The general procedure for the synthesis of 4-bromo-5-formylthiazole from 4-bromo-5-hydroxymethylthiazole was carried out as follows: at room temperature, (4-bromothiazol-5-yl)methanol (870 mg) was dissolved in dichloromethane (25 mL) to form a light yellow solution. Subsequently, Dess-Martin periodinane (DMP, 2.16 g) was added to this solution and the reaction mixture was transformed into a yellow suspension. The reaction mixture was stirred continuously for 18 hours under argon protection and at room temperature. After completion of the reaction, ethyl acetate and saturated aqueous sodium bicarbonate solution were added to the reaction mixture and stirred for 5 minutes. Next, water was added and the mixture was extracted three times with dichloromethane. All organic layers were combined, dried with anhydrous magnesium sulfate, filtered and the solvent was evaporated under vacuum. Purification by column chromatography (using a Biotage system, SNAP 50g column, solvent A: heptane; solvent B: ethyl acetate; gradient elution procedure: keep 10% B for 5 column volumes of elution, then step up from 10% B to 30% B in 2 column volumes, and finally keep 30% B for 3 column volumes of elution) gave 708 mg of a yellow solid product. The product was characterized by 1H-NMR (CDCl3): δ 10.0 (s, 1H); 9.04 (s, 1H).
