Acetone → (3E, 5E)-5-Fluoro-6-(5,5,8,8-tetramethyl-3-propoxy-5,6,7,8-tetrahydro-naphthalen-2-yl)-hepta-3,5-dien-2-one

Participants

Reaction Steps

To a solution of (E)-2-fluoro-3-(5,5,8,8-tetramethyl-3-propoxy-5,6,7,8-tetrahydro-naphthalen-2-yl)-but-2-enal (Intermediate 8, 208 mg, 0.63 mmol) in acetone (2 mL) was added 1M NaOH (2 mL) at 0° C. The mixture was stirred for 40 min, quenched with 2M H2SO4 (2 mL), and was stirred for 10 min. The mixture was then extracted with Et2O (×3). The combined organic layer was washed successively with brine, NaHCO3, brine, was dried over Na2SO4 and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel (5%→10%→20% EtOAc-hexane) to give the title compound (35 mg) and the intermediate β-hydroxy ketone (173 mg), which was converted to the title compound using catalytic para-tolunesulfonic acid (PTSA) in refluxing benzene.

Provenance & Evidence