Cesium carbonate → 4-((S)-4-tert-Butoxycarbonyl-2-{[5-(1-ethoxycarbonyl-cyclobutoxy)-1-phenyl-1H-pyrazole-3-carbonyl]-amino}-butyryl)-piperazine-1-carboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 1.5 g of 4-{(S)-4-tert-Butoxycarbonyl-2-[(5-hydroxy-1-phenyl-1H-pyrazole-3-carbonyl)-amino]-butyryl}-piperazine-1-carboxylic acid ethyl ester in 20 ml of DMF, 1.8 g of cesium carbonate and 1.2 g of 1-Bromo-cyclobutanecarboxylic acid ethyl ester was added and heated to 100° C. for 2 h. Then, the reaction mixture was diluted with water and extracted with ethyl acetate (3×150 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: 860 mg.

Provenance & Evidence