反应详情

2,3-Diamino-5-chloro-4-methylpyridine (prepared by a method similar to Example 206a) (3.2 g, 20.3 mmol), was dissolved in acetonitrile (150 ml). 4-Hydroxy-3-nitrobenzaldehyde (3.1 g) was added, followed by p-toluenesulfonic acid monohydrate (0.7 g) and the resulting mixture was heated to reflux overnight. The solvent was then removed in vacuo and the residue dissolved in a mixture of dichloromethane and methanol (1:1). To this solution was added silica gel and the solvents were evaporated in vacuo. The silica-supported product mixture was then applied to column chromatography, eluting with first dichloromethane and then a mixture of dichloromethane and methanol 4:1. This afforded the title compound of approx. 75% purity. This material was suspended in hot EtOAc and filtered while still hot. The collected solid was approx. 95% pure. An analytical sample was prepared by semi-preparative HPLC-C18.

1. temperaturethe resulting mixture was heated
2. temperatureto reflux overnight
3. customThe solvent was then removed in vacuo
4. dissolutionthe residue dissolved in a mixture of dichloromethane and methanol (1:1)
5. additionTo this solution was added silica gel
6. customthe solvents were evaporated in vacuo
7. washeluting with first dichloromethane
8. additiona mixture of dichloromethane and methanol 4:1