反应详情

The starting material is prepared as follows: A mixture of 2,5-dihydroxybenzaldehyde (5.0 g, 36.2 mmol), crotonaldehyde (3.8 g, 54.3 mmol), and potassium carbonate (10.0 g, 72.4 mmol) in 75 ml of 1,4-dioxane is heated at reflux for 6 hours. The mixture is cooled and poured into water. This is extracted (3×) with dichloromethane, and the combined organic layers are dried (MgSO4) and concentrated to dryness to give 6-hydroxy-2-methyl-2H-1-benzopyran-3-carboxaldehyde as a colored solid. Such is converted to 6-benzyloxy-2-methyl-2H-1-benzopyran-3-carboxaldehyde, m.p. 107°-109° C., which is in turn converted to 3-(N-hydroxyaminomethyl)-6-benzyloxy-2-methyl-2H-1-benzopyran as described above.

1. customThe starting material is prepared
2. temperatureis heated
3. temperatureat reflux for 6 hours
4. temperatureThe mixture is cooled
5. extractionThis is extracted (3×) with dichloromethane
6. dry with materialthe combined organic layers are dried (MgSO4)
7. concentrationconcentrated to dryness