A short and efficient synthesis of ketene O,O- and S,S-acetals under focused microwave irradiation and solvent-free conditions

A new methodology leading to ketene O,O- and S,S-acetals is reported. The title compounds were prepared from the corresponding halogenated precursors under microwave irradiation in the absence of solvent within 5-25 minutes with excellent yields. Yields obtained under microwaves are by far the best when compared to those obtained by ultrasound or classical heating in the same conditions of time and temperature.