Treatment of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with alpha -chlorocarboxylic acid chlorides resulted in chemo- and regioselective formation of 6-chloro-3,5-dioxo esters, which were regioselectively converted into functionalised 3(2 H)furanones. Chemo- and regioselective condensation of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with alpha -chloroacetic dimethyl acetal afforded 6-chloro-5-methoxy-3-oxo esters, which could be regio- and stereoselectively transformed into 2-alkylidene-4-methoxytetrahydrofurans.