645 ml of anhydrous ethanol and 52 ml of a 4 N solution of hydrogen chloride in dioxane were added to 25.8 g (82.59 mmol) of 5-{[2-(2-hydroxyphenyl)ethyl]amino}-5,6,7,8-tetrahydroquinoline-2-carboxylic acid, and the mixture was stirred under reflux overnight. The reaction solution was then cooled to room temperature, and first ethyl acetate and then, slowly, saturated aqueous sodium bicarbonate solution were added. Subsequently, the organic phase was separated off, dried over sodium sulphate, filtered and concentrated to dryness. This gave 23.9 g (70.21 mmol, 85% of theory) of the target compound.
