A facile and efficient one-pot synthesis of 3-[bis(alkylthio/alkylamino)methylene]-5-(pyridyl/quinoylmethyl) furan-2,4(3H,5H)-diones 3 and 10, based on a sequential aldol condensation and lactonization reaction between α-oxo ketene-S,S-acetals 1 and pyridine/qinoline-carboxaldehydes 2 in aqueous media, has been developed. A mechanism involving an acid-catalyzed intramolecular oxa-pyridylethylation