Phosphorus tribromide → 2-Propylthiazol-5-amine

A solution of the product of Example 5C (395 mg, 2.465 mmol) in anhydrous ethyl acetate (12 mL) was treated with phosphorous tribromide (0.189 mL, 1.972 mmol) under a nitrogen atmosphere and stirred at room temperature for 20 minutes. Added additional phosphorous tribromide (0.050 mL) and let stir for 5 minutes. The reaction mixture was diluted with ethyl acetate (50 mL) and washed with saturated aqueous sodium bicarbonate (25 mL). The aqueous wash was extracted with ethyl acetate (2×50 mL), and the organic extracts were combined and washed with brine, dried over anhydrous sodium sulfate, filtered and concentrated under vacuum giving the title compound. Purification by silica gel flash chromatography with 3% methanol/methylene afforded the title product (175 mg, 1.23 mmol, 50%).