N(C(OCC)=O)=NC(OCC)=O.C(OC([NH:20][C@H:21]([CH3:24])[CH2:22][OH:23])=O)(C)(C)C.O[C:26]1[CH:31]=[CH:30][C:29]([CH2:32][C:33]([O:35][CH3:36])=[O:34])=[CH:28][CH:27]=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C(=O)([O-])[O-].[K+].[K+]>C1C=CC=CC=1.O>[NH2:20][C@H:21]([CH3:24])[CH2:22][O:23][C:26]1[CH:31]=[CH:30][C:29]([CH2:32][C:33]([O:35][CH3:36])=[O:34])=[CH:28][CH:27]=116.6 g of diethyl azodicarboxylate were added, whilst ice-cooling, to a solution of 16.8 g of (R)-2-t-butoxycarbonylamino-1-propanol, 10.0 g of methyl 4-hydroxyphenylacetate and 24.0 g of triphenylphosphine in 50 ml of dry benzene, and the resulting mixture was stirred at room temperature for 2 days. At the end of this time, the benzene solvent was removed by distillation under reduced pressure. The resulting residue was dissolved in 100 ml of methanol, and 200 ml of a 4N solution of hydrogen chloride in dioxane were added to the solution thus obtained, whilst ice-cooling, after which the mixture was allowed to stand at room temperature for 3 hours. The reaction mixture was then poured into water, and the pH of the aqueous mixture was adjusted to a value of 8 to 9 by the addition of an aqueous solution of potassium carbonate, and then the mixture was extracted with ethyl acetate. The extract was dried over anhydrous sodium sulfate, and the ethyl acetate solvent was removed by distillation under reduced pressure. The resulting residue was purified by column chromatography through silica gel, using a 3:1 by volume mixture of ethyl acetate and ethanol as the eluent, to give the title compound. [α]D23 -13.2° (c=1.048, chloroform)
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