5-Chlorooxindole → 3-(5-Amino-3H-isobenzofuran-1-ylidene)-5-chloro-1,3-dihydro-indol-2-one

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Reaction Steps

To a solution of 5-chlorooxindole (0.629 g, 3.78 mmol) in 10.0 mL monoglyme was added 7.51 mL sodium hexamethyldisilazane (1.0 M in THF) over 3 min. After stirring at room temperature for 8 min, a solution of 5-aminophthalide (0.561 g, 3.78 mmol) in 3.0 mL of DMF was added over 1 min. The mixture was stirred for 40 min and then quenched into 4% aqueous HCl solution. The aqueous solution was neutralized to pH 7 with 1 M NaOH and then made basic with saturated NaHCO3. The solid was filtered and washed with H2O and then partitioned between EtOAc and saturated NaHCO3 (heated to dissolve the solid). The organic phase was washed with H2O, brine and then dried with Na2SO4. The solvent was removed in vacuo and the residue triturated with MeOH to give the title compound (353 mg, 31%) as a yellow solid.

Provenance & Evidence