反应详情

A suspension of 9H-indeno[1,2-b]pyrazine-3,9(4H)-dione (2.0 g, 10.09 mmol) in toluene (50 ml), 2,3-butanediol (20 ml) and p-toluenesulfonic acid (40 mg) was refluxed with water separation for 20 hours. The reaction mixture was evaporated in vacuo to dryness and another portion of toluene, 2,3-butanediol and p-toluenesulfonic acid was added and the mixture was refluxed again for 20 hours. After evaporation to dryness, the residue was suspended in ethanol (10 ml) and the precipitate was filtered off and washed with ethanol and dried to give 2.14 g (78.5%) of the title compound as a mixture of isomers. 1H-NMR (DMSO-d6, δ): 1.24-1.4 (m, 6H), 4.03-4.87 (m, 2H), 7.42-7.91 (m, 5H), 12.6 (s, 1H).

1. customThe reaction mixture was evaporated in vacuo to dryness
2. additionanother portion of toluene, 2,3-butanediol and p-toluenesulfonic acid was added
3. temperaturethe mixture was refluxed again for 20 hours
4. customAfter evaporation to dryness
5. filtrationthe precipitate was filtered off
6. washwashed with ethanol
7. customdried