Isatin → 1-Allylisatin

Isatin (10.102 g, 68.7 mmol) was dissolved in 100 mL dry DMF, and Cs2CO3 (24.609 g, 75.5 mmol) was added. To the resulting purple-brown suspension was added allyl bromide (7.2 mL, 83 mmol) and the reaction was stirred at room temperature for 16 h. The resulting cloudy orange-brown mixture was concentrated in vacuo, and the residue was partitioned between EtOAc (160 mL) and water (80 mL). The layers were separated, and the aqueous layer was extracted with additional EtOAc (2×80 mL). The combined organic phases were dried over Na2SO4, filtered, and concentrated in vacuo. To the residue was added 300 mL hexanes. The mixture was heated to 70° C. with a water bath, and EtOAc was added until the compound went into solution (approx. 80 mL EtOAc). A small amount of insoluble red material was removed, and then the solution was allowed to cool. The resulting red crystals were filtered, washed with 3×30 mL hexanes, and then dried under vacuum to provide the title compound (11.740 g, 91%). 1H NMR (600 MHz, CHLOROFORM-D) δ ppm 4.36 (d, J=5.6 Hz, 2H), 5.26-5.34 (m, 2H), 5.78-5.88 (m, 1H), 6.88 (d, J=7.9 Hz, 1H), 7.11 (t, J=7.6 Hz, 1H), 7.56 (td, J=7.8, 1.3 Hz, 1H), 7.61 (d, J=7.4 Hz, 1H). MS (ESI) (M+H)+=188.