Enol silyl ethers

Silyl enol ethers in organic chemistry are a class of organic compounds that share a common functional group composed of an enolate bonded through its oxygen terminus to an organosilicon group.

Silyl enol ethers are important intermediates in organic synthesis.

Silyl enol ethers react as nucleophiles in:

In the Saegusa–Ito oxidation certain silyl enol ethers are oxidized to enones with palladium(II) acetate. In the original publication equal amounts of palladium and 1,4-benzoquinone are used to achieve the reaction with the benzoquinone acting as a co-oxidant. The intermediate is an oxo-allylpalladium complex.

In one application, a dienone is synthesized in two steps from a cyclohexanone:

Cyclic silyl enol ethers have been demonstrated to be viable substrates for regiocontrolled one-carbon ring contractions. These reactions employ electron-deficient sulfonyl azides, which undergo chemoselective, uncatalyzed [3+2] cycloaddition to the silyl enol ether, followed by loss of dinitrogen, and alkyl migration to give ring-contracted products in good yield. These reactions may be directed by substrate stereochemistry, giving rise to stereoselective ring-contracted product formation.

Ketene silyl acetals are related compounds formally derived from ketenes and acetals with general structure R-C=C(OSiR₃)(OR').

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