[Cl:1][C:2]1[C:3]([OH:14])=[CH:4][C:5]2[CH:9]=[C:8]([CH2:10][OH:11])[S:7][C:6]=2[C:12]=1[Cl:13].Br[CH2:16][C:17]([O:19][CH2:20][CH3:21])=[O:18].C(=O)([O-])[O-].[K+].[K+].CC(=O)CC>CN(C)C=O>[CH2:20]([O:19][C:17](=[O:18])[CH2:16][O:14][C:3]1[C:2]([Cl:1])=[C:12]([Cl:13])[C:6]2[S:7][C:8]([CH2:10][OH:11])=[CH:9][C:5]=2[CH:4]=1)[CH3:21]
A solution of 1.24 g of 6,7-dichloro-5-hydroxy-2-hydroxymethylbenzo[b]thiophene, 0.9 g of ethyl bromoacetate, 0.6 g of potassium carbonate, 25 ml of 2-butanone and 0.5 ml of dimethylformamide is stirred under reflux for 2 hrs. The aqueous layer is extracted twice with 50 ml portions of dichloromethane. The combined organic extracts, are washed with brine, dried over anhydrous magnesium sulfate, filtered and concentrated to give a clear oil which crystallizes on standing. Recrystallization of the crude product from acetone-hexane gives 1.8 g of ethyl[ (6,7-dichloro-2-hydroxymethylbenzo[b]thien-5-yl)oxy]acetate mp 117°-118.5°.
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