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Copper-oxygen species are proposed as intermediates in oxidation catalysis by the identification of a Cu(II)-superoxide complex supported by a sterically hindered, pyridinedicarboxamide ligand. The complex has produced a trans-1,2-peroxodicopper(II) species upon reaction with [(tmpa)Cu(C[H.sub.3]CN)]OTf and has acted as a base rather than an electrophilic (H-atom abstracting) reagent in reactions with phenols.

The successful, rapid in silico screening of chiral catalysts is demonstrated for the hydrogenation of enamides as the first application of this model. The possibility of rapidly predicting the enantioselectivity of related reactions has not only permitted ligands selection but has also added significant value to the wealth of available information for organo-metallic reaction mechanisms.

The rhodium-catalyzed hydrogenation reaction of enamides is studied for a range of ligands and substrates. It found that the mechanism of hydrogenation is not consistent for all substrates.

The complexes (Bu4N)(LMeMII-OH) (LMe = 2,6-dimethylphenyl-substituted pyridine(dicarboxamide); M = Cu or Ni) react with CH3CN to yield (Bu4N)(LMeM-CH2CN) cyanomethide complexes, which were fully characterized, including by X-ray crystallography. These conversions contrast with the usual reactions of metal hydroxide complexes with nitriles, which typically involve attack at the nitrile carbon atom and formation of amides or carboxylic acids. Kinetic studies (M = Cu) revealed a first-order dependence on the complex and a kinetic isotope effect [ k(CH3CN)/ k(CD3CN)] of 4. Various mechanisms involving either intra- or intermolecular deprotonation steps are proposed. In addition, (Bu4N)(LMeCu-OH) was oxidized by ferrocenium hexafluorophospate (FcPF6) to a proposed CuIII complex LMeCuOH at low temperature, and comparisons of its stability and reactivity with dihydroanthracene were drawn to its previously described congener with isopropyl substituents on the phenyl rings of the supporting ligand. The cyanomethide complex (Bu4N)(LMeCu(CH2CN)) was also reversibly oxidized both electrochemically ( E1/2 = -0.345 V vs. Fc/Fc+) and chemically (FcPF6, -25 °C). The product was formulated as LMeCuIII(CH2CN), a new CuIII-alkyl complex relevant to such species proposed during copper-catalyzed organic reactions. [ABSTRACT FROM AUTHOR]

Intramolecular hydroamination of several aminoalkynes catalyzed by silver-phenanthroline complexes is reported. This catalyst system complements previous protocols by employing air- and moisture-stable complexes without compromising activity or reaction control. Some of the hydroamination products are subject to a useful aerobic oxidation. Silver-phenanthroline complexes have successfully demonstrated efficacy in the desymmetrization of a prochiral diyne.