ethyl 6-fluoro-3,4-dihydro-2H-chromene-2-carboxylate

Conditions: temp:15.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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). were added dropwise, during a 1 hour-period at reflux temperature at reflux The reaction mixture was poured onto ice water The organic layer was separated washed with water dried filtered evaporated The oily residue was purified by column chromatography over silica gel The pure fractions were collected the eluent was evaporated