Step 1. Synthesis of 2-(4-chlorophenyl)-1,3-thiazole-5-carbaldehyde. 4-Chlorobenzamide (5 g, 29.1 mmol), magnesium bicarbonate pentahydrate (7.06 g, 14.55 mmol) and 2-chloromalonaldehyde (4.65 g, 43.65 mmol) were added to a flask and the reaction was stirred for 3 hr at 60 °C under nitrogen protection. Upon completion of the reaction, the reaction mixture was allowed to pass through a silica plug for rapid column chromatography and washed with ethyl acetate. The solvent was removed by concentration under reduced pressure to afford the target product 2-(4-chlorophenyl)-1,3-thiazole-5-carbaldehyde (6 g, 92% yield). The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 10.06 (s, 1H), 8.43 (s, 1H), 7.99-7.96 (m, 2H), 7.49-7.46 (m, 2H).
