Phosphorus oxychloride → 2-chloro-7,8-dihydro-5H-pyrano[4,3-b]pyridine-3-carbonitrile

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Reaction Steps

step 2 2-Oxo-1,5,7,8-tetrahydro-2H-pyrano[4,3-b]pyridine-3-carbonitrile (2.50 g, 14.4 mmol) obtained in step 1 was dissolved in phosphoryl chloride (20 mL), and the mixture was stirred with heating under reflux for 4 hr. The mixture was allowed to cool to room temperature, and slowly added to a saturated aqueous sodium hydrogen carbonate solution at 0° C., then the mixture was extracted with chloroform. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (hexane:ethyl acetate=50:50) to give 2-chloro-7,8-dihydro-5H-pyrano[4,3-b]pyridine-3-carbonitrile (1.85 g, 66%) as a white solid.

Provenance & Evidence