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

Participants

Reaction Steps

To a solution of 3.000 g 4-((S)-4-tert-Butoxycarbonyl-2-{[1-(3-fluoro-phenyl)-5-hydroxy-1H-pyrazole-3-carbonyl]-amino}-butyryl)-piperazine-1-carboxylic acid ethyl ester in 20 ml DMF were added 0.908 ml benzyl bromoacetate and 3.571 g cesium carbonate. After stirring at RT for 12 h the solution was reduced to a volume of 50 ml, diluted with 200 ml ethyl acetate and extracted with aqueous LiCl (4% w/w) and aqueous NaHCO3. The crude product obtained after evaporation of the solvent was used in the subsequent reaction.

Provenance & Evidence