The title compound was prepared according to the procedure as described in Example 14 step 2 using N-(3-(5-(4-chlorophenyl)-1H-pyrrolo[2,3-b]pyridine-3-carbonyl)-2,4-difluorophenyl)propane-1-sulfonamide (0.3 g, 0.61 mmol) in anhydrous DMF (2.5 mL), KOH (69 mg, 1.22 mmol) and a solution of 1-chloroethyl 2-((tert-butoxycarbonyl)amino)-3-methylbutanoate (172 mg, 0.61 mmol) in anhydrous DMF (0.5 mL). The crude product was purified by a silica gel column chromatography (PE/EtOAc (v/v)=4/1 to 3/1) to afford the title compound as orange oil (0.29 g, 65%). The title compound was characterized by 1H NMR as shown below:
