Ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate → HCID 178469202, compound

Participants

Reaction Conditions

Reaction Steps

To a solution of ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate (33.8 g; 150 mmol) and ethyl-3-ethoxybut-2-enoate (25 g; 157.5 mmol) in xylene (600 mL) was added a catalytic amount of p-toluenesulfonic acid mono hydrate. The resulting reaction mixture was heated to reflux (temp. of bath 165° C.) equipped with a Dean-Stark trap and condenser to collect ethanol. After 18 h, the solution was cooled to room temperature, transferred to a dropping funnel and then added dropwise to a stirred solution of sodium ethoxide (21% in ethanol, 59 mL; 157.5 mmol) in ethanol (350 mL). The resulting solution is heated to reflux for 18 h and, after cooling, the volatiles were removed under reduced pressure to yield a black oil. This material was suspended in water (150 mL) and washed with diethylether (2×150 mL). The aqueous phase was separated, cooled at 0° C. and slowly acidified to pH 4 with a 1N HCl with rapid stirring. The resulting precipitate was filtered, washed with diluted hydrochloric acid solution and dried to furnish 25.5 g (58%) of the title compound as a black solid.

Provenance & Evidence