[H-].[Na+].[I-].[CH3:4][S+](C)(C)=O.[CH2:9]([O:16][C:17]([NH:19][C@@H:20]([CH2:23][CH:24]1[CH2:29][CH2:28][CH2:27][CH2:26][CH2:25]1)[CH:21]=[O:22])=[O:18])[C:10]1[CH:15]=[CH:14][CH:13]=[CH:12][CH:11]=1>C1COCC1>[CH2:9]([O:16][C:17]([NH:19][C@H:20]([CH:21]1[CH2:4][O:22]1)[CH2:23][CH:24]1[CH2:29][CH2:28][CH2:27][CH2:26][CH2:25]1)=[O:18])[C:10]1[CH:15]=[CH:14][CH:13]=[CH:12][CH:11]=118.9 g of sodium hydride dispersion (55% in oil) are freed of oil in a dry reaction flask under argon by stirring three times in 50 ml of petroleum ether (b.p. 40°-60°) and subsequently decanting off the solvent each time. After drying under a high vacuum, a grey powder is obtained which is placed in 500 ml of THF; 55.6 g of trimethylsulphoxonium iodide are added thereto, the temperature increasing to approximately 40°. The grey suspension is boiled under reflux for 1 hour and then, within a period of 50 minutes at -70°, a solution of 108.6 g of 2(S)-benzyloxycarbonylamino-3-cyclohexylpropanal in 250 ml of THF is added. The yellow suspension is stirred at 0° for 2 hours. The yellowish turbid solution is poured onto 500 g of ice. The aqueous solution is extracted with 2.5 liters of ether, and the organic phase is washed with water and, after being dried over sodium sulphate, concentrated by evaporation. The oily residue is separated by means of flash chromatography (2.5 kg of silica gel 60, 40-63 μm, eluant C). The product-containing fractions are combined, concentrated by evaporation and dried under a high vacuum. The title compound (diastereoisomeric mixture, approximately 4:1) is obtained in the form of a slightly yellowish oil. Rf (K)=0.71; Rf (C)=0.16.
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