Benzene → 6-Fluoro-3,4-dihydro-2H-1-benzopyran-2-methanol

Temperature

15 °C

To a stirred mixture of 50 parts of ethyl 6-fluoro-3,4-dihydro-2H-1-benzopyran-2-carboxylate and 540 parts of benzene were added dropwise, during a 1 hour-period, a mixture of 89 parts of a solution of sodium dihydro-bis(2-methoxyethoxy)aluminate in methylbenzene (3.4M) and 135 parts of benzene at reflux temperature and under nitrogen atmosphere. Upon completion, stirring was continued for 2.5 hours at reflux. After cooling to 15° C., the reaction mixture was decomposed by the dropwise addition of 24 parts of ethanol and 10 parts of water. The reaction mixture was poured onto ice water. Concentrate hydrochloric acid and 350 parts of 1,1'-oxybisethane were added. The organic layer was separated, washed with water, 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, yielding 34 parts (85%) of 6-fluoro-3,4-dihydro-2H-1-benzopyran-2-methanol as an oily residue (intermediate 7).

1. additionwere added dropwise, during a 1 hour-period
2. temperatureat reflux temperature
3. temperatureat reflux
4. additionThe reaction mixture was poured onto ice water
5. customThe organic layer was separated
6. washwashed with water
7. customdried
8. filtrationfiltered
9. customevaporated
10. customThe oily residue was purified by column chromatography over silica gel
11. customThe pure fractions were collected
12. customthe eluent was evaporated

ORD record

ord-0bc697c8c2ce439a99271b63d3339b7a

Source dataset

uspto-grants-1987_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04654362