Hydrochloric Acid → 3-Hydroxy-2-(4-methoxyphenyl)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one, (2S,3S)-

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Reaction Conditions

Reaction Steps

A mixture of L-tert-leucine (393 mg), sodium borohydride (98 mg) and tetrahydrofuran (100 ml) is refluxed under nitrogen atmosphere for three hours. The mixture is cooled to -15° C., and thereto is added 2-(4-methoxyphenyl)-1,5-benzothiazepine-3,4(2H,5H)-dione (599 mg), and the mixture is further stirred at -15° C. for 48 hours. To the reaction solution are added 1N hydrochloric acid (10 ml) and ethyl acetate (20 ml), and the mixture is stirred for 30 minutes. The organic layer is separated, washed with water, dried, and evaporated under reduced pressure to remove the solvent. The resulting residue is dissolved in ethanol (22 ml) with heating, and the mixture is cooled gradually for crystallization. The precipitated crystal is collected by filtration to give (2S,3S)-3-hydroxy-2-(4-methoxyphenyl)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one (376 mg).

Provenance & Evidence