反应详情

To a stirred mixture of 38 parts of 3,4-dihydro-6-nitro-2H-1-benzopyran-2-methanol, 30 parts of 3,4-dihydro-2H-pyran and 750 parts of trichloromethane were added 3 drops of 2-propanol saturated with hydrogen chloride (slightly exothermic reaction). The whole was stirred for 3 hours in a water bath at room temperature. The whole was washed with a cold sodium hydroxide solution 10% and with water. The organic layer was dried, filtered and evaporated. The oily residue was purified by column chromatography over silica gel using trichloromethane as eluent. The pure fractions were collected and the eluent was evaporated. The oily residue was solidified in petroleumether. The product was filtered off and dried, yielding 34 parts (64%) of 3,4-dihydro-6-nitro-2-[[(tetrahydro-2H-pyran -2-yl)oxy]methyl]-2H-1-benzopyran; mp. 66.4° C. (intermediate 9).

1. customslightly exothermic reaction)
2. washThe whole was washed with a cold sodium hydroxide solution 10% and with water
3. customThe organic layer was dried
4. filtrationfiltered
5. customevaporated
6. customThe oily residue was purified by column chromatography over silica gel
7. customThe pure fractions were collected
8. customthe eluent was evaporated
9. filtrationThe product was filtered off
10. customdried