18-Crown-6 → (E)-2-(3-(3-(2,5-dimethylstyryl)phenyl)propyl)isoindoline-1,3-dione

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Reaction Steps

To a suspension of the crude 2,5-dimethylmethylbenzyltriphenylphosphonium bromide in THF (10 mL) and CH2Cl2 (5 mL) were added potassium tert-butoxide (0.163 g, 1.45 mmol) and 18-crown-6 (0.163 g, 1.45 mmol). The mixture was stirred at room temperature under argon for 30 min then sonicated for 1 min A solution of phthalimide 29 (0.193 g, 0.658 mmol) in CH2Cl2 (2 mL) was added and the mixture stirred at room temperature for 2 h. The mixture was concentrated under reduced pressure and the residue partitioned between EtOAc and saturated aqueous NH4Cl. The combined organics were washed with brine, dried over MgSO4 and concentrated under reduced pressure. Purification by flash chromatography (20 to 50% EtOAc-hexanes) gave (E)-2-(3-(3-(2,5-dimethylstyryl)phenyl)propyl)isoindoline-1,3-dione as an oil. Yield (0.225 g, 86%), trans-/cis-isomer 1:1.5. Cis-isomer: 1H NMR (400 MHz, CDCl3) δ 7.69-7.76 (m, 4H), 6.91-7.44 (m, 7H) 6.63 (d, J=12.0 Hz, 1H), 6.57 (d, J=12.0 Hz, 1H), 3.81 (t, J=7.2 Hz, 2H), 2.75 (t, J=7.6 Hz, 2H), 2.44 (s, 3H), 2.39 (s, 3H), 2.08-2.17 (m, 2H).

Provenance & Evidence