反应详情

To a solution of 4-chloro-3-nitrobenzaldehyde (5.0 g, 27 mmol) in 42 mL of ethonal was added methyl 4-aminobenzoate (4.07 g, 27 mmol), and the reaction mixture was stirred over weekend. The yellow precipitates were filtered, and 8.47 g of (E)-methyl 4-(4-chloro-3-nitrobenzylidenamino)benzoate a yellow solid was obtained. (Yield=98%). (E)-methyl 4-(4-chloro-3-nitrobenzylideneamino)benzoate (8.47 g, 26.6 mmol) and yttrium(III) trifluoromethanesulfonate (800 mg, 1.33 mmol) was dissolved in dry tetrahydrofuran (100 mL), and then cooled below 0° C. Isobutyl aldehyde (2.30 g, 31.9 mmol) was added below 0° C. The reaction mixture was stirred at room temperature overnight. Thin layer chromatography showed most of starting material was consumed. 50 mL of ethyl acetate and 50 mL of water were added to the mixture, and the separated organic layer was washed with brine again. The organic layer was dried over sodium sulfate and purified on silica gel to afford 4.9 g of methyl 2-(4-chloro-3-nitrophenyl)-4-hydroxy-3,3-dimethyl-1,2,3,4-tetrahydroquinoline-6-carboxylate. (Yield=47%). MS (ESI+APCI) M+1=373.

1. customThe yellow precipitates
2. filtrationwere filtered