Methyl iodide → (2S,3R)-3-Hydroxy-2-methylpyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester

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Reaction Conditions

Reaction Steps

To a solution of (2S,3R)—N-tert-butyloxycarbonyl-3-hydroxy-2 pyrrolidinecarboxylic acid methyl ester (1D) (1.13 g, 4.61 mmol) in THF (73 mL) at −78° C. was slowly added a 1.8 M solution of LDA (7.70 mL, 13.86 mmol). After stirring for 1 h, iodomethane (2.87 mL, 46.10 mmol) was added, and the reaction was stirred for 1 h at −78° C., before warming gradually to −20° C. for 3 h, and then was stored at −40° C. overnight. After quenching with saturated aqueous NH4Cl, water and EtOAc were added and the layers were separated. The organic layer was washed with brine, and the aqueous layer was extracted with EtOAc. The combined organics were dried (MgSO4), filtered and concentrated under reduced pressure. The residue was purified using preparative HPLC (Luna C-18, 21.2×250 mm, eluting with 50-90% solvent B (A=90% H2O-10% MeOH and B=10% H2O-90% MeOH) over 30 min; Flow rate at 10 mL/min. UV detection at 220 nm) to provide a mixture of the starting material and its epimer as a yellow oil (490 mg) and the title compound as a yellow oil (362 mg); LC/MS m/z 260 [M+H]+.

Provenance & Evidence