反应详情

To a solution of 3-chloro-5-nitrobenzaldehyde (371 mg, 0.1 mmol) in ethanol (6 mL) was added methyl 4-aminobenzoate (302 mg, 2.0 mmol). After a while, solids precipitated from the resulting clear yellow solution. The precipitated solid was filtered and 346 mg of (E)-methyl 4-(3-chloro-5-nitrobenzylideneamino)benzoate as a yellow solid was obtained. Yield=54%. To a solution of (E)-methyl 4-(3-chloro-5-nitrobenzylideneamino)benzoate (346 mg, 1.09 mmol) in dry tetrahydrofuran (4 mL) was added yttrium(III) trifluoromethanesulfonate (34 mg, 0.054 mmol). The mixture was stirred under a nitrogen atmosphere. Then a solution of isobutyl aldehyde (95 mg, 1.30 mmol) in tetrahydrofuran (1 mL) was added via syringe. The mixture was stirred overnight. The reaction mixture was purified by column chromatography (petroleum ether:ethyl acetate=10:1) to afford 250 mg of methyl 2-(3-chloro-5-nitrophenyl)-4-hydroxy-3,3-dimethyl-1,2,3,4-tetrahydroquinoline-6-carboxylate as a crude product. (Yield=59%). MS (ESI+APCI) M+1-water=373.

1. customAfter a while, solids precipitated from the resulting clear yellow solution
2. filtrationThe precipitated solid was filtered