反应详情

To a stirred mixture of 11.1 parts of 3,4-dihydro-6-nitro-2H-1-benzopyran-2-carboxylic acid and 63 parts of tetrahydrofuran were added dropwise, during a 30 minutes-period, 23.6 parts of a borane dimethyl sulfide complex solution 2M in tetrahydrofuran (slightly exothermic reaction: temp. rose to 27° C.). Upon completion, the whole was heated to reflux and stirring was continued for 2 hours at reflux temperature. The reaction mixture was decomposed by the dropwise addition of 8 parts of methanol at reflux temperature. After stirring and refluxing for 10 minutes, the solvents were distilled off and the residue was taken up in water. The solution was treated with concentrate hydrochloric acid and extracted with 1,1'-oxybisethane. The extract was washed with water, dried, filtered and evaporated. The solid residue was suspended in warm 2,2'-oxybispropane. The product was filtered off and dried, yielding 7.0 parts (70%) of 3,4-dihydro-6-nitro-2H-1-benzopyran-2-methanol; mp. 96.5° C. (intermediate 8).

1. customslightly exothermic reaction
2. customrose to 27° C.
3. temperatureUpon completion, the whole was heated
4. temperatureto reflux
5. temperatureat reflux temperature
6. temperatureat reflux temperature
7. stirringAfter stirring
8. temperaturerefluxing for 10 minutes
9. distillationthe solvents were distilled off
10. additionThe solution was treated with concentrate hydrochloric acid
11. extractionextracted with 1,1'-oxybisethane
12. washThe extract was washed with water
13. customdried
14. filtrationfiltered
15. customevaporated
16. filtrationThe product was filtered off
17. customdried