[C:1]([NH:5][C:6](=[N:9][S:10](=[O:20])(=[O:19])[NH:11][CH2:12][C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1)[O:7][CH3:8])(OC)=[O:2].[H-].[Na+].O>C1COCC1>[CH2:12]([N:11]1[C:1](=[O:2])[NH:5][C:6]([O:7][CH3:8])=[N:9][S:10]1(=[O:20])=[O:19])[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1A solution of N-carbomethoxy-N'-benzylsulfamoyl-O-methylisourea (215 g) in anhydrous THF (200 ml) is added dropwise to a stirred suspension of sodium hydride (43 g of 60% dispersion) in anhydrous THF (900 ml) and refluxed for 2 hours under nitrogen. Water (800 ml) is added to the cooled reaction mixture and the aqueous mixture washed with ether. The pH of the aqueous layer is adjusted to about 3.2 and the resulting suspension extracted with methylene chloride. The methylene chloride extract is dried, filtered, and evaporated in vacuo. The residue is taken up in hot isopropyl alcohol, treated with charcoal, filtered hot, concentrated, cooled, the resulting precipitate filtered and dried in vacuo yielding the desired product, M.P.=141°-144° C.
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