Huisgen 1,3-dipolar cycloadditions [1] are exergonic fusion processes that unite two unsaturated reactants and provide fast access to an enormous variety of five-membered hetero-Cl atoms having a marked anionic character. [30] This feature is also realized, but to a lesser extent, in the MÀCl bonds of complexes 2 ± 6.The present study illustrates for the first time the ability of an a-cyclodextrin cavity to recognize a transition metal MÀCl bond through weak Cl ¥¥¥ H-5 interactions in the solid state as well as in solution. The fact that such subtle interactions could be observed in non-aqueous media is a consequence of the absence of stronger competing supramolecular forces, such as the hydrophobic effect, which usually plays a prevailing role in the formation of CD inclusion complexes. Overall these results illustrate the potential of modified cyclodextrins as second-sphere ligands.

Huisgen 1,3-dipolar cycloadditions [1] are exergonic fusion processes that unite two unsaturated reactants and provide fast access to an enormous variety of five-membered hetero-Cl atoms having a marked anionic character. [30] This feature is also realized, but to a lesser extent, in the MÀCl bonds of complexes 2 ± 6.The present study illustrates for the first time the ability of an a-cyclodextrin cavity to recognize a transition metal MÀCl bond through weak Cl ¥¥¥ H-5 interactions in the solid state as well as in solution. The fact that such subtle interactions could be observed in non-aqueous media is a consequence of the absence of stronger competing supramolecular forces, such as the hydrophobic effect, which usually plays a prevailing role in the formation of CD inclusion complexes. Overall these results illustrate the potential of modified cyclodextrins as second-sphere ligands.

Huisgen's 1,3-dipolar cycloadditions become nonconcerted when copper(I) acetylides react with azides and nitrile oxides, providing ready access to 1,4-disubstituted 1,2,3-triazoles and 3,4-disubstituted isoxazoles, respectively. The process is highly reliable and exhibits an unusually wide scope with respect to both components. Computational studies revealed a stepwise mechanism involving unprecedented metallacycle intermediates, which appear to be common for a variety of dipoles.

Triazole derivatives R 0280Copper(I)-Catalyzed Synthesis of Azoles. DFT Study Predicts Unprecedented Reactivity and Intermediates. -Cu-catalyzed addition of azides or nitrile oxides to acetylenes offers an efficient, widely applicable and regiospecific approach to 1,4-disubstituted 1,2,3-triazoles and 3,5-disubstituted isoxazoles, respectively. A stepwise mechanism is revealed which involves unprecedented metallacycle intermediates. -(HIMO, F.; LOVELL, T.; HILGRAF, R.; ROSTOVTSEV, V. V.; NOODLEMAN*, L.; SHARPLESS, K. B.; FOKIN, V. V.; J.

The oxidation of (tmeda)Pt(II)(CH(3))(2) (1, tmeda = N,N,N',N'-tetramethylethylenediamine) to (tmeda)Pt(IV)(OH)(OCH(3))(CH(3))(2) (3) by dioxygen in methanol proceeds via a two-step mechanism. The initial reaction between (tmeda)Pt(CH(3))(2) and dioxygen yields a hydroperoxoplatinum(IV) intermediate, (tmeda)Pt(OOH)(OCH(3))(CH(3))(2) (2), which reacts with a second equivalent of (tmeda)Pt(CH(3))(2) to afford the final product 3. Both 2 and 3 have been fully characterized, including X-ray crystallographic structure determinations. The effect of ligand variation on the oxidation of several dimethylplatinum(II) complexes by 2 as well as by dioxygen has been examined.