Ammonium Hydroxide → Thieno[2,3-b]quinoline-4-carboxylic acid, methyl ester

Participants

Reaction Steps

To a mixture of 1.8 g (7.2 mmol) Methyl-2-oxo-3-vinyl-1,2-dihydroquinoline-4-carboxylate 5 in 40 mL chloroform was added slowly over a dropping funnel a solution of 1.15 g (7.2 mmol) bromine in 40 mL chloroform and the reaction mixture was stirred for 1 hour at ambient temperature. After evaporation of the solvent the residue was mixed with 40 mL ethanol and 1.7 g (18 mmol) thiourea and refluxed for 2.5 h. After cooling the mixture was poured on ice, the pH-value was adjusted with ammonium hydroxide at pH=7-8 and the solution was extracted with 100 mL chloroform. The organic layer was separated, dried over sodium sulfate and filtered. Then the solvent was removed under reduced pressure and the crude product was purified by column chromatography on silica gel, eluting with methylene chloride/acetone 9:1, to give 1.0 of the desired product 14.

Provenance & Evidence