反应详情

To a stirred solution of 8 parts of (-)-3,4-dihydro-2H-1-benzopyran-2-carboxylic acid in 225 parts of tetrahydrofuran were added 7.2 parts of 1,1'-carbonylbis[1H-imidazole]. After stirring for 1 hour at room temperature, the whole was cooled to -65° C. and 84 parts of a solution of bis(2-methylpropyl)aluminum hydride 1.5M in methylbenzene were added dropwise during a 10 minutes-period. Upon completion, stirring was continued for 15 minutes at -65° C. After the addition of 16 parts of methanol, the reaction mixture was poured onto water. The whole was acidified and the product was extracted with 1,1'-oxybisethane. The extract was washed with water, dried, filtered and evaporated. The residue was purified by filtration over silica gel using trichloromethane as eluent. The pure fractions were collected and the eluent was evaporated, yielding 6.6 parts (65%) of (-)-3,4-dihydro-2H-1-benzopyran-2-carboxaldehyde as a residue; [α]D =-97.96° (c=1% in CH3OH) (intermediate 50).

1. temperaturethe whole was cooled to -65° C.
2. stirringUpon completion, stirring
3. waitwas continued for 15 minutes at -65° C
4. additionthe reaction mixture was poured onto water
5. extractionthe product was extracted with 1,1'-oxybisethane
6. washThe extract was washed with water
7. customdried
8. filtrationfiltered
9. customevaporated
10. filtrationThe residue was purified by filtration over silica gel
11. customThe pure fractions were collected
12. customthe eluent was evaporated