Hydrochloric Acid → 4-Hydroxy-7-methoxy-8-methyl-quinoline

Participants

Reaction Conditions

Reaction Steps

A suspension of ethyl 4-hydroxy-7-methoxy-8-methylquinoline-3-carboxylate (58, 9.2 g, 35.2 mmol) in 5N NaOH (150 mL) was refluxed for 1.5 h (until a clear solution was obtained). Then, the solution was cooled to 0° C. and the pH adjusted to 2-3 with concentrated HCl. The solid was filtered off and successively washed with water, acetone and ether. This powder was added in small portions to diphenylether (40 mL), pre-heated at 250° C. The resulting suspension became a solution after 20 min (CO2 formation was observed). After 1 h at 250° C., the brown solution was cooled to room temperature and diluted with heptanes (200 mL). The precipitate was filtered off and washed with heptanes and ether to give 6.4 g (96%) of the target product 59 as a yellow powder: m/z=190 (M+H)+.

Provenance & Evidence