetic results, a common mechanism was proposed to operate in all the reactions: (1) protonation of Pt(II) to generate an alkylhydridoplatinum(IV) intermediate, (2) dissociation of solvent or chloride to generate a cationic, fivecoordinate platinum(IV) species, (3) reductive C-H bond formation, producing a platinum(II) alkane σ-complex, and (4) loss of the alkane either through an associative or dissociative substitution pathway. These results implicate the presence of both alkane σ-complexes and alkylhydridoplatinum(IV) complexes as intermediates in the Pt(II)-induced C-H activation reactions. Thus, the first step in the alkane activation reaction is formation of a σ-complex with the alkane, which then undergoes oxidative addition to produce an alkylhydrido complex. Reversible interconversion of these intermediates, together with reversible deprotonation of the alkylhydridoplatinum(IV) complexes, leads to multiple H-D exchange

Activation of c-h bonds by metal complexes

Collectively, palladium-catalyzed coupling reactions represent some of the most powerful and versatile tools available to synthetic organic chemists. Their widespread popularity stems in part from the fact that they are generally tolerant to a large number of functional groups, which allows them to be employed in a wide range of applications. However, for many years a major limitation of palladium-catalyzed coupling processes has been the poor reactivity of aryl chlorides, which from the standpoints of cost and availability are more attractive substrates than the corresponding bromides, iodides, and triflates. Traditional palladium/triarylphosphane catalysts are only effective for the coupling of certain activated aryl chlorides (for example, heteroaryl chlorides and substrates that bear electron-withdrawing groups), but not for aryl chlorides in general. Since 1998, major advances have been described by a number of research groups addressing this challenge; catalysts based on bulky, electron-rich phosphanes and carbenes have proved to be particularly mild and versatile. This review summarizes both the seminal early work and the exciting recent developments in the area of palladium-catalyzed couplings of aryl chlorides.

/pdf/palladium-catalyzed-coupling-reactions-of-aryl-chlorides-2jld2ekpnf.pdf

Palladium-Catalyzed Coupling Reactions of Aryl Chlorides

6.4. Polyynes 3123 6.5. Using R-Hydroxy Stannanes 3124 6.6. Using the Hurtley Reaction 3124 6.7. Using a Methylenation Reaction 3125 7. Conclusions and Future Prospects 3125 8. Uncommon Abbreviations 3125 9. Acknowledgments 3125 10. Note Added in Proof 3125 11. References 3126 * Authorstowhomcorrespondenceshouldbeaddressed(evano@chimie.uvsq.fr, nicolas.blanchard@uha.fr). † Université de Versailles Saint Quentin en Yvelines. ‡ Université de Haute-Alsace. Chem. Rev. 2008, 108, 3054–3131 3054

Copper-mediated coupling reactions and their applications in natural products and designed biomolecules synthesis.

https://www.chem.ccu.edu.tw/~joyce/referance/ericyang/Coord.%20Chem.%20Rev/Coord.%20Chem.%20Rev.%202004,%20248,%202337-2364.pdf

Copper in cross-coupling reactions: The post-Ullmann chemistry

Metalation of N‐Allenylpyrrole with Superbasic Reagents. Synthesis of New N‐Substituted Pyrroles.

Preparation et reactivite des lithiens des ethers et des thioethers cumuleniques

Conversions via polar organometallic intermediates are among the most frequently applied procedures in organic synthesis. Since chemists usually strive to attain satisfactory yields of products with the highest possible purity, considerable effort must be expended in finding the most favorable reaction conditions. This may be done by varying concentrations, temperature or other conditions systematically. A much easier and often applied procedure is to mix the reactants in high dilution (on the order of 0.1 mol per litre or less) at a low temperature, and then either allow the temperature to rise slowly, or maintaining the low temperature for a long period. Indeed, some reactions give good results only when carried out in a relatively large amount of solvent at very low temperatures (e.g. the generation of o-Li—C6H4—Br and of o-Li—C6H4—NO2 from BuLi and 1,2-dibromobenzene [35] or l-bromo-2-nitrobenzene [36], respectively. In most cases, however, synthetic operations can be performed successfully at more practical and economical concentrations of 0.5 to 1 mol/1 or higher. Then heating effects are often significant and routine observations with a thermometer can serve as a probe of the course of the reaction (more reliable than the appearance of a thin precipitate or a colour change); the selection of the most favorable temperature range is thus facilitated. Some conversions do not give problems, since they generally are fast, even at low temperatures (e.g. carboxylations of RLi with CO2, coupling with carbonyl compounds, reactions with disulfides and trialkylchlorosilane). Selections of reaction conditions, such as solvent and counter ion, can, in principle, be derived from analogous reactions described in the literature. However, this often requires an extensive, and complicated literature search.

Lambert Brandsma

Papers

Metalation of N‐Allenylpyrrole with Superbasic Reagents. Synthesis of New N‐Substituted Pyrroles.

Preparation et reactivite des lithiens des ethers et des thioethers cumuleniques

Reactivity of Polar Organometallic Intermediates

Chemistry of acetylenic ethers 106: Synthesis of 1‐alkoxy‐3‐alken‐1‐ynes, a new class of acetylenic ethers

Deprotonation of benzyl isothiocyanate: a simple route to silylated benzyl isothiocyanates