Radical-chain isomerisation of allyl silyl ethers to silyl enol ethers in the presence of thiols as polarity reversal catalysts

The radical-chain isomerisation of allyl silyl ethers to silyl enol ethers takes place on heating in the presence of an initiator and an arenethiol as a protic polarity reversal catalyst; pentafluorothiophenol is particularly effective in this role. The reaction complements the transition-metal-catalysed isomerisation and could be useful for the preparation of silyl enol ethers from readily available allylic alcohols.