Water → (2S,4R)-4-Hydroxy-1-(naphthalene-2-sulfonyl)-pyrrolidine-2-carboxylic acid methyl ester

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Reaction Steps

40 g (220 mmol) of L-hydroxyproline methylester hydrochloride (twice suspended in toluene and evaporated under reduced pressure to remove water) was suspended in 600 ml hexamethyldisilazane and refluxed for 2 h. The solution was evaporated under reduced pressure and dissolved in 100 ml THF. 49.9 g (220 mmol) of 2-naphthalene-sulphonyl chloride in 200 ml of THF were added slowly and stirred for 16 h at room temperature. 150 ml H2O were added and after 1 h the solvents were evaporated. The residue was partitioned between water/EtOAc (3×), the organic phases were washed with 10% NaCl and dried over Na2SO4 to give 60.4 g (82%) of (2S,4R)-4-hydroxy-1-(naphthalene-2-sulfonyl)-pyrrolidine-2-carboxylic acid methyl ester, MS: 335 (M+).

Provenance & Evidence