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

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Reaction Conditions

Reaction Steps

2.0 grams (4.8 mmol) of the mixture of (2R,3S)-3-(4-methoxyphenyl)oxirane-2-carboxylic (1S,2R)-1-(diethylamino)-2-indanyl ester (diastereomeric ratio 89:11) and (2R,3S)-3-(4-methoxyphenyl)oxirane-2-carboxylic tert-butyl ester (enantiomeric excess 80%) of Example V was dissolved in 20 ml of xylene+1 ml of methanol. This solution was heated to 120° C. and 600 mg (5.0 mmol) of 2-aminothiophenol was added drop by drop in 5 min. After 6 hours' heating at 120° C. the solution was cooled to 20° C. and 1.1 grams (6,0 mmol) of p-toluene sulphonic monohydrate was added. This was followed by 6 hours' heating at reflux temperature, during which 1-2 ml of a xylene/methanol mixture was removed through distillation. After cooling, the brown solution was dissolved in dichloromethane and washed with a 5% Na2CO3 solution in water and a 0.5M KH2PO4 solution in water. After drying with the aid of Na2SO4 and evaporation, the chemically pure product was obtained after chromatography using silica gel (eluant:toluene/ethyl acetate 2:1). 85% enantiomeric excess (determined with the aid of anisochrony in 1H NMR, see C. Giordano et al.; J. Org. Chem. 1991, (59), 2270). The enantiomeric excess was increased to >95% through one recrystallisation from toluene. White needles. Melting point: 200-202° C. [α]20D +109 (c=0.4, methanol). 1H NMR (200 MHz, CDCl3): 2.93 (d, 1H), 3.71 (s, 3H), 4.41 (dd, 1H), 5.02 (d, 1H), 6.74 (d, 2H), 7.03-7.21 (m, 2H), 7.29-7.44 (d+m, 3H), 7.61 (d, 1H) and 8.47 (br s, 1H). The (1S,2R)-1-(diethylamino)-2-indanol was recovered from the 0.5M KH2PO4 extraction solution.

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