Synthesis of Silyl Dienol Ethers via Peterson Olefination of Siloxyallylpotassium Species

We report herein a general method for synthesizing a diverse array of silyl dienol ethers via the Peterson olefination of aldehydes using 3-silyl-substituted siloxyallylpotassium species. The reaction proceeds cleanly at –78 °C and tolerates a wide range of functional groups on aldehyde substrates (OMe, NMe2, F, Cl, Br, CN, CO2tBu, 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.