Development of a Highly Efficient Complex Catalysts for Selective Aerobic Oxidation

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In the presence of a catalytic amount of dioxo (tetramesitylporphyrinato) ruthenium (VI) complex, nitrous oxide (N_2O) oxidized trisubstituted olefins into the corresponding epoxides in good-to-high yields with high selectivity. Catalytic N_2O oxidation was successfully applied to various secondary and benzylic alcohols to afford the corresponding ketones and aldehydes in high yields. During the nitrous oxide oxidation of 9, 10-dihydroanthracene derivatives catalyzed by the ruthenium-porphyrin complexes, anthraquinones were selectively afforded by the C-H oxidation of the benzylic carbon under the appropriate reaction conditions, whereas anthracenes as a result of oxidative aromatization were selectively obtained in the presence of sulfuric acid. Preparation of 3-oxobutylideneaminato-rutheniumu complexes were also examined.A DFT study of the 3-oxobutylideneaminatocobalt (II) complex catalyzed cyclopropanation was performed to reveal the overall reaction pathway and the effects of the axial ligands. The reaction of cobalt (II) complexes with diazoacetate were traced by time-resolved FT-IR spectroscopy. It is generally considered that metal-carbene carbon bonds in carbene complexes should be double-bonded, however, the theoretical and FT-IR analyses revealed that the cobalt-carbene carbon bond was characterized as a single bond. It is expected that these observations would provide a promising method for design of oxidation catalysts.