Phosphorus oxychloride → Ethyl 4,7-dichloroquinoline-3-carboxylate

Participants

Reaction Steps

7-Chloro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid ethyl ester [76.0 g, 302 mmol, prepared as described by C. C. Price et al in J. Am. Chem. Soc., 68, 1204 (1946)]was refluxed for 4.5 h in 310 ml of POCl3. The resulting black solution was then concentrated in vacuo and the residue was dissolved in 100 ml of acetone. It was poured onto 1 kg of ice and brought to pH 7 with 50% NaOH. The mixture was then extracted with 3×125 ml of CH2Cl2 and the pooled extracts were dried over Na2SO4 and concentrated to a black solid that was dried in vacuo overnight affording 74.7 g (276 mmol, 92% crude yield) of 4,7-dichloro-3-quinolinecarboxylic acid ethyl ester that was used in the next step without purification.

Provenance & Evidence