Sodium Hydroxide → [(6,7-Dichloro-2-(1-hydroxy-1-methylethyl)benzo[b]thien-5-yl]oxy]acetic acid

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Reaction Steps

To 8.5 g of t-butyl [[6,7-dichloro-2-(1-hydroxy-1-methylethyl)benzo[b]thien-5-yl]oxy]acetate in 200 ml of ethanol is added 150 ml of a 6N sodium hydroxide solution and the mixture is refluxed at 100° for 30 mins. The cooled mixture is concentrated in vacuo to a white slurry which is diluted with 200 ml of ice water and 200 ml of ethyl ether. With stirring and efficient cooling, the mixture is acidified with 6N hydrochloric acid. The acidic mixture is extracted with ethyl ether and the ether extracts are washed, dried over anhydrous magnesium sulfate, filtered and the solvent is removed. Recrystallization of the residue from acetone and pentane gives 6.8 g of [[6,7-dichloro-2-(1-hydroxy-1-methylethyl)benzo[b]thien-5-yl]oxy]acetic acid, mp 194°-196°.

Provenance & Evidence