[CH2:1]([O:3][CH:4]1[N:8]([S:9]([C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)(=[O:11])=[O:10])[C:7](=[O:18])[CH2:6][CH2:5]1)[CH3:2].[Li].[Cl-].[NH4+].[Cl-].[Na+].[O:24]1CCCC1>CCCCCC.C1COCC1>[C:12]1([S:9]([N:8]2[CH:4]([O:3][CH2:1][CH3:2])[CH2:5][CH:6]([OH:24])[C:7]2=[O:18])(=[O:10])=[O:11])[CH:13]=[CH:14][CH:15]=[CH:16][CH:17]=1To a solution of 10 g of 5-ethoxy-1-benzenesulfonylpyrrolidin-2-one in 300 cm3 of anhydrous tetrahydrofuran, cooled to -78° C., 0.037 moles of a solution of lithium bis-trimethylsylylamide in a mixture of hexane-tetrahydrofuran (1-1) is added drop by drop at a temperature of -78° C. This mixture is agitated for 1 hour at -78° C., then 14.55 g of 2-sulfonyloxaziridine is added. The mixture is then agitated at -78° C. for 2 hours, brought to -5° C., then cooled to -30° C., after which 130 cm3 of an aqueous solution of saturated ammonium chloride is added, while the temperature is maintained at approximately -30° C. The temperature is brought to 20° C., then 130 cm3 of an aqueous solution of saturated sodium chloride is added. The organic phase is separated and the aqueous phase is extracted with chloroform. The organic phases are combined, dried, and the solvent is evaporated under reduced pressure, then the residue is chromatographed on silica, using an ethyl acetate-hexane (2-1) mixture as eluent. The product is dissolved in isopropyl ether, and 250 g of the expected product is obtained, m.p. 108°-116° C. (mixture of cis and trans isomers in which the trans isomer predominates).
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