Silylenolether-Funktionalisierung, 3. Mitt. Regioselektive Acylierung von Trimethylsilylenolethern mit 2-Alkoxy-1,3-dioxolanen - Synthese von α- und γ-geschützten Dicarbonylverbindungen.

Acylation of silylenol ethers 1 and 9 yield with 2-alkoxy-2-alkyl(or aryl)-1,3-dioxolanes 5 in a simple way by zinc dichloride-diethyl ether-catalysis regioselectively the α- and γ-protected dicarbonyl derivatives 6, 7, and 10. The enhanced reactivity of the cyclic orthoesters 5 in this reaction is discussed in comparison with acyclic reagents. The yield is influenced by steric effects at the reaction center. [ABSTRACT FROM AUTHOR]