(2R,3S)-1-[4-(3,5-Difluoro-benzyloxy)-benzenesulfonyl]-3-methyl-piperazine-2-carboxylic acid tert-butyl ester

(2R,3S)-4-Acetyl-1-[4-(2-ethyl-benzyloxy)-benzenesulfonyl]-3-methyl-piperazine-2-carboxylic acid tert-butyl ester

(2R,3S)-2-[4-(5-Fluoro-2-methyl-benzyloxy)-benzenesulfonylamino]-3-(2-hydroxy-ethylamino)-butyric acid tert-butyl ester

(2R,3S)-4-Acetyl-3-methyl-1-[4-(quinolin-4-ylmethoxy)-benzenesulfonyl]-piperazine-2-carboxylic acid tert-butyl ester