9.4 g (26.1 mmol) of 5-[6-(N-benzyloxycarbonylamino)hex-1-en-2-yl]-oxazoline-4-carboxylic acid methyl ester are dissolved in 40 ml of tetrahydrofuran and 20 ml of water, a few drops of triethylamine are added and the mixture is heated under reflux for 18 hours. The solvent is removed under reduced pressure and the oil that remains is taken up in a total of 125 ml of methylene chloride, dried over magnesium sulfate and concentrated to dryness by evaporation. 8-(N-benzyloxycarbonylamino)-2-formylamino-3-hydroxy-4-methylene-octanoic acid methyl ester is obtained.
