反应详情

A mixture of 2-methylindolizine 1 (3.8 g, 29.0 mmol) and methyl chloroformate (22 g (18 ml), 231.6 mmol) was heated at reflux for 2 h. A further 12.2 g (10 ml) of methyl chloroformate were added, and the mixture was heated at reflux for 2 h. The reaction mixture was concentrated under vacuum and then purified by chromatography on a silica column (hexane/ethyl acetate 5:1, silica gel 200-425 mesh) to give 4 g of compound 2 (colorless oil). 1H NMR (CDCl3): δ 9.43 (d, J=7.1 Hz, 1H), 7.35 (d, J=8.8 Hz, 1H), 6.99-6.93 (m, 1H), 6.73-6.68 (m, 1H), 6.29 (s, 1H), 3.91 (s, 3H), 2.53 (s, 3H), 13C NMR (CDCl3): δ 162.7, 137.0, 134.6, 127.6, 121.8, 117.6, 111.8, 103.5, 103.48, 50.6, 15.1.

1. temperaturewas heated
2. temperatureat reflux for 2 h
3. temperaturethe mixture was heated
4. temperatureat reflux for 2 h
5. concentrationThe reaction mixture was concentrated under vacuum
6. custompurified by chromatography on a silica column (hexane/ethyl acetate 5:1, silica gel 200-425 mesh)