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 97) (320 mg, 0.730 mmol) was added to a cold (ice bath) suspension of aluminium chloride (370 mg, 2.77 mmol) in dichloromethane (DCM) (4 mL). The reaction was stirred at approximately 0° C. for 30 min, then treated with a solution of methanol (0.320 mL) and triethylamine (1.230 mL, 8.82 mmol). The resulting mixture was stirred further at approximately 0° C. for 20 min then was diluted with EtOAc (25 mL) and a saturated NaHCO3 aqueous solution (25 mL). The reaction mixture was then filtered through celite and the insoluble residues were washed with EtOAc (15 mL) and a saturated NaHCO3 aqueous solution (15 ml). The filtered aluminum residues were suspended in MeOH and sonicated. The resulting suspension was filtered and the filtrate was concentrated in vacuo to give a white solid. This solid was loaded onto a 20 G SCX cartridge and eluted with MeOH then with 2M NH3 in MeOH. The ammonia fractions were combined and concentrated in vacuo to give methyl 4-[(2S,4R)-1-acetyl-4-amino-2-methyl-1,2,3,4-tetrahydro-6-quinolinyl]-3-methylbenzoate (145 mg, 56%).
