4-Fluoroaniline → Carbamic acid, N-[2-[2-(4-fluorophenyl)-3-[(4-fluorophenyl)amino]-5,6-dihydro-8,8-dimethylimidazo[1,2-a]pyrazin-7(8H)-yl]-2-oxoethyl]-, 1,1-dimethylethyl ester

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In a microwave vial, cesium carbonate (135 mg, 0.42 mmol), 4-fluoroaniline (92 mg, 0.83 mmol), tris(dibenzylideneacetone)dipalladium(0) (19.02 mg, 0.02 mmol), Xantphos (24.04 mg, 0.04 mmol) and dry 1,4-dioxane (6 mL) were stirred for 5 minutes at room temperature. tert-butyl (2-(3-bromo-2-(4-fluorophenyl)-8,8-dimethyl-5,6-dihydroimidazo[1,2-a]pyrazin-7(8H)-yl)-2-oxoethyl)carbamate (200 mg, 0.42 mmol) was added to the reaction mixture after which the reaction mixture was degassed for 15 mins and then stirred at 120 °C under N2 for 20 h. The reaction was monitored by LCMS. The profile showed formation of title product. The reaction mixture was filtered through a pad opf celite and the filtrate was concentrated to give a residue. The residue was purified by silica gel followed by reverse phase HPLC to give tert-butyl (2-(2-(4-fluorophenyl)-3-((4-fluorophenyl)amino)-8,8-dimethyl-5,6-dihydroimidazo[1,2-a]pyrazin-7(8H)-yl)-2-oxoethyl)carbamate (177 mg, 83 %) as a white solid. Conclusion: The product was used for the next step.

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