Current Organic Chemistry - Volume 14, Issue 12, 2010

These days the organophosphorus discipline is in focus within organic chemistry. After the success of Organophosphorus (OP) special issues 1-7 of Current Organic Chemistry, the 8th OP special issue is announced here showing up mainly green and synthetic aspects. Two articles illustrate the advantages of applying ionic liquids instead of traditional solvents. In the first of these, efficient organophosphorus syntheses that were carried out in ionic liquids, or in some cases in water, have been collected. In the second, typical homogeneous catalytic reactions involving hydrogen, carbon monoxide or carbon dioxide as the reagents are described to illustrate the activating ability of ionic liquids. The third paper presents alkenylphosphines as versatile intermediates. They can be involved in nucleophilic addition, or cycloaddition or polymerization reactions, or may be the building blocks of bidentate ligands or dendrimers. Finally, prototropic isomerizations within the C=N-CH triad of imidoylphosphonates are discussed.

The application of 'green' solvents such as ionic liquids and water is currently being vigorously pursued because of attractive features such as the acceleration of a variety of reactions, their non-toxic nature, the possibility of dissolving a variety of reactants and recyclability in the case of ionic liquids, and cheapness in the case of water. The present review summarizes and critically discusses the data accumulated in recent years on the utilization of these solvents in the field of the synthesis of organophosphorus compounds. Ionic liquids and water were found to be especially suitable for P=O olefinations, synthesis of α- and β-aminophosphonates and some nucleophilic displacement reactions while in some cases they may change the reaction course observed in common organic solvents.

This review deals with the application of ionic liquids in the activation of small molecules such as dihydrogen, carbon monoxide and carbon dioxide in various homogeneous catalytic reactions. The catalysts were restricted to transition metal catalysts containing phosphorus ligands (mainly phosphines).

Alkenylphosphines are compounds of great interest in view of their structures. The most interesting feature is the carbon-carbon double bond, which is directly linked to the phosphorus atom. Nucleophilic addition or cycloaddition reactions can take place at this unsaturation, which can also be used as a coordinating part in the presence of a metal. Thus, alkenylphosphines have found numerous applications in various fields of chemistry. They are useful intermediates in organic synthesis: numerous studies are devoted to their transformation into bidentate ligands, to their use as precursors for dendrimer and polymer chemistry or as ligand for homogeneous catalysis. Due to the presence of both the phosphorus atom and the carbon-carbon double bond, they are also of great interest in coordination chemistry and their different bonding modes have been largely documented. Moreover, after complexation to transition metal, a great amount of work has been carried out on their reactivity in cycloaddition reactions, as well as in functionalization of the carbon-carbon double bond and other miscellaneous reactions. These main applications will be reviewed hereafter.

In the present review we attempt to systematize and generalize the available data on prototropy in imidoylphosphonates containing α-hydrogen atoms in the N- or C-alkyl groups of the C=N bond. Prototropic transitions in C=N-CH triad of imidoylphosphonates leading to biorelevant α-aminophosphonates are in main focus of the review. Central to this endeavour is elucidation of the effect that the phosphoryl or phosphonium moiety exerts on prototropy in the phosphorylated 2-azaallylic triad.

Heteroaromatics-containing polymers comprise a huge class of materials that have received considerable attention due to their interesting electrical, electrochemical and optical properties. In this review, the recent advances on the use of cross-coupling reactions for the synthesis of heteroaromatic, conjugated monomers and polymers for the optoelectronic interests and applications are summarized. This review article focuses on synthesis, polymerization, structures, properties and application of crowded symmetric arylenes, which are of interest because of their viewpoint as material for environmental devices. Synthesis of the symmetric heteroarylenes was provided due to Suzuki and Stille coupling. Polymerization was mostly processed as two steps two-electron oxidation of molecules. In single-electron oxidation, stable radical cation is formed with spin located on main unit of structure. The electrochemical properties of polymer are dependent on film thickness deposited on electrode. Analysis of polymer behavior and results of spectrochemical measurements of obtained derivatives point to mixed type of electroconductivity of material.

The concept of π-acid catalysis has emerged as a powerful principle for the chemists to create diversity and originality from simple molecules. Carbophilic late transition metals such as gold or platinum have appeared as fascinating catalysts able to activate alkenes, alkynes and other unsaturated derivatives towards anti nucleophilic addition via complexation on a single empty coordination site. Tunable chiral square-planar cationic platinum complexes created by combination of a mono- and a bidentate ligand appear as a new class of highly promising asymmetric catalytic systems. This highlight intends to stress the potential applications in enantioselective catalytic reactions associated with a variety of chiral cationic tricoordinated platinum complexes recently described in the literature.

The intermolecular radical addition to the carbon atom of imine derivatives has received much less attention until recently, although the use of radical reaction in organic synthesis has continued to increase. This review highlights the intermolecular carbon-carbon bond forming reactions based on carbon radical addition to the carbon-nitrogen double bond. Particularly, the radical reactions of oxime ethers, hydrazones, sulfonylimines, ketimines, and so on are summarized. In this review, strategies for diastereo- and enantioselective radical reactions of imine derivatives are also summarized.