反应详情

4-Azidobenzyl (4-nitrophenyl) carbonate synthesized by the method described in the literature (Bioconjugate Chem. 2008, 19, 714.) (Compound tk32) (521 mg, 1.658 mmol) was added to a suspension of Boc-Orn-OH (Compound tk56) (321 mg, 1.382 mmol) and sodium bicarbonate (290 mg, 3.45 mmol) in 1,4-dioxane (3 mL)-water (2 mL). The reaction mixture was stirred at room temperature for 23 hours and then cooled in an ice bath and diluted with ethyl acetate and water, and a saturated aqueous potassium bisulfate solution (2 mL) was added to the resulting mixture. The mixture was extracted with ethyl acetate (×2), and the organic phase was washed with water (10 mL×2) and brine (10 mL) and dried over sodium sulfate. Following concentration under reduced pressure, the resulting crude product was purified by normal-phase silica gel column chromatography (hexane/ethyl acetate) to afford ((S)-5-((((4-azidobenzyl)oxy)carbonyl)amino)-2-((tert-butoxycarbonyl)amino)pentanoic acid (Compound tk57) (501.3 mg, 89%).

1. temperaturecooled in an ice bath
2. extractionThe mixture was extracted with ethyl acetate (×2)
3. washthe organic phase was washed with water (10 mL×2) and brine (10 mL)
4. dry with materialdried over sodium sulfate
5. concentrationconcentration under reduced pressure
6. customthe resulting crude product was purified by normal-phase silica gel column chromatography (hexane/ethyl acetate)