Sesamol → 4-chloro-3-hydroxy-3-(6-hydroxy-1,3-benzodioxol-5-yl)-1,3-dihydro-2H-indol-2-one

Participants

Reaction Steps

To a solution of 1,3-benzodioxol-5-ol (4.86 g, 22.0 mmol) in anhydrous tetrahydrofuran (100 mL) was added dropwise a solution of isopropyl magnesium chloride (49.6 mmol, 24.8 mL, 2.0 M solution in tetrahydrofuran) over 10 min at 0° C. The reaction mixture was stirred for 30 min upon which time 4-chloroisatin (4.00 g, 22.0 mmol) was added in one portion. The reaction mixture was stirred at ambient temperature for 2 h and quenched by the addition of 10% aqueous hydrochloric acid (25.0 mL) and the mixture was concentrated in vacuo to dryness. The residue was diluted with ethyl acetate (100 mL), washed with saturated ammonium chloride (3×30.0 mL), dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated in vacuo to dryness. The residue was triturated with hot diethyl ether to afford 4-chloro-3-hydroxy-3-(6-hydroxy-1,3-benzodioxol-5-yl)-1,3-dihydro-2H-indol-2-one (6.70 g, 95%) as a beige solid: mp 250-253° C.; 1H NMR (300 MHz, DMSO-d6) δ 10.30, (s, 1H), 9.04 (s, 1H), 7.20 (s, 1H), 7.12 (t, J=8.0 Hz, 1H), 6.74 (d, J=8.2 Hz, 1H), 6.70 (d, J=7.7 Hz, 1H), 6.45 (s, 1H), 6.17 (s, 1H), 5.88 (d, J=6.7 Hz, 2H); 13C NMR (75 MHz, DMSO-d6) δ 178.1, 148.6, 147.0, 145.6, 139.6, 130.6, 130.1, 129.6, 122.3, 118.6, 108.9, 108.4, 101.1, 97.4, 75.8; MS (ES−) m/z 304.2 (M−17), 302.2 (M−17).

Provenance & Evidence