Potassium Iodide → 6-(cyclopentyloxy)-7-hydroxy-2H-1-benzopyran-2-one

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Reaction Steps

50.0 g (186 mmol) of 6-hydroxy-7-phenylmethoxy-2H-1-benzopyran-2-one, 41.7 g (280 mmol) of cyclopentylbromide, 51.4 g (372 mmol) of potassium carbonate and 5.0 g of potassium iodide are agitated in 500 ml DMF for 18 h at 80° C. This is followed by filtration, evaporation, dissolution in chloroform, washing with water, drying over sodium sulfate and renewed evaporation: yield: 60.0 g (96%) of 6-(cyclopentyloxy)-7-(phenylmethoxy)-2H-1-benzopyran-2-one, fusion point 140°-141° C. (from isopropanol). Of this 15.0 g (45 mmol) in 200 ml ethanol are hydrogenated in the presence of 2.0 g Pd on active carbon (5%) for 3 h at 25° C. and 7 bar hydrogen pressure. After filtration the solvent is removed: yield 9.0 g (82%), fusion point 154°-155° C. (from isopropanol and TBME).

Provenance & Evidence