Phenyl chloroformate → Phenyl 5-cyano-3-(2-ethoxypyridin-3-yl)-2-oxo-3-[(phenoxycarbonyl)-oxy]indoline-1-carboxylate

Participants

Reaction Steps

4.63 ml (36.98 mmol) of phenyl chloroformate were slowly added dropwise, undiluted, at the preset temperature to a suspension, cooled to 0° C., of 5.20 g (17.61 mmol) of (±)-5-cyano-3-hydroxy-3-(2-ethoxypyridin-3-yl)-1,3-dihydroindol-2-one from example 1.2 in 100 ml of pyridine. After the reaction mixture had thawed to room temperature it was stirred for 2 hours. The progress of the reaction was followed by thin-layer chromatography (silica gel, dichloromethane/methanol 9:1). Excess pyridine was removed in vacuo, and the residue was poured into 200 ml of ice-water and extracted with ethyl acetate (3×). The organic phase was washed with water (2×). Traces of pyridine were still present in the phase. The organic phase was dried over sodium sulfate. After removal of the ethyl acetate in vacuo, the remaining pyridine was driven off by addition of toluene and removal in vacuo several times. The residue was dried under high vacuum. 8.20 g (15.31 mmol, 87%) of phenyl 5-cyano-3-(2-ethoxypyridin-3-yl)-2-oxo-3-[(phenoxycarbonyl)-oxy]indoline-1-carboxylate were obtained.

Provenance & Evidence