The Huisgen 1,3-dipolar cycloaddition reaction of organic azides and alkynes has gained considerable attention in recent years due to the introduction in 2001 of Cu(1) catalysis by Tornoe and Meldal, leading to a major improvement in both rate and regioselectivity of the reaction, as realized independently by the Meldal and the Sharpless laboratories. The great success of the Cu(1) catalyzed reaction is rooted in the fact that it is a virtually quantitative, very robust, insensitive, general, and orthogonal ligation reaction, suitable for even biomolecular ligation and in vivo tagging or as a polymerization reaction for synthesis of long linear polymers. The triazole formed is essentially chemically inert to reactive conditions, e.g. oxidation, reduction, and hydrolysis, and has an intermediate polarity with a dipolar moment of ∼5 D. The basis for the unique properties and rate enhancement for triazole formation under Cu(1) catalysis should be found in the high ∆G of the reaction in combination with the low character of polarity of the dipole of the noncatalyzed thermal reaction, which leads to a considerable activation barrier. In order to understand the reaction in detail, it therefore seems important to spend a moment to consider the structural and mechanistic aspects of the catalysis. The reaction is quite insensitive to reaction conditions as long as Cu(1) is present and may be performed in an aqueous or organic environment both in solution and on solid support.

Cu-catalyzed azide-alkyne cycloaddition.

Pd-catalyzed cross-coupling reactions that form C–N bonds have become useful methods to synthesize anilines and aniline derivatives, an important class of compounds throughout chemical research. A key factor in the widespread adoption of these methods has been the continued development of reliable and versatile catalysts that function under operationally simple, user-friendly conditions. This review provides an overview of Pd-catalyzed N-arylation reactions found in both basic and applied chemical research from 2008 to the present. Selected examples of C–N cross-coupling reactions between nine classes of nitrogen-based coupling partners and (pseudo)aryl halides are described for the synthesis of heterocycles, medicinally relevant compounds, natural products, organic materials, and catalysts.

Applications of Palladium-Catalyzed C–N Cross-Coupling Reactions

Scaling of ab initio force fields by MOLVIB

Raman spectroscopy is a branch of vibrational spectroscopy in which a sample is exposed to an intense light beam such as a laser, and the spectrum of Raman-active vibrational modes induced in the sample molecules is obtained through analysis of the inelastically scattered photons. The diversity of applications and high content of molecular structure information provided, combined with recent advances in instrumentation, have rekindled interest in this technique in many diverse disciplines, including food science. Suitable analytes cover the entire range of food constituents, including the macro-components (proteins, lipids, carbohydrates and water) as well as minor components such as carotenoid pigments or synthetic dyes, and even microorganisms or packaging materials in contact with foods. Raman spectroscopy may be used as a tool for quality control, for compositional identification or for the detection of adulteration, as well as for basic research in the elucidation of structural or conformational changes that occur during processing of foods.

The applications of Raman spectroscopy in food science

"Comprehensive Heterocyclic Chemistry" was published in 1984 and is now available on CD-ROM.

Comprehensive heterocyclic chemistry on CD-ROM

Spectroscopic studies on β-cyclodextrin

Structure determination of copper(II)-β-cyclodextrin complex by Fourier transform infrared spectroscopy

The Raman spectra of six polymorphic crystal forms of N-cyano-N'-methyl-N"-{2-[(5-methyl-1H-imidazol-4-yl)methylthio]ethyl}-guanidine (Cimetidine) have been studied to investigate the possibility of quantitative analysis of polymorphic mixtures. Characteristic Raman bands of the various polymorphs have been found, some of which proved to be appropriate for quantitative analysis. The applicability of various mathematical techniques has been investigated, of which partial least-squares (PLS) has been found to be the best.

Investigation of the Morphological Composition of Cimetidine by FT-Raman Spectroscopy

Highly efficient fluorous tagging methodology was developed based on catalytic 1,3-dipolar cycloaddition as the key step.

Orsolya Egyed

Papers

Spectroscopic studies on β-cyclodextrin

Spectroscopic studies on β-cyclodextrin

Structure determination of copper(II)-β-cyclodextrin complex by Fourier transform infrared spectroscopy

Investigation of the Morphological Composition of Cimetidine by FT-Raman Spectroscopy

Fluorous click chemistry as a practical tagging method.