C([Li])CCC.[CH2:6]([O:12][CH:13]1[NH:17][C:16](=[O:18])[CH:15]=[CH:14]1)[CH2:7][CH2:8][CH2:9][CH2:10][CH3:11].[C:19]1([S:25](Cl)(=[O:27])=[O:26])[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1>CCCCCC.O1CCCC1>[C:19]1([S:25]([N:17]2[CH:13]([O:12][CH2:6][CH2:7][CH2:8][CH2:9][CH2:10][CH3:11])[CH:14]=[CH:15][C:16]2=[O:18])(=[O:27])=[O:26])[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=139.37 cm3 of a 1.4M solution of n-butyllithium in n-hexane is added to a solution of 10.1 g of 1,5-dihydro-5-n-hexyloxy-2H-pyrrol-2-one obtained at stage A in 170 cm3 of tetrahydrofuran cooled to -30° C. The temperature is maintained at -30° C. while agitating for 15 minutes, then is reduced to -35° C. and a solution of 9.73 g of benzenesulphonyl chloride in 70 cm3 of tetrahydrofuran is added, while maintaining the temperature at between -35° C. and -53° C. The temperature is allowed to return to the ambient, the solvent is evaporated under reduced pressure, and the residue is chromatographed on silica (eluent: ethyl acetate-n-hexane, 1-2). 5.68 g of the expected product is obtained.
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