The Michael Reaction of Silyl Enol Ethers with α,β-Unsaturated Eetones and Acetals in the Presence of Titanium Tetraalkoxide and Titanium Tetrachloride
Silyl enol ethers react with α,β-unsaturated ketones and esters in the presence of TiCl4 or in the coexistence of TiCl4 and Ti(Oi-Pr)4 to give 1,5-dicarbonyl compounds in good yields. The reactions of acetals derived from α,β-unsaturated ketones with silyl enol ethers in the coexistence of TiCl4 and Ti(Oi-Pr)4, followed by successive addition of 1,2-ethanedithiol, give the Michael products, δ-keto