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

Participants

Reaction Steps

A mixture of L-tert-leucine (721 mg), sodium borohydride (189 mg) and tetrahydrofuran (25 ml) is refluxed under nitrogen atmosphere for three hours. The mixture is cooled to room temperature, and thereto is added tetrahydrofuran (25 ml). The mixture is cooled to -30° C., and thereto is added 2-(4-methoxyphenyl)-1,5-benzothiazepine-3,4(2H,5H)-dione (997 mg). Each 139 μl of conc. hydrochloric acid (1.67 mmole as hydrogen chloride) is added at 1, 3, 5 and 22 hours after the beginning of the reaction, and the reaction is carried out for 45 hours. After confirming by HPLC that the starting compound is completely consumed, the mixture is evaporated under reduced pressure to remove the solvent, and water (70 ml) is added to the residue. The mixture is stirred at room temperature for one hour, and the precipitated crystal is collected by filtration and dried. The resulting residue is suspended in isopropyl alcohol (13 ml), and the mixture is refluxed for one hour. The mixture is cooled to 5° C., and allowed to stand overnight. The precipitated crystal is collected by filtration, and washed with cold isopropyl alcohol, and dried to give (2S,3S)-3-hydroxy-2-(4-methoxyphenyl)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one (842 mg).

Provenance & Evidence