反应详情

Ethyl-6-methoxy-8-(4-Methyl-piperazin-1-yl)-4-oxo-4H-chromene-2-carboxylate (1.0 g. 2.89 mmol), as prepared in Reference Example 2d above, was suspended in 6 M HCl (60 ml) and methanol (10 mL) and warmed to reflux for 3.0 h. The reaction was allowed to cool. The solution was concentrated in vacuo and anhydrous toluene was added (×3) and the solution was again concentrated in vacuo. The residue was dried under vacuum (17 h) to yield 6-methoxy-8-(4-methyl-1-piperazinyl)-4-oxo-4H-chromene-2-carboxylic acid hydrochloride as a yellow powder (1.0 g, quantitative yield).

1. temperatureto reflux for 3.0 h
2. temperatureto cool
3. concentrationThe solution was concentrated in vacuo and anhydrous toluene
4. additionwas added (×3)
5. concentrationthe solution was again concentrated in vacuo
6. customThe residue was dried under vacuum (17 h)