N,O-di(phenoxycarbonyl)-5-chlorooxindole synthesis

Yield:-

Reaction Conditions:

with triethylamine in tetrahydrofuran at 0; for 1 h;

Steps:

Phenyl 5-Chloro-2-oxoindoline-1-carboxylate (10)

Step 1: Synthesis of Phenyl 5-Chloro-2-[(phenoxycarbonyl)oxy]-1H-indole-1-carboxylate. To a flask charged with 5-chloro-2-oxindole (1 g, 6 mmol, 1 equiv) was added anhydrous THF (20 mL) followed by triethylamine (1.75 mL, 12.6 mmol, 2.1 equiv). The reaction mixture was cooled to 0 °C before the dropwise addition of phenyl chloroformate (1.6 mL, 13.2 mmol, 2.2 equiv). The mixture was stirred at 0 °C for 1 h, the resulting precipitate was then removed by filtration and the filter cake was washed with THF (2 × 20 mL). The filtrate was concentrated under vacuum to obtain a pink solid which was stirred in H₂O (20 mL) to form an emulsion, which was then filtered, washed with H₂O (2 × 20 mL), and dried by drawing air through the filter cake to afford the desired product phenyl 5-chloro-2-((phenoxycarbonyl)oxy)-1H-indole-1-carboxylate (2.4 g crude weight) as a white solid. The product was used directly in the next step without further purification. Step 2. A solution of phenyl 5-chloro-2-[(phenoxycarbonyl)oxy]-1H-indole-1-carboxylate (1.11 g, 2.75 mmol, 1 equiv) in anhydrous DMF (10 mL) was cooled to 0 °C, followed by the portionwise addition of ammonium carbonate powder (300 mg, 3.16 mmol, 1.15 equiv). The resulting solution was stirred for 1 h at 0 °C. Upon consumption of the starting material, the pale-yellow solution was then poured into ice water (30 mL) to provide a white precipitate. The suspension was then stirred for 30 min before being filtered, washed with H₂O (2 × 10 mL) and dried by pulling air through the filter cake to afford the desired product 10. Yield: 585 mg (73% over two steps); white amorphous solid.

References:

Seath, Ciaran P.;Fyfe, James W. B.;Molloy, John J.;Watson, Allan J. B. [Synthesis,2017,vol. 49,# 4,art. no. SS-2016-Z0431-OP,p. 891 - 898]