Zirconium alkoxide catalyzed oxidation of phenols, alcohols, and amines

The development of the zirconium alkoxide catalyzed oxygenation and dehydrogenation is described. Mono-, di-, and tri-nuclear phenols are selectively oxidized to the corresponding ortho-quinones. Oxygenation also takes place with 2-alkylated phenols yielding highly functionalized alpha-hydroxy ketones. A very fast dehydrogenation of benzylic alcohols to the corresponding aldehydes and ketones occurs with the system Zr(O-n-Pr)(4)/hydroperoxide. Non-activated alcohols are also readily oxidized using the more active Zr(O-t-Bu)(4)/hydroperoxide or Zr(O-t-Bu)(4)/chloral system, higher reaction temperatures, and rigorous trapping of water with powdered molecular sieves. Silyl enol ethers are converted to the oc-chloro ketones with the system ClTi(O-i-Pr)(3)/hydroperoxide and phenols are selectively halogenated in the para-position by the same system. Electron-donor as well as electron-acceptor substituted anilines are oxidized in good yields to the corresponding nitro compounds with the Zr(Ot-Bu)(4)/hydroperoxide system. 1. Introduction 2. Phenols to ortho-Quinones 3. ortho-Substituted Phenols to alpha-Hydroxy Ketones 4. alpha-Chloro Ketones from Silyl Enol Ethers and Selective para-Chlorination of Phenols 5. Deydrogenation of Alcohols 5.1 Benzylic Alcohols 5.2 Dehydrogenation of Non-Activated Alcohols 5.3 Heterogeneous Catalysis 6. Oppenauer Oxidations 7. Oxidation of Primary Aromatic Amines to Nitro Compounds.