1-(Phenylmethyl) (2S,4R)-4-hydroxy-1,2-pyrrolidinedicarboxylate → Benzyl (2S,4R)-4-hydroxy-2-(hydroxymethyl)pyrrolidine-1-carboxylate

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Reaction Steps

To an ice cold solution of 4.76 g (18 mmoles) of CBZ hydroxyproline (Sigma Chemical Co.) in 20 mL of dry THF was added 45 mL of a 1M solution borane-THF complex in THF (Aldrich). After stirring under argon for 15 min at 0°-5° C., and 4.5 h at room temperature, the mixture was quenched with 50 mL of methanol. After 30 min, the solution was concentrated. The residual colorless syrup was purified by flash chromatography (3.5×23 cm silica) using a gradient of methanol in methylene chloride. The product eluted with 10% methanol. The fractions containing pure product were stripped of solvent to give 2.18 g (46% yield) of 1 as a colorless syrup.

Provenance & Evidence