(A) new method for α-alkoxyalkylation of α,β-unsaturated ketones using β-functionalized silyl enol ethers

Abstract

Reactions of phosphonium salt silyl enol ethers derived from $\alpha,\beta$-unsaturated ketones, trimethylsilyl trifluoromethane sulfonate, triphenylphosphine with acetal or ketal in the presence of trimethylsilyl triflate (TMS OTf) or titanium tetrachloride ($TiCl_4$) and $\beta$-elimination of phosphonium salt gave $\alpha$-alkoxyalkylated $\alpha,\beta$-unsaturated ketones in good overall yields. Iodotrimethylsilyl enol ethers derived from $\alpha,\beta$-unsaturated ketones and trimethylsilyliodide reacted with acetals in the presence of iodotrimethylsilane to give $\alpha$-alkoxyalkylated $\alpha,\beta$-enones via $\beta$ -elimination of iodide. Also, reactions of phosphonium salt silyl enol ether with aldehydes in the presence of tin (IV) chloride gave $\alpha$-alkylidene enones.