Silyl enolates electrochemical syntheses

Silyl enol ethers are powerful intermediates in organic synthesis. Reactions of silyl enol ethers with various electrophiles provide effective methods for the synthesis of various carbonyl compounds. In this section we will briefly touch on the electrochemical reactions of silyl enol ethers and related compounds. The electrochemical behaviour of silyl enol ethers is expected to be closely related to that of allylsilanes and benzylsilanes because silyl enol ethers also have a silyl group ft to the re-system. 

Quite recently, stereoselective electrochemical synthesis of silyl enol ethers using a sacrificial magnesium anode was reported, as shown in equation 100126. 

Silyl enolates are a class of electron-rich, non aromatic compounds which can be described as masked enols or enolates since hydrolysis following their reaction yields ketones they can be purified by distillation or chromatography, and then converted back to the enolate anion. The electron-rich character of these species can be used for oxidation reactions and examples have been described in the preceding sections. In this section, additional examples of chemical, PET and electrochemical redox reactions involving silyl enolates will be discussed, for a better appreciation of these interesting species in organic synthesis. 

An elegant access to natural product synthesis was realized by Wright and co-workers, who obtained a cis-junction through the cyclization reaction of 91. The silyl enol ether 91 is electrochemically oxidized and subsequently cyclizes to yield compound 92. In three further steps, the cyathin core 93 can be prepared. 

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