1H-Isoindole-1,3(2H)-dione, 2-(2-bromoethyl)- → Diallyl 2-[2-(1,3-dioxoisoindolin-2-yl)ethyl]propanedioate

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A solution of sodium hydride (4.35 g, 0.18 mol) in freshly distilled THF (100 mL) was cooled to 0° C. and treated with diallyl malonate (35 g, 0.19 mol) over 40 min via a dropping funnel. After stirring at room temperature for 30 min, N-(2-bromoethyl)phthalimide (43.9 g, 0.17 mol) was added to the solution in one portion and the mixture was heated to reflux. After 48 h the solution was cooled to 0° C., quenched with 2N HCl and concentrated to about 20% of its original volume. The concentrate was diluted with ethyl acetate (300 mL) and washed successively with satd. aq. K2CO3 and NaCl. The organic layer was dried over MgSO4, filtered and concentrated under reduced pressure. Purification by flash column chromatography (5-25% ethyl acetate:hexanes) provided diallyl 2-phthalimidoethylmalonate (41.2 g, 67%) as a colorless oil. 1H NMR (300 MHz, CDCl3) d 7.82 (m, 2H), 7.72 (m, 2H), 5.85 (m, 2H), 5.30 (m, 2H), 5.22 (m, 2H), 4.60 (m, 4H), 3.80 (t, J=6.6 Hz, 2H), 3.46 (t, J=7.2 Hz, 1H), 2.30 (dd, J=13.8, 6.9 Hz, 2H). ##STR222## Step 3

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