Ethyl 3-phenylprop-2-enoate → Ethyl 2-amino-1-benzothiophene-3-carboxylate

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Reaction Steps

2 g of palladium catalyst (5% Pd/C, approx. 50% moisture content; Degussa-Hüls; E 101 RW 5%) are added to a solution of 10 g of ethyl 2-acetylaminotetrahydrobenzothiophenecarboxylate in 80 ml of mesitylene and the mixture is heated to 170° under nitrogen. 2 g of ethyl cinnamate are metered in over 30 min and stirring is continued for 21 h. The temperature is then lowered to 100° and 10 ml of pyrrolidine are added. The reaction mixture is stirred for 25 h under nitrogen. The catalyst is then filtered off and rinsed with 60 g of ethanol. The solutions are combined and the solvent is distilled off. The residue is taken up in ethyl acetate and washed twice with 1 N HCl and once with water. After distillation of the solvent and subsequent crystallization from 2-propanol, ethyl 2-aminobenzo[b]thiophene-3-carboxylate is obtained with a yield of 64%.

Provenance & Evidence