A solution of methyl 4-[(2S,4R)-1-acetyl-2-methyl-4-({[(1-methylethyl)oxy]carbonyl}amino)-1,2,3,4-tetrahydro-6-quinolinyl]-3-methylbenzoate (for a preparation see Intermediate 108) (20 mg, 0.046 mmol) in ethanol (0.5 mL) was treated with NaOH (1M in water, 0.182 mL, 0.182 mmol) and the resulting mixture was stirred at room temperature for 30 min. It was then made up to 0.9 mL by addition of 1:1 solvent mixture of DMSO/CH3CN and purified by MDAP to give 4-[(2S,4R)-1-acetyl-2-methyl-4-({[(1-methylethyl)oxy]carbonyl}amino)-1,2,3,4-tetrahydro-6-quinolinyl]-3-methylbenzoic acid (16 mg, 0.038 mmol, 83%) as a white solid. LCMS (method A): Retention time 0.91 min, [M+H]+=425.18
