2-((S)-1-{[2-((S)-1-tert-Butoxycarbonylamino-2-methylcarbamoyl-ethyl)-5-methyl-thiazole-4-carbonyl]-amino}-2-methyl-propyl)-5-methoxymethyl-thiazole-4-carboxylic acid methyl ester

2-tert-butoxycarbonylamino-4-methoxy-3-oxo-butyric acid methyl ester

2-(2-tert-butoxycarbonylamino-3-methyl-thiobutyrylamino)-3-hydroxy-4-methoxy-butyric acid methyl ester

2-(2-tert-butoxycarbonylamino-3-methyl-thiobutyrylamino)-3-(tert-butyl-dimethyl-silanyloxy)-4-methoxy-butyric acid methyl ester

2-(2-tert-butoxycarbonylamino-3-methyl-butyrylamino)-3-(tert-butyl-dimethyl-silanyloxy)-4-methoxy-butyric acid methyl ester