A mixture of l-valine, two equivalents of arenealdehyde 2a-k, and diisopropylethylamine (DIPEA) in toluene was refluxed for four hours with a Dean-Stark trap. The mercaptoacetic acid was then added and the reaction mixture was heated until the reaction was complete (CG analysis). Products 3 were obtained in moderate yields after column chromatography (Table [1] ). The 1,3-thiazolidin-4-ones 3a-k were also obtained in a one-step reaction when all ...