反应详情

A stirred suspension of 1,2,3,4-tetrahydro-8-methyl-5H-[1]benzopyrano[3,4-c]pyridin-5-one (10.0 g, 0.046 moles) in water (10 ml) is cooled in an ice bath. Concentrated sulfuric acid (25 ml) is added, followed after 15 minutes by the dropwise addition of concentrated nitric acid (12 ml). The ice bath is removed and the mixture allowed to warm to room temperature. After 48 hours the mixture is poured over crushed ice, stirred, and made strongly basic by the addition of concentrated ammonium hydroxide. The precipitated product is filtered off, rinsed with water and dried. Recrystallization from acetonitrile gave the product (8.7 g), mp 197°-199° C.

1. temperatureis cooled in an ice bath
2. customThe ice bath is removed
3. additionAfter 48 hours the mixture is poured
4. customover crushed ice
5. additionmade strongly basic by the addition of concentrated ammonium hydroxide
6. filtrationThe precipitated product is filtered off
7. washrinsed with water
8. customdried
9. customRecrystallization from acetonitrile