(4S)-isobutyl-(5S)-(2-methoxycarbonyl-1-methyl-5-oxo-4-(toluene-4-sulfonyl)-pyrrolidin-3-yl)-2,2-dimethyl-oxazolidine-3-carboxylic acid tert-butyl ester

(5S)-tert-butoxycarbonylamino-(4S,R)-hydroxy-7-methyl-oct-2-ynoic acid methyl ester

(4S)-isobutyl-(5S)-(2-methoxycarbonyl-vinyl)-2,2-dimethyl-oxazolidine-3-carboxylic acid tert-butyl ester

(5S)-((Z)-2-bromo-2-methoxycarbonyl-vinyl)-(4S)-isobutyl-2,2-dimethyl-oxazolidine-3-carboxylic acid tert-butyl ester

(4S,5S)-isobutyl-5-methoxycarbonylethynyl-2,2-dimethyl-oxazolidine-3-carboxylic acid tert-butyl ester