4-Methylmorpholine → (2R)-3-({2-[(4-[1-(tert-Butoxycarbonyl)-4-piperidyl]-2-{2-[1-(tert-butoxycarbonyl)-4-piperidyl]ethyl}butanoyl)amino]acetyl}amino)-2-[(2-naphthylsulphonyl)amino]propanoic Acid

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Reaction Steps

Isobutyl chloroformate (3.3 g, 24.2 mmol) is added, at room temperature, to a solution of 2-[(4-[1-(tert-butoxycarbonyl)-4-piperidyl]-2-{2-[1-(tert-butoxycarbonyl)-4-piperidyl]ethyl}butanoyl)amino]acetic acid (compound 4) (10.8 g, 20 mmol) in 200 ml of THF and N-methylmorpholine (5 g, 49.5 mmol). A suspension is obtained. After stirring for 20 minutes, a mixture of (2R)-3-amino-2-[(2-naphthylsulphonyl)amino]propanoic acid (8 g, 25 mmol) and water (80 ml) is added, at 0° C. Stirring is continued at 0˜5° C. for 30 minutes and then at room temperature for 18 hours. The THF is evaporated off and the aqueous solution is acidified to pH 2 with 1N hydrochloric acid. The mixture is extracted with ether. The extracts are washed with water, dried over sodium sulphate and evaporated to give the crude product, which is purified by flash chromatography (10/0.5/0.5 dichloromethane/methanol/acetic acid) to give 8.3 g of a beige-coloured solid.

Provenance & Evidence