Aerobic Oxidation of Alcohols with Bifunctional Transition‐Metal Catalysts Bearing C–N Chelate Ligands

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<jats:title>Abstract</jats:title><jats:p>The aerobic oxidation of alcohols with a family of bifunctional Ir, Rh, and Ru complexes bearing C–N chelating ligands derived from primary benzylic amines was investigated. The isolable amido–Ir complexes [Cp*Ir{κ<jats:sup>2</jats:sup>(<jats:italic>N</jats:italic>,<jats:italic>C</jats:italic>)‐(NHCR<jats:sub>2</jats:sub>‐2‐C<jats:sub>6</jats:sub>H<jats:sub>4</jats:sub>)}] (R=C<jats:sub>6</jats:sub>H<jats:sub>5</jats:sub>, CH<jats:sub>3</jats:sub>; Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) effected the oxidation of secondary alcohols smoothly under atmospheric pressure of air at 30 °C in THF to give the corresponding ketones in good yields. The hydrido(amine)–Ir complexes [Cp*IrH{κ<jats:sup>2</jats:sup>(<jats:italic>N</jats:italic>,<jats:italic>C</jats:italic>)‐(NH<jats:sub>2</jats:sub>CR<jats:sub>2</jats:sub>‐2‐C<jats:sub>6</jats:sub>H<jats:sub>4</jats:sub>)}] and the combined catalyst system involving the chloro(amine)–Ir complex [Cp*IrCl{κ<jats:sup>2</jats:sup>(<jats:italic>N</jats:italic>,<jats:italic>C</jats:italic>)‐(NH<jats:sub>2</jats:sub>CR<jats:sub>2</jats:sub>‐2‐C<jats:sub>6</jats:sub>H<jats:sub>4</jats:sub>)}] and KOC(CH<jats:sub>3</jats:sub>)<jats:sub>3</jats:sub> were also found to be effective catalysts, whereas the tertiary amine complex [Cp*IrCl{κ<jats:sup>2</jats:sup>(<jats:italic>N</jats:italic>,<jats:italic>C</jats:italic>)‐(N(CH<jats:sub>3</jats:sub>)<jats:sub>2</jats:sub>CH<jats:sub>2</jats:sub>‐2‐C<jats:sub>6</jats:sub>H<jats:sub>4</jats:sub>)}], which does not have a metal/NH moiety, did not show catalytic activity. The employment of primary alcohols in the aerobic reaction with the Cp*IrCl complex and KOC(CH<jats:sub>3</jats:sub>)<jats:sub>3</jats:sub> resulted in the formation of esters through oxidative dimerization.</jats:p>

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