To a stirred solution of 2-[2-(3,5-dimethoxyphenyl)ethyl]-5-(phenylsulfonyl)-6-(1H-pyrazol-4-yl)-5H-pyrrolo[2,3-b]pyrazine (from Example 35, Step 1, 30.0 mg, 0.0613 mmol) in acetonitrile (1 mL), cesium carbonate (20.0 mg, 0.0613 mmol) and (2-bromoethoxy) (tert-butyl)dimethylsilane (13.1 μL, 0.0613 mmol) were added sequentially at ambient temperature. The reaction mixture was then warmed up to 60° C. After 2 hours, the reaction was quenched with water, and extracted with methylene chloride. The combined organic layers were dried over MgSO4, concentrated. The residue was dissolved in methylene chloride (1.0 m)/trifluoroacetic acid (1.0 mL) at ambient temperature. After 2 hours, the volatiles were removed under vacuum and the residues were dissolved in methanol (2.0 mL). Potassium carbonate (16.9 mg, 0.122 mmol) was added and the reaction mixture was warmed up to 60° C. After 1 hour, the crude mixture was purified on RP-HPLC (XBridge C18 column, eluting with a gradient of acetonitrile/water containing 0.05% TFA, at flow rate of 30 mL/min) to give the desired product (3.5 mg) as its TFA salt. LCMS calculated for C21H24N5O3 (M+H)+: m/z=394.2. Found: 394.2.
