4-Toluenesulfonyl chloride → 1-(Tert-butyl) 2-methyl (2S,4S)-4-(tosyloxy)pyrrolidine-1,2-dicarboxylate

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Reaction Steps

4-Dimethylaminopyridine (2.28 g) and p-toluenesulfonyl chloride (2.66 g) were added to a cold (0° C.) stirred solution of N-tert-butoxycarbonyl-cis-4-hydroxy-L-proline methyl ester (J, 2.76 g) in dichloromethane (50 mL). After stirring at room temperature for 16 hr, the solvent was removed in vacuo. The residue was diluted with ethyl acetate, and washed with 0.5 M saturated citric acid, water, and brine. The organic layer was dried over anhydrous sodium sulfate and evaporated in vacuo to give the title compound (3.10 g) as a pale yellow oil: 1H NMR (400 MHz, CDCl3) δ 1.35-1.52 (m, 9H), 2.30-2.53 (m, 2H), 2.46 (s, 3H), 3.51-3.78 (m, 2H), 3.68-3.69 (s, 3H), 4.30-4.56 (m, 1H), 5.00-5.09 (m, 1H), 7.32-7.38 (m, 1H), and 7.74-7.79 (m, 1H).

Provenance & Evidence