A mixture of tert-butyl 5-carbamoyl-3-iodo-1H-indole-1-carboxylate (460 mg, 1.42 mmol) and tert-butyl 1-(6-(tributylstannyl)pyrazin-2-yl)piperidin-4-ylcarbamate (1d) (807 mg, 1.42 mmol) in DMF (4.6 mL) was purged with argon gas for 5 min, added Cut (405 mg, 2.13 mmol), palladium tetrakis (170 mg, 0.14 mmol) and again purged with argon gas for 5 min. The reaction mixture was stirred at 90° C. under nitrogen atmosphere for 1 h. The reaction mixture was then poured into water. The resulting precipitate was collected by filtration. The filtrate was extracted with diethyl ether. The organic layer was concentrated and combined with the above precipitate to give the crude product, which was purified by column chromatography to obtain the title compound as a brown solid (200 mg, 31%). MS (ESI, pos. ion) m/z: 537.0 (M+1).
