Benzyl Alcohol → (S)-6-tert-Butoxycarbonylamino-2-(9H-fluoren-9-ylmethoxycarbonylamino)-hexanoic acid benzyl ester

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Reaction Steps

(S)-6-tert-Butoxycarbonylamino-2-(9H-fluoren-9-ylmethoxycarbonylamino)-hexanoic acid (5.00 g, 10.67 mmol) and phenyl-methanol (2.305 g, 21.34 mmol) were dissolved in 25 mL of CH2Cl2 and treated successively with N-hydroxybenzotriazole (1.933 g, 11.74 mmol), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC, 2.250 g, 11.74 mmol), and ethyl-diisopropyl-amine (2.137 ml, 12.49 mmol). After stirring for 90 min, the volatiles were removed i.V. at ambient temperature, the residue taken up in ethyl acetate, washed with water, NH4Cl-solution and brine, dried over Na2SO4, and evaporated. The crude mixture was then dissolved in 20 mL of ethanol, and the product precipitated by adding 10 mL of water. Filtration and drying yielded 5.669 g of the title compound which was recrystallized from ethanol/hexane to give 4.27 g of pure benzyl ester. MS (ISP): 559.2 [M+H]+.

Provenance & Evidence