N-Boc-pyrrolidine → (R)-tert-butyl 2-(2-oxoindolin-4-yl)pyrrolidine-1-carboxylate

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sec-Butyl lithium (25.3 mL, 35.4 mmol) was added into a solution of tert-butyl 1-pyrrolidinecarboxylate (6.2 mL, 35.4 mmol) and (−)-spartiene (8.29 g, 35.4 mmol) in MTBE (100 mL) at −78° C. The mixture was stirred for 1 hour at −78° C. Zinc chloride solution (35.4 mL, 35.4 mmol) was added, and the reaction was stirred for 15 minutes at −78° C. The reaction was allowed to warm up to room temperature. 4-Bromoindolin-2-one (5.00 g, 23.6 mmol), palladium (II) acetate (0.53 g, 2.4 mmol) and tri-tert-butylphosphine tetrafluoroborate (0.68 g, 2.4 mmol) was added into the reaction mixture. The reaction was stirred for 12 hours at room temperature. The reaction mixture was poured into EtOAc (200 mL), and the suspension was filtered with a pad of celite. The filtrate was concentrated, and the residue was purified by flash chromatography (silica gel eluted with 4:1 hexanes:ethyl acetate) to give (R)-tert-butyl 2-(2-oxoindolin-4-yl)pyrrolidine-1-carboxylate (1.9 g, 27%) as a solid. 1H NMR (CDCl3, 400 MHz) δ 7.80 (s, 1H), 7.10-7.20 (m, 1H), 6.75-6.82 (m, 1H), 6.62-6.78 (m, 1H), 4.65-4.93 (m, 1H), 3.34-3.73 (m, 4H), 2.20-2.40 (m, 1H), 1.84-2.00 (m, 2H), 1.68-1.83 (m, 1H), 1.45 (2, 4H), 1.14 (s, 5H). MS (APCI+) [M+H]+ 303.

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