1-Hydroxybenzotriazole → 4-((S)-2-{[5-[2-((S)-2-Benzyloxycarbonyl-pyrrolidin-1-yl)-2-oxo-ethoxy]-1-(3,4-difluoro-phenyl)-1H-pyrazole-3-carbonyl]-amino}-4-tert-butoxycarbonyl-butyryl)-piperazine-1-carboxylic acid ethyl ester

Participants

Reaction Steps

To a solution of 2.5 g 4-((S)-4-tert-Butoxycarbonyl-2-{[5-carboxymethoxy-1-(3,4-difluoro-phenyl)-1H-pyrazole-3-carbonyl]-amino}-butyryl)-piperazine-1-carboxylic acid ethyl ester in 30 ml DMF were added 0.614 g HOBt, 1.32 ml DIPEA and 0.969 g L-proline benzyl ester hydrochloride at RT. Then 0.769 g EDC were added portionwise and the suspension stirred at RT for 12 h. The reaction mixture was diluted with ethyl acetate and subsequently extracted with aqueous LiCl (4% w/w), 0.1 M HCl and aqueous NaHCO3. The organic layer was dried over MgSO4 and the solvent was removed under reduced pressure. The crude product thus obtained was used in the subsequent reaction.

Provenance & Evidence