beta-Hydroxyacrylic acid ethyl ester → Ethyl 7-chloroquinoline-3-carboxylate

Beteiligte Stoffe

Reaktionsschritte

A solution of 4-chloro-2-aminobenzaldehyde (15 g, 96 mmol, 1 equiv) and 3-hydroxy-acrylic acid ethyl ester, sodium salt (6.65 g, 48 mmol, 0.5 equiv) in glacial acetic acid (175 mL), was heated at reflux for 3 hours. Additional 3-hydroxy-acrylic acid ethyl ester, sodium salt (6.65 grams, 48 mmol, 0.5 equivalents) was added and the reaction was heated at reflux for another 2.5 hours. Additional 3-hydroxy-acrylic acid ethyl ester, sodium salt (4 g, 28.8 mmol, 0.3 equiv) was added and the reaction was heated at reflux for an additional 12 hours. Additional 3-hydroxy-acrylic acid ethyl ester, sodium salt (4 g, 28.8 mmol, 0.3 equiv) was added and the reaction was heated at reflux for 4 hours. The reaction mixture was cooled and concentrated in vacuo. The residue was dissolved in ethyl acetate (200 mL) and washed with saturated sodium bicarbonate solution (200 mL). The organic layer was then washed with brine (200 mL), dried over sodium sulfate, and treated with activated charcoal (Darco G-60®) (20 g). The mixture was filtered through diatomaceous earth. Silica gel (15 g) (EM Science, Gibbstown, N.J., 230-400 mesh, 0.04-0.06 mm particle size) was added to the solution and stirred for 3 hours. The slurry was filtered, rinsed with toluene (100 ml) and then 10% ethyl acetate in toluene (200 mL). The combined organic layers were concentrated and the resulting solid was stirred in isopropanol overnight to yield 7-chloro-quinoline-3-carboxylic acid ethyl ester (3 g, 13% yield) as a pale yellow powder.

Herkunft & Nachweise