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Aerobic Palladium‐Catalyzed Oxidations in the Upgrading of Biorenewables: Oxidation of β‐Ionone and α‐Ionone
Author(s) -
dos Santos Costa Maíra,
de Meireles Augusto L. P.,
Gusevskaya Elena V.
Publication year - 2017
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.201700337
Subject(s) - ionone , chemistry , catalysis , palladium , allylic rearrangement , benzoquinone , redox , ketone , organic chemistry , aromatization , terpenoid , oxygen , combinatorial chemistry , stereochemistry
α‐Ionone and β‐ionone are natural products that are found in a variety of essential oils and are also produced synthetically on an industrial scale. Both ionones were selectively oxidized by molecular oxygen in the presence of chloride‐free Pd(OAc) 2 / para ‐benzoquinone catalytic systems. Highly functionalized oxygenated terpenoids that were obtained in these new processes are potentially useful as ingredients in synthetic perfumes, cosmetics, and pharmaceuticals. β‐Ionone (known as rose ketone) was converted into a single major product, whereas α‐ionone gave three isomeric products, all of which resulted from the allylic oxidation of their endocyclic double bonds. These processes operated with an efficient dioxygen‐coupled catalytic turnover under 5–10 atm pressure, in the absence of conventionally used metal‐redox‐active cocatalysts. Alternatively, the reactions could be efficiently conducted under atmospheric pressure in the presence of copper acetate to assist in the regeneration of BQ by molecular oxygen.