[CH2:1]([N:8]1[CH2:15][CH:14]([OH:16])[CH2:13][N:12]([S:17]([C:20]2[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=2)(=[O:19])=[O:18])[CH2:11][CH:10](O)[CH2:9]1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.O.S(=O)(=O)(O)O.N>ClC1C=CC=CC=1.CCO>[CH2:1]([N:8]1[CH2:9][CH:10]2[O:16][CH:14]([CH2:13][N:12]([S:17]([C:20]3[CH:21]=[CH:22][CH:23]=[CH:24][CH:25]=3)(=[O:18])=[O:19])[CH2:11]2)[CH2:15]1)[C:2]1[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=1
The chlorobenzene solution from step (ii) above was treated at 50° C. with water (6 mL) and then concentrated sulfuric acid (60 mL) was added over 10 min. whilst maintaining the temperature at between 50 and 60° C. The mixture was then heated to 110° C. for 1 hour. The mixture was allowed to cool to 50° C. and EtOH (60 mL) was added in one portion, causing the internal temperature to rise to 67° C. The mixture was basified by the addition of aqueous ammonia (17.5%, 300 mL) with external cooling to keep the internal temperature between 60 and 70° C. Chlorobenzene (600 mL) was added and the mixture was stirred rapidly for 10 minutes. The mixture was allowed to settle and the layers were separated. The upper (chlorobenzene) layer was subjected to reduced pressure (50 mbar) distillation to remove 380 mL of solvent. The mixture was allowed to cool to 50° C. and 480 mL of ethanol was added. The mixture was cooled to 7° C. and the resulting solid was filtered and washed with ethanol (2×50 mL) before drying to constant weight under reduced pressure at 40° C. The product was obtained as an off white solid, 10.25 g (9.0% yield).
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