Hydrochloric Acid → alpha-(2-Propenyl)-[2-(2-amino-6-trifluoromethylphenyl)-1-(4-methoxyphenyl)ethyl]propanedioic acid, dimethyl ester

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Reaction Steps

α-(2-Propenyl)-[2-(2-nitro-6-trifluoromethylphenyl)-1-(4-methoxyphenyl)ethyl]propanedioic acid, dimethyl ester (15.42 g; 31.12 mmole) was dissolved in methanol (110 ml) under argon at room temperature. Powdered stannous chloride dihydrate (36.52 g; 161.8 mmol; 5.2 eq.) was added followed by concentrated hydrochloric acid (50 ml) with stirring. After ~1.5 hours, Celite, ethyl acetate, and saturated potassium carbonate solution were added with stirring (the potassium carbonate solution was added portionwise). The suspension was filtered, and the solid rinsed with ethyl acetate (three times). The filtrate was concentrated, and the residue was washed with 10% methanol/water. The washings were concentrated and dried in vacuo giving ~16 g of a yellow oil. The solids (tin salts, Celite, potassium bicarbonate, etc.) that had been filtered from the reaction mixture were triturated in acetone (several times) and suction filtered through a pad of Celite. The acetone filtrate was concentrated, and the remaining residue was partitioned between chloroform and water. The chloroform layer was dried (magnesium sulfate) and concentrated, leaving 9.06 g of the title compound as a solid. The remaining product was assumed to be in the aforementioned ~16 g of yellow oil. The yellow oil was used "as is" in the next step, as was the 9.06 g of solid.

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