Trifluoroacetic acid → Methyl 3,3-dimethyl-2-(4-nitrophenyl)-1,2,3,4-tetrahydroquinoline-6-carboxylate

Participants

Reaction Steps

To a solution of methyl 4-hydroxy-3,3-dimethyl-2-(4-nitrophenyl)-1,2,3,4-tetrahydroquinoline-6-carboxylate (61 mg 0.18 mmol) and triethylsilane (0.06 mL, 0.34 mmol) in dichloromethane (10 mL) was added dropwise a solution of trifluoroacetic acid (0.04 mL, 0.51 mol) in dichloromethane (5 mL) below 0° C. Upon completion of addition, the resultant mixture was stirred at room temperature for 24 h, then was quenched with sodium bicarbonate solution and separated. The organic layer was dried over anhydrous sodium sulfate and concentrated. The residue was purified by column chromatography to afford 50 mg of methyl 3,3-dimethyl-2-(4-nitrophenyl)-1,2,3,4-tetrahydroquinoline-6-carboxylate as a yellow solid Yield: 78%. Methyl-3,3-dimethyl-2-(4-nitrophenyl)-1,2,3,4-tetrahydroquinoline-6-carboxylate (110 mg, 0.32 mmol) was dissolved in methanol/water Solution, iron powder (25 mg, 3.2 mmol) was added. The reaction mixture was heated to reflux for 2 hrs The mixture was filtered, the filtration was concentrated and purified by column chromatography on silica gel (petroleum ether/ethyl acetate=4:1) to afford 95 mg of methyl 2-(4-aminophenyl)-3,3-dimethyl-1,2,3,4-tetrahydroquinoline-6-carboxylate as a yellow solid. (yield: 96%). MS (ESI+APCI) M+1=311.5.

Provenance & Evidence