4-((S)-4-tert-butoxycarbonyl-2-{[1-(3-fluoro-phenyl)-5-hydroxy-1H-pyrazole-3-carbonyl]-amino}-butyryl)-piperazine-1-carboxylic acid ethyl ester
4-((S)-4-tert-butoxycarbonyl-2-{[1-(3,4-difluoro-phenyl)-5-hydroxy-1H-pyrazole-3-carbonyl]-amino}-butyryl)-piperazine-1-carboxylic acid ethyl ester
4-{(S)-4-tert-butoxycarbonyl-2-[(6-phenyl-4-pyrazol-1-yl-pyridine-2-carbonyl)-amino]-butyryl}-piperazine-1-carboxylic acid ethyl ester
4-{(S)-4-tert-butoxycarbonyl-2-[(6-chloro-4-phenyl-pyridine-2-carbonyl)-amino]-butyryl}-piperazine-1-carboxylic acid ethyl ester
4-{(S)-4-tert-butoxycarbonyl-2-[(4-chloro-5-fluoro-6-phenyl-pyridine-2-carbonyl)-amino]-butyryl}-piperazine-1-carboxylic acid ethyl ester