In the presence of catalytic amounts 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 bound is in conjugation with the oxygen atom whereas (E) isomers prevail if silyl dienethers or trienethers and O-dienesters or O-trienesters are formed.
