Ethanol → 1-Cyclopentyl-3-(4-methoxyphenyl)propane-1,3-dione

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Reaction Steps

Sodium hydride (1.378 g, 59.9 mmol, 60% suspension in mineral oil) and ethanol (2.0 mL) were added to a solution of methyl cyclopentanecarboxylate (6.14 g, 47.9 mmol) and 1-(4-methoxyphenyl)ethanone (6.00 g, 40.0 mmol) in THF (200 mL). The mixture was heated to reflux for 11 h, quenched with water (100 mL) and acidified to pH˜2 with 1 N HCl. The THF solvent was evaporated in vacuo. The residue was extracted with ethyl acetate (3×100 mL). The combined extracts were washed with brine (25 mL), dried (MgSO4) and concentrated. Silica gel chromatography, loading with hexanes and small amount of toluene and eluting with 0-15% ethyl acetate in hexanes, gave 1-cyclopentyl-3-(4-methoxyphenyl)propane-1,3-dione as yellow liquid (5.494 g, 56% yield). MS (ES+) m/z: 247 (M+H); LC retention time: 4.510 and 3.578 min, likely a mixture of keto and enol forms (analytical HPLC Method A).

Provenance & Evidence