The selective O-acylation of enolates providing simple entry to O-enesters

In the presence of catalytic amts. of a fluoride source, O-trimethylsilyl enethers undergo condensation with acyl fluorides to afford O-enesters with high yields. The intermediates and final products are pure (Z) isomers if only one double bond is in conjugation with the oxygen atom whereas (E) isomers prevail if silyl dienethers or trienethers and O-dienesters or O-triensesters are formed. [on SciFinder (R)]