Benzene → Ethyl alpha-(2,5-dimethoxybenzyl)acetoacetate

Participants

Reaction Steps

A mixture of 2,5-dimethoxybenzaldehyde (100 g), ethyl acetoacetate (84.5 g) and anhydrous benzene (200 ml), piperidine (6 ml) and acetic acid (12 ml) was heated at reflux for 3 hours in an apparatus fitted with a Dean-Stark trap to collect the azeotropically distilled water. The reaction mixture was cooled, benzene (300 ml) added, and the solution was washed successively with water (100 ml), cold 0.1N hydrochloric acid (200 ml), 5% aqueous sodium bicarbonate (200 ml) and dilute acetic acid (100 ml) and dried over anhydrous magnesium sulfate. The solvent was then removed under reduced pressure and the residual oil distilled, b.p. 169°-170° C./0.3 mm Hg. The product, ethyl α-(2,5-dimethoxybenzylidene)acetoacetate, solidified on standing (104 g, m.p. 68°-69° C.) and was recrystallized from ethanol-pentane (m.p. 72°-73° C.). A portion (38 g) of the product was reduced catalytically in the presence of palladium on charcoal catalyst (Pd/C) in ethyl acetate (150 ml). The product, after removal of solvent, was purified by distillation under reduced pressure to give ethyl α-(2,5-dimethoxybenzyl)acetoacetate, b.p. 146°-148° C./0.3 mm Hg.

Provenance & Evidence