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

Participants

Reaction Conditions

Reaction Steps

To a solution of 100 mg of 4-{(S)-5-tert-Butoxycarbonyl-2-[(5-hydroxy-1-phenyl-1H-pyrazole-3-carbonyl)-amino]-pentanoyl}-piperazine-1-carboxylic acid ethyl ester in 2 ml of DMF, 119 mg of cesium carbonate and 76 mg 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 filtered through a Chem Elut® cartridge by eluting with DCM. The solvents were removed under reduced pressure and the residue was dissolved in 1 ml of DCM, 0.2 ml of TFA was added at RT. After 4 h 20 ml of toluene was added and the solvents were removed under reduced pressure. The residue was purified by preparative HPLC (C18 reverse phase column, elution with a water/MeCN gradient with 0.1% TFA). The fractions containing the product were evaporated and lyophilized to yield a white solid.

Provenance & Evidence