(Diethylamino)sulfur trifluoride → (2R,3R)-3-Fluoro-pyrrolidine-1,2-dicarboxylic acid 2-benzyl ester 1-tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

The title compound was prepared in a similar manner as described by L. Demange et al., Tetrahedron Letters 2001, 42, 651-653: To a solution of (2S,3R)-3-hydroxy-pyrrolidine-1,2-dicarboxylic acid 2-benzyl ester 1-tert-butyl ester (360 mg, 1.12 mmol) in CH2Cl2 (30 mL), cooled to −78° C., was added dropwise DAST (0.740 mL, 5.60 mmol). The reaction mixture was stirred at −78° C. for 5 h, and then was allowed to warm to RT and stirred overnight. After cooling to 0° C., the reaction was quenched with MeOH, followed by addition of aqueous NaHCO3 solution. Volatiles were removed under reduced pressure and the residue was taken up in EtOAc. The organics were washed with aqueous NaHCO3 (3×), water and brine, dried (Phase separator) and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel (EtOAc/c-hexane 1:9) to give the title compound (99% purity by HPLC/215 nm). TLC Rf (EtOAc/c-hexane 1:4)=0.2; MS (LC/MS): 346 [M+Na]+, 268 [MH−tBu]+, 224 [MH−Boc]+; tR (HPLC conditions b): 5.01 min.

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