反应详情

18.4 g of N,N'-carbonyldiimidazole was gradually added to a solution containing 20.5 g of N-tert-butoxycarbonyl-D-alanine dissolved in 200 mL of tetrahydrofuran, and the reaction mixture was stirred for 30 minutes at room temperature. 16.5 g of 2-amino-3-chlorothiophenol was added to the reaction mixture, and the whole mixture was refluxed for 3 hours. After completion of the reaction, the resulting mixture was poured into ice-cold water. The organic layer was extracted with ethyl acetate, washed using water, and then dried over anhydrous sodium sulfate. The solvent was removed under reduced pressure. The residue was purified by column chromatography on silica gel, thus yielding 16.8 g of (R)-N-tert-butoxycarbonyl-1-(4-chloro-2-benzothiazolyl)ethylamine (melting point: 95°~96° C.). Furthermore, a hydrogen chloride gas was bubbled into a solution containing 10 g of the crystals obtained above dissolved in 50 mL of methylene chloride, for 3 hours at room temperature. After completion of the reaction, the reaction mixture was extracted with water, and was made basic using a saturated aqueous solution of sodium bicarbonate. The solution was extracted with ethyl acetate, washed with water, and then dried over anhydrous magnesium sulfate, followed by concentration under reduced pressure. The residue was purified by column chromatography on silica gel to afford 5.7 g (yield 84%) of the desired product.

1. temperaturethe whole mixture was refluxed for 3 hours
2. customAfter completion of the reaction
3. additionthe resulting mixture was poured into ice-cold water
4. extractionThe organic layer was extracted with ethyl acetate
5. washwashed
6. dry with materialdried over anhydrous sodium sulfate
7. customThe solvent was removed under reduced pressure
8. customThe residue was purified by column chromatography on silica gel