[Cl:1][C:2]1[C:3]([OH:15])=[CH:4][C:5]2[CH:9]=[C:8]([CH:10]([CH3:12])[OH:11])[S:7][C:6]=2[C:13]=1[Cl:14].Br[CH2:17][C:18]([O:20][CH2:21][CH3:22])=[O:19].C(=O)([O-])[O-].[K+].[K+].CN(C)C=O>CC(=O)CC>[CH2:21]([O:20][C:18](=[O:19])[CH2:17][O:15][C:3]1[C:2]([Cl:1])=[C:13]([Cl:14])[C:6]2[S:7][C:8]([CH:10]([OH:11])[CH3:12])=[CH:9][C:5]=2[CH:4]=1)[CH3:22]To a solution of 17 g of 6,7-dichloro-5-hydroxy-α-methylbenzo[b]thiophene-2-methanol in 250 ml of 2-butanone is added a solution of 11.8 g of ethyl bromoacetate in 50 ml 2-butanone and the mixture is heated at 95°. To the mixture is added 12 g of potassium carbonate and 5.3 ml of dimethylformamide and the reaction mixture is refluxed at 100° C. for 21/2 hrs. The cooled mixture is filtered and 100 ml of water is added. The aqueous phase is extracted two times with ethyl ether. The ether extracts are washed, dried over anhydrous magnesium sulfate, filtered and concentrated to give a solid. Recrystallization from acetone and hexane gives 19.5 g of ethyl[(6,7-dichloro-2-(1-hydroxyethyl)benzo[b]thien-5-yl)oxy]acetate, mp 101°-103°.
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