Lithium Hexamethyldisilazide → (1S,5S)-7-Hydroxy-4-oxo-3-[(1R)-1-phenylethyl]-3-azabicyclo[3.3.0]octan-1-ylcarboxylic acid tert-butyl ester

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Reaction Steps

3-(Oxiran-2-ylmethyl)-5-oxo-1-[(1R)-1-phenylethyl]pyrrolidine-3-carboxylic acid tert-butyl ester (4.2 g, 12.16 mmol) was dissolved in tetrahydrofuran (50 mL). A 1 M solution of lithium hexamethyldisilazide in tetrahydrofuran (18 mL, 1.5 equivalents) was added in an argon atmosphere at −78° C., and the mixture was gradually heated. When the reaction temperature reached about room temperature, the reaction was quenched with an ammonium chloride solution, followed by extraction with ethyl acetate. The extract was dried over magnesium sulfate. After filtration, the solvent was evaporated under reduced pressure. The resulting residue was purified by silica gel chromatography (hexane:ethyl acetate=4:1→2:1→1:1→1:2) to give 1.07 g (26%) of the title compound having a single isomer as a colorless oil. 1.0 g (24%) of the raw material was collected. 1.20 g (29%) of a four-membered ring-closed compound as a by-product was obtained as a diastereomer mixture.

Provenance & Evidence