Hydrochloric Acid → 6-(Piperidin-4-yloxy)-benzo[b]thiophene-2-carboxylic acid ethyl ester

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Reaction Steps

The above prepared 4-(2-ethoxycarbonyl-benzo[b]thiophen-6-yloxy)-piperidine-1-carboxylic acid tert-butyl ester (0.330 g, 0.814 mmol) was dissolved in 2 mL of dioxane and treated with HCl (4.1 mL of 4N [dioxane], 20 eq.) and the mixture kept at ambient temperature for 2 h. Reducing the volume, adding heptane, and direct crystallization produced 0.261 g of 6-(piperidin-4-yloxy)-benzo[b]thiophene-2-carboxylic acid ethyl ester as hydrochloride as white crystals, which was further processed as follows:

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