Pyridine → 3-Chloro-3-(2-ethoxypyridin-3-yl)-2-oxoindoline-5-carbonitrile

Participants

Reaction Conditions

Reaction Steps

2.30 ml (28.45 mmol) of pyridine were added to a suspension of 6.00 g (20.32 mmol) of 5-cyano-3-hydroxy-3-(2-ethoxypyridin-3-yl)-1,3-dihydroindol-2-one from example 1.2 in 60 ml of anhydrous dichloromethane (dried over molecular sieves) under nitrogen. After the reaction mixture had been cooled to 0° C., 2.06 ml (28.45 mmol) of thionyl chloride, undiluted, were added dropwise (exothermic reaction), and the reaction mixture was then stirred at room temperature for one hour. A yellow suspension formed. The progress of the reaction was followed by thin-layer chromatography (TLC) (silica gel, dichloromethane/methanol in the ratio 95:5). The reaction mixture was cautiously poured into ice-water. After stirring for 15 minutes, the organic phase was separated off. The aqueous phase was extracted with dichloromethane (2×). All the organic phases were combined and dried over magnesium sulfate and filtered, and the solvent was removed in vacuo. 5.70 g (18.17 mmol, 89%) of the title compound were obtained as an amorphous solid which was employed without further purification in the next stage.

Provenance & Evidence