Cesium carbonate → 4-{(S)-2-[(4-Benzyloxycarbonylmethoxy-7-methyl-quinoline-2-carbonyl)-amino]-4-tert-butoxycarbonyl-butyryl}-piperazine-1-carboxylic acid ethyl ester

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Reaction Steps

To a solution of 26.4 g of 4-{(S)-4-tert-Butoxycarbonyl-2-[(4-hydroxy-7-methyl-quinoline-2-carbonyl)-amino]-butyryl}-piperazine-1-carboxylic acid ethyl ester (prepared analogously as in example 1) in 150 ml of DMF, 18 g of cesium carbonate and 12.7 g of Bromo-acetic acid benzyl ester was added and stirred for 16 h. Then, the reaction mixture was diluted with water and extracted with ethyl acetate (3×300 ml). The combined organic phases were dried over MgSO4 and the solvents were removed under reduced pressure. The crude product was purified by chromatography on silica gel eluting with a gradient of n-heptane/ethyl acetate. The fractions containing the product were combined and the solvent evaporated under reduced pressure. Yield: 23.6 g.

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