The 1-(2-(trimethylsilyl)ethyl) 1′-tert-butyl 5-bromospiro[indoline-3,3′-pyrrolidine]-1,1′-dicarboxylate (100 mg, 0.201 mmol) obtained in Step 2 of Example 383 was dissolved in tetrahydrofuran (1.5 mL). Thereafter, palladium diacetate (10.0 mg, 0.045 mmol), S-Phos (33.0 mg, 0.080 mmol), and 4-ethoxy-4-oxobutylzinc bromide (0.5 M tetrahydrofuran solution, 0.5 mL) were added to the above obtained solution at room temperature, and the thus obtained mixture was then stirred at room temperature for 14 hours. Thereafter, a saturated aqueous solution of ammonium chloride was added to the reaction solution, and the mixed solution was then extracted with chloroform. The organic layer was washed with brine, and was then dried over anhydrous sodium sulfate, followed by concentration in vacuo. The obtained residue was purified by silica gel column chromatography (hexane ethyl acetate=10:1) to obtain 1-(2-(trimethylsilyl)ethyl) 1′-tert-butyl 5-(4-ethoxy-4-oxobutyl)spiro[indoline-3,3′-pyrrolidine]-1,1′-dicarboxylate (75.2 mg, 70%.) in the form of a white solid.
