Saegusa Oxidation Reaction Mechanism with Applications

The Saegusa oxidation is known for the regioselective introduction of the α,β carbon-carbon double bond to cyclic and acyclic ketones via the Pd-mediated oxidation of the corresponding silyl enol ether. its also known as Saegusa–Ito oxidation.

T. Saegusa reported oxidation of silyl enol ethers in the presence of stoichiometric amounts of Pd(OAc)2 and p-benzoquinone in acetonitrile at room temperature to afford the corresponding α,β-unsaturated carbonyl compounds in 1978.

Stereochemistry: predominantly (E) stereoisomer will form in this oxidation even if substrate silyl enol ether was a mixture of (E) and (Z) stereoisomers.

Both acyclic and cyclic silyl enol ethers undergo the Saegusa Oxidation transformation . Drawback of the this oxidation is high cost of the palladium acetate.

Saegusa Oxidation of cyclic silyl enol ether

Modifications of Saegusa–Ito Oxidation :

  • Larock modifications of Saegusa–Ito oxidation = 10 mol% of Pd(OAc)2 instead of stoichiometric amount and oxygen atmosphere in DMSO.
  • Nicolaou oxidation : use of IBX and IBX-N-oxides instead of Saegusa Oxidation condition for Oxidation of silyl enol ether oxidation to the corresponding enones.

Saegusa Oxidation Mechanism:

Here this Oxidation Mechanism are shown When substoichiometric/stoichiometric amounts of Pd(OAc)2 is used: The mechanism involves the coordination of palladium to the enol olefin by leaving Me3SiOAc and form an oxoallyl-palladium complex. palladium hydride enone complex is unstable in nature and further undergoes β-hydride elimination leading product.

Mechanism of Saegusa Oxidation | Saegusa–Ito oxidation Mechanism

Saegusa Oxidation Applications:

  1. The first total synthesis of (–)-preussomerin and G (–)-gambierol the marine polycyclic ether toxin
  2. Total synthesis of (±)-8,14-cedranoxide by using Larock modified oxidation conditions

Related Reaction:

Baeyer-Villiger OxidationCorey-Kim Oxidation
Criegee OxidationDakin Oxidation
Davis’ Oxaziridine OxidationsDess-Martin Oxidation
Fleming-Tamao OxidationJones Oxidation/
Oxidation of Alcohols by Chromium Reagents
Kornblum OxidationLey Oxidation
Oppenauer OxidationPfitzner-Moffatt Oxidation
Pinnick OxidationSwern Oxidation
Riley Selenium Dioxide OxidationRubottom Oxidation
Wacker OxidationWacker Oxidation
list of oxidation reactions | all oxidation reaction list

References :

  1. J. Am. Chem. Soc. 1975, 97, 3, 649–651

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