To a solution of tert-butyl{1-[2-(6-chloro-1-oxido-3-oxo-1,2,4-benzotriazin-4(3H)-yl)ethyl]piperidin-4-yl}carbamate (Intermediate 206) (0.43 g) in acetic acid (8 mL) and water (2 mL) was added zinc dust (0.50 g). After 30 minutes, the solution was filtered and the filtrate concentrated. The residue was then treated with potassium ferricyanide (1.0 g) in water (20 mL). After 2 hours, the reaction was diluted with ethyl acetate. The aqueous layer was collected, the pH adjusted with solid Na2CO3 and extracted with ethyl acetate. The combined organic washes were dried (Na2SO4), filtered and concentrated. The residue was purified by chromatography on silica gel with 0-25% acetone in dichloromethane to yield 66 mg of the product.
