Hydrochloric Acid → 4-[(2s,4r)-1-Acetyl-4-[(4-Chlorophenyl)amino]-2-Methyl-1,2,3,4-Tetrahydroquinolin-6-Yl]benzoic Acid

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Reaction Steps

Ethyl 4-{(2S,4R)-1-acetyl-4-[(4-chlorophenyl)amino]-2-methyl-1,2,3,4-tetrahydro-6-quinolinyl}benzoate (for a preparation see Intermediate 17) (5.41 g, 11.69 mmol) was dissolved in ethanol (100 mL) and the solution was treated with aqueous NaOH solution (2M, 50 mL, 100 mmol). The resulting mixture was stirred at room temperature (air atmosphere) for approximately 2 h then most of the ethanol was removed in vacuo. The resulting yellow solution was diluted with water (resulting in the formation of an oily yellow precipitate). The aqueous phase was washed twice with DCM (which didn't dissolve the precipitate previously formed) then was acidified with hydrochloric acid (2N) to pH 1 and extracted with EtOAc (×2). The combined EtOAc phases were washed with brine, dried (hydrophobic frit) and concentrated in vacuo. The residual yellow foam was triturated with Et2O over approximately 1 h. The resulting solid was isolated by filtration, washed with Et2O and air-dried to give 4-{(2S,4R)-1-acetyl-4-[(4-chlorophenyl)amino]-2-methyl-1,2,3,4-tetrahydro-6-quinolinyl}benzoic acid (4.41 g, 10.1 mmol, 87%) as a cream solid. LCMS (HpH), Retention time 1.08 min, [M−H]-=433

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