Four new (Z)-2-phenoxymethylene-4-pentanolide derivatives and four (Z)-2-phenoxymethyl-2penten-γ-lactone derivatives were prepared via Pd-catalyzed carbon monoxide insertion and intramolecular cyclization. All compounds were characterized by IR, iH NMR, 13C NMR, MS spectra and elemental analysis. The plausible mechanism of the reaction was discussed.