Br[CH2:2]/[C:3](/[C:11]([O:13][CH3:14])=[O:12])=[CH:4]\[C:5]1[CH:10]=[CH:9][CH:8]=[CH:7][CH:6]=1.[S:15]([O-:18])([O-:17])=[O:16].[Na+:19].[Na+].[Br-].[Na+].[K+].[Br-]>CO>[Na+:19].[C:11](/[C:3](=[CH:4]/[C:5]1[CH:10]=[CH:9][CH:8]=[CH:7][CH:6]=1)/[CH2:2][S:15]([O-:18])(=[O:17])=[O:16])([O:13][CH3:14])=[O:12]To a 12L, 3-neck round bottom flask fitted with a mechanical stirrer, thermometer and an addition funnel was added the resultant product from Example 3B (400 g, 1.57 mol) and methanol (4L). The mixture was warmed to 50° C. and a solution of sodium sulfite (199 g, 1.57 mol) dissolved in water (4L) was added over 75 min while the internal temperature of the flask was maintained at 50° C. After the addition was complete, the clear solution was allowed to stir at 50° C. for an additional 45 min. The reaction mixture in solution was taken to the next step without additional purification. The compound can be isolated by concentration to an amorphous powder, which is contaminated with an equivalent of sodium bromide: IR (KBr) 1711, 1628, 1215 cm-1 ; 1H NMR (DMSO D-6) delta 3.70 (s, 3H), 3.77 (s, 2H), 7.33-7.41 (m, 3H), 7.48 (s, 1H), 7.87-7.89 (m, 2H); 13C NMR (75 MHz, DMSO D-6) delta 49.88, 51.93, 127.36, 128.33, 128.91, 129.82, 134.75, 139.06, 168.60.
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