Synthesis of Ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b] thiophene-3-carboxylate

In an RBF, 5.7 mL of ethyl cyanoacetate and 5.2 mL of cyclohexanone are dissolved in 15 mL of anhydrous ethanol by magnetic stirring. To this solution, 1.6 g of sulfur is added, after which a slow addition of 4 mL of morpholine over a few minutes is started over stirring. Then the RBF is capped and the mixture is stirred for 2 h after the stirring is completed the solution will be completely crystallized. The stirring is stopped and the mixture is let to stay at room temperature for 2 h. The mixture is then broken down, washed with a little bit of cold ethanol and filtered. The crude product is recrystallized with hot ethanol.

Source

The solution before the additions

The solution after the additions

Agitation of the solution

The solution crystallized

The crude product

The recrystallized product

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