A solution of 27 (0.20 g, 0.73 mmol) in THF (2 mL) was added dropwise to a solution of fumaryl chloride (0.08 mL, 0.73 mmole) in THF (1 mL). The mixture was stirred at room temperature for 10 min and was then dried under vacuum to provide a residue. The residue was then dissolved in THF (mL). In another vessel, to a suspension of hydroxylamine hydrochloride (0.26 g, 3.77 mmole) in THF (4 mL), a sat. NaHCO3 solution (3 ml) was added, and the reaction mixture was stirred at room temperature for 10 min. The contents of both vessels were combined and stirred at room temperature for 1 h. The mixture was partitioned between EtOAc (15 mL×3) and water. The combined organic layer was dried over anhydrous MgSO4 and concentrated under reduced pressure to give a yellow residue, which was purified by silica gel chromatography (CH2Cl2:CH3OH=10:1:1% AcOH) to afford Compound 27 (0.12 g). 1H NMR (500 MHz, CD3OD): δ 7.70 (d, J=3.3 Hz, 1H), 6.86 (d, J=15.0 Hz, 1H), 7.10 (d, J=15.0 Hz, 1H), 7.46-7.51 (m, 3H), 7.58-7.61 (m, 1H), 7.65 (d, J=3.4 Hz, 1H), 7.90-7.97 (m, 4H). HRMS (EI) for C18H15N3O5S (M+): calcd, 385.0732. found, 385.0732.
