(E)-(S)-4-((2R,5S)-2-Benzyl-5-benzylsulfanylcarbonylamino-6-methyl-4-oxo-heptanoylamino)-6-(trityl-carbamoyl)-hex-2-enoic acid ethyl ester

(2R,4S,5S)-2-Benzyl-5-tert-butoxycarbonylamino-4-(tert-butyl-dimethyl-silanyloxy)-6-methyl-heptanoic acid

(E)-(S)-4-{(2R,4S,5S)-2-Benzyl-4-hydroxy-6-methyl-5-[(5-methyl-isoxazole-3-carbonyl)-amino]-heptanoylamino}-5-((S)-2-oxo-pyrrolidin-3-yl)-pent-2-enoic acid ethyl ester

(E)-(S)-4-[(2R,4S,5S)-2-Benzyl-5-tert-butoxycarbonylamino-4-(tert-butyl-dimethyl-silanyloxy)-6-methyl-heptanoylamino]-5-((S)-2-oxo-pyrrolidin-3-yl)-pent-2-enoic acid ethyl ester

(E)-(S)-4-{(2R,4S,5S)-2-Benzyl-4-(tert-butyl-dimethyl-silanyloxy)-6-methyl-5-[(5-methyl-isoxazole-3-carbonyl)-amino]-heptanoylamino}-5-((S)-2-oxo-pyrrolidin-3-yl)-pent-2-enoic acid ethyl ester