反应详情

To a stirred solution of 12 parts of (+)-3,4-dihydro-2H-1-benzopyran-2-carboxylic acid in 270 parts of tetrahydrofuran were added 11 parts of 1,1'-carbonylbis[1H-imidazole]. After stirring for 1 hour at room temperature, the whole was cooled to -70° C. and 84 parts of a solution of bis(2-methylpropyl)aluminum hydride 1.5M in methylbenzene were added dropwise. Upon completion, stirring was continued for 20 minutes at -70° C. After the addition of 40 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 9.50 parts (84% ) of (+)-3,4-dihydro-2H-1-benzopyran-2-carboxaldehyde as a residue; [α]D =+94.8° (c=1% in CH3OH) (intermediate 49).

1. temperaturethe whole was cooled to -70° C.
2. stirringUpon completion, stirring
3. waitwas continued for 20 minutes at -70° 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