Acetic Acid → Ethyl 5-oxo-2-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl]pyrrolidine-2-carboxylate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Ethyl (2S)-5-oxopyrrolidine-2-carboxylate (0.200 g, 1.27 mmol) was azeotroped three times from toluene (25 mL each), dissolved in tetrahydrofuran (4.4 mL) and cooled to −78° C. 1 M lithium hexamethyldisilazide in tetrahydrofuran (1 M, 3.75 mL) was added via syringe and the colorless solution was stirred 30 min before addition of 2-[4-(bromomethyl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (0.4 g, 1.0 mmol) in tetrahydrofuran (2.0 mL). The slightly yellow solution was stirred at −78° C. for 30 min and then at −10° C. for 1 h and warmed to rt for an additional 1 h before it was cooled back to −78° C. and quenched with acetic acid (1.00 mL, 17.6 mmol). Evaporation and purification by preparative LCMS gave the desired product as a colorless glass, (296 mg, 62%). 1H NMR (400 MHz, CD3OD): δ 7.67 (d, J=7.4 Hz, 2H), 7.22 (d, J=7.4 Hz, 2H), 4.20 (q, J=7.2 Hz, 2H), 3.08 (d, J=13.0 Hz, 1H), 3.05 (d, J=13.0 Hz, 1H), 2.35 (m, 1H), 2.23 (m, 1H), 2.15 (m, 1H), 1.79 (m, 1H), 1.35 (s, 12H), 1.25 (t, J=7.0 Hz, 3H); LCMS found for C20H29BNO5 (M+H)+: m/z=374.

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