Ito Y,
Hirao T,
Saegusa T.
*
Kyoto University, Japan
Synthesis of α,β-Unsaturated Carbonyl Compounds by Palladium(II)-Catalyzed Dehydrosilylation of Silyl Enol Ethers.
J. Org. Chem. 1978;
43: 1011-1013
DOI:
10.1021/jo00399a052
Key words
palladium catalysis - silyl enol ethers - α,β-unsaturated carbonyls
Significance
The Saegusa–Ito oxidation, introduced in 1978, is a synthetically important transformation, allowing to convert silyl enol ethers into the corresponding α,β-unsaturated carbonyl compounds. With acyclic and large ring substrates, the reaction is completely stereoselective towards the E-isomer, regardless of the stereochemistry of the starting silyl enol ether.
Comment
The original reaction was barely substoichiometric, using 0.5 equiv of Pd(OAc)2 and p-benzoquinone as the oxidant. Reducing the catalyst loading would systematically result in lower yields. One way to circumvent this drawback is the Larock modification (Tetrahedron Lett. 1995, 36, 2423). In this protocol, the reaction is carried out in DMSO under an oxygen atmosphere, which reoxidizes Pd(0) back to Pd(OAc)2.
