2,6-Lutidine → (S)-2-[(1-Benzyl-cyclopentanecarbonyl)-amino]-3-[4-(2,6-dichloro-benzoylamino)-phenyl]-propionic acid

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Reaktionsschritte

4-Amino-N-[[1-(phenylmethyl)cyclopentyl]carbonyl]-L-phenylalanine methyl ester (67 mg, 0.176 mmol) and 2,6-dichlorobenzoyl chloride (50 mg, 0.23 mmol) were dissolved in 5 mL of dichloromethane and 2,6-lutidine (50 μL, 0.43 mmol) were added. After 4 hours, the mixture was diluted with ether and dichloromethane and washed with 1 N HCl, water, and saturated NaHCO3 and was dried (MgSO4). The crude product was dissolved in 4 mL of methanol and treated with 4 N NaOH (0.1 mL). After 2 hours, the excess base was quenched with 0.1 mL of acetic acid, the solution was filtered through a 0.2μ nylon filter and the filtrate was purified by RP-HPLC on a 4×30 cm Rainin C-18 column using a gradient of 5 to 95% acetonitrile:water containing 0.75% trifluoroacetic acid at a flow of 49 mL/min over 30 min. The peak eluting at 87% acetonitrile was concentrated and lyophilized to give 4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-(phenylmethyl)cyclopentyl]carbonyl]-L-phenylalanine (46 mg), LR(+)LSIMS: m/z 539 (M+H) (2 Cl)

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