Potassium Carbonate → (3aRS,7aRS)-2-benzyl-7,7-bis(2-fluorophenyl)perhydro-4-isoindolone

Participants

Reaction Steps

Trifluoroacetic acid (3 drops) is added to a solution of 4,4-bis(2-fluorophenyl)cyclohexenone (4.3 g) and N-butoxymethyl-N-(trimethylsilylmethyl)benzylamine (5.8 cc) in dry dichloromethane (30 cc). The reaction mixture is brought to reflux and then stirred for 16 hours after the temperature has been allowed to return to 25° C. N-Butoxymethyl-N-(trimethylsilylmethyl)benzylamine (2.5 cc) and trifluoroacetic acid (3 drops) are added and the mixture is stirred for 3 hours under reflux. The reaction mixture is treated with potassium carbonate (3 g) and stirred for 15 minutes. After filtration and concentration to dryness under reduced pressure (2.7 kPa), the residue is chromatographed on a column of silica gel (particle size 0.04-0.063 mm, diameter 4 cm, height 32 cm), eluting under a nitrogen pressure of 0.5 bar with a mixture of cyclohexane and ethyl acetate (85:15) and collecting 20-cc fractions. Fractions 13 to 22 are combined and concentrated to dryness under reduced pressure (2.7 kPa) to give (3aRS,7aRS)-2-benzyl-7,7-bis(2-fluorophenyl)perhydro-4-isoindolone (2.28 g). M.p. 138° C.

Provenance & Evidence