Carbon Dioxide → 4-Isobutoxy-benzo[b]thiophene-2-carboxylic acid

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Reaction Steps

A 1.6 M solution of n-butyl lithium in hexane (18 ml, 28.8 mmol) is dissolved under an argon atmosphere in 100 ml of dry diethyl ether, followed by dropwise addition of a solution of 4-Isobutoxy-benzo[b]thiophene (201, 5.4 g, 26.1 mmol) in 40 ml of diethyl ether. The reaction mixture is refluxed for 45 min, then cooled down and transferred via syringe to a mixture of excess dry ice (115 g, 2.61 mol) in diethyl ether (the dry ice is washed before twice with diethyl ether). The mixture is allowed to stir overnight at room temperature, then distributed between diethyl ether and water. The ether layers are reextracted with water. The aqueous layers are acidified with 2M aqueous HCl solution, and the precipitate is filtered off, washed with water and dried under high vacuum.

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