Trichloroisocyanuric Acid → (R)-tert-butyl 2-(3-cyano-5-fluorophenyl)-4-oxopyrrolidine-1-carboxylate

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Reaction Conditions

Reaction Steps

To a solution of (2R,4R)-tert-butyl 2-(3-cyano-5-fluorophenyl)-4-hydroxypyrrolidine-1-carboxylate (I-13A) (0.52 g, 1.7 mmol) and trichloroisocyanuric acid (0.4 g, 1.7 mmol) in DCM (20 mL) at −10° C. was added 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) (27 mg, 0.17 mmol). The mixture was stirred at −10° C. for 15 minutes, then to room temperature over 1 hour and subsequently poured into cold aqueous NaHCO3 containing ice while stirring. The organic layer was separated, washed with brine, dried over sodium sulfate, filtered and reduced to dryness to yield (R)-tert-butyl 2-(3-cyano-5-fluorophenyl)-4-oxopyrrolidine-1-carboxylate (I-16). 1H NMR (400 MHz, CDCl3) δ 7.27-7.22 (m, 2 H), 7.12 (td, J=2.0, 8.8 Hz, 1 H), 5.33 (bs, 1 H), 4.06 (d, J=19.6 Hz, 1 H), 3.86 (d, J=19.6 Hz, 1 H), 3.15 (dd, J=10.0, 18.8 Hz, 1 H), 2.47 (dd, J=3.2, 18.8 Hz, 1 H), 1.35 (bs, 9 H). MS m/z 249.1 (M−56)+.

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