Hydrochloric Acid → 3-{2-Ethyl-4-[3-(3-ethyl-5,5-dimethyl-4,5,6,7-tetrahydro-benzo[c]thiophen-1-yl)-3-oxo-propenyl]-6-methyl-phenyl}-propionic acid ethyl ester

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Reaction Steps

A solution of 1-(3-ethyl-5,5-dimethyl-4,5,6,7-tetrahydro-benzo[c]thiophen-1-yl)-ethanone (143 mg, 0.606 mmol) and 3-(2-ethyl-4-formyl-6-methyl-phenyl)-propionic acid (200 mg, 0.908 mmol) in ethanol (15 mL) is treated with 5 N HCl in isopropanol (3 mL). The dark brown reaction mixture is stirred at rt for 3 h, then at 50° C. for 48 h before DIPEA (4 mL) is added. The solvent is removed in vacuo and the crude product is purified by prep. HPLC (Grom-Sil 120 ODS-4-HE, 30×75 mm, 10 μm, acetonitrile/water (0.5% HCOOH), 10% to 95% acetonitrile) to give 3-{2-ethyl-4-[3-(3-ethyl-5,5-dimethyl-4,5,6,7-tetrahydro-benzo[c]thiophen-1-yl)-3-oxo-propenyl]-6-methyl-phenyl}-propionic acid ethyl ester (157 mg) as a yellow oil; LC-MS: tR=1.27 min, [M+1]=467.43.

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