[OH:1][CH2:2][CH2:3][NH:4][S:5]([C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][C:9]=1[N+:14]([O-:16])=[O:15])(=[O:7])=[O:6].Br[CH2:18][CH2:19][C:20]([O:22][C:23]([CH3:26])([CH3:25])[CH3:24])=[O:21].C([O-])([O-])=O.[K+].[K+]>CN(C=O)C>[OH:1][CH2:2][CH2:3][N:4]([S:5]([C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][C:9]=1[N+:14]([O-:16])=[O:15])(=[O:7])=[O:6])[CH2:18][CH2:19][C:20]([O:22][C:23]([CH3:26])([CH3:25])[CH3:24])=[O:21]To a solution of 8.7 g of N-(2-hydroxy-ethyl)-2-nitro-benzenesulfonamide (Skerlj, R. T.; Nan, S.; Zhou, Y.; Bridger, G. J. Tetrahedron Lett. 2002 (43) 7569-7571) in 87 ml of DMF, under argon, was added 8.8 ml of tert-butyl 3-bromopropionate and 14.6 g of K2CO3. The mixture was stirred for 15 hours at 40° C. and a further 5 ml of tert-butyl 3-bromopropionate were then added. The mixture was heated at 40° C. overnight and then filtered through a sinter of porosity 4. The cake was washed with ethyl acetate and the filtrate was then concentrated under reduced pressure and purified by flash chromatography on silica (Merck EasyVarioPrep 400 g column, Si60 15-40 μm), using a gradient of 0 to 10% EtOAc in DCM. The fractions containing the desired product were combined and concentrated under reduced pressure. 9.54 g of tert-butyl 3-[(2-hydroxy-ethyl)-(2-nitro-benzenesulfonyl)-amino]-propionate were obtained. LC/MS (C): tr=3.39 min; [M+Na]+: m/z 397.
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