Synthesis of Silyl Dienol Ethers via Peterson Olefination of Siloxyallylpotassium Species

We report a general method for synthesizing a diverse array of silyl dienol ethers via the Peterson olefination of aldehydes and benzophenone using 3-silyl-substituted siloxyallylpotassium species. The reaction proceeds smoothly at -78 °C and tolerates a wide range of functional groups on the aldehyde substrate (OMe, NMe₂, F, Cl, Br, CN, CO₂^<i>t</i>Bu, CF₃, and epoxide). Under our conditions, organolithium bases are ineffective, underscoring the critical role of potassium carbanions. The resulting silyl dienol ethers are readily converted to β,γ-unsaturated ketones. This two-step sequence thus constitutes a formal β-olefination of ketones.