C(=O)([O-])O.[Na+].Br.[S:7]1[CH:11]=[CH:10][C:9]2[C:12]([C:16]3[N:17]4[CH2:24][CH2:23][N:22]=[C:18]4[S:19][C:20]=3[CH3:21])=[CH:13][CH:14]=[CH:15][C:8]1=2.[Cl:25]CCl>O>[ClH:25].[S:7]1[CH:11]=[CH:10][C:9]2[C:12]([C:16]3[N:17]4[CH2:24][CH2:23][N:22]=[C:18]4[S:19][C:20]=3[CH3:21])=[CH:13][CH:14]=[CH:15][C:8]1=2A solution of sodium hydrogencarbonate (17.84 g) in water (300 ml) was added at 0° C. to a suspension of 3-(benzo[b]thiophen-4-yl)-2-methyl-5,6-dihydroimidazo[2,1-b]thiazole hydrobromide (15.0 g) in dichloromethane (300 ml), the mixture was stirred vigorously for 25 minutes, then the organic phase was separated, dried (Na2SO4), and the solvent was removed in vacuo. The residue was dissolved in ethanol (100 ml), the solution was cooled to 0° C., and 2M ethereal hydrogen chloride solution (28 ml) was added. The mixture was stirred for 20 minutes then the solvent was removed in vacuo. The residue was triturated with a 1:1 mixture of ethanol and ether (50 ml), then the resulting solid was collected by filtration and recrystallised from propan-2-ol to give 3-(benzo[b]thiophen-4-yl)-2-methyl-5,6-dihydroimidazo[2,1-b]thiazole hydrochloride (6.3 g) as a colourless solid, m.p. 235-238° C. Concentration of the liquor yielded a second crop of 3-(benzo[b]thiophen-4-yl)-2-methyl-5,6-dihydroimidazo[2,1-b]thiazole hydrochloride (2.7 g) as a colourless solid, m.p. 234-237° C.
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