Reactions of Ketones with Sodium Hydride or Potassium Hydride in the Presence of Trimethylsilyl Chloride. Preparation of Trimethylsilyl Enol Ethers

Reactions of cyclohexanone with NaH and Me3SiCl in various solvents yielded predominantly (90-97%) the silyl enol ether 2 resulting from enolization, with only a few percent of the alkyl silyl ether 1 resulting from initial reduction. Similar reactions with KH and Me3SiCl proceeded well only in dioxane to give >99% of 2. Cyclohexanone, 2-methylcyclohexanone, acetophenone, 2-heptanone were converted to trimethylsilyl enol ethers in good yields by this method.