Benzaldehyde → 8-Benzylidene-2-(2-phenylethenyl)-5,6,7,8-tetrahydroquinoline

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Reaction Conditions

Reaction Steps

A 1 L round-bottomed flask equipped with a stirring bar, condenser and nitrogen gas inlet was charged with 2-methyl-5,6,7,8-tetrahydroquinoline (2, 80.5 g, 0.547 mol), PhCHO (222 mL, 2.19 mol), and Ac20 (206 mL, 2.19 mol). The mixture was heated under reflux at 160-170° C. under nitrogen atmosphere for 5 days. Then all volatile materials were removed by distillation under atmospheric pressure at ˜170° C. The residue was mixed with hot EtOH (200 mL) and stirred at 70° C. The stirred solution was cooled to room temperature and seeded with crystals of the product 3 to facilitate crystallization. The precipitate was collected by vacuum filtration, washed with EtOH (100 mL) and dried in vacuo to give the pale brown solid (175 g), which was impure. The crude material was chromatographed over silica gel (hexane only) to give bisbenzylidene 3 (142.4 g, 83%) as a pale yellow solid. Physical data see A. B. Khasanov's Ph. D. Thesis (2000).

Provenance & Evidence