Water → 5-(2,2-Dimethyl-1,3-dioxolan-4-yl)-1,3-thiazole-2-carbaldehyde

To a solution of 1-[2-(1,3-dioxolan-2-yl)-1,3-thiazol-5-yl]ethane-1,2-diol (1.50 g) in acetone (10 mL) were added water (1 mL) and pyridinium p-toluenesulfonate (0.52 g) and the mixture was stirred with heating under reflux overnight. The reaction mixture was extracted with ethyl acetate, and the ethyl acetate layer was washed with saturated brine, dried (MgSO4) and concentrated to give a crude product (1.20 g). To a solution of the obtained crude product (1.20 g) in acetone (80 mL) was added pyridinium p-toluenesulfonate (1.80 g), and the mixture was stirred with heating under reflux overnight. The reaction mixture was concentrated, the residue was dissolved in ethyl acetate, and the solution was washed with water. The ethyl acetate layer was washed with saturated aqueous sodium hydrogen carbonate and saturated brine, dried (MgSO4) and concentrated. The residue was subjected to silica gel column chromatography, and the title compound (0.50 g, yield 34%) was obtained as a yellow oil from a fraction eluted with ethyl acetate-hexane (2:3, volume ratio). MS: 214 (MH+).