Trifluoroacetic acid → HCID 67441977, compound

Participants

Reaction Steps

To a mixture of (E)-methyl 4-(2-nitrobenzylideneamino) benzoate (3.26 g, 11.5 mmol) and yttrium(III) trifluoromethanesulfonate (140 mg, 0.27 mmol) in tetrahydrofuran (28 mL) was added isobutylaldehyde (1.9 mL, 20.6 mmol) at room temperature under nitrogen, then the resultant mixture was stirred at room temperature overnight. Thin layer chromatography and LC-MS showed the starting material was completely consumed. The reaction was quenched with water and separated. The aqueous layer was extracted with ethyl acetate twice and the combined organic layers were concentrated in vacuo. The residue was purified by column chromatography (petroleum ether/ethyl acetate=3:1) to afford 1.34 g of methyl 4-hydroxy-3,3-dimethyl-2-(2-nitrophenyl)-1,2,3,4-tetrahydroquinoline-6-carboxylate as a yellow solid. Yield: 32.7%. To an ice-cooled mixture of methyl 4-hydroxy-3,3-dimethyl-2-(2-nitrophenyl)-1,2,3,4-tetrahydroquinoline-6-carboxylate (1.5 g, 4.2 mmol) and triethylsilane (1.48 g, 12.6 mmol) in dichloro methane (150 mL) was added dropwise a solution of trifluoroacetic acid (1.92 g, 16.8 mmol) in dichloromethane (50 mL) over 45 min under nitrogen. The mixture was kept at 0° C. at room temperature for 12 h. Thin layer chromatography and LC-MS showed the starting material was completely consumed. Solid sodium carbonate (2.0 g) was added to the reaction mixture and stirred for 10 min., filtered. The filtrate was concentrated and purified by column chromatography (petroleum ether/ethyl acetate=3:1) to afford 1.26 g of methyl 2-(2-aminophenyl)-3,3-dimethyl-1,2,3,4-tetrahydroquinoline-6-carboxylate as a yellow solid. Yield: 86%.

Provenance & Evidence