Hydrochloric Acid → (3S,4R)-1-(tert-butoxycarbonyl)-4-(3,4-dichlorophenyl)pyrrolidine-3-carboxylic acid

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Reaction Steps

Boc anhydride (3.0 g, 13.7 mmol) was added to a solution of (3S,4R)-methyl 4-(3,4-dichlorophenyl)pyrrolidine-3-carboxylate (3.10 g, 11.3 mmol) in THF (100 mL) and TEA (4 mL). The mixture was stirred at room temperature overnight. The solvent was removed, and the residue was subject to column chromatography, eluted by hexane/ethyl acetate (8:1) to give (3S,4R)-1-tert-butyl 3-methyl 4-(3,4-dichlorophenyl)pyrrolidine-1,3-dicarboxylate (LCMS (APCI+) [M−Boc+H]+ 274.1; Rt: 4.17 min). The (3S,4R)-1-tert-butyl 3-methyl 4-(3,4-dichlorophenyl)pyrrolidine-1,3-dicarboxylate was redissolved in MeOH (50 mL), and LiOH (3M, 10 mL) was added. The mixture was stirred at room temperature for 6 hours. 2N HCl (15 mL) was added to the mixture. The solvent was removed, and the residue was subject to column chromatography, eluted by DCM/MeOH (40:1-10:1) to give (3S,4R)-1-(tert-butoxycarbonyl)-4-(3,4-dichlorophenyl)pyrrolidine-3-carboxylic acid (1.95 g). (LCMS (APCI+) [M−Boc+H]+ 260.1; Rt: 3.67 min.)

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