Oxazolidine-2, 4-diones were synthesised by tetraethylammonium hydrogen carbonate (TEAHC) promoted carboxylation of secondary carboxamides bearing a leaving group at the α-position. Several oxazolidine-2, 4-diones, including clinically used malidone®, have been prepared in moderate to excellent yields as a results of a formal proton extraction- carboxylation-intramolecular SN2 one-pot sequence.