To a mixture of 3-Iodo-5-nitro-indole-1-carboxylic acid tert-butyl ester (480 mg, 1.23 mmol) and tert-butyl 1-(6-(tributylstannyl)pyrazin-2-yl)piperidin-4-ylcarbamate 1d (700 mg, 1.23 mmol) in DMF (4.8 mL) was purged with argon gas for 5 min and added Cut (352 mg, 1.84 mmol) and palladium tetrakis (171 mg, 0.15 mmol). The resulting mixture was purged with argon gas for 5 min and stiffed under nitrogen atmosphere at 90° C. 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. Purification was carried out by column chromatography to obtain the title compound as a white solid (200 mg, 30%). MS (ESI, pos. ion) m/z: 539.3 (M+1).
