[NH2:1][CH:2]([CH2:5][OH:6])[CH2:3][OH:4].[O-2].[Mg+2].[Cl:9][C:10]1[S:14][C:13]([S:15](Cl)(=[O:17])=[O:16])=[CH:12][C:11]=1[N+:19]([O-:21])=[O:20]>O.C1COCC1>[OH:4][CH2:3][CH:2]([NH:1][S:15]([C:13]1[S:14][C:10]([Cl:9])=[C:11]([N+:19]([O-:21])=[O:20])[CH:12]=1)(=[O:17])=[O:16])[CH2:5][OH:6]To a stirred solution of 2-amino-1,3-propanediol (0.5 g, 5.49 mmol) in water (2 ml) was added at room temperature magnesium oxide (1.11 g, 27.5 mmol) and THF (6 ml). The suspension was stirred at room temperature for 30 min and a solution of 5-chloro-4-nitrothiophene-2-sulfonyl chloride (2.88 g, 10.9 mmol) in THF (2 ml) was added. The light yellow suspension was stirred at room temperature for 1 h and, after filtration on Dicalit, evaporated. Water (60 ml) was added and the mixture was extracted with ethyl acetate (3×50 ml). The combined organic layers were washed with brine (70 ml), dried (MgSO4) and evaporated. The crude product was further purified by column chromatography on silica gel (heptane/ethyl acetate 1:1) and subsequent crystallization from ethyl acetate/hexane to yield 5-chloro-4-nitro-thiophene-2-sulfonic acid (2-hydroxy-1-hydroxymethyl-ethyl)-amide (0.76 g, 44%) as a light yellow solid. MS (ISP) 314.9 [(M−H)−], mp 142° C.
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